INTEL 82801DB

Intel® 82801DB I/O Controller
Hub 4 (ICH4)
Datasheet
May 2002
Document Number: 290744-001
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Designers must not rely on the absence or characteristics of any features or instructions marked "reserved" or "undefined." Intel reserves these for
future definition and shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to them.
The Intel® I/O Controller Hub 4 (ICH4) chipset component may contain design defects or errors known as errata which may cause the product to
deviate from published specifications. Current characterized errata are available on request.
Contact your local Intel sales office or your distributor to obtain the latest specifications and before placing your product order.
I2C is a two-wire communications bus/protocol developed by Philips. SMBus is a subset of the I 2C bus/protocol and was developed by Intel.
Implementations of the I2C bus/protocol may require licenses from various entities, including Philips Electronics N.V. and North American Philips
Corporation.
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*Other names and brands may be claimed as the property of others.
Copyright © 2002, Intel Corporation
2
Intel® 82801DB ICH4 Datasheet
Intel® 82801DB ICH4 Features
■ PCI Bus Interface
■
■
■
■
■
■
■
— Supports PCI Revision 2.2 Specification at
33 MHz
— 133 MB/sec maximum throughput
— Supports up to six master devices on PCI
— One PCI REQ/GNT pair can be given higher
arbitration priority (intended for external 1394
host controller)
— Support for 44-bit addressing on PCI using DAC
protocol
Integrated LAN Controller
— WfM 2.0 and IEEE 802.3 compliant
— LAN Connect Interface (LCI)
— 10/100 Mbit/sec ethernet support
Integrated IDE Controller
— Supports “Native Mode” register and interrupts
— Independent timing of up to 4 drives, with separate
primary and secondary IDE cable connections
— Ultra ATA/100/66/33, BMIDE and PIO modes
— Tri-state modes to enable swap bay
USB
— Includes three UHCI host controllers that support
six external ports
— New: Includes one EHCI high-speed USB 2.0
Host Controller that supports all six ports
— New: Supports a USB 2.0 high-speed debug port
— Supports wake-up from sleeping states S1–S5
— Supports legacy keyboard/mouse software
AC-Link for Audio and Telephony CODECs
— Supports AC ’97 2.3
— New: Third AC_SDATA_IN line for three codec
support
— New: Independent bus master logic for seven
channels (PCM In/Out, Mic 1 input, Mic 2 input,
modem
in/out, S/PDIF out)
— Separate independent PCI functions for audio and
modem
— Support for up to six channels of PCM audio
output (full AC3 decode)
— Supports wake-up events
Interrupt Controller
— Support up to eight PCI interrupt pins
— Supports PCI 2.2 message signaled interrupts
— Two cascaded 82C59 with 15 interrupts
— Integrated I/O APIC capability with 24 interrupts
— Supports serial interrupt protocol
— Supports processor system bus interrupt delivery
New: 1.5 V operation with 3.3 V I/O
— 5 V tolerant buffers on IDE, PCI, USB overcurrent and legacy signals
Timers Based on 82C54
— System timer, refresh request, speaker tone output
■ Power Management Logic
■
■
■
■
■
■
■
■
■
■
— ACPI 2.0 compliant
— ACPI-defined power states (C1–C2, S3–S5 )
— Supports Desktop S1 state (like C2 state, only
STPCLK# active)
— ACPI power management timer
— PCI PME# support
— SMI# generation
— All registers readable/restorable for proper resume
from 0 V suspend states
External Glue Integration
— Integrated pull-up, pull-down and series
termination resistors on IDE, processor interface
— Integrated Pull-down and Series resistors on USB
Enhanced Hub Interface Buffers Improve Routing
flexibility (Not available with all Memory Controller
Hubs)
Firmware Hub (FWH) Interface Supports BIOS
memory size up to 8 MB
Low Pin Count (LPC) Interface
— Supports two Master/DMA devices.
Enhanced DMA Controller
— Two cascaded 8237 DMA controllers
— PCI DMA: Supports PC/PCI — Includes two
PC/PCI REQ#/GNT# pairs
— Supports LPC DMA
— Supports DMA collection buffer to provide
Type-F DMA performance for all DMA channels
Real-Time Clock
— 256-byte battery-backed CMOS RAM
System TCO Reduction Circuits
— Timers to generate SMI# and Reset upon detection
of system hang
— Timers to detect improper processor reset
— Supports ability to disable external devices
SMBus
— New: Hardware packet error checking
— New: Supports SMBus 2.0 Specification
— Host interface allows processor to communicate
via SMBus
— Slave interface allows an external microcontroller
to access system resources
— Compatible with most 2-wire components that are
also I2C compatible
GPIO
— TTL, open-drain, inversion
Package 31x31 mm 421 BGA
The Intel® 82801DB ICH4 may contain design defects or errors known as errata which may cause the products to deviate from
published specifications. Current characterized errata are available on request.
Intel® 82801DB ICH4 Datasheet
3
System Configuration
Processor
Host Controller
AGP
Memory
USB
(Supports 6
USB 2.0 ports)
Power Management
IDE-Primary
Clock
ClockGenerators
Generators
IDE-Secondary
AC’97 Codec(s)
System Management (TCO)
Intel®
82801DB ICH4
LAN Connect
SMBus/I2C
PCI Bus
Firmware
FirmwareHub(s)
Hubs
(1-8)
Slot
Slot
GPIO
LPC Interface
Super
Super I/O
I/O
Othe ASICs
ASIC
Other
r
s
(Optional)
4
Intel® 82801DB ICH4 Datasheet
Contents
1
Introduction ...........................................................................................................27
1.1
1.2
2
Signal Description ..............................................................................................37
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
2.15
2.16
2.17
2.18
2.19
2.20
3
About This Datasheet ....................................................................................27
Overview ........................................................................................................30
Hub Interface to Host Controller ....................................................................39
Link to LAN Connect ......................................................................................39
EEPROM Interface ........................................................................................40
Firmware Hub Interface .................................................................................40
PCI Interface ..................................................................................................40
IDE Interface ..................................................................................................43
LPC Interface .................................................................................................44
Interrupt Interface...........................................................................................44
USB Interface.................................................................................................45
Power Management Interface........................................................................46
Processor Interface........................................................................................47
SMBus Interface ............................................................................................48
System Management Interface ......................................................................48
Real Time Clock Interface..............................................................................49
Other Clocks ..................................................................................................49
Miscellaneous Signals ...................................................................................49
AC-Link ..........................................................................................................50
General Purpose I/O ......................................................................................51
Power and Ground.........................................................................................52
Pin Straps ......................................................................................................53
2.20.1 Functional Straps ..............................................................................53
2.20.2 External RTC Circuitry ......................................................................54
2.20.3 V5REF / Vcc3_3 Sequencing Requirements ....................................54
2.20.4 Test Signals ......................................................................................55
Intel® ICH4 Power Planes and Pin States .................................................57
3.1
3.2
3.3
3.4
3.5
Power Planes.................................................................................................57
Integrated Pull-Ups and Pull-Downs ..............................................................58
IDE Integrated Series Termination Resistors.................................................58
Output and I/O Signals Planes and States ....................................................59
Power Planes for Input Signals......................................................................63
4
Intel® ICH4 and System Clock Domains ....................................................65
5
Functional Description .....................................................................................67
5.1
Hub Interface to PCI Bridge (D30:F0)............................................................67
5.1.1 PCI Bus Interface..............................................................................67
5.1.2 PCI-to-PCI Bridge Model ..................................................................68
5.1.3 IDSEL to Device Number Mapping ...................................................68
5.1.4 SERR# Functionality.........................................................................68
5.1.5 Parity Error Detection........................................................................70
5.1.6 Standard PCI Bus Configuration Mechanism ...................................71
5.1.7 PCI Dual Address Cycle (DAC) Support...........................................72
Intel® 82801DB ICH4 Datasheet
5
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
6
LAN Controller (B1:D8:F0)............................................................................. 72
5.2.1 LAN Controller Architectural Overview ............................................. 73
5.2.2 LAN Controller PCI Bus Interface ..................................................... 75
5.2.3 Serial EEPROM Interface ................................................................. 83
5.2.4 CSMA/CD Unit.................................................................................. 84
5.2.5 Media Management Interface ........................................................... 85
5.2.6 TCO Functionality ............................................................................. 85
LPC Bridge (w/ System and Management Functions) (D31:F0).................... 86
5.3.1 LPC Interface .................................................................................... 86
DMA Operation (D31:F0) ............................................................................... 92
5.4.1 Channel Priority ................................................................................ 93
5.4.2 Address Compatibility Mode ............................................................. 93
5.4.3 Summary of DMA Transfer Sizes ..................................................... 94
5.4.4 Autoinitialize...................................................................................... 94
5.4.5 Software Commands ........................................................................ 95
PCI DMA........................................................................................................ 96
5.5.1 PCI DMA Expansion Protocol ........................................................... 96
5.5.2 PCI DMA Expansion Cycles ............................................................. 97
5.5.3 DMA Addresses................................................................................ 98
5.5.4 DMA Data Generation ...................................................................... 98
5.5.5 DMA Byte Enable Generation........................................................... 98
5.5.6 DMA Cycle Termination .................................................................... 99
5.5.7 LPC DMA .......................................................................................... 99
5.5.8 Asserting DMA Requests.................................................................. 99
5.5.9 Abandoning DMA Requests ........................................................... 100
5.5.10 General Flow of DMA Transfers ..................................................... 100
5.5.11 Terminal Count ............................................................................... 101
5.5.12 Verify Mode..................................................................................... 101
5.5.13 DMA Request Deassertion ............................................................. 101
5.5.14 SYNC Field / LDRQ# Rules ............................................................ 102
8254 Timers (D31:F0).................................................................................. 103
5.6.1 Timer Programming ........................................................................ 103
5.6.2 Reading from the Interval Timer ..................................................... 104
8259 Interrupt Controllers (PIC) (D31:F0) ................................................... 106
5.7.1 Interrupt Handling ........................................................................... 107
5.7.2 Initialization Command Words (ICWx) ............................................ 108
5.7.3 Operation Command Words (OCW) ............................................... 109
5.7.4 Modes of Operation ........................................................................ 109
5.7.5 Masking Interrupts .......................................................................... 112
5.7.6 Steering PCI Interrupts ................................................................... 112
Advanced Interrupt Controller (APIC) (D31:F0) ........................................... 113
5.8.1 Interrupt Handling ........................................................................... 113
5.8.2 Interrupt Mapping............................................................................ 113
5.8.3 APIC Bus Functional Description.................................................... 114
5.8.4 PCI Message-Based Interrupts....................................................... 121
5.8.5 Processor System Bus Interrupt Delivery ....................................... 122
Serial Interrupt (D31:F0) .............................................................................. 124
5.9.1 Start Frame..................................................................................... 125
5.9.2 Data Frames ................................................................................... 125
5.9.3 Stop Frame ..................................................................................... 125
5.9.4 Specific Interrupts Not Supported via SERIRQ............................... 126
Intel® 82801DB ICH4 Datasheet
5.10
5.11
5.12
5.13
5.14
5.15
5.16
5.17
5.9.5 Data Frame Format.........................................................................126
Real Time Clock (D31:F0) ...........................................................................127
5.10.1 Update Cycles.................................................................................127
5.10.2 Interrupts.........................................................................................128
5.10.3 Lockable RAM Ranges ...................................................................128
5.10.4 Century Rollover .............................................................................128
5.10.5 Clearing Battery-Backed RTC RAM................................................128
Processor Interface (D31:F0).......................................................................130
5.11.1 Processor Interface Signals ............................................................130
5.11.2 Dual-Processor Designs .................................................................132
5.11.3 Speed Strapping for Processor.......................................................134
Power Management (D31:F0)......................................................................135
5.12.1 Intel® ICH4 and System Power States............................................135
5.12.2 System Power Planes.....................................................................137
5.12.3 Intel® ICH4 Power Planes...............................................................137
5.12.4 SMI#/SCI Generation......................................................................137
5.12.5 Dynamic Processor Clock Control ..................................................139
5.12.6 Sleep States....................................................................................141
5.12.7 Thermal Management.....................................................................145
5.12.8 Event Input Signals and Their Usage .............................................146
5.12.9 ALT Access Mode...........................................................................148
5.12.10 System Power Supplies, Planes, and Signals ................................151
5.12.11 Clock Generators ............................................................................152
5.12.12 Legacy Power Management Theory of Operation ..........................153
System Management (D31:F0)....................................................................154
5.13.1 Theory of Operation ........................................................................154
5.13.2 Alert on LAN* ..................................................................................155
General Purpose I/O ....................................................................................159
5.14.1 GPIO Mapping ................................................................................159
5.14.2 Power Wells ....................................................................................161
5.14.3 SMI# and SCI Routing ....................................................................161
IDE Controller (D31:F1) ...............................................................................161
5.15.1 PIO Transfers..................................................................................162
5.15.2 Bus Master Function .......................................................................164
5.15.3 Ultra ATA/33 Protocol .....................................................................168
5.15.4 Ultra ATA/66 Protocol .....................................................................170
5.15.5 Ultra ATA/100 Protocol ...................................................................170
5.15.6 Ultra ATA/33/66/100 Timing............................................................171
5.15.7 IDE Swap Bay.................................................................................171
USB UHCI Controllers (D29:F0, F1 and F2)................................................172
5.16.1 Data Structures in Main Memory ....................................................172
5.16.2 Data Transfers to/from Main Memory .............................................178
5.16.3 Data Encoding and Bit Stuffing .......................................................184
5.16.4 Bus Protocol....................................................................................184
5.16.5 Packet Formats...............................................................................187
5.16.6 USB Interrupts ................................................................................189
5.16.7 USB Power Management ...............................................................192
5.16.8 USB Legacy Keyboard Operation...................................................192
USB EHCI Controller (D29:F7) ....................................................................195
5.17.1 EHC Initialization.............................................................................195
5.17.2 Data Structures in Main Memory ....................................................196
Intel® 82801DB ICH4 Datasheet
7
5.18
5.19
6
Register and Memory Mapping ................................................................... 243
6.1
6.2
6.3
6.4
7
PCI Devices and Functions ......................................................................... 244
PCI Configuration Map ................................................................................ 245
I/O Map ........................................................................................................ 245
6.3.1 Fixed I/O Address Ranges.............................................................. 245
6.3.2 Variable I/O Decode Ranges .......................................................... 248
Memory Map................................................................................................ 249
6.4.1 Boot-Block Update Scheme............................................................ 250
LAN Controller Registers (B1:D8:F0) ....................................................... 251
7.1
8
5.17.3 USB 2.0 Enhanced Host Controller DMA ....................................... 196
5.17.4 Data Encoding and Bit Stuffing....................................................... 199
5.17.5 Packet Formats............................................................................... 199
5.17.6 USB EHCI Interrupts and Error Conditions..................................... 200
5.17.7 USB EHCI Power Management...................................................... 201
5.17.8 Interaction with Classic Host Controllers ........................................ 202
5.17.9 USB 2.0 Legacy Keyboard Operation............................................. 204
5.17.10 USB 2.0 EHCI Based Debug Port .................................................. 205
SMBus Controller Functional Description (D31:F3) ..................................... 210
5.18.1 Host Controller ................................................................................ 210
5.18.2 Bus Arbitration ................................................................................ 220
5.18.3 Bus Timing...................................................................................... 220
5.18.4 Interrupts / SMI# ............................................................................. 221
5.18.5 SMBALERT# .................................................................................. 222
5.18.6 SMBus CRC Generation and Checking.......................................... 222
5.18.7 SMBus Slave Interface ................................................................... 222
AC ’97 Controller Functional Description (Audio D31:F5, Modem D31:F6). 227
5.19.1 PCI Power Management................................................................. 229
5.19.2 AC-Link Overview ........................................................................... 230
5.19.3 AC-Link Low Power Mode .............................................................. 238
5.19.4 AC ’97 Cold Reset .......................................................................... 239
5.19.5 AC ’97 Warm Reset ........................................................................ 239
5.19.6 System Reset ................................................................................. 240
5.19.7 Hardware Assist to Determine AC_SDIN Used Per Codec ............ 241
5.19.8 Software Mapping of AC_SDIN to DMA Engine ............................. 241
PCI Configuration Registers (B1:D8:F0)...................................................... 251
7.1.1 VID—Vendor ID Register (LAN Controller—B1:D8:F0) .................. 252
7.1.2 DID—Device ID Register (LAN Controller—B1:D8:F0) .................. 252
7.1.3 PCICMD—PCI Command Register (LAN Controller—B1:D8:F0) .. 253
7.1.4 PCISTS—PCI Status Register (LAN Controller—B1:D8:F0) .......... 254
7.1.5 REVID—Revision ID Register (LAN Controller—B1:D8:F0)........... 255
7.1.6 SCC—Sub-Class Code Register (LAN Controller—B1:D8:F0) ...... 255
7.1.7 BCC—Base-Class Code Register (LAN Controller—B1:D8:F0)..... 255
7.1.8 CLS—Cache Line Size Register (LAN Controller—B1:D8:F0) ....... 255
7.1.9 PMLT—PCI Master Latency Timer Register
(LAN Controller—B1:D8:F0) ........................................................... 256
7.1.10 HEADTYP—Header Type Register (LAN Controller—B1:D8:F0) .. 256
7.1.11 CSR_MEM_BASE CSR — Memory-Mapped Base Address
Register (LAN Controller—B1:D8:F0)............................................. 256
7.1.12 CSR_IO_BASE — CSR I/O-Mapped Base Address Register
(LAN Controller—B1:D8:F0) ........................................................... 257
Intel® 82801DB ICH4 Datasheet
7.1.13
7.1.14
7.1.15
7.1.16
7.1.17
7.1.18
7.2
8
SVID — Subsystem Vendor ID (LAN Controller—B1:D8:F0) .........257
SID — Subsystem ID (LAN Controller—B1:D8:F0) ........................257
CAP_PTR — Capabilities Pointer (LAN Controller—B1:D8:F0) .....258
INT_LN — Interrupt Line Register (LAN Controller—B1:D8:F0).....258
INT_PN — Interrupt Pin Register (LAN Controller—B1:D8:F0) ......258
MIN_GNT — Minimum Grant Register
(LAN Controller—B1:D8:F0) ...........................................................258
7.1.19 MAX_LAT — Maximum Latency Register
(LAN Controller—B1:D8:F0) ...........................................................259
7.1.20 CAP_ID — Capability ID Register
(LAN Controller—B1:D8:F0) ...........................................................259
7.1.21 NXT_PTR — Next Item Pointer (LAN Controller—B1:D8:F0) ........259
7.1.22 PM_CAP — Power Management Capabilities
(LAN Controller—B1:D8:F0) ...........................................................260
7.1.23 PMCSR — Power Management Control/Status Register
(LAN Controller—B1:D8:F0) ...........................................................260
7.1.24 PCIDATA — PCI Power Management Data Register
(LAN Controller—B1:D8:F0) ...........................................................261
LAN Control / Status Registers (CSR) .........................................................262
7.2.1 System Control Block Status Word Register ..................................262
7.2.2 System Control Block Command Word Register ............................264
7.2.3 System Control Block General Pointer Register .............................266
7.2.4 PORT Register................................................................................266
7.2.5 EEPROM Control Register .............................................................267
7.2.6 Management Data Interface (MDI) Control Register ......................268
7.2.7 Receive DMA Byte Count Register.................................................269
7.2.8 Early Receive Interrupt Register .....................................................269
7.2.9 Flow Control Register .....................................................................270
7.2.10 Power Management Driver (PMDR) Register .................................271
7.2.11 General Control Register ................................................................272
7.2.12 General Status Register..................................................................272
7.2.13 Statistical Counters .........................................................................273
Hub Interface to PCI Bridge Registers (D30:F0) ..................................275
8.1
PCI Configuration Registers (D30:F0) .........................................................275
8.1.1 VID—Vendor ID Register (HUB-PCI—D30:F0) ..............................276
8.1.2 DID—Device ID Register (HUB-PCI—D30:F0)...............................276
8.1.3 CMD—Command Register (HUB-PCI—D30:F0)............................277
8.1.4 PD_STS—Primary Device Status Register
(HUB-PCI—D30:F0) .......................................................................278
8.1.5 RID—Revision Identification Register (HUB-PCI—D30:F0) ...........279
8.1.6 SCC—Sub-Class Code Register (HUB-PCI—D30:F0)...................279
8.1.7 BCC—Base-Class Code Register (HUB-PCI—D30:F0) .................279
8.1.8 PMLT—Primary Master Latency Timer Register
(HUB-PCI—D30:F0) .......................................................................279
8.1.9 HEADTYP—Header Type Register (HUB-PCI—D30:F0)...............280
8.1.10 PBUS_NUM—Primary Bus Number Register
(HUB-PCI—D30:F0) .......................................................................280
8.1.11 SBUS_NUM—Secondary Bus Number Register
(HUB-PCI—D30:F0) .......................................................................280
8.1.12 SUB_BUS_NUM—Subordinate Bus Number Register
(HUB-PCI—D30:F0) .......................................................................280
Intel® 82801DB ICH4 Datasheet
9
8.1.13 SMLT—Secondary Master Latency Timer Register
(HUB-PCI—D30:F0) ....................................................................... 281
8.1.14 IOBASE—I/O Base Register (HUB-PCI—D30:F0) ......................... 281
8.1.15 IOLIM—I/O Limit Register (HUB-PCI—D30:F0) ............................. 281
8.1.16 SECSTS—Secondary Status Register (HUB-PCI—D30:F0).......... 282
8.1.17 MEMBASE—Memory Base Register (HUB-PCI—D30:F0) ............ 283
8.1.18 MEMLIM—Memory Limit Register (HUB-PCI—D30:F0) ................ 283
8.1.19 PREF_MEM_BASE—Prefetchable Memory Base Register
(HUB-PCI—D30:F0) ....................................................................... 283
8.1.20 PREF_MEM_MLT—Prefetchable Memory Limit Register
(HUB-PCI—D30:F0) ....................................................................... 284
8.1.21 IOBASE_HI—I/O Base Upper 16 Bits Register
(HUB-PCI—D30:F0) ....................................................................... 284
8.1.22 IOLIM_HI—I/O Limit Upper 16 Bits Register
(HUB-PCI—D30:F0) ....................................................................... 284
8.1.23 INT_LINE—Interrupt Line Register (HUB-PCI—D30:F0) ............... 284
8.1.24 BRIDGE_CNT—Bridge Control Register (HUB-PCI—D30:F0) ...... 285
8.1.25 HI1_CMD—Hub Interface 1 Command Control Register
(HUB-PCI—D30:F0) ....................................................................... 286
8.1.26 DEVICE_HIDE—Secondary PCI Device Hiding Register
(HUB-PCI—D30:F0) ....................................................................... 287
8.1.27 CNF—ICH4 Configuration Register (HUB-PCI—D30:F0) .............. 288
8.1.28 MTT—Multi-Transaction Timer Register (HUB-PCI—D30:F0) ....... 288
8.1.29 PCI_MAST_STS—PCI Master Status Register
(HUB-PCI—D30:F0) ....................................................................... 289
8.1.30 ERR_CMD—Error Command Register (HUB-PCI—D30:F0) ......... 289
8.1.31 ERR_STS—Error Status Register (HUB-PCI—D30:F0)................. 290
9
LPC Interface Bridge Registers (D31:F0) ................................................ 291
9.1
10
PCI Configuration Registers (D31:F0) ......................................................... 291
9.1.1 VID—Vendor ID Register (LPC I/F—D31:F0)................................. 292
9.1.2 DID—Device ID Register (LPC I/F—D31:F0) ................................. 292
9.1.3 PCICMD—PCI COMMAND Register (LPC I/F—D31:F0)............... 293
9.1.4 PCISTA—PCI Device Status (LPC I/F—D31:F0) ........................... 294
9.1.5 REVID—Revision ID Register (LPC I/F—D31:F0).......................... 294
9.1.6 PI—Programming Interface (LPC I/F—D31:F0) ............................. 295
9.1.7 SCC—Sub-Class Code Register (LPC I/F—D31:F0) ..................... 295
9.1.8 BCC—Base-Class Code Register (LPC I/F—D31:F0) ................... 295
9.1.9 HEADTYP—Header Type Register (LPC I/F—D31:F0) ................. 295
9.1.10 PMBASE—ACPI Base Address (LPC I/F—D31:F0)....................... 296
9.1.11 ACPI_CNTL—ACPI Control (LPC I/F — D31:F0)........................... 296
9.1.12 BIOS_CNTL—BIOS Control Register (LPC I/F—D31:F0).............. 297
9.1.13 TCO_CNTL — TCO Control (LPC I/F — D31:F0) .......................... 297
9.1.14 GPIOBASE—GPIO Base Address (LPC I/F—D31:F0) .................. 298
9.1.15 GPIO_CNTL—GPIO Control (LPC I/F—D31:F0) ........................... 298
9.1.16 PIRQ[n]_ROUT—PIRQ[A,B,C,D] Routing Control
(LPC I/F—D31:F0) .......................................................................... 298
9.1.17 SERIRQ_CNTL—Serial IRQ Control (LPC I/F—D31:F0) ............... 299
9.1.18 PIRQ[n]_ROUT—PIRQ[E,F,G,H] Routing Control
(LPC I/F—D31:F0) .......................................................................... 299
9.1.19 D31_ERR_CFG—Device 31 Error Configuration Register
(LPC I/F—D31:F0) .......................................................................... 300
Intel® 82801DB ICH4 Datasheet
9.2
9.3
9.4
9.1.20 D31_ERR_STS—Device 31 Error Status Register
(LPC I/F—D31:F0) ..........................................................................300
9.1.21 PCI_DMA_CFG—PCI DMA Configuration (LPC I/F—D31:F0) ......301
9.1.22 GEN_CNTL — General Control Register (LPC I/F — D31:F0) ......302
9.1.23 GEN_STA—General Status Register (LPC I/F—D31:F0) ..............304
9.1.24 BACK_CNTL—Backed Up Control Register
(LPC I/F—D31:F0) ..........................................................................304
9.1.25 RTC_CONF—RTC Configuration Register (LPC I/F—D31:F0)......305
9.1.26 COM_DEC—LPC I/F Communication Port Decode Ranges
(LPC I/F—D31:F0) ..........................................................................305
9.1.27 FDD/LPT_DEC—LPC I/F FDD & LPT Decode Ranges
(LPC I/F—D31:F0) ..........................................................................306
9.1.28 SND_DEC—LPC I/F Sound Decode Ranges
(LPC I/F—D31:F0) ..........................................................................306
9.1.29 FWH_DEC_EN1—FWH Decode Enable 1 Register
(LPC I/F—D31:F0) ..........................................................................307
9.1.30 GEN1_DEC—LPC I/F Generic Decode Range 1 Register
(LPC I/F—D31:F0) ..........................................................................308
9.1.31 LPC_EN—LPC I/F Enables Register (LPC I/F—D31:F0) ...............308
9.1.32 FWH_SEL1—FWH Select 1 Register (LPC I/F—D31:F0) ..............310
9.1.33 GEN2_DEC—LPC I/F Generic Decode Range 2 Register
(LPC I/F—D31:F0) ..........................................................................311
9.1.34 FWH_SEL2—FWH Select 2 Register (LPC I/F—D31:F0) ..............311
9.1.35 FWH_DEC_EN2—FWH Decode Enable 2 Register
(LPC I/F—D31:F0) ..........................................................................312
9.1.36 FUNC_DIS—Function Disable Register (LPC I/F—D31:F0) ..........313
DMA I/O Registers .......................................................................................315
9.2.1 DMABASE_CA—DMA Base and Current Address Registers ........316
9.2.2 DMABASE_CC—DMA Base and Current Count Registers............316
9.2.3 DMAMEM_LP—DMA Memory Low Page Registers ......................317
9.2.4 DMACMD—DMA Command Register ............................................317
9.2.5 DMASTA—DMA Status Register ....................................................318
9.2.6 DMA_WRSMSK—DMA Write Single Mask Register ......................318
9.2.7 DMACH_MODE—DMA Channel Mode Register............................319
9.2.8 DMA Clear Byte Pointer Register ...................................................319
9.2.9 DMA Master Clear Register ............................................................320
9.2.10 DMA_CLMSK—DMA Clear Mask Register ....................................320
9.2.11 DMA_WRMSK—DMA Write All Mask Register ..............................320
Timer I/O Registers......................................................................................321
9.3.1 TCW—Timer Control Word Register ..............................................321
9.3.2 SBYTE_FMT—Interval Timer Status Byte Format Register ...........323
9.3.3 Counter Access Ports Register.......................................................323
8259 Interrupt Controller (PIC) Registers ....................................................324
9.4.1 ICW1—Initialization Command Word 1 Register ............................325
9.4.2 ICW2—Initialization Command Word 2 Register ............................326
9.4.3 ICW3—Master Controller Initialization Command Word 3 Register326
9.4.4 ICW3—Slave Controller Initialization Command Word 3 Register .327
9.4.5 ICW4—Initialization Command Word 4 Register ............................327
9.4.6 OCW1—Operational Control Word 1 (Interrupt Mask) Register .....327
9.4.7 OCW2—Operational Control Word 2 Register ...............................328
9.4.8 OCW3—Operational Control Word 3 Register ...............................328
9.4.9 ELCR1—Master Controller Edge/Level Triggered Register ...........329
Intel® 82801DB ICH4 Datasheet
11
9.5
9.6
9.7
9.8
9.9
9.10
10
IDE Controller Registers (D31:F1) ............................................................. 383
10.1
12
9.4.10 ELCR2—Slave Controller Edge/Level Triggered Register ............. 330
Advanced Interrupt Controller (APIC) .......................................................... 331
9.5.1 APIC Register Map ......................................................................... 331
9.5.2 IND—Index Register ....................................................................... 332
9.5.3 DAT—Data Register ....................................................................... 332
9.5.4 IRQPA—IRQ Pin Assertion Register .............................................. 332
9.5.5 EOIR—EOI Register ....................................................................... 333
9.5.6 ID—Identification Register .............................................................. 333
9.5.7 VER—Version Register .................................................................. 334
9.5.8 ARBID—Arbitration ID Register ...................................................... 334
9.5.9 BOOT_CONFIG—Boot Configuration Register .............................. 334
9.5.10 Redirection Table............................................................................ 335
Real Time Clock Registers .......................................................................... 337
9.6.1 I/O Register Address Map .............................................................. 337
9.6.2 Indexed Registers ........................................................................... 338
Processor Interface Registers ..................................................................... 342
9.7.1 NMI_SC—NMI Status and Control Register ................................... 342
9.7.2 NMI_EN—NMI Enable (and Real Time Clock Index) Register ....... 343
9.7.3 PORT92—Fast A20 and Init Register............................................. 343
9.7.4 COPROC_ERR—Coprocessor Error Register ............................... 343
9.7.5 RST_CNT—Reset Control Register ............................................... 344
Power Management Registers (D31:F0) ..................................................... 345
9.8.1 Power Management PCI Configuration Registers (D31:F0) ........... 345
9.8.2 APM I/O Decode ............................................................................. 352
9.8.3 Power Management I/O Registers.................................................. 353
System Management TCO Registers (D31:F0) ........................................... 371
9.9.1 TCO1_RLD—TCO Timer Reload and Current Value Register....... 371
9.9.2 TCO1_TMR—TCO Timer Initial Value Register ............................. 372
9.9.3 TCO1_DAT_IN—TCO Data In Register ......................................... 372
9.9.4 TCO1_DAT_OUT—TCO Data Out Register................................... 372
9.9.5 TCO1_STS—TCO1 Status Register............................................... 373
9.9.6 TCO2_STS—TCO2 Status Register............................................... 374
9.9.7 TCO1_CNT—TCO1 Control Register............................................. 375
9.9.8 TCO2_CNT—TCO2 Control Register............................................. 376
9.9.9 TCO_MESSAGE1 and TCO_MESSAGE2 Registers ..................... 376
9.9.10 TCO_WDSTATUS—TCO2 Control Register .................................. 377
9.9.11 SW_IRQ_GEN—Software IRQ Generation Register...................... 377
General Purpose I/O Registers (D31:F0) .................................................... 378
9.10.1 GPIO_USE_SEL—GPIO Use Select Register ............................... 378
9.10.2 GP_IO_SEL—GPIO Input/Output Select Register ......................... 379
9.10.3 GP_LVL—GPIO Level for Input or Output Register........................ 379
9.10.4 GPO_BLINK—GPO Blink Enable Register..................................... 380
9.10.5 GPI_INV—GPIO Signal Invert Register.......................................... 381
9.10.6 GPIO_USE_SEL2—GPIO Use Select 2 Register .......................... 381
9.10.7 GP_IO_SEL2—GPIO Input/Output Select 2 Register .................... 382
9.10.8 GP_LVL2—GPIO Level for Input or Output 2 Register................... 382
PCI Configuration Registers (IDE—D31:F1) ............................................... 383
10.1.1 VID—Vendor ID Register (LPC I/F—D31:F1)................................. 384
10.1.2 DID—Device ID Register (LPC I/F—D31:F1) ................................. 384
10.1.3 CMD — Command Register (IDE—D31:F1) .................................. 384
Intel® 82801DB ICH4 Datasheet
10.2
11
10.1.4 STS — Device Status Register (IDE—D31:F1) ..............................385
10.1.5 REVID—Revision ID Register (IDE—D31:F1) ................................385
10.1.6 PI — Programming Interface Register (IDE—D31:F1) ...................386
10.1.7 SCC — Sub Class Code Register (IDE—D31:F1)..........................386
10.1.8 BCC — Base Class Code Register (IDE—D31:F1) ........................386
10.1.9 MLT — Master Latency Timer Register (IDE—D31:F1) .................387
10.1.10 PCMD_BAR—Primary Command Block Base Address Register
(IDE—D31:F1) ................................................................................387
10.1.11 PCNL_BAR—Primary Control Block Base Address Register
(IDE—D31:F1) ................................................................................387
10.1.12 SCMD_BAR—Secondary Command Block Base Address Register
(IDE D31:F1)...................................................................................388
10.1.13 SCNL_BAR—Secondary Control Block Base Address Register
(IDE D31:F1)...................................................................................388
10.1.14 BM_BASE — Bus Master Base Address Register
(IDE—D31:F1) ................................................................................388
10.1.15 EXBAR — Expansion Base Address Register (IDE—D31:F1) .......389
10.1.16 IDE_SVID — Subsystem Vendor ID Register (IDE—D31:F1) ........389
10.1.17 IDE_SID — Subsystem ID Register (IDE—D31:F1).......................389
10.1.18 INTR_LN—Interrupt Line Register (IDE—D31:F1) .........................390
10.1.19 INTR_PN—Interrupt Pin Register (IDE—D31:F1) ..........................390
10.1.20 IDE_TIM — IDE Timing Register (IDE—D31:F1) ...........................390
10.1.21 SLV_IDETIM—Slave (Drive 1) IDE Timing Register
(IDE—D31:F1) ................................................................................392
10.1.22 SDMA_CNT—Synchronous DMA Control Register
(IDE—D31:F1) ................................................................................393
10.1.23 SDMA_TIM—Synchronous DMA Timing Register
(IDE—D31:F1) ................................................................................394
10.1.24 IDE_CONFIG—IDE I/O Configuration Register
(IDE—D31:F1) ................................................................................395
Bus Master IDE I/O Registers (D31:F1).......................................................396
10.2.1 BMIC[P,S]—Bus Master IDE Command Register ..........................397
10.2.2 BMIS[P,S]—Bus Master IDE Status Register .................................398
10.2.3 BMID[P,S]—Bus Master IDE Descriptor Table Pointer Register ....398
USB UHCI Controllers Registers ................................................................399
11.1
PCI Configuration Registers (D29:F0/F1/F2)...............................................399
11.1.1 VID—Vendor Identification Register (USB—D29:F0/F1/F2)...........399
11.1.2 DID—Device Identification Register (USB—D29:F0/F1/F2) ...........400
11.1.3 CMD—Command Register (USB—D29:F0/F1/F2).........................400
11.1.4 STA—Device Status Register (USB—D29:F0/F1/F2) ....................401
11.1.5 RID—Revision Identification Register (USB—D29:F0/F1/F2) ........401
11.1.6 PI—Programming Interface (USB—D29:F0/F1/F2) ........................401
11.1.7 SCC—Sub Class Code Register (USB—D29:F0/F1/F2) ................402
11.1.8 BCC—Base Class Code Register (USB—D29:F0/F1/F2) ..............402
11.1.9 HTYPE—Header Type Register (USB—D29:F0/F1/F2).................402
11.1.10 BASE—Base Address Register (USB—D29:F0/F1/F2) .................403
11.1.11 SVID — Subsystem Vendor ID (USB—D29:F0/F1/F2) ..................403
11.1.12 SID — Subsystem ID (USB—D29:F0/F1/F2) .................................403
11.1.13 INTR_LN—Interrupt Line Register (USB—D29:F0/F1/F2) .............404
11.1.14 INTR_PN—Interrupt Pin Register (USB—D29:F0/F1/F2) ..............404
11.1.15 USB_RELNUM—USB Release Number Register
Intel® 82801DB ICH4 Datasheet
13
11.2
12
EHCI Controller Registers (D29:F7) .......................................................... 417
12.1
14
(USB—D29:F0/F1/F2) .................................................................... 404
11.1.16 USB_LEGKEY—USB Legacy Keyboard/Mouse Control Register
(USB—D29:F0/F1/F2) .................................................................... 405
11.1.17 USB_RES—USB Resume Enable Register
(USB—D29:F0/F1/F2) .................................................................... 406
USB I/O Registers ....................................................................................... 407
11.2.1 USBCMD—USB Command Register ............................................. 408
11.2.2 USBSTS—USB Status Register ..................................................... 411
11.2.3 USBINTR—Interrupt Enable Register............................................. 412
11.2.4 FRNUM—Frame Number Register................................................. 412
11.2.5 FRBASEADD—Frame List Base Address ...................................... 413
11.2.6 SOFMOD—Start of Frame Modify Register.................................... 414
11.2.7 PORTSC[0,1]—Port Status and Control Register........................... 415
USB EHCI Configuration Registers (D29:F7) .............................................. 417
12.1.1 VID—Vendor ID Register (USB EHCI—D29:F7) ............................ 418
12.1.2 DID—Device ID Register (USB EHCI—D29:F7) ............................ 418
12.1.3 PCICMD—PCI Command Register (USB EHCI—D29:F7) ............ 419
12.1.4 PCISTS—PCI Device Status Register (USB EHCI—D29:F7) ........ 420
12.1.5 REVID—Revision ID Register (USB EHCI—D29:F7)..................... 420
12.1.6 PI—Programming Interface Register (USB EHCI—D29:F7) .......... 421
12.1.7 SCC—Sub Class Code Register (USB EHCI—D29:F7)................. 421
12.1.8 BCC—Base Class Code Register (USB EHCI—D29:F7)............... 421
12.1.9 MLT— PCI Master Latency Timer Register (USB EHCI—D29:F7) 421
12.1.10 MEM_BASE—Memory Base Address Register
(USB EHCI—D29:F7) ..................................................................... 422
12.1.11 SVID—USB EHCI Subsystem Vendor ID Register
(USB EHCI—D29:F7) ..................................................................... 422
12.1.12 SID—USB EHCI Subsystem ID Register (USB EHCI—D29:F7).... 422
12.1.13 CAP_PTR—Capabilities Pointer Register (USB EHCI—D29:F7)... 423
12.1.14 INT_LN—Interrupt Line Register (USB EHCI—D29:F7)................. 423
12.1.15 INT_PN—Interrupt Pin Register (USB EHCI—D29:F7).................. 423
12.1.16 PWR_CAPID—PCI Power Management Capability ID Register
(USB EHCI—D29:F7) ..................................................................... 423
12.1.17 NXT_PTR1—Next Item Pointer #1 Register
(USB EHCI—D29:F7) ..................................................................... 424
12.1.18 PWR_CAP—Power Management Capabilities Register
(USB EHCI—D29:F7) ..................................................................... 424
12.1.19 PWR_CNTL_STS—Power Management Control/Status Register (USB
EHCI—D29:F7)............................................................................... 425
12.1.20 DEBUG_CAPID—Debug Port Capability ID Register
(USB EHCI—D29:F7) ..................................................................... 425
12.1.21 NXT_PTR2—Next Item Pointer #2 Register
(USB EHCI—D29:F7) ..................................................................... 426
12.1.22 DEBUG_BASE—Debug Port Base Offset Register
(USB EHCI—D29:F7) ..................................................................... 426
12.1.23 USB_RELNUM—USB Release Number Register
(USB EHCI—D29:F7) ..................................................................... 426
12.1.24 FL_ADJ—Frame Length Adjustment Register
(USB EHCI—D29:F7) ..................................................................... 427
12.1.25 PWAKE_CAP—Port Wake Capability Register
(USB EHCI—D29:F7) ..................................................................... 427
Intel® 82801DB ICH4 Datasheet
12.2
13
12.1.26 LEG_EXT_CAP—USB EHCI Legacy Support Extended Capability
Register (USB EHCI—D29:F7).......................................................428
12.1.27 LEG_EXT_CS—USB EHCI Legacy Support Extended Control /
Status Register (USB EHCI—D29:F7)............................................428
12.1.28 SPECIAL_SMI—Intel Specific USB EHCI SMI Register
(USB EHCI—D29:F7) .....................................................................430
12.1.29 ACCESS_CNTL—Access Control Register
(USB EHCI—D29:F7) .....................................................................431
12.1.30 HS_Ref_V—USB HS Reference Voltage Register
(USB EHCI—D29:F7) .....................................................................431
Memory-Mapped I/O Registers....................................................................432
12.2.1 Host Controller Capability Registers ...............................................432
12.2.2 Host Controller Operational Registers ............................................435
12.2.3 USB 2.0-Based Debug Port Register..............................................447
SMBus Controller Registers (D31:F3) ......................................................451
13.1
13.2
PCI Configuration Registers (SMBUS—D31:F3).........................................451
13.1.1 VID—Vendor Identification Register (SMBUS—D31:F3)................451
13.1.2 DID—Device Identification Register (SMBUS—D31:F3) ................451
13.1.3 CMD—Command Register (SMBUS—D31:F3)..............................452
13.1.4 STA—Device Status Register (SMBUS—D31:F3) .........................452
13.1.5 REVID—Revision ID Register (SMBUS—D31:F3) .........................453
13.1.6 SCC—Sub Class Code Register (SMBUS—D31:F3) .....................453
13.1.7 BCC—Base Class Code Register (SMBUS—D31:F3) ...................453
13.1.8 SMB_BASE—SMBUS Base Address Register
(SMBUS—D31:F3) .........................................................................453
13.1.9 SVID — Subsystem Vendor ID (SMBUS—D31:F2/F4) ..................454
13.1.10 SID — Subsystem ID (SMBUS—D31:F2/F4) .................................454
13.1.11 INTR_LN—Interrupt Line Register (SMBUS—D31:F3) ..................454
13.1.12 INTR_PN—Interrupt Pin Register (SMBUS—D31:F3) ...................454
13.1.13 HOSTC—Host Configuration Register (SMBUS—D31:F3) ............455
SMBUS I/O Registers ..................................................................................456
13.2.1 HST_STS—Host Status Register ...................................................456
13.2.2 HST_CNT—Host Control Register .................................................458
13.2.3 HST_CMD—Host Command Register............................................459
13.2.4 XMIT_SLVA—Transmit Slave Address Register ............................459
13.2.5 HST_D0—Data 0 Register..............................................................459
13.2.6 HST_D1—Data 1 Register..............................................................460
13.2.7 Host_BLOCK_DB—Host Block Data Byte Register .......................460
13.2.8 PEC—Packet Error Check (PEC) Register.....................................460
13.2.9 RCV_SLVA—Receive Slave Address Register ..............................461
13.2.10 SLV_DATA—Receive Slave Data Register ....................................461
13.2.11 AUX_STS—Auxiliary Status Register .............................................461
13.2.12 AUX_CTL—Auxiliary Control Register............................................462
13.2.13 SMLINK_PIN_CTL—SMLink Pin Control Register .........................462
13.2.14 SMBUS_PIN_CTL—SMBUS Pin Control Register .........................463
13.2.15 SLV_STS—Slave Status Register ..................................................463
13.2.16 SLV_CMD—Slave Command Register ..........................................464
13.2.17 NOTIFY_DADDR—Notify Device Address .....................................464
13.2.18 NOTIFY_DLOW—Notify Data Low Byte Register ..........................465
13.2.19 NOTIFY_DHIGH—Notify Data High Byte Register .........................465
Intel® 82801DB ICH4 Datasheet
15
14
AC ’97 Audio Controller Registers (D31:F5) .......................................... 467
14.1
14.2
15
AC ’97 Modem Controller Registers (D31:F6) ....................................... 493
15.1
16
AC ’97 Audio PCI Configuration Space (D31:F5) ........................................ 467
14.1.1 VID—Vendor Identification Register (Audio—D31:F5) ................... 468
14.1.2 DID—Device Identification Register (Audio—D31:F5).................... 468
14.1.3 PCICMD—PCI Command Register (Audio—D31:F5) .................... 469
14.1.4 PCISTS—PCI Device Status Register (Audio—D31:F5)................ 470
14.1.5 RID—Revision Identification Register (Audio—D31:F5)................. 471
14.1.6 PI—Programming Interface Register (Audio—D31:F5) .................. 471
14.1.7 SCC—Sub Class Code Register (Audio—D31:F5) ........................ 471
14.1.8 BCC—Base Class Code Register (Audio—D31:F5)....................... 471
14.1.9 HEDT—Header Type Register (Audio—D31:F5) ........................... 472
14.1.10 NAMBAR—Native Audio Mixer Base Address Register
(Audio—D31:F5) ............................................................................. 472
14.1.11 NABMBAR—Native Audio Bus Mastering Base Address Register
(Audio—D31:F5) ............................................................................. 473
14.1.12 MMBAR—Mixer Base Address Register (Audio—D31:F5) ............ 473
14.1.13 MBBAR—Bus Master Base Address Register
(Audio—D31:F5) ............................................................................. 474
14.1.14 SVID—Subsystem Vendor ID Register (Audio—D31:F5)............... 474
14.1.15 SID—Subsystem ID Register (Audio—D31:F5).............................. 475
14.1.16 CAP_PTR—Capabilities Pointer Register (Audio—D31:F5) .......... 475
14.1.17 INTR_LN—Interrupt Line Register (Audio—D31:F5)...................... 475
14.1.18 INTR_PN—Interrupt Pin Register (Audio—D31:F5) ....................... 476
14.1.19 PCID—Programmable Codec ID Register (Audio—D31:F5).......... 476
14.1.20 CFG—Configuration Register (Audio—D31:F5) ............................. 477
14.1.21 PID—PCI Power Management Capability ID Register
(Audio—D31:F5) ............................................................................. 477
14.1.22 PC—Power Management Capabilities Register
(Audio—D31:F5) ............................................................................. 477
14.1.23 PCS—Power Management Control and Status Register
(Audio—D31:F5) ............................................................................. 478
AC ’97 Audio I/O Space (D31:F5)................................................................ 479
14.2.1 x_BDBAR—Buffer Descriptor Base Address Register ................... 482
14.2.2 x_CIV—Current Index Value Register ............................................ 483
14.2.3 x_LVI—Last Valid Index Register ................................................... 483
14.2.4 x_SR—Status Register ................................................................... 484
14.2.5 x_PICB—Position In Current Buffer Register ................................. 485
14.2.6 x_PIV—Prefetched Index Value Register ....................................... 485
14.2.7 x_CR—Control Register ................................................................. 486
14.2.8 GLOB_CNT—Global Control Register............................................ 487
14.2.9 GLOB_STA—Global Status Register ............................................. 488
14.2.10 CAS—Codec Access Semaphore Register .................................... 490
14.2.11 SDM—SDATA_IN Map Register .................................................... 491
AC ’97 Modem PCI Configuration Space (D31:F6) ..................................... 493
15.1.1 VID—Vendor Identification Register (Modem—D31:F6) ................ 494
15.1.2 DID—Device Identification Register (Modem—D31:F6)................. 494
15.1.3 PCICMD—PCI Command Register (Modem—D31:F6) ................. 494
15.1.4 PCISTA—Device Status Register (Modem—D31:F6) .................... 495
15.1.5 RID—Revision Identification Register (Modem—D31:F6) .............. 495
15.1.6 PI—Programming Interface Register (Modem—D31:F6) ............... 495
Intel® 82801DB ICH4 Datasheet
15.2
15.1.7 SCC—Sub Class Code Register (Modem—D31:F6)......................496
15.1.8 BCC—Base Class Code Register (Modem—D31:F6) ....................496
15.1.9 HEDT—Header Type Register (Modem—D31:F6).........................496
15.1.10 MMBAR—Modem Mixer Base Address Register
(Modem—D31:F6) ..........................................................................497
15.1.11 MBAR—Modem Base Address Register (Modem—D31:F6) .........497
15.1.12 SVID—Subsystem Vendor ID (Modem—D31:F6) ..........................498
15.1.13 SID—Subsystem ID (Modem—D31:F6) .........................................498
15.1.14 CAP_PTR—Capabilities Pointer (Modem—D31:F6) ......................498
15.1.15 INTR_LN—Interrupt Line Register (Modem—D31:F6) ...................499
15.1.16 INT_PIN—Interrupt Pin (Modem—D31:F6) ....................................499
15.1.17 PID—PCI Power Management Capability ID Register
(Modem—D31:F6) ..........................................................................499
15.1.18 PC—Power Management Capabilities Register
(Modem—D31:F6) ..........................................................................500
15.1.19 PCS—Power Management Control and Status Register
(Modem—D31:F6) ..........................................................................500
AC ’97 Modem I/O Space (D31:F6) .............................................................501
15.2.1 x_BDBAR—Buffer Descriptor List Base Address Register .............503
15.2.2 x_CIV—Current Index Value Register ............................................503
15.2.3 x_LVI—Last Valid Index Register ...................................................503
15.2.4 x_SR—Status Register ...................................................................504
15.2.5 x_PICB—Position in Current Buffer Register..................................505
15.2.6 x_PIV—Prefetch Index Value Register ...........................................505
15.2.7 x_CR—Control Register .................................................................506
15.2.8 GLOB_CNT—Global Control Register............................................507
15.2.9 GLOB_STA—Global Status Register .............................................508
15.2.10 CAS—Codec Access Semaphore Register ....................................510
16
Ballout Definition ..............................................................................................511
17
Electrical Characteristics ..............................................................................519
17.1
17.2
17.3
17.4
17.5
Absolute Maximum Ratings .........................................................................519
Functional Operating Range ........................................................................519
DC Characteristics .......................................................................................520
AC Characteristics .......................................................................................526
Timing Diagrams..........................................................................................539
18
Package Information .......................................................................................549
19
Testability.............................................................................................................551
19.1
19.2
19.3
Test Mode Description .................................................................................551
Tri-State Mode .............................................................................................552
XOR Chain Mode.........................................................................................552
19.3.1 XOR Chain Testability Algorithm Example .....................................552
A
Register Index ....................................................................................................561
B
Register Bit Index .............................................................................................580
Intel® 82801DB ICH4 Datasheet
17
Figures
n
2-1
2-2
2-3
4-1
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
5-15
5-16
5-17
5-18
5-19
5-20
5-21
5-22
5-23
5-24
16-1
16-2
17-1
17-2
17-3
17-4
17-5
17-6
17-7
17-8
17-9
17-10
17-11
17-12
17-13
17-14
17-15
17-16
17-17
17-18
18
System Configuration ...................................................................................... 4
Intel® ICH4 Interface Signals Block Diagram................................................. 38
Example External RTC Circuit ....................................................................... 54
Example V5REF Sequencing Circuit ............................................................. 55
Conceptual System Clock Diagram ............................................................... 66
Primary Device Status Register Error Reporting Logic.................................. 69
Secondary Status Register Error Reporting Logic ......................................... 69
NMI# Generation Logic.................................................................................. 70
Integrated LAN Controller Block Diagram...................................................... 73
64-Word EEPROM Read Instruction Waveform............................................ 83
LPC Interface Diagram .................................................................................. 86
Typical Timing for LFRAME#......................................................................... 90
Abort Mechanism........................................................................................... 90
Intel® ICH4 DMA Controller ........................................................................... 92
DMA Serial Channel Passing Protocol .......................................................... 96
DMA Request Assertion Through LDRQ# ..................................................... 99
Coprocessor Error Timing Diagram ............................................................. 131
Signal Strapping .......................................................................................... 134
Physical Region Descriptor Table Entry ...................................................... 165
Transfer Descriptor ...................................................................................... 173
Example Queue Conditions ......................................................................... 181
USB Data Encoding..................................................................................... 184
USB Legacy Keyboard Enable and Status Paths........................................ 193
Intel® ICH4 USB Port Connections.............................................................. 202
Intel® ICH4 Based Audio Codec ’97 Specification, Revision 2.3 ................. 229
AC ’97 2.3 Controller-Codec Connection..................................................... 230
AC-Link Protocol.......................................................................................... 231
AC-Link Powerdown Timing ........................................................................ 238
SDIN Wake Signaling .................................................................................. 239
Intel® ICH4 Ballout (Topview—Left Side) .................................................... 512
Intel® ICH4 Ballout (Topview—Right Side).................................................. 513
Clock Timing ................................................................................................ 539
Valid Delay from Rising Clock Edge ............................................................ 539
Setup and Hold Times ................................................................................. 539
Float Delay................................................................................................... 540
Pulse Width.................................................................................................. 540
Output Enable Delay.................................................................................... 540
IDE PIO Mode.............................................................................................. 541
IDE Multiword DMA ..................................................................................... 541
Ultra ATA Mode (Drive Initiating a Burst Read) ........................................... 542
Ultra ATA Mode (Sustained Burst) .............................................................. 542
Ultra ATA Mode (Pausing a DMA Burst) ..................................................... 543
Ultra ATA Mode (Terminating a DMA Burst) ............................................... 543
USB Rise and Fall Times............................................................................. 543
USB Jitter..................................................................................................... 544
USB EOP Width........................................................................................... 544
SMBus Transaction ..................................................................................... 544
SMBus Timeout ........................................................................................... 545
Power Sequencing and Reset Signal Timings............................................. 545
Intel® 82801DB ICH4 Datasheet
17-19
17-20
17-21
17-22
17-23
18-1
18-2
19-1
19-2
G3 (Mechanical Off) to S0 Timings..............................................................546
S0 to S1 to S0 Timing ..................................................................................546
S0 to S5 to S0 Timings ................................................................................547
C0 to C2 to C0 Timings................................................................................547
AC ’97 Data Input and Output Timings ........................................................548
Intel® ICH4 Package (Top and Side Views) ................................................549
Intel® ICH4 Package (Bottom View) ............................................................550
Test Mode Entry (XOR Chain Example) ......................................................551
Example XOR Chain Circuitry......................................................................552
Intel® 82801DB ICH4 Datasheet
19
Tables
1-1
1-2
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
2-14
2-15
2-16
2-17
2-18
2-19
2-20
2-21
3-1
3-2
3-3
3-4
3-5
4-1
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
5-15
5-16
5-17
5-18
5-19
5-20
20
Industry Specifications................................................................................... 27
PCI Devices and Functions ........................................................................... 30
Hub Interface Signals .................................................................................... 39
LAN Connect Interface Signals...................................................................... 39
EEPROM Interface Signals ........................................................................... 40
Firmware Hub Interface Signals .................................................................... 40
PCI Interface Signals ..................................................................................... 40
IDE Interface Signals ..................................................................................... 43
LPC Interface Signals .................................................................................... 44
Interrupt Signals............................................................................................. 44
USB Interface Signals.................................................................................... 45
Power Management Interface Signals........................................................... 46
Processor Interface Signals........................................................................... 47
SM Bus Interface Signals .............................................................................. 48
System Management Interface Signals ......................................................... 48
Real Time Clock Interface ............................................................................. 49
Other Clocks .................................................................................................. 49
Miscellaneous Signals ................................................................................... 49
AC-Link Signals ............................................................................................. 50
General Purpose I/O Signals ......................................................................... 51
Power and Ground Signals............................................................................ 52
Functional Strap Definitions........................................................................... 53
Test Mode Selection ...................................................................................... 55
Intel® ICH4 System Power Planes................................................................. 57
Integrated Pull-Up and Pull-Down Resistors ................................................. 58
IDE Series Termination Resistors.................................................................. 58
Power Plane and States for Output and I/O Signal ....................................... 59
Power Plane for Input Signals ....................................................................... 63
Intel® ICH4 and System Clock Domains........................................................ 65
Type 0 Configuration Cycle Device Number Translation............................... 71
LPC Cycle Types Supported ......................................................................... 87
Start Field Bit Definitions ............................................................................... 87
Cycle Type Bit Definitions.............................................................................. 88
Transfer Size Bit Definition ............................................................................ 88
SYNC Bit Definition........................................................................................ 88
Intel® ICH4 Response to Sync Failures......................................................... 89
DMA Transfer Size ........................................................................................ 94
Address Shifting in 16-bit I/O DMA Transfers................................................ 94
DMA Cycle vs. I/O Address ........................................................................... 98
PCI Data Bus vs. DMA I/O Port Size ............................................................. 98
DMA I/O Cycle Width vs. BE[3:0]# ................................................................ 98
Counter Operating Modes ........................................................................... 104
Interrupt Controller Core Connections ......................................................... 106
Interrupt Status Registers ............................................................................ 107
Content of Interrupt Vector Byte .................................................................. 107
APIC Interrupt Mapping ............................................................................... 113
Arbitration Cycles......................................................................................... 115
APIC Message Formats............................................................................... 115
EOI Message ............................................................................................... 116
Intel® 82801DB ICH4 Datasheet
5-21
5-22
5-23
5-24
5-25
5-26
5-27
5-28
5-29
5-30
5-31
5-32
5-33
5-34
5-35
5-36
5-37
5-38
5-39
5-40
5-41
5-42
5-43
5-44
5-45
5-46
5-47
5-48
5-49
5-50
5-51
5-52
5-53
5-54
5-55
5-56
5-57
5-58
5-59
5-60
5-61
5-62
5-63
5-64
5-65
5-66
5-67
5-68
5-69
5-70
5-71
Short Message.............................................................................................117
APIC Bus Status Cycle Definition ................................................................118
Lowest Priority Message (Without Focus Processor) ..................................119
Remote Read Message ...............................................................................120
Interrupt Message Address Format .............................................................123
Interrupt Message Data Format ...................................................................124
Stop Frame Explanation ..............................................................................125
Data Frame Format......................................................................................126
Configuration Bits Reset By RTCRST# Assertion .......................................129
INIT# Going Active.......................................................................................131
NMI Sources ................................................................................................132
DP Signal Differences..................................................................................132
Frequency Strap Behavior Based on Exit State...........................................134
Frequency Strap Bit Mapping ......................................................................134
General Power States for Systems Using Intel® ICH4 ................................135
State Transition Rules for Intel® ICH4 .........................................................136
System Power Plane....................................................................................137
Causes of SMI# and SCI .............................................................................138
Break Events................................................................................................139
Sleep Types .................................................................................................142
Causes of Wake Events...............................................................................143
GPI Wake Events.........................................................................................143
Transitions Due to Power Failure.................................................................144
Transitions Due to Power Button .................................................................146
Transitions Due to RI# Signal ......................................................................147
Write Only Registers with Read Paths in ALT Access Mode.......................149
PIC Reserved Bits Return Values................................................................150
Register Write Accesses in ALT Access Mode............................................151
Intel® ICH4 Clock Inputs ..............................................................................152
Alert on LAN* Message Data .......................................................................158
GPIO Implementation ..................................................................................159
IDE Legacy I/O Ports: Command Block Registers (CS1x# Chip Select) .....163
IDE Transaction Timings (PCI Clocks) .......................................................164
Interrupt/Active Bit Interaction Definition......................................................168
UltraATA/33 Control Signal Redefinitions ....................................................169
Frame List Pointer Bit Description ...............................................................172
TD Link Pointer ............................................................................................173
TD Control and Status .................................................................................174
TD Token .....................................................................................................176
TD Buffer Pointer .........................................................................................176
Queue Head Block.......................................................................................177
Queue Head Link Pointer.............................................................................177
Queue Element Link Pointer ........................................................................177
Command Register, Status Register, and TD Status Bit Interaction ...........180
Queue Advance Criteria...............................................................................182
USB Schedule List Traversal Decision Table ..............................................183
PID Format...................................................................................................185
PID Types ....................................................................................................185
Address Field ...............................................................................................186
Endpoint Field ..............................................................................................186
Token Format...............................................................................................187
Intel® 82801DB ICH4 Datasheet
21
5-72
5-73
5-74
5-75
5-76
5-77
5-78
5-79
5-80
5-81
5-82
5-83
5-84
5-85
5-86
5-87
5-88
5-89
5-90
5-91
5-92
5-93
5-94
5-95
5-96
5-97
5-98
5-99
5-100
5-101
5-102
5-103
6-1
6-2
6-3
6-4
7-1
7-2
7-3
7-4
7-5
7-6
8-1
9-1
9-2
9-3
9-4
9-5
9-6
9-7
22
SOF Packet ................................................................................................. 188
Data Packet Format..................................................................................... 188
Bits Maintained in Low Power States .......................................................... 192
USB Legacy Keyboard State Transitions .................................................... 194
UHCI vs. EHCI............................................................................................. 195
Debug Port Behavior ................................................................................... 206
Quick Protocol ............................................................................................. 211
Send / Receive Byte Protocol without PEC ................................................. 211
Send/Receive Byte Protocol with PEC ........................................................ 212
Write Byte/Word Protocol without PEC........................................................ 212
Write Byte/Word Protocol with PEC............................................................. 213
Read Byte/Word Protocol without PEC ....................................................... 214
Read Byte/Word Protocol with PEC ............................................................ 214
Process Call Protocol without PEC.............................................................. 215
Process Call Protocol with PEC................................................................... 216
Block Read/Write Protocol without PEC ...................................................... 217
Block Read/Write Protocol with PEC ........................................................... 218
I2C Block Read ............................................................................................ 219
Enable for SMBALERT# .............................................................................. 221
Enables for SMBus Slave Write and SMBus Host Events........................... 221
Enables for the Host Notify Command ........................................................ 221
Slave Write Cycle Format ............................................................................ 223
Slave Write Registers .................................................................................. 223
Command Types ......................................................................................... 224
Read Cycle Format...................................................................................... 225
Data Values for Slave Read Registers ........................................................ 225
Host Notify Format....................................................................................... 227
Features Supported by Intel® ICH4 ............................................................. 228
AC ’97 Signals ............................................................................................. 231
Input Slot 1 Bit Definitions............................................................................ 235
Output Tag Slot 0......................................................................................... 237
AC-link State during PCIRST#..................................................................... 240
PCI Devices and Functions ......................................................................... 244
Fixed I/O Ranges Decoded by Intel® ICH4.................................................. 246
Variable I/O Decode Ranges ....................................................................... 248
Memory Decode Ranges from Processor Perspective ................................ 249
LAN Controller PCI Configuration Register Address Map
(LAN Controller—B1:D8:F0) ........................................................................ 251
Configuration of Subsystem ID and Subsystem Vendor ID via EEPROM... 257
Data Register Structure ............................................................................... 261
Intel® ICH4 Integrated LAN Controller CSR Space ..................................... 262
Self-Test Results Format ............................................................................. 267
Statistical Counters...................................................................................... 273
Hub Interface PCI Configuration Register Address Map
(HUB-PCI—D30:F0) .................................................................................... 275
LPC I/F PCI Configuration Register Address Map (LPC I/F—D31:F0)........ 291
DMA Registers............................................................................................. 315
Interrupt Controller I/O Address Map (PIC Registers) ................................. 324
APIC Direct Registers.................................................................................. 331
APIC Indirect Registers ............................................................................... 331
RTC I/O Registers ....................................................................................... 337
RTC (Standard) RAM Bank ......................................................................... 338
Intel® 82801DB ICH4 Datasheet
9-8
9-9
9-10
9-11
9-12
10-1
10-2
11-1
11-2
11-3
12-1
12-2
12-3
12-4
13-1
13-2
14-1
14-2
14-3
15-1
15-2
15-3
16-1
17-1
17-2
17-3
17-4
17-5
17-6
17-7
17-8
17-9
17-10
17-11
17-12
17-13
17-14
17-15
17-16
17-18
17-17
17-19
17-20
19-1
19-2
19-3
19-4
19-5
19-6
PCI Configuration Map (PM—D31:F0) ........................................................345
APM Register Map.......................................................................................352
ACPI and Legacy I/O Register Map.............................................................353
TCO I/O Register Map .................................................................................371
Registers to Control GPIO ...........................................................................378
PCI Configuration Register Address Map (IDE—D31:F1) ...........................383
Bus Master IDE I/O Registers......................................................................396
PCI Configuration Register Address Map (USB—D29:F0/F1/F2) ...............399
USB I/O Registers........................................................................................407
Run/Stop, Debug Bit Interaction SWDBG (Bit 5), Run/Stop (Bit 0)
Operation .....................................................................................................409
USB EHCI PCI Configuration Register Address Map (D29:F7)...................417
Enhanced Host Controller Capability Registers...........................................432
Enhanced Host Controller Operational Registers ........................................435
Debug Port Register Address Map ..............................................................447
SMBus Controller PCI Configuration Register Address Map
(SMBUS—D31:F3) ......................................................................................451
SMB I/O Registers .......................................................................................456
AC ‘97 Audio PCI Configuration Register Address Map (Audio—D31:F5) ..467
Intel® ICH4 Audio Mixer Register Configuration ..........................................479
Native Audio Bus Master Control Registers.................................................481
AC ‘97 Modem Controller PCI Configuration Register Address Map
(Modem—D31:F6) .......................................................................................493
Intel® ICH4 Modem Mixer Register Configuration .......................................501
Modem Registers.........................................................................................502
Intel® ICH4 Ball List .....................................................................................514
DC Current Characteristics ..........................................................................520
DC Characteristic Input Signal Association .................................................520
DC Input Characteristics ..............................................................................521
DC Characteristic Output Signal Association...............................................523
DC Output Characteristics ...........................................................................524
Other DC Characteristics .............................................................................525
AC Input Characteristics ..............................................................................526
Clock Timings ..............................................................................................526
PCI Interface Timing ....................................................................................528
IDE PIO and Multiword DMA ModeTiming...................................................529
Ultra ATA Timing (Mode 0, Mode 1, Mode 2) ..............................................530
Ultra ATA Timing (Mode 3, Mode 4, Mode 5) ..............................................532
Universal Serial Bus Timing.........................................................................534
IOAPIC Bus Timing......................................................................................535
SMBus Timing..............................................................................................535
AC ’97 Timing ..............................................................................................535
Miscellaneous Timings.................................................................................536
LPC Timing ..................................................................................................536
Power Sequencing and Reset Signal Timings.............................................537
Power Management Timings .......................................................................538
Test Mode Selection ....................................................................................551
XOR Test Pattern Example..........................................................................552
XOR Chain 1................................................................................................553
XOR Chain 2................................................................................................554
XOR Chain 3................................................................................................555
XOR Chain 4-1.............................................................................................556
Intel® 82801DB ICH4 Datasheet
23
19-7
19-8
19-9
A-1
A-2
A-3
24
XOR Chain 4-2 ............................................................................................ 557
XOR Chain 6................................................................................................ 557
LONG XOR Chain ....................................................................................... 558
Intel® ICH4 PCI Configuration Registers ..................................................... 561
Intel® ICH4 Fixed I/O Registers ................................................................... 571
Intel® ICH4 Variable I/O Registers............................................................... 573
Intel® 82801DB ICH4 Datasheet
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Intel® 82801DB ICH4 Datasheet
25
Revision History
Revision
-001
26
Description
Initial release
Date
May 2002
Intel® 82801DB ICH4 Datasheet
Introduction
1
Introduction
1.1
About This Datasheet
This datasheet is intended for Original Equipment Manufacturers and BIOS vendors creating
ICH4-based products. This datasheet assumes a working knowledge of the vocabulary and
principles of USB, IDE, AC ’97, SMBus, PCI, ACPI and LPC. Although some details of these
features are described within this datasheet, refer to the individual industry specifications listed in
Table 1-1 for the complete details.
Table 1-1. Industry Specifications
Specification
Location
Low Pin Count Interface Specification, Revision 1.0 (LPC)
http://developer.intel.com/design/chipsets/
industry/lpc.htm
Audio Codec ‘97 Component Specification, Version 2.3 (AC ’97)
http://developer.intel.com/ial/
scalableplatforms/audio/index.htm
Wired for Management Baseline, Version 2.0 (WfM)
http://www.intel.com/labs/manage/wfm/
index.htm
System Management Bus Specification, Version 2.0 (SMBus)
http://www.smbus.org/specs/
PCI Local Bus Specification, Revision 2.2 (PCI)
http://pcisig.com/specifications.htm
AT Attachment - 6 with Packet Interface (ATA/ATAPI - 6)
Specification
http://www.t13.org
Universal Serial Bus (USB) Specification, Revision 2.0
http://www.usb.org
Advanced Configuration and Power Interface (ACPI)
Specification, Revision 2.0
http://www.acpi.info
Enhanced Host Controller Interface (EHCI) Specification for
Universal Serial Bus, Revision 1.0
http://developer.intel.com/technology/usb/
ehcispec.htm
Chapter 1. Introduction
Chapter 1 provides information on datasheet organization and introduces the ICH4.
Chapter 2. Signal Description
Chapter 2 provides a detailed description of each ICH4 signal. Signals are arranged according to
interface and details are provided as to the drive characteristics (Input/Output, Open Drain, etc.) of
all signals.
Chapter 3. ICH4 Power Planes and Pin States
Chapter 3 provides a complete list of signals, their associated power well, their logic level in each
suspend state, and their logic level before and after reset.
Chapter 4. ICH4 and System Clock Domains
Chapter 4 provides a list of each clock domain associated with the ICH4 in an ICH4-based system.
Intel® 82801DB ICH4 Datasheet
27
Introduction
Chapter 5. Functional Description
Chapter 5 provides a detailed description of the functions in the ICH4. All PCI buses, devices, and
functions in this datasheet are abbreviated using the following nomenclature;
Bus:Device:Function. This datasheet abbreviates buses as B0 and B1, devices as D8, D29, D30 and
D31 and functions as F0, F1, F2, F3, F4, F5, F6 and F7. For example Device 31 Function 5 is
abbreviated as D31:F5, Bus 1 Device 8 Function 0 is abbreviated as B1:D8:F0. Generally, the bus
number will not be used, and can be considered to be Bus 0. Note that the ICH4’s external PCI bus
is typically Bus 1, but may be assigned a different number depending upon system configuration.
Chapter 6. Register, Memory and I/O Address Maps
Chapter 6 provides an overview of the registers, fixed I/O ranges, variable I/O ranges and memory
ranges decoded by the ICH4.
Chapter 7. LAN Controller Registers
Chapter 7 provides a detailed description of all registers that reside in the ICH4’s integrated LAN
controller. The integrated LAN controller resides on the ICH4’s external PCI bus (typically Bus 1)
at Device 8, Function 0 (B1:D8:F0).
Chapter 8. Hub Interface to PCI Bridge Registers
Chapter 8 provides a detailed description of all registers that reside in the Hub Interface to PCI
bridge. This bridge resides at Device 30, Function 0 (D30:F0).
Chapter 9. LPC Bridge Registers
Chapter 9 provides a detailed description of all registers that reside in the LPC bridge. This bridge
resides at Device 31, Function 0 (D31:F0). This function contains registers for many different units
within the ICH4 including DMA, Timers, Interrupts, CPU Interface, GPIO, Power Management,
System Management and RTC.
Chapter 10. IDE Controller Registers
Chapter 10 provides a detailed description of all registers that reside in the IDE controller. This
controller resides at Device 31, Function 1 (D31:F1).
Chapter 11. USB UCHI Controller Registers
Chapter 11 provides a detailed description of all registers that reside in the three UHCI host
controllers. These controllers reside at Device 29, Functions 0, 1 and 2 (D29:F0/F1/F2).
Chapter 12. USB EHCI Controller Registers
Chapter 12 provides a detailed description of all registers that reside in the EHCI host controller.
This controller resides at Device 29, Function 7 (D29:F7).
Chapter 13. SMBus Controller Registers
Chapter 13 provides a detailed description of all registers that reside in the SMBus controller. This
controller resides at Device 31, Function 3 (D31:F3).
Chapter 14. AC ’97 Audio Controller Registers
Chapter 14 provides a detailed description of all registers that reside in the audio controller. This
controller resides at Device 31, Function 5 (D31:F5). Note that this chapter of the datasheet does
not include the native audio mixer registers. Accesses to the mixer registers are forwarded over the
AC-link to the codec where the registers reside.
Chapter 15. AC ’97 Modem Controller Registers
Chapter 15 provides a detailed description of all registers that reside in the modem controller. This
controller resides at Device 31, Function 6 (D31:F6). Note that this chapter of the datasheet does
not include the modem mixer registers. Accesses to the mixer registers are forwarded over the AClink to the codec where the registers reside.
28
Intel® 82801DB ICH4 Datasheet
Introduction
Chapter 16. Pinout Definition
Chapter 16 provides a table of each signal and its ball assignment in the 421 BGA package.
Chapter 17. Electrical Characteristics
Chapter 17 provides all AC and DC characteristics including detailed timing diagrams.
Chapter 18. Package Information
Chapter 18 provides drawings of the physical dimensions and characteristics of the 421-BGA
package.
Chapter 19. Testability
Chapter 19 provides detail about the implementation of test modes provided in the ICH4.
Index
This document ends with indexes of registers and register bits.
Intel® 82801DB ICH4 Datasheet
29
Introduction
1.2
Overview
The ICH4 provides extensive I/O support. Functions and capabilities include:
•
•
•
•
•
•
PCI Local Bus Specification, Revision 2.2-compliant with support for 33 MHz PCI operations.
PCI slots ( supports up to 6 Req/Gnt pairs)
ACPI Power Management Logic Support
Enhanced DMA controller, Interrupt controller, and timer functions
Integrated IDE controller supports Ultra ATA100/66/33
USB host interface with support for 6 USB ports; 3 UHCI host controllers; 1 EHCI high-speed
USB 2.0 Host controller
• Integrated LAN controller
• System Management Bus (SMBus) Specification, Version 2.0 with additional support for I2C
devices
• Supports Audio Codec ’97, Revision 2.3 specification (a.k.a., AC ’97 Component
Specification, Revision 2.3) Link for Audio and Telephony codecs (up to seven channels)
• Low Pin Count (LPC) interface
• Firmware Hub (FWH) interface support
• Alert On LAN* (AOL) and Alert On LAN 2* (AOL2)
The ICH4 incorporates a variety of PCI functions that are divided into three logical devices
(29, 30, and 31) on PCI Bus 0 and one device on Bus 1. Device 30 is the Hub Interface-To-PCI
bridge. Device 31 contains all the other PCI functions, except the USB controllers and the LAN
controller, as shown in Table 1-2. The LAN controller is located on Bus 1.
Table 1-2. PCI Devices and Functions
Bus:Device:Function
Bus 0:Device 30:Function 0
30
Function Description
Hub Interface to PCI Bridge
Bus 0:Device 31:Function 0
PCI to LPC Bridge
Bus 0:Device 31:Function 1
IDE Controller
Bus 0:Device 31:Function 3
SMBus Controller
Bus 0:Device 31:Function 5
AC ’97 Audio Controller
Bus 0:Device 31:Function 6
AC ’97 Modem Controller
Bus 0:Device 29:Function 0
USB UHCI Controller #1
Bus 0:Device 29:Function 1
USB UHCI Controller #2
Bus 0:Device 29:Function 2
USB UHCI Controller #3
Bus 0:Device 29:Function 7
USB 2.0 EHCI Controller
Bus n:Device 8:Function 0
LAN Controller
Intel® 82801DB ICH4 Datasheet
Introduction
The following sub-sections provide an overview of the ICH4 capabilities.
Hub Architecture
As I/O speeds increase, the demand placed on the PCI bus by the I/O bridge has become
significant. With AC ’97, USB 2.0, and Ultra ATA/100, coupled with the existing USB, I/O
requirements could impact PCI bus performance. The chipset’s hub interface architecture ensures
that the I/O subsystem; both PCI and the integrated I/O features (IDE, AC ‘97, USB, etc.), receive
adequate bandwidth. By placing the I/O bridge on the hub interface (instead of PCI), the hub
architecture ensures that both the I/O functions integrated into the ICH4 and the PCI peripherals
obtain the bandwidth necessary for peak performance.
PCI Interface
The ICH4 PCI interface provides a 33 MHz, Rev. 2.2 compliant implementation. All PCI signals
are 5 V tolerant, except PME#. The ICH4 integrates a PCI arbiter that supports up to six external
PCI bus masters in addition to the internal ICH4 requests.
IDE Interface (Bus Master Capability and Synchronous DMA Mode)
The fast IDE interface supports up to four IDE devices providing an interface for IDE hard disks
and ATAPI devices. Each IDE device can have independent timings. The IDE interface supports
PIO IDE transfers up to 16 Mbytes/sec and Ultra ATA transfers up 100 Mbytes/sec. It does not
consume any ISA DMA resources. The IDE interface integrates 16x32-bit buffers for optimal
transfers.
The ICH4’s IDE system contains two independent IDE signal channels. They can be electrically
isolated independently. They can be configured to the standard primary and secondary channels
(four devices). There are integrated series resistors on the data and control lines (see Section 5.15
for details).
Low Pin Count (LPC) Interface
The ICH4 implements an LPC Interface as described in the LPC 1.0 specification. The Low Pin
Count (LPC) Bridge function of the ICH4 resides in PCI Device 31:Function 0. In addition to the
LPC bridge interface function, D31:F0 contains other functional units including DMA, Interrupt
controllers, Timers, Power Management, System Management, GPIO, and RTC.
Note that in the current chipset platform, the Super I/O (SIO) component has migrated to the Low
Pin Count (LPC) interface. Migration to the LPC interface allows for lower cost Super I/O designs.
Intel® 82801DB ICH4 Datasheet
31
Introduction
Compatibility Modules (DMA Controller, Timer/Counters, Interrupt
Controller)
The DMA controller incorporates the logic of two 82C37 DMA controllers, with seven
independently programmable channels. Channels 0–3 are hardwired to 8-bit, count-by-byte
transfers, and channels 5–7 are hardwired to 16-bit, count-by-word transfers. Any two of the seven
DMA channels can be programmed to support fast Type-F transfers.
The ICH4 supports two types of DMA (LPC and PC/PCI). DMA via LPC is similar to ISA DMA.
LPC DMA and PC/PCI DMA use the ICH4’s DMA controller. The PC/PCI protocol allows
PCI-based peripherals to initiate DMA cycles by encoding requests and grants via two PC/PCI
REQ#/GNT# pairs.
LPC DMA is handled through the use of the LDRQ# lines from peripherals and special encodings
on LAD[3:0] from the host. Single, Demand, Verify, and Increment modes are supported on the
LPC interface. Channels 0–3 are 8-bit channels. Channels 5–7 are 16-bit channels. Channel 4 is
reserved as a generic bus master request.
The timer/counter block contains three counters that are equivalent in function to those found in
one 82C54 programmable interval timer. These three counters are combined to provide the system
timer function, and speaker tone. The 14.31818 MHz oscillator input provides the clock source for
these three counters.
The ICH4 provides an ISA-Compatible Programmable Interrupt Controller (PIC) that incorporates
the functionality of two 82C59 interrupt controllers. The two interrupt controllers are cascaded so
that 14 external and two internal interrupts are possible. In addition, the ICH4 supports a serial
interrupt scheme.
All of the registers in these modules can be read and restored. This is required to save and restore
system state after power has been removed and restored to the platform.
Advanced Programmable Interrupt Controller (APIC)
In addition to the standard ISA compatible Programmable Interrupt Controller (PIC) described in
the previous section, the ICH4 incorporates the Advanced Programmable Interrupt Controller
(APIC).
Universal Serial Bus (USB) Controller
The ICH4 contains an Enhanced Host Controller Interface (EHCI) compliant host controller that
supports USB high-speed signaling. High-speed USB 2.0 allows data transfers up to 480 Mb/s
which is 40 times faster than full-speed USB. The ICH4 also contains three Universal Host
Controller Interface (UHCI) controllers that support USB full-speed and low-speed signaling.
The ICH4 supports 6 USB 2.0 ports. All six ports are high-speed, full-speed, and low-speed
capable. ICH4’s port-routing logic determines whether a USB port is controlled by one of the
UHCI controllers or by the EHCI controller. See Section 5.16, “USB UHCI Controllers (D29:F0,
F1 and F2) and Section 5.17, “USB EHCI Controller (D29:F7) for details.
32
Intel® 82801DB ICH4 Datasheet
Introduction
LAN Controller
The ICH4’s integrated LAN controller includes a 32-bit PCI controller that provides enhanced
scatter-gather bus mastering capabilities and enables the LAN controller to perform high-speed
data transfers over the PCI bus. Its bus master capabilities enable the component to process highlevel commands and perform multiple operations; this lowers processor utilization by off-loading
communication tasks from the processor. Two large transmit and receive FIFOs of 3 KB each help
prevent data underruns and overruns while waiting for bus accesses. This enables the integrated
LAN controller to transmit data with minimum interframe spacing (IFS).
The LAN controller can operate in either full duplex or half duplex mode. In full duplex mode the
LAN controller adheres with the IEEE 802.3x Flow Control specification. Half duplex
performance is enhanced by a proprietary collision reduction mechanism. See Section 5.2 for
details.
RTC
The ICH4 contains a Motorola MC146818A-compatible real-time clock with 256 bytes of batterybacked RAM. The real-time clock performs two key functions: keeping track of the time of day
and storing system data, even when the system is powered down. The RTC operates on a
32.768 KHz crystal and a separate 3 V lithium battery that provides up to seven years of protection.
The RTC also supports two lockable memory ranges. By setting bits in the configuration space,
two 8-byte ranges can be locked to read and write accesses. This prevents unauthorized reading of
passwords or other system security information.
The RTC also supports a date alarm that allows for scheduling a wake up event up to 30 days in
advance, rather than just 24 hours in advance.
GPIO
Various general purpose inputs and outputs are provided for custom system design. The number of
inputs and outputs varies depending on ICH4 configuration.
Enhanced Power Management
The ICH4’s power management functions include enhanced clock control, local and global
monitoring support for 14 individual devices, and various low-power (suspend) states
(e.g., Suspend-to-DRAM and Suspend-to-Disk). A hardware-based thermal management circuit
permits software-independent entrance to low-power states. The ICH4 contains full support for the
Advanced Configuration and Power Interface (ACPI) Specification, Revision 2.0.
System Management Bus (SMBus 2.0)
The ICH4 contains an SMBus Host interface that allows the processor to communicate with
SMBus slaves. This interface is compatible with most I2C devices. Special I2C commands are
implemented.
The ICH4’s SMBus host controller provides a mechanism for the processor to initiate
communications with SMBus peripherals (slaves). Also, the ICH4 supports slave functionality,
including the Host Notify protocol. Hence, the host controller supports 8 command protocols of the
SMBus interface (see System Management Bus (SMBus) Specification, Version 2.0): Quick
Command, Send Byte, Receive Byte, Write Byte/Word, Read Byte/Word, Process Call, Block
Read/Write, and Host Notify.
Intel® 82801DB ICH4 Datasheet
33
Introduction
Manageability
The ICH4 integrates several functions designed to manage the system and lower the total cost of
ownership (TC0) of the system. These system management functions are designed to report errors,
diagnose the system, and recover from system lockups without the aid of an external
microcontroller.
• TCO Timer. The ICH4’s integrated programmable TCO Timer is used to detect system locks.
The first expiration of the timer generates an SMI# that the system can use to recover from a
software lock. The second expiration of the timer causes a system reset to recover from a
hardware lock.
• Processor Present Indicator. The ICH4 looks for the processor to fetch the first instruction
after reset. If the processor does not fetch the first instruction, the ICH4 will reboot the system.
• ECC Error Reporting. When detecting an ECC error, the host controller has the ability to
send one of several messages to the ICH4. The host controller can instruct the ICH4 to
generate either an SMI#, NMI, SERR#, or TCO interrupt.
• Function Disable. The ICH4 provides the ability to disable the following functions: AC ’97
Modem, AC ’97 Audio, IDE, LAN, USB, or SMBus. Once disabled, these functions no longer
decode I/O, memory, or PCI configuration space. Also, no interrupts or power management
events are generated from the disable functions.
• Intruder Detect. The ICH4 provides an input signal (INTRUDER#) that can be attached to a
switch that is activated by the system case being opened. The ICH4 can be programmed to
generate an SMI# or TCO interrupt due to an active INTRUDER# signal.
• SMBus 2.0. The ICH4 integrates an SMBus controller that provides an interface to manage
peripherals (e.g., serial presence detection (SPD) and thermal sensors) with host notify
capabilities.
• Alert On LAN*. The ICH4 supports Alert On LAN and Alert On LAN 2. In response to a
TCO event (intruder detect, thermal event, processor not booting) the ICH4 sends a message
over the SMBus. A LAN controller can decode this SMBus message and send a message over
the network to alert the network manager.
34
Intel® 82801DB ICH4 Datasheet
Introduction
AC ’97 2.3 Controller
The Audio Codec ’97, Revision 2.3 specification defines a digital interface that can be used to
attach an audio codec (AC), a modem codec (MC), an audio/modem codec (AMC) or a
combination of ACs and MC. The AC ’97 specification defines the interface between the system
logic and the audio or modem codec, known as the AC-link.
By using an audio codec, the AC-link allows for cost-effective, high-quality, integrated audio on
Intel’s chipset-based platform. In addition, an AC ’97 soft modem can be implemented with the use
of a modem codec. Several system options exist when implementing AC ’97. The ICH4-integrated
digital link allows several external codecs to be connected to the ICH4. The system designer can
provide audio with an audio codec, a modem with a modem codec, or an integrated audio/modem
codec. The digital link is expanded to support three audio codecs or two audio codecs and one
modem codec.
The modem implementations for different countries must be taken into consideration, because
telephone systems may vary. By using a split design, the audio codecs can be on-board and the
modem codec can be placed on a riser.
The digital link in the ICH4 supports the Audio Codec ’97, Revision 2.3 specification, so it
supports three codecs with independent PCI functions for audio and modem. Microphone input and
left and right audio channels are supported for a high quality, two-speaker audio solution. Wake on
Ring from Suspend also is supported with the appropriate modem codec.
The ICH4 expands the audio capability with support for up to six channels of PCM audio output
(full AC3 decode). Six-channel audio consists of Front Left, Front Right, Back Left, Back Right,
Center, and Subwoofer, for a complete surround-sound effect. ICH4 has expanded support for three
audio codecs on the AC-link.
Intel® 82801DB ICH4 Datasheet
35
Introduction
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36
Intel® 82801DB ICH4 Datasheet
Signal Description
Signal Description
2
This section provides a detailed description of each signal. The signals are arranged in functional
groups according to their associated interface.
The “#” symbol at the end of the signal name indicates that the active, or asserted state occurs when
the signal is at a low voltage level. When “#” is not present, the signal is asserted when at the high
voltage level.
The following notations are used to describe the signal type:
I
Input Pin
O
Output Pin
OD
Open Drain Output Pin.
I/O
Bi-directional Input / Output Pin.
Intel® 82801DB ICH4 Datasheet
37
Signal Description
Figure 2-1. Intel® ICH4 Interface Signals Block Diagram
AD[31:0]
C/BE[3:0]#
DEVSEL#
FRAME#
IRDY#
TRDY#
STOP#
PAR
PERR#
REQ[4:0]#
REQ5# / REQB# / GPIO1
REQA# / GPIO0
GNT[4:0]#
GNT5# / GNTB# / GPIO17
GNTA# / GPIO[16]
PCICLK
PCIRST#
PLOCK#
SERR#
PME#
A20M#
CPUSLP#
FERR#
IGNNE#
INIT#
INTR
NMI
SMI#
STPCLK#
RCIN#
A20GATE
CPUPWRGD
SERIRQ
PIRQ[D:A]#
PIRQ[H:E] / GPIO[5:2]
IRQ[15:14]
APICCLK
APICD[1:0]
PCI
Interface
Power
Mgnt.
Processor
Interface
Interrupt
Interface
ACLink
THRM#
THRMTRIP#
SYS_RESET#
SLP_S3#
SLP_S4#
SLP_S5#
PWROK
PWRBTN#
RI#
RSMRST#
SUS_STAT# / LPCPD#
SUSCLK
LAN_RST#
VRMPWRGD
AC_RST#
AC_SYNC
AC_BIT_CLK
AC_SDOUT
AC_SDIN[2:0]
Hub
Interface
HI[11:0]
HI_STB / HI_STBS
HI_STB# / HI_STBF
HICOMP
HI_VSWING
RTC
Firmware
Hub
FWH[3:0] / LAD[3:0]
FWH[4] / LFRAME#
CLK14
CLK48
CLK66
Clocks
LPC
Interface
LAD[3:0] / FWH[3:0]
LFRAME# / FWH[4]
LDRQ[1:0]#
SPKR
RTCRST#
TP[0]
Misc.
Signals
SMBus
Interface
SMBDATA
SMBCLK
SMBALERT# / GPIO[11]
GPIO[43:32, 28:27, 25:24]
GPIO[13:11, 8:0]
GPIO[23:16]
General
Purpose
I/O
System
Mgnt.
INTRUDER#
SMLINK[1:0]
USBP0P–USB5P
USBP0N–USB5N
OC[5:0]#
USBRBIAS#
USBRBIAS
USB
RTCX1
RTCX2
EE_SHCLK
EE_DIN
EE_DOUT
EE_CS
38
IDE
Interface
PDCS1#
SDCS1#
PDCS3#
SDCS3#
PDA[2:0]
SDA[2:0]
PDD[15:0]
SDD[15:0]
PDDREQ
SDDREQ
PDDACK#
SDDACK#
PDIOR# (PDWSTB / PRDMARDY#)
SDIOR# (SDWSTB / SRDMARDY#)
PDIOW# (PDSTOP)
SDIOW# (SDSTOP)
PIORDY (PDRSTB / PWDMARDY#)
SIORDY (SDRSTB / SWDMARDY#)
EEPROM
Interface
LAN
Link
LAN_CLK
LAN_RXD[2:0]
LAN_TXD[2:0]
LAN_RSTSYNC
Intel® 82801DB ICH4 Datasheet
Signal Description
2.1
Hub Interface to Host Controller
Table 2-1. Hub Interface Signals
Name
Type
HI[11:0]
I/O
HI_STB /
HI_STBS
I/O
HI_STB# /
HI_STBF
I/O
HICOMP
I/O
Description
Hub Interface Signals
Hub Interface Strobe/ Hub Interface Strobe Second: One of two differential
strobe signals used to transmit and receive data through the hub interface.
Hub Interface 1.5 mode this signal is not differential and is the second of the
two strobe signals.
Hub Interface Strobe Complement / Hub Interface Strobe First: One of two
differential strobe signals used to transmit and receive data through the hub
interface.
Hub Interface 1.5 mode this signal is not differential and is the first of the two
strobe signals.
Hub Interface Compensation: Used for hub interface buffer compensation.
Hub Interface Voltage Swing: Analog input used to control the voltage swing
and impedance strength of hub interface pins.
HI_VSWING
2.2
I
NOTES:
1. Refer to the platform design guide for expected voltages.
2. Refer to the platform design guide for resistor values and routing guidelines
for each hub interface mode.
Link to LAN Connect
Table 2-2. LAN Connect Interface Signals
Name
Type
LAN_CLK
I
LAN I/F Clock: Driven by the LAN Connect component. Frequency range is
5 MHz to 50 MHz.
LAN_RXD[2:0]
I
Received Data: The LAN Connect component uses these signals to transfer
data and control information to the integrated LAN controller. These signals
have integrated weak pull-up resistors.
LAN_TXD[2:0]
O
Transmit Data: The integrated LAN controller uses these signals to transfer
data and control information to the LAN Connect component.
LAN_RSTSYNC
O
LAN Reset/Sync: The LAN Connect component’s Reset and Sync signals are
multiplexed onto this pin.
Intel® 82801DB ICH4 Datasheet
Description
39
Signal Description
2.3
EEPROM Interface
Table 2-3. EEPROM Interface Signals
2.4
Name
Type
Description
EE_SHCLK
O
EEPROM Shift Clock: This signal is the serial shift clock output to the
EEPROM.
EE_DIN
I
EEPROM Data In: This signal transfers data from the EEPROM to the Intel®
ICH4. This signal has an integrated pull-up resistor.
EE_DOUT
O
EEPROM Data Out: EE_DOUT transfers data from the ICH4 to the EEPROM.
EE_CS
O
EEPROM Chip Select: EE_CS is the chip select signal to the EEPROM.
Firmware Hub Interface
Table 2-4. Firmware Hub Interface Signals
2.5
Name
Type
Description
FWH[3:0] /
LAD[3:0]
I/O
Firmware Hub Signals: FWH[3:0] are muxed with LPC address signals.
FWH[4] /
LFRAME#
I/O
Firmware Hub Signals: FWH[4] is muxed with the LPC LFRAME# signal.
PCI Interface
Table 2-5. PCI Interface Signals (Sheet 1 of 3)
Name
AD[31:0]
Type
Description
I/O
PCI Address/Data: AD[31:0] is a multiplexed address and data bus. During
the first clock of a transaction, AD[31:0] contain a physical address (32 bits).
During subsequent clocks, AD[31:0] contain data. The Intel® ICH4drives all 0s
on AD[31:0] during the address phase of all PCI Special Cycles.
Bus Command and Byte Enables: The command and byte enable signals
are multiplexed on the same PCI pins. During the address phase of a
transaction, C/BE[3:0]# define the bus command. During the data phase, C/
BE[3:0]# define the Byte Enables.
C/BE[3:0]#
I/O
C/BE[3:0]#
0000
0001
0010
0011
0110
0111
1010
1011
1100
1110
1111
Command Type
Interrupt Acknowledge
Special Cycle
I/O Read
I/O Write
Memory Read
Memory Write
Configuration Read
Configuration Write
Memory Read Multiple
Memory Read Line
Memory Write and Invalidate
All command encodings not shown are reserved. The ICH4 does not decode
reserved values, and therefore will not respond if a PCI master generates a
cycle using one of the reserved values.
40
Intel® 82801DB ICH4 Datasheet
Signal Description
Table 2-5. PCI Interface Signals (Sheet 2 of 3)
Name
Type
Description
I/O
Device Select: The ICH4 asserts DEVSEL# to claim a PCI transaction. As an
output, the ICH4 asserts DEVSEL# when a PCI master peripheral attempts an
access to an internal ICH4 address or an address destined for the hub
interface (main memory or AGP). As an input, DEVSEL# indicates the
response to an ICH4-initiated transaction on the PCI bus. DEVSEL# is tristated from the leading edge of PCIRST#. DEVSEL# remains tri-stated by the
ICH4 until driven by a Target device.
I/O
Cycle Frame: The current Initiator drives FRAME# to indicate the beginning
and duration of a PCI transaction. While the Initiator asserts FRAME#, data
transfers continue. When the Initiator negates FRAME#, the transaction is in
the final data phase. FRAME# is an input to the ICH4 when the ICH4 is the
Target, and FRAME# is an output from the ICH4 when the ICH4 is the Initiator.
FRAME# remains tri-stated by the ICH4 until driven by an Initiator.
I/O
Initiator Ready: IRDY# indicates the ICH4's ability, as an Initiator, to complete
the current data phase of the transaction. It is used in conjunction with TRDY#.
A data phase is completed on any clock that both IRDY# and TRDY# are
sampled asserted. During a write, IRDY# indicates the ICH4 has valid data
present on AD[31:0]. During a read, it indicates the ICH4 is prepared to latch
data. IRDY# is an input to the ICH4 when the ICH4 is the Target and an output
from the ICH4 when the ICH4 is an Initiator. IRDY# remains tri-stated by the
ICH4 until driven by an Initiator.
I/O
Target Ready: TRDY# indicates the ICH4's ability, as a Target, to complete the
current data phase of the transaction. TRDY# is used in conjunction with
IRDY#. A data phase is completed when both TRDY# and IRDY# are sampled
asserted. During a read, TRDY# indicates that the ICH4, as a Target, has
placed valid data on AD[31:0]. During a write, TRDY# indicates that the ICH4,
as a Target, is prepared to latch data. TRDY# is an input to the ICH4 when the
ICH4 is the Initiator and an output from the ICH4 when the ICH4 is a Target.
TRDY# is tri-stated from the leading edge of PCIRST#. TRDY# remains tristated by the ICH4 until driven by a Target.
I/O
Stop: STOP# indicates that the ICH4, as a Target, is requesting the Initiator to
stop the current transaction. STOP# causes the ICH4, as an Initiator, to stop
the current transaction. STOP# is an output when the ICH4 is a Target and an
input when the ICH4 is an Initiator. STOP# is tri-stated from the leading edge of
PCIRST#. STOP# remains tri-stated until driven by the ICH4.
PAR
I/O
Calculated/Checked Parity: PAR uses “even” parity calculated on 36 bits,
AD[31:0] plus C/BE[3:0]#. “Even” parity means that the ICH4 counts the
number of 1s within the 36 bits plus PAR and the sum is always even. The
ICH4 always calculates PAR on 36 bits regardless of the valid byte enables.
The ICH4 generates PAR for address and data phases and only guarantees
PAR to be valid one PCI clock after the corresponding address or data phase.
The ICH4 drives and tri-states PAR identically to the AD[31:0] lines except that
the ICH4 delays PAR by exactly one PCI clock. PAR is an output during the
address phase (delayed one clock) for all ICH4 initiated transactions. PAR is
an output during the data phase (delayed one clock) when the ICH4 is the
Initiator of a PCI write transaction, and when it is the Target of a read
transaction. ICH4 checks parity when it is the Target of a PCI write transaction.
If a parity error is detected, the ICH4 will set the appropriate internal status bits,
and has the option to generate an NMI# or SMI#.
PERR#
I/O
Parity Error: An external PCI device drives PERR# when it receives data that
has a parity error. The ICH4 drives PERR# when it detects a parity error. The
ICH4 can either generate an NMI# or SMI# upon detecting a parity error (either
detected internally or reported via the PERR# signal).
I
PCI Requests: The ICH4 supports up to 6 masters on the PCI bus. REQ[5]# is
muxed with PC/PCI REQ[B]# (must choose one or the other, but not both). If
not used for PCI or PC/PCI, REQ[5]#/REQ[B]# can instead be used as
GPIO[1].
NOTE: REQ[0]# is programmable to have improved arbitration latency for
supporting PCI-based 1394 controllers.
DEVSEL#
FRAME#
IRDY#
TRDY#
STOP#
REQ[0:4]#
REQ[5]# /
REQ[B]# /
GPIO[1]
Intel® 82801DB ICH4 Datasheet
41
Signal Description
Table 2-5. PCI Interface Signals (Sheet 3 of 3)
Name
Type
GNT[0:4]#
PCI Grants: The ICH4 supports up to 6 masters on the PCI bus. GNT[5]# is
muxed with PC/PCI GNT[B]# (must choose one or the other, but not both). If
not needed for PCI or PC/PCI, GNT[5]# can instead be used as a GPIO.
GNT[5]# /
GNT[B]# /
GPIO[17]#
O
PCICLK
I
NOTE: PCI Clock: This is a 33 MHz clock. PCICLK provides timing for all
transactions on the PCI Bus.
PCIRST#
O
PCI Reset: ICH4 asserts PCIRST# to reset devices that reside on the PCI bus.
The ICH4 asserts PCIRST# during power-up and when S/W initiates a hard
reset sequence through the RC (CF9h) register. The ICH4 drives PCIRST#
inactive a minimum of 1 ms after PWROK is driven active. The ICH4 drives
PCIRST# active a minimum of 1 ms when initiated through the RC register.
PLOCK#
I/O
PCI Lock: This signal indicates an exclusive bus operation and may require
multiple transactions to complete. ICH4 asserts PLOCK# when it performs
non-exclusive transactions on the PCI bus. PLOCK# is ignored when PCI
masters are granted the bus.
SERR#
I/OD
System Error: SERR# can be pulsed active by any PCI device that detects a
system error condition. Upon sampling SERR# active, the ICH4 has the ability
to generate an NMI, SMI#, or interrupt.
I/OD
PCI Power Management Event: PCI peripherals drive PME# to wake the
system from low-power states S1–S5. PME# assertion can also be enabled to
generate an SCI from the S0 state. In some cases the ICH4 may drive PME#
active due to an internal wake event. The ICH4 will not drive PME# high, but it
will be pulled up to VccSus3_3 by an internal pull-up resistor.
PME#
REQ[A]# /
GPIO[0]
REQ[B]# /
REQ[5]# /
GPIO[1]
I
GNT[B]# /
GNT[5]# /
GPIO[17]
Pull-up resistors are not required on these signals. If pull-ups are used, they
should be tied to the Vcc3_3 power rail. GNT[B]#/GNT[5]#/GPIO[17] has an
internal pull-up.
PC/PCI DMA Request [A:B]: This request serializes ISA-like DMA Requests
for the purpose of running ISA-compatible DMA cycles over the PCI bus. This
is used by devices such as PCI based Super I/O or audio codecs which need to
perform legacy 8237 DMA but have no ISA bus.
When not used for PC/PCI requests, these signals can be used as General
Purpose Inputs. REQ[B]# can instead be used as the 6th PCI bus request.
GNT[A]# /
GPIO[16]
42
Description
O
PC/PCI DMA Acknowledges [A: B]: This grant serializes an ISA-like DACK#
for the purpose of running DMA/ISA Master cycles over the PCI bus. This is
used by devices such as PCI based Super/IO or audio codecs which need to
perform legacy 8237 DMA but have no ISA bus.
When not used for PC/PCI, these signals can be used as General Purpose
Outputs. GNTB# can also be used as the 6th PCI bus master grant output.
These signal have internal pull-up resistors.
Intel® 82801DB ICH4 Datasheet
Signal Description
2.6
IDE Interface
Table 2-6. IDE Interface Signals
Name
PDCS1#,
SDCS1#
PDCS3#,
SDCS3#
PDA[2:0],
SDA[2:0]
PDD[15:0],
SDD[15:0]
PDDREQ,
SDDREQ
PDDACK#,
SDDACK#
Type
O
Primary and Secondary IDE Device Chip Selects for 100 Range: For ATA
command register block. This output signal is connected to the corresponding
signal on the primary or secondary IDE connector.
O
Primary and Secondary IDE Device Chip Select for 300 Range: For ATA
control register block. This output signal is connected to the corresponding
signal on the primary or secondary IDE connector.
O
Primary and Secondary IDE Device Address: These output signals are
connected to the corresponding signals on the primary or secondary IDE
connectors. They are used to indicate which byte in either the ATA command
block or control block is being addressed.
I/O
Primary and Secondary IDE Device Data: These signals directly drive the
corresponding signals on the primary or secondary IDE connector. There is a
weak internal pull-down resistor on PDD[7] and SDD[7].
I
Primary and Secondary IDE Device DMA Request: These input signals are
directly driven from the DRQ signals on the primary or secondary IDE
connector. It is asserted by the IDE device to request a data transfer, and used
in conjunction with the PCI bus master IDE function and are not associated with
any AT compatible DMA channel. There is a weak internal pull-down resistor on
these signals.
O
Primary and Secondary IDE Device DMA Acknowledge: These signals
directly drive the DAK# signals on the primary and secondary IDE connectors.
Each is asserted by the Intel® ICH4 to indicate to IDE DMA slave devices that a
given data transfer cycle (assertion of DIOR# or DIOW#) is a DMA data transfer
cycle. This signal is used in conjunction with the PCI bus master IDE function
and are not associated with any AT-compatible DMA channel.
Primary and Secondary Disk I/O Read (PIO and Non-Ultra DMA): This is the
command to the IDE device that it may drive data onto the PDD or SDD lines.
Data is latched by the ICH4 on the deassertion edge of PDIOR# or SDIOR#.
The IDE device is selected either by the ATA register file chip selects (PDCS1#
or SDCS1#, PDCS3# or SDCS3#) and the PDA or SDA lines, or the IDE DMA
acknowledge (PDDAK# or SDDAK#).
PDIOR# /
(PDWSTB /
PRDMARDY#)
O
SDIOR# /
(SDWSTB /
SRDMARDY#)
PDIOW# /
(PDSTOP)
SDIOW# /
(SDSTOP)
Description
Primary and Secondary Disk Write Strobe (Ultra DMA Writes to Disk): This is
the data write strobe for writes to disk. When writing to disk, ICH4 drives valid
data on rising and falling edges of PDWSTB or SDWSTB.
Primary and Secondary Disk DMA Ready (Ultra DMA Reads from Disk): This is
the DMA ready for reads from disk. When reading from disk, ICH4 deasserts
PRDMARDY# or SRDMARDY# to pause burst data transfers.
O
Primary and Secondary Disk I/O Write (PIO and Non-Ultra DMA): This is the
command to the IDE device that it may latch data from the PDD or SDD lines.
Data is latched by the IDE device on the deassertion edge of PDIOW# or
SDIOW#. The IDE device is selected either by the ATA register file chip selects
(PDCS1# or SDCS1#, PDCS3# or SDCS3#) and the PDA or SDA lines, or the
IDE DMA acknowledge (PDDAK# or SDDAK#).
Primary and Secondary Disk Stop (Ultra DMA): ICH4 asserts this signal to
terminate a burst.
PIORDY /
(PDRSTB /
PWDMARDY#)
SIORDY /
(SDRSTB /
SWDMARDY#)
Intel® 82801DB ICH4 Datasheet
Primary and Secondary I/O Channel Ready (PIO): This signal will keep the
strobe active (PDIOR# or SDIOR# on reads, PDIOW# or SDIOW# on writes)
longer than the minimum width. It adds wait states to PIO transfers.
I
Primary and Secondary Disk Read Strobe (Ultra DMA Reads from Disk): When
reading from disk, ICH4 latches data on rising and falling edges of this signal
from the disk.
Primary and Secondary Disk DMA Ready (Ultra DMA Writes to Disk): When
writing to disk, this is de-asserted by the disk to pause burst data transfers.
43
Signal Description
2.7
LPC Interface
Table 2-7. LPC Interface Signals
Name
Type
LAD[3:0] /
FWH[3:0]
I/O
LPC Multiplexed Command, Address, Data: For the LAD[3:0] signals,
internal pull-ups are provided.
LFRAME# /
FWH[4]
O
LPC Frame: LFRAME# indicates the start of an LPC cycle, or an abort.
I
LPC Serial DMA/Master Request Inputs: LDRQ[1:0]# are used to request
DMA or bus master access. These signals are typically connected to an
external Super I/O device. An internal pull-up resistor is provided on these
signals.
LDRQ[1:0]#
2.8
Description
Interrupt Interface
Table 2-8. Interrupt Signals
Name
Type
SERIRQ
I/O
PIRQ[D:A]#
44
I/OD
Description
Serial Interrupt Request: This pin implements the serial interrupt protocol.
PCI Interrupt Requests: In Non-APIC Mode the PIRQx# signals can be routed
to interrupts 3, 4, 5, 6, 7, 9, 10, 11, 12, 14 or 15 as described in the Interrupt
Steering section. Each PIRQx# line has a separate Route Control Register.
In APIC mode, these signals are connected to the internal I/O APIC in the
following fashion: PIRQ[A]# is connected to IRQ16, PIRQ[B]# to IRQ17,
PIRQ[C]# to IRQ18, and PIRQ[D]# to IRQ19. This frees the legacy interrupts.
PCI Interrupt Requests: In Non-APIC Mode the PIRQx# signals can be routed
to interrupts 3, 4, 5, 6, 7, 9, 10, 11, 12, 14 or 15 as described in the Interrupt
Steering section. Each PIRQx# line has a separate Route Control Register.
PIRQ[H:E]# /
GPIO[5:2]
I/OD
IRQ[14:15]
I
Interrupt Request 14:15: These interrupt inputs are connected to the IDE
drives. IRQ14 is used by the drives connected to the Primary controller and
IRQ15 is used by the drives connected to the Secondary controller.
APICCLK
I
APIC Clock: This clock operates up to 33.33 MHz.
APICD[1:0]
I/OD
In APIC mode, these signals are connected to the internal I/O APIC in the
following fashion: PIRQ[E]# is connected to IRQ20, PIRQ[F]# to IRQ21,
PIRQ[G]# to IRQ22, and PIRQ[H]# to IRQ23. This frees the legacy interrupts. If
not needed for interrupts, these signals can be used as GPIO.
APIC Data: These bi-directional open drain signals are used to send and
receive data over the APIC bus. As inputs the data is valid on the rising edge of
APICCLK. As outputs, new data is driven from the rising edge of the APICCLK.
Intel® 82801DB ICH4 Datasheet
Signal Description
2.9
USB Interface
Table 2-9. USB Interface Signals
Name
Type
Description
I/O
Universal Serial Bus Port 1:0 Differential: These differential pairs are used to
transmit data/address/command signals for ports 0 and 1. These ports can be
routed to USB UHCI controller #1 or the USB EHCI controller.
NOTE: No external resistors are required on these signals. The Intel® ICH4
integrates 15 kΩ pull-downs and provides an output driver impedance
of 45 Ω which requires no external series resistor
I/O
Universal Serial Bus Port 3:2 Differential: These differential pairs are used to
transmit data/address/command signals for ports 2 and 3. These ports can be
routed to USB UHCI controller #2 or the USB EHCI controller.
NOTE: No external resistors are required on these signals. The ICH4
integrates 15 kΩ pull-downs and provides an output driver impedance
of 45 Ω which requires no external series resistor
USBP4P,
USBP4N,
USBP5P,
USBP5N
I/O
Universal Serial Bus Port 5:4 Differential: These differential pairs are used to
transmit data/address/command signals for ports 4 and 5. These ports can be
routed to USB UHCI controller #3 or the USB EHCI controller.
NOTE: No external resistors are required on these signals. The ICH4
integrates 15 kΩ pull-downs and provides an output driver impedance
of 45 Ω which requires no external series resistor
OC[5:0]#
I
Overcurrent Indicators: These signals set corresponding bits in the USB
controllers to indicate that an overcurrent condition has occurred.
USBRBIAS
O
USB Resistor Bias: Analog connection point for an external resistor to ground.
USBRBIAS should be connected to USBRBIAS# as close to the resistor as
possible.
USBRBIAS#
I
USB Resistor Bias Complement: Analog connection point for an external
resistor to ground. USBRBIAS# should be connected to USBRBIAS as close to
the resistor as possible.
USBP0P,
USBP0N,
USBP1P,
USBP1N
USBP2P,
USBP2N,
USBP3P,
USBP3N
Intel® 82801DB ICH4 Datasheet
45
Signal Description
2.10
Power Management Interface
Table 2-10. Power Management Interface Signals
Name
Type
Description
THRM#
I
Thermal Alarm: This is an active low signal generated by external hardware to
start the hardware clock throttling mode. The signal can also generate an SMI#
or an SCI.
THRMTRIP#
I
Thermal Trip: When low, THRMTRIP# indicates that a thermal trip from the
processor occurred; the Intel® ICH4 will immediately transition to a S5 state.
The ICH4 will not wait for the processor stop grant cycle since the processor
has overheated.
SLP_S3#
O
S3 Sleep Control: SLP_S3# is for power plane control. It shuts off power to all
non-critical systems when in S3 (Suspend To RAM), S4 (Suspend to Disk), or
S5 (Soft Off) states.
SLP_S4#
O
S4 Sleep Control: SLP_S4# is for power plane control. It shuts power to all
non-critical systems when in the S4 (Suspend to Disk) or S5 (Soft Off) state.
SLP_S5#
O
S5 Sleep Control: SLP_S5# is for power plane control. The signal is used to
shut power off to all non-critical systems when in the S5 (Soft Off) states.
I
Power OK: When asserted, PWROK is an indication to the ICH4 that core
power and PCICLK have been stable for at least 1 ms. PWROK can be driven
asynchronously. When PWROK is negated, the ICH4 asserts PCIRST#.
NOTE: PWROK must deassert for a minimum of 3 RTC clock periods for the
ICH4 to fully reset the power and properly generate the PCIRST#
output
PWRBTN#
I
Power Button: The Power Button causes SMI# or SCI to indicate a system
request to go to a sleep state. If the system is already in a sleep state, this
signal causes a wake event. If PWRBTN# is pressed for more than 4 seconds,
this causes an unconditional transition (power button override) to the S5 state
with only the PWRBTN# available as a wake event. Override occurs even if the
system is in the S1–S4 states. This signal has an internal pull-up resistor.
RI#
I
Ring Indicate: This signal is an input from the modem interface. It can be
enabled as a wake event, and this is preserved across power failures.
SYS_RESET#
I
System Reset: This pin forces an internal reset after being debounced. The
ICH4 will reset immediately if the SMBus is idle; otherwise, it will wait up to
25 ms ± 2 ms for the SMBus to idle before forcing a reset on the system.
RSMRST#
I
Resume Well Reset: This signal is used for resetting the resume power plane
logic.
LAN_RST#
I
LAN Reset: This signal must be asserted at least 10 ms after the resume well
power (VccSus3_3 and VccSus1_5) is valid. When deasserted, this signal is
an indication that the resume well power is stable.
SUS_STAT# /
LPCPD#
O
Suspend Status: This signal is asserted by the ICH4 to indicate that the
system will be entering a low power state soon. This can be monitored by
devices with memory that need to switch from normal refresh to suspend
refresh mode. It can also be used by other peripherals as an indication that
they should isolate their outputs that may be going to powered-off planes. This
signal is called LPCPD# on the LPC I/F.
SUSCLK
O
Suspend Clock: Output of the RTC generator circuit to use by other chips for
refresh clock.
VRMPWRGD
I
VRM Power Good: This should be connected to be the processor’s VRM
Power Good.
PWROK
46
Intel® 82801DB ICH4 Datasheet
Signal Description
2.11
Processor Interface
Table 2-11. Processor Interface Signals (Sheet 1 of 2)
Name
Type
Description
Mask A20: A20M# will go active based on either setting the appropriate bit in
the Port 92h register, or based on the A20GATE input being active.
A20M#
O
CPUSLP#
O
CPU Sleep: This signal puts the processor into a state that saves substantial
power compared to Stop-Grant state. However, during that time, no snoops
occur. The ICH4 can optionally assert the CPUSLP# signal when going to the
S1 state.
I
Numeric Coprocessor Error: This signal is tied to the coprocessor error
signal on the processor. FERR# is only used if the ICH4 coprocessor error
reporting function is enabled in the General Control Register (Device
31:Function 0, Offset D0, bit 13). If FERR# is asserted, the ICH4 generates an
internal IRQ13 to its interrupt controller unit. It is also used to gate the IGNNE#
signal to ensure that IGNNE# is not asserted to the processor unless FERR# is
active. FERR# requires an external weak pull-up to ensure a high level when
the coprocessor error function is disabled.
NOTE: FERR# can be used in some states for notification by the processor of
pending interrupt events. This functionality is independent of the
General Control Register bit setting.
FERR#
IGNNE#
O
Speed Strap: During the reset sequence, Intel® ICH4 drives A20M# high if the
corresponding bit is set in the FREQ_STRP register.
Ignore Numeric Error: This signal is connected to the ignore error pin on the
processor. IGNNE# is only used if the ICH4 coprocessor error reporting
function is enabled in the General Control Register (Device 31:Function 0,
Offset D0,
bit 13). If FERR# is active, indicating a coprocessor error, a write to the
Coprocessor Error Register (F0h) causes the IGNNE# to be asserted. IGNNE#
remains asserted until FERR# is negated. If FERR# is not asserted when the
Coprocessor Error Register is written, the IGNNE# signal is not asserted.
Speed Strap: During the reset sequence, ICH4 drives IGNNE# high if the
corresponding bit is set in the FREQ_STRP register.
INIT#
INTR
O
O
Initialization: INIT# is asserted by the ICH4 for 16 PCI clocks to reset the
processor. ICH4 can be configured to support CPU BIST. In that case, INIT#
will be active when PCIRST# is active.
CPU Interrupt: INTR is asserted by the ICH4 to signal the processor that an
interrupt request is pending and needs to be serviced. It is an asynchronous
output and normally driven low.
Speed Strap: During the reset sequence, ICH4 drives INTR high if the
corresponding bit is set in the FREQ_STRP register.
NMI
O
Non-Maskable Interrupt: NMI is used to force a non-Maskable interrupt to the
processor. The ICH4 can generate an NMI when either SERR# or IOCHK# is
asserted. The processor detects an NMI when it detects a rising edge on NMI.
NMI is reset by setting the corresponding NMI source enable/disable bit in the
NMI Status and Control Register.
Speed Strap: During the reset sequence, ICH4 drives NMI high if the
corresponding bit is set in the FREQ_STRP register.
SMI#
O
System Management Interrupt: SMI# is an active low output synchronous to
PCICLK. It is asserted by the ICH4 in response to one of many enabled
hardware or software events.
STPCLK#
O
Stop Clock Request: STPCLK# is an active low output synchronous to
PCICLK. It is asserted by the ICH4 in response to one of many hardware or
software events. When the processor samples STPCLK# asserted, it responds
by stopping its internal clock.
Intel® 82801DB ICH4 Datasheet
47
Signal Description
Table 2-11. Processor Interface Signals (Sheet 2 of 2)
Name
2.12
Type
Description
RCIN#
I
Keyboard Controller Reset CPU: The keyboard controller can generate INIT#
to the processor. This saves the external OR gate with the ICH4’s other
sources of INIT#. When the ICH4 detects the assertion of this signal, INIT# is
generated for 16 PCI clocks.
NOTE: The ICH4 ignores RCIN# assertion during transitions to the S3, S4
and S5 states.
A20GATE
I
A20 Gate: A20GATE is from the keyboard controller. The signal acts as an
alternative method to force the A20M# signal active. It saves the external OR
gate needed with various other PCIsets.
CPUPWRGD
OD
CPU Power Good: This signal should be connected to the processor’s
PWRGOOD input. This is an open-drain output signal (external pull-up resistor
required) that represents a logical AND of the ICH4’s PWROK and
VRMPWRGD signals.
SMBus Interface
Table 2-12. SM Bus Interface Signals
2.13
Name
Type
Description
SMBDATA
I/OD
SMBus Data: External pull-up is required.
SMBCLK
I/OD
SMBus Clock: External pull-up is required.
SMBALERT#/
GPIO[11]
I
SMBus Alert: This signal is used to wake the system or generate SMI#. If not
used for SMBALERT#, it can be used as a GPI.
System Management Interface
Table 2-13. System Management Interface Signals
48
Name
Type
Description
INTRUDER#
I
Intruder Detect: This signal can be set to disable the system if the box is
detected open. This signal’s status is readable, so it can be used like a GPI if
the Intruder Detection is not needed.
SMLINK[1:0]
I/OD
System Management Link: SMBus link to optional external system
management ASIC or LAN controller. External pull-ups are required. Note that
SMLINK[0] corresponds to an SMBus Clock signal and SMLINK[1]
corresponds to an SMBus Data signal.
Intel® 82801DB ICH4 Datasheet
Signal Description
2.14
Real Time Clock Interface
Table 2-14. Real Time Clock Interface
2.15
Name
Type
Description
RTCX1
Special
Crystal Input 1: This signal is connected to the 32.768 kHz crystal.
RTCX2
Special
Crystal Input 2: This signal is connected to the 32.768 kHz crystal.
Other Clocks
Table 2-15. Other Clocks
2.16
Name
Type
Description
CLK14
I
Oscillator Clock: This clock is used for 8254 timers. It runs at 14.31818 MHz.
This clock is permitted to stop during S3 (or lower) states
CLK48
I
48 MHz Clock: This clock is used to run the USB controllers. It runs at 48
MHz. This clock is permitted to stop during S3 (or lower) states
CLK66
I
66 MHz Clock: This clock is used to run the hub interface. It runs at 66 MHz.
This clock is permitted to stop during S3 (or lower) states
Miscellaneous Signals
Table 2-16. Miscellaneous Signals
Name
Type
Description
O
Speaker: The SPKR signal is the output of counter 2 and is internally “ANDed”
with Port 61h bit 1 to provide Speaker Data Enable. This signal drives an
external speaker driver device, which in turn drives the system speaker. Upon
PCIRST#, its output state is 0.
NOTE: SPKR is sampled at the rising edge of PWROK as a functional strap.
See Section 2.20.1 for more details. There is a weak integrated pulldown resistor on SPKR pin.
RTCRST#
I
RTC Reset: When asserted, this signal resets register bits in the RTC well and
sets the RTC_PWR_STS bit (bit 2 in GEN_PMCON3 register).
NOTES:
1. Clearing CMOS in an Intel® ICH4-based platform can be done by using a
jumper on RTCRST# or GPI, or using SAFEMODE strap. Implementations
should not attempt to clear CMOS by using a jumper to pull VccRTC low.
2. Unless entering the XOR Chain Test Mode, the RTCRST# input must
always be high when all other RTC power planes are on.
TP[0]
I
Test Point: This signal must have an external pull-up to VccSus3_3.
SPKR
Intel® 82801DB ICH4 Datasheet
49
Signal Description
2.17
AC-Link
Table 2-17. AC-Link Signals
Name
Type
Description
AC_RST#
O
AC97 Reset: This signal is a master hardware reset to external Codec(s).
AC_SYNC
O
AC97 Sync: This signal is a 48 kHz fixed rate sample sync to the Codec(s).
AC_BIT_CLK
I
AC97 Bit Clock: This signal is a 12.288 MHz serial data clock generated by
the external Codec(s). This signal has an integrated pull-down resistor (see
Note at the end of the table).
AC_SDOUT
O
AC_SDIN[2:0]
I
AC97 Serial Data Out: Serial TDM data output to the Codec(s).
NOTE: AC_SDOUT is sampled at the rising edge of PWROK as a functional
strap. See Section 2.20.1 for more details.
AC97 Serial Data In 2:0: These signals are Serial TDM data inputs from the
three Codecs.
NOTE: An integrated pull-down resistor on AC_BIT_CLK is enabled when either:
- The ACLINK Shutoff bit in the AC ’97 Global Control Register (See Section 15.2.8) is set to 1, or
- Both Function 5 and Function 6 of Device 31 are disabled.
Otherwise, the integrated pull-down resistor is disabled.
50
Intel® 82801DB ICH4 Datasheet
Signal Description
2.18
General Purpose I/O
Table 2-18. General Purpose I/O Signals
Name
Type
Description
GPIO[47:44]
I/O
Not implemented.
GPIO[43:38]
I/O
Can be input or output. Main power well.
GPIO[37:32]
I/O
Can be input or output. Main power well.
GPIO[31:29]
O
Not implemented.
GPIO[28:27]
I/O
Can be input or output. Resume power well. Unmuxed.
GPIO[26]
I/O
Not implemented.
GPIO[25]
I/O
Can be input or output. Resume power well. Unmuxed.
GPIO[24]
I/O
Can be input or output. Resume power well.
GPIO[23]
O
Fixed as output only. Main power well.
GPIO[22]
OD
Fixed as output only. Main power well.
GPIO[21]
O
Fixed as output only. Main power well.
GPIO[20]
O
Fixed as output only. Main power well.
GPIO[19]
O
Fixed as output only. Main power well.
GPIO[18]
O
Fixed as output only. Main power well.
GPIO[17:16]
O
Fixed as Output only. Main power well. Can be used instead as PC/PCI
GNT[A:B]#. GPIO[17] can also alternatively be used for PCI GNT[5]#.
Integrated pull-up resistor.
GPIO[15:14]
I
Not implemented.
GPIO[13:12]
I
Fixed as Input only. Resume power well. Unmuxed.
GPIO[11]
I
Fixed as Input only. Resume power well. Can be used instead as SMBALERT#.
GPIO[10:9]
I
Not implemented.
GPIO[8]
I
Fixed as Input only. Resume power well. Unmuxed.
GPIO[7]
I
Fixed as Input only. Main power well. Unmuxed.
GPIO[6]
I
Fixed as Input only. Main power well.
GPIO[5:2]
I
Fixed as Input only. Main power well. Can be used instead as PIRQ[E:H]#.
GPIO[1:0]
I
Fixed as Input only. Main power well. Can be used instead as PC/PCI
REQ[A:B]#. GPIO[1] can also alternatively be used for PCI REQ[5]#.
NOTE: Main power well GPIO will be 5 V tolerant, except for GPIO[43:32]. Resume power well GPIO are not
5 V tolerant.
Intel® 82801DB ICH4 Datasheet
51
Signal Description
2.19
Power and Ground
Table 2-19. Power and Ground Signals
Name
Description
Vcc3_3
3.3 V supply for core well I/O buffers. This power may be shut off in S3, S4, S5 or G3
states.
Vcc1_5
1.5 V supply for core well logic. This power may be shut off in S3, S4, S5 or G3 states.
1.5 V supply for Hub Interface 1.5 logic.
VccHI
1.8 V supply for Hub Interface 1.0 logic.
This power may be shut off in S3, S4, S5 or G3 states.
V5REF
Reference for 5 V tolerance on core well inputs. This power may be shut off in S3, S4,
S5 or G3 states.
Analog Input. Expected voltages are:
HIREF
• 0.9 V for HI 1.0 (Normal Hub Interface) Series Termination
• 350 mV for HI 1.5 (Enhanced Hub Interface) Parallel Termination
This power is shut off in S3, S4, S5, and G3 states.
VccSus3_3
3.3 V supply for resume well I/O buffers. This power is not expected to be shut off
unless the system is unplugged.
VccSus1_5
1.5 V supply for resume well logic. This power is not expected to be shut off unless the
system is unplugged.
V5REF_Sus
Reference for 5 V tolerance on resume well inputs. This power is not expected to be
shut off unless the system is unplugged.
VccRTC
3.3 V (can drop to 2.0 V min. in G3 state) supply for the RTC well. This power is not
expected to be shut off unless the RTC battery is removed or completely drained.
NOTE: Implementations should not attempt to clear CMOS by using a jumper to pull
VccRTC low. Clearing CMOS in an Intel® ICH4-based platform can be done
by using a jumper on RTCRST# or GPI, or using SAFEMODE strap.
VccPLL
1.5 V supply for core well logic. This signal is used for the USB PLL. This power may
be shut off in S3, S4, S5, or G3 states.
VBIAS
RTC well bias voltage. The DC reference voltage applied to this pin sets a current that
is mirrored throughout the oscillator and buffer circuitry. See Section 2.20.4.
V_CPU_IO
Powered by the same supply as the processor I/O voltage. This supply is used to drive
the processor interface outputs.
Vss
52
Grounds.
Intel® 82801DB ICH4 Datasheet
Signal Description
2.20
Pin Straps
2.20.1
Functional Straps
The following signals are used for static configuration. They are sampled at the rising edge of
PWROK to select configurations, and then revert later to their normal usage. To invoke the
associated mode, the signal should be driven at least four PCI clocks prior to the time it is sampled.
Table 2-20. Functional Strap Definitions
Signal
Usage
When Sampled
Rising Edge of
PWROK
Comment
The signal has a weak internal pull-down. If the
signal is sampled high, the Intel® ICH4 will set the
processor speed strap pins for safe mode. Refer to
processor specification for speed strapping
definition. The status of this strap is readable via the
SAFE_MODE bit (bit 2, D31: F0, Offset D4h).
AC_SDOUT
Safe Mode
EE_DOUT
Reserved
System designers should include a placeholder for a
pull-down resistor on EE_DOUT but do not
populate the resistor.
Top-Block Swap
Override
The signal has a weak internal pull-up. If the signal
is sampled low, this indicates that the system is
strapped to the “top-block swap” mode (ICH4 will
invert A16 for all cycles targeting FWH BIOS space).
The status of this strap is readable via the
Top_Swap bit (bit 13, D31: F0, Offset D4h). Note
that software will not be able to clear the Top-Swap
bit until the system is rebooted without GNT[A]#
being pulled down.
GNT[A]#
Hub Interface
Termination
Scheme
DPRSLPVR
(correlated to
HICOMP)
Rising Edge of
PWROK
Low (default): Hub Interface 1.0 series or Hub
Interface 1.5 parallel termination
Rising Edge of
PWROK
High (external pull-up to VccHI): Not supported by
ICH4
See the specific platform design guide for resistor
values and routing guidelines for each hub interface
mode
Low (default due to weak internal pull-down): Hub
Interface 1.0 buffer mode (series termination) will be
selected.
Hub Interface
SCHEME (HI 1.0
vs. HI 1.5)
HICOMP
Rising Edge of
PWROK
High (external pullup to VccHI): Hub Interface 1.5
buffer mode (parallel termination) will be selected.
See the specific platform design guide for resistor
values and routing guidelines for each hub interface
mode.
SPKR
No Reboot
Intel® 82801DB ICH4 Datasheet
Rising Edge of
PWROK
The signal has a weak internal pull-down. If the
signal is sampled high, this indicates that the system
is strapped to the “No Reboot” mode (ICH4 will
disable the TCO Timer system reboot feature). The
status of this strap is readable via the NO_REBOOT
bit (bit 1, D31: F0, Offset D4h).
53
Signal Description
2.20.2
External RTC Circuitry
To reduce RTC well power consumption, the ICH4 implements an internal oscillator circuit that is
sensitive to step voltage changes in VccRTC and VBIAS. Figure 2-2 shows a schematic diagram of
the circuitry required to condition these voltages to ensure correct operation of the ICH4 RTC.
Figure 2-2. Example External RTC Circuit
3.3 V
VccSus
VccRTC
1 µF
RTCX2
1 kΩ
32.768 kHz
Xtal
Vbatt
R1
10 MΩ
RTCX1
C3
0.047 uF
C1
18 pF
C2
18 pF
R2
10 MΩ
VBIAS
RTC_osc_circ
NOTES:
1. Reference designators arbitrarily assigned.
2. 3.3 V VccSus is active when system plugged in.
3. Vbatt is voltage provided by battery.
4. VBIAS, VccRTC, RTCX1, and RTCX2 are Intel® ICH4 pins.
5. VBIAS is used to bias the ICH4 internal oscillator.
6. VccRTC powers the RTC well of the ICH4.
7. RTCX1 is the input to the internal oscillator.
8. RTCX2 is the feedback for the external crystal.
9. C1 and C2 depend on crystal load.
2.20.3
V5REF / Vcc3_3 Sequencing Requirements
V5REF is the reference voltage for 5 V tolerance on inputs to the ICH4. V5REF must be powered
up before Vcc3_3, or after Vcc3_3 within 0.7 V. Also, V5REF must power down after Vcc3_3, or
before Vcc3_3 within 0.7 V. The rule must be followed in order to ensure the safety of the ICH4. If
the rule is violated, internal diodes will attempt to draw power sufficient to damage the diodes from
the Vcc3_3 rail. Figure 2-3 shows a sample implementation of how to satisfy the V5REF/3.3 V
sequencing rule.
This rule also applies to the standby rails, but in most platforms, the VccSus3_3 rail is derived from
the VccSus5 rail and therefore, the VccSus3_3 rail will always come up after the VccSus5 rail. As
a result, V5REF_Sus will always be powered up before VccSus3_3. In platforms that do not derive
the VccSus3_3 rail from the VccSus5 rail, this rule must be comprehended in the platform design.
54
Intel® 82801DB ICH4 Datasheet
Signal Description
Figure 2-3. Example V5REF Sequencing Circuit
Vcc Supply
(3.3 V)
5 V Supply
1 kΩ
Diode
To System
2.20.4
Test Signals
2.20.4.1
Test Mode Selection
1 µF
5VREF
To System
When PWROK is active (high) for at least 76 PCI clocks, driving RTCRST# active (low) for a
number of PCI clocks (33 MHz) will activate a particular test mode a specified in Table 2-21.
Note:
RTCRST# may be driven low any time after PCIRST is inactive. Refer to Section 19.1 for a
detailed description of the ICH4 test modes.
Table 2-21. Test Mode Selection
Number of PCI Clocks RTCRST#
Driven Low after PWROK Active
Test Mode
<4
No Test Mode Selected
4
XOR Chain 1
5
XOR Chain 2
6
XOR Chain 3
7
XOR Chain 4
8
All “Z”
9–13
Reserved. DO NOT ATTEMPT
14
Long XOR
15–42
Reserved. DO NOT ATTEMPT
43–51
No Test Mode Selected
Intel® 82801DB ICH4 Datasheet
52
XOR Chain 6
53
XOR Chain 4 Bandgap
>53
No Test Mode Selected
55
Signal Description
This page is intentionally left blank.
56
Intel® 82801DB ICH4 Datasheet
Intel® ICH4 Power Planes and Pin States
Intel® ICH4 Power Planes and
Pin States
3
This chapter describes the describes the system power planes for the ICH4. In addition, the ICH4
power planes and reset pin states for various signals are presented.
3.1
Power Planes
Table 3-1. Intel® ICH4 System Power Planes
Plane
Main I/O
(3.3 V)
Vcc3_3: Powered by the main power supply. When the system is in the S3, S4, S5, or
G3 state, this plane is assumed to be shut off.
Main Logic
(1.5 V)
Vcc1_5: Powered by the main power supply. When the system is in the S3, S4, S5, or
G3 state, this plane is assumed to be shut off.
Resume I/O
(3.3 V Standby)
VccSUS3_3: Powered by the main power supply in S0–S1 states. Powered by the
trickle power supply when the system is in the S3, S4, S5, state. Assumed to be shut off
only when in the G3 state (system is unplugged).
Resume Logic
(1.5 V Standby)
VccSUS1_5: Powered by the main power supply in S0–S1 states. Powered by the
trickle power supply when the system is in the S3, S4, S5, state. Assumed to be shut off
only when in the G3 state (system is unplugged).
CPU I/F
(0.8 ~ 1.75 V)
Description
V_CPU_IO: Powered by the main power supply via CPU voltage regulator. When the
system is in the S3, S4, S5, or G3 state, this plane is assumed to be shut off.
Hub Interface Logic
(1.5 V or 1.8 V)
VccHI: Powered by the main power supply. Assumed to be 1.5 V when operating in
Hub Interface 1.5 mode and 1.8 V when operating in Hub Interface 1.0 mode. When the
system is in the S3, S4, S5, or G3 state, this plane is assumed to be shut off.
RTC
VccRTC: When other power is available (from the main supply), external diode
coupling will provide power to reduce the drain on the RTC battery. Assumed to operate
from 3.3 V down to 2.0 V.
Intel® 82801DB ICH4 Datasheet
57
Intel® ICH4 Power Planes and Pin States
3.2
Integrated Pull-Ups and Pull-Downs
Table 3-2. Integrated Pull-Up and Pull-Down Resistors
Signal
AC_BITCLK
AC_RST#
AC_SDIN[2:0]
AC_SDOUT
AC_SYNC
EE_DIN
EE_DOUT
GNT[B:A]# / GNT[5]# /
GPIO[17:16]
LAD[3:0]# / FWH[3:0]#
LDRQ[1:0]
LAN_RXD[2:0]
LAN_CLK
PME#
PWRBTN#
PDD[7] / SDD[7]
PDDREQ / SDDREQ
SPKR
USB[5:0] [P,N]
Resistor Type
Nominal Value
pull-down
pull-down
pull-down
pull-down
pull-down
pull-up
pull-up
20 kΩ
20 kΩ
20 kΩ
20 kΩ
20 kΩ
20 kΩ
20 kΩ
Notes
1
2
2
2, 8
2, 8
3
3
pull-up
20 kΩ
3
pull-up
pull-up
pull-up
pull-down
pull-up
pull-up
pull-down
pull-down
pull-down
pull-down
20 kΩ
20 kΩ
10 kΩ
100 kΩ
20 kΩ
20 kΩ
11.5 kΩ
11.5 kΩ
20 kΩ
15 kΩ
3
3
4
5
3
3
6
6
2, 8
7
NOTES:
1. Simulation data shows that these resistor values can range from 10 kΩ to 40 kΩ.
2. Simulation data shows that these resistor values can range from 9 kΩ to 50 kΩ.
3. Simulation data shows that these resistor values can range from 15 kΩ to 35 kΩ
4. Simulation data shows that these resistor values can range from 7.5 kΩ to 16 kΩ.
5. Simulation data shows that these resistor values can range from 45 kΩ to 170 kΩ
6. Simulation data shows that these resistor values can range from 5.7 kΩ to 28.3 kΩ.
7. Simulation data shows that these resistor values can range from 14.25 kΩ to 24.8 kΩ
8. The pull-up or pull-down on this signal is only enabled at boot/reset for strapping function.
3.3
IDE Integrated Series Termination Resistors
Table 3-3 shows the ICH4 IDE signals that have integrated series termination resistors.
Table 3-3. IDE Series Termination Resistors
Signal
Integrated Series Termination
Resistor Value
PDD[15:0], SDD[15:0, PDIOW#, SDIOW#, PDIOR#, PDIOW#, PDREQ,
SDREQ, PDDACK#, SDDACK#, PIORDY, SIORDY, PDA[2:0], SDA[2:0],
PDCS1#, SDCS1#, PDCS3#, SDCS3#, IRQ14, IRQ15]
approximately 33 Ω (See Note)
NOTE: Simulation data indicates that the integrated series termination resistors are a nominal 33 Ω but can
range from 31 Ω to 43 Ω.
58
Intel® 82801DB ICH4 Datasheet
Intel® ICH4 Power Planes and Pin States
3.4
Output and I/O Signals Planes and States
Table 3-4 shows the power plane associated with the output and I/O signals, as well as the state at
various times. Within the table, the following terms are used:
“High-Z”
Tri-state. ICH4 not driving the signal high or low.
“High”
ICH4 is driving the signal to a logic ‘1’
“Low”
ICH4 is driving the signal to a logic ‘0’
“Defined”
Driven to a level that is defined by the function (will be high or low)
“Undefined”
ICH4 is driving the signal, but the value is indeterminate.
“Running”
Clock is toggling or signal is transitioning because function not stopping
“Off”
The power plane is off, so ICH4 is not driving
Note that the signal levels are the same in S4 and S5.
Table 3-4. Power Plane and States for Output and I/O Signal (Sheet 1 of 4)
Signal Name
Power
Plane
During
PCIRST#4 /
RSMRST#5,7
Immediately
after
PCIRST#4 /
RSMRST#5
S1
S3
S4/S5
PCI Bus
AD[31:0]
Main I/O
High-Z
Undefined
Defined
Off
Off
C/BE#[3:0]
Main I/O
High-Z
Undefined
Defined
Off
Off
DEVSEL#
Main I/O
High-Z
High-Z
High-Z
Off
Off
FRAME#
Main I/O
High-Z
High-Z
High-Z
Off
Off
GNT[0:4]#
Main I/O
High
High
High
Off
Off
GNT[A:B]#
Main I/O
High-Z with
Internal PullUp
High
High
Off
Off
IRDY#, TRDY#
Main I/O
High-Z
High-Z
High-Z
Off
Off
PAR
Main I/O
High-Z
Undefined
Defined
Off
Off
Resume I/O
Low
High
High
Low
Low
PERR#
Main I/O
High-Z
High-Z
High-Z
Off
Off
PLOCK#
Main I/O
High-Z
High-Z
High-Z
Off
Off
STOP#
Main I/O
High-Z
High-Z
High-Z
Off
Off
PCIRST#
Intel® 82801DB ICH4 Datasheet
59
Intel® ICH4 Power Planes and Pin States
Table 3-4. Power Plane and States for Output and I/O Signal (Sheet 2 of 4)
Signal Name
Power
Plane
During
PCIRST#4 /
RSMRST#5,7
Immediately
after
PCIRST#4 /
RSMRST#5
S1
S3
S4/S5
LPC Interface
LAD[3:0]
Main I/O
High
High
High
Off
Off
LFRAME#
Main I/O
High
High
High
Off
Off
LAN Connect and EEPROM Interface
EE_CS
Resume I/O
Low
Running
Defined
Defined
Defined
EE_DOUT
Resume I/O
High
High
Defined
Defined
Defined
EE_SHCLK
Resume I/O
Low
Running
Defined
Defined
Defined
LAN_RSTSYNC
Resume I/O
High
Defined
Defined
Defined
Defined
LAN_TXD[2:0]
Resume I/O
Low
Defined
Defined
Defined
Defined
IDE Interface
PDA[2:0], SDA[2:0]
Main I/O
Undefined
Undefined
Undefined
Off
Off
PDCS1#, PDCS3#
Main I/O
High
High
High
Off
Off
PDD[15:8], SDD[15:8],
PDD[6:0], SDD[6:0]
Main I/O
High-Z
High-Z
High-Z
Off
Off
PDD[7], SDD[7[
Main I/O
Low
Low
Low
Off
Off
PDDACK#, SDDACK#
Main I/O
High
High
High
Off
Off
PDIOR#, PDIOW#
Main I/O
High
High
High
Off
Off
SDCS1#, SDCS3#
Main I/O
High
High
High
Off
Off
SDIOR#, SDIOW#
Main I/O
High
High
High
Off
Off
Interrupts
PIRQ[A:H]#
Main I/O
High-Z
High-Z
High-Z
Off
Off
SERIRQ
Main I/O
High-Z
High-Z
High-Z
Off
Off
APICD[1:0]
Main I/O
High-Z
High-Z
High-Z
Off
Off
USB Interface
60
USBP[5:0][P,N]
Resume I/O
Low
Low
Low
Low
Low
USBRBIAS
Resume I/O
High-Z
High-Z
Defined
Defined
Defined
Intel® 82801DB ICH4 Datasheet
Intel® ICH4 Power Planes and Pin States
Table 3-4. Power Plane and States for Output and I/O Signal (Sheet 3 of 4)
Signal Name
Power
Plane
During
PCIRST#4 /
RSMRST#5,7
Immediately
after
PCIRST#4 /
RSMRST#5
S1
S3
S4/S5
Power Management
SLP_S3#
Resume I/O
Low
High
High
Low
Low
SLP_S4#
Resume I/O
Low
High
High
High
Low
SLP_S5#
Resume I/O
Low
High
High
High
Note 6
SUS_STAT#
Resume I/O
Low
High
High
Low
Low
SUSCLK
Resume I/O
Running
Processor Interface
A20M#
CPU I/O
See Note 1
High
High
Off
Off
CPUPWRGD
Main I/O
See Note 3
High-Z
High-Z
Off
Off
CPUSLP#
CPU I/O
High
High
Defined
Off
Off
IGNNE#
CPU I/O
See Note 1
High
High
Off
Off
INIT#
CPU I/O
High
High
High
Off
Off
INTR
CPU I/O
See Note 1
Low
Low
Off
Off
NMI
CPU I/O
See Note 1
Low
Low
Off
Off
SMI#
CPU I/O
High
High
High
Off
Off
STPCLK#
CPU I/O
High
High
Low
Off
Off
Defined
Defined
Defined
Defined
Defined
Defined
Defined
Off
Off
SMBus Interface
SMBCLK, SMBDATA
Resume I/O
High-Z
High-Z
System Management Interface
SMLINK[1:0]
Resume I/O
High-Z
High-Z
Miscellaneous Signals
SPKR
Main I/O
Low with
Internal PullDown
Low
AC ’97 Interface
Resume I/O
Low
Low
Cold Reset
Bit (High)
Low
Low
AC_SDOUT
Main I/O
Low
Running
Low
Off
Off
AC_SYNC
Main I/O
Low
Running
Low
Off
Off
AC_RST#
Intel® 82801DB ICH4 Datasheet
61
Intel® ICH4 Power Planes and Pin States
Table 3-4. Power Plane and States for Output and I/O Signal (Sheet 4 of 4)
Signal Name
Power
Plane
During
PCIRST#4 /
RSMRST#5,7
Immediately
after
PCIRST#4 /
RSMRST#5
S1
S3
S4/S5
Unmuxed GPIO Signals
GPIO[18]
Main I/O
High
See Note 2
Defined
Off
Off
GPIO[19:20]
Main I/O
High
High
Defined
Off
Off
GPIO[21]
Main I/O
High
High
Defined
Off
Off
GPIO[22]
Main I/O
High-Z
High-Z
Defined
Off
Off
GPIO[23]
Main I/O
Low
Low
Defined
Off
Off
GPIO[24]
Resume I/O
High
High
Defined
Defined
Defined
GPIO[25]
Resume I/O
High
High
Defined
Defined
Defined
GPIO[27:28]
Resume I/O
High
High
Defined
Defined
Defined
GPIO[32:43]
Main I/O
High
High
Defined
Off
Off
NOTES:
1. ICH4 sets these signals at reset for processor frequency strap.
2. GPIO[18] will toggle at a frequency of approximately 1 Hz when the ICH4 comes out of reset
3. CPUPWRGD is an open-drain output that represents a logical AND of the ICH4’s VRMPWRGD and
PWROK signals, and thus will be driven low by ICH4 when either VRMPWRGD or PWROK are inactive.
During boot, or during a hard reset with power cycling, CPUPWRGD will be expected to transition from low to
High-Z.
4. The states of main I/O signals are taken at the times During PCIRST# and Immediately after PCIRST#.
5. The states of resume I/O signals are taken at the times During RSMRST# and Immediately after RSMRST#.
6. SLP_5# is high in the S4 state and asserted low in the S5 state.
7. SUSCLK is running during PCIRST#, but is driven low during RSMRST#.
62
Intel® 82801DB ICH4 Datasheet
Intel® ICH4 Power Planes and Pin States
3.5
Power Planes for Input Signals
Table 3-5 shows the power plane associated with each input signal, as well as what device drives
the signal at various times. Valid states include:
High
Low
Static: Will be high or low, but will not change
Driven: Will be high or low, and is allowed to change
Running: For input clocks
Table 3-5. Power Plane for Input Signals (Sheet 1 of 2)
Signal Name
Power Well
Driver During Reset
S1
S3
S5
A20GATE
Main I/O
External Microcontroller
Static
Low
Low
AC_BIT_CLK
Main I/O
AC ’97 Codec
Low
Low
Low
AC_SDIN[2:0]
Resume I/O
AC ’97 Codec
Low
Low
Low
APICCLK
Main I/O
Clock Generator
Running
Low
Low
CLK14
Main I/O
Clock Generator
Running
Low
Low
CLK48
Main I/O
Clock Generator
Running
Low
Low
CLK66
Main Logic
Clock Generator
Running
Low
Low
EE_DIN
Resume I/O
EEPROM Component
Driven
Driven
Driven
FERR#
CPU I/O
External Pull-Up
Static
High
High
RTC
External Switch
Driven
Driven
Driven
IRQ[15:14]
Main I/O
IDE
Static
Low
Low
LAN_CLK
Resume I/O
LAN Connect Component
Driven
Driven
Driven
LAN_RXD[2:0]
INTRUDER#
Resume I/O
LAN Connect Component
Driven
Driven
Driven
LDRQ[0]#
Main I/O
LPC Devices
High
Low
Low
LDRQ[1]#
Main I/O
LPC Devices
High
Low
Low
OC[5:0]#
Resume I/O
External Pull-Ups
Driven
Driven
Driven
PCICLK
Main I/O
Clock Generator
Running
Low
Low
PDDREQ
Main I/O
IDE Device
Static
Low
Low
PIORDY
Main I/O
IDE Device
Static
Low
Low
PME#
Resume I/O
Internal Pull-Up
Driven
Driven
Driven
PWRBTN#
Resume I/O
Internal Pull-Up
Driven
Driven
Driven
RTC
System Power Supply
Driven
Low
Low
RCIN#
Main I/O
External Microcontroller
High
Low
Low
REQ[0:5]#
Main I/O
PCI Master
Driven
Low
Low
Main I/O
PC/PCI Devices
Driven
Low
Low
Resume I/O
Serial Port Buffer
Driven
Driven
Driven
PWROK
REQ[B:A]#
RI#
Intel® 82801DB ICH4 Datasheet
63
Intel® ICH4 Power Planes and Pin States
Table 3-5. Power Plane for Input Signals (Sheet 2 of 2)
Signal Name
64
Power Well
Driver During Reset
S1
S3
S5
LAN_RST#
Resume I/O
External RC Circuit
High
High
High
RSMRST#
RTC
External RC Circuit
High
High
High
RTCRST#
RTC
External RC Circuit
High
High
High
SDDREQ
Main I/O
IDE Drive
Static
Low
Low
SERR#
Main I/O
PCI Bus Peripherals
High
Low
Low
SIORDY
Main I/O
IDE Drive
Static
Low
Low
SMBALERT#
Resume I/O
External Pull-Up
Driven
Driven
Driven
SYS_RESET#
Resume I/O
External Circuit
Driven
Driven
Driven
THRM#
Main I/O
Thermal Sensor
Driven
Low
Low
THRMTRIP#
CPU I/O
External Pull-Up
Driven
High
High
USBRBIAS#
Resume I/O
External Pull-Down
Driven
Driven
Driven
VRMPWRGD
Main I/O
CPU Voltage Regulator
High
Low
Low
Intel® 82801DB ICH4 Datasheet
Intel® ICH4 and System Clock Domains
Intel® ICH4 and System Clock Domains 4
Table 4-1 shows the system clock domains. Figure 4-1 shows the assumed connection of the
various system components, including the clock generator in both desktop and mobile systems. For
complete details of the system clocking solution refer to the system’s clock generator component
specification.
Table 4-1. Intel® ICH4 and System Clock Domains
Clock
Domain
Frequency
Source
Usage
ICH4
CLK66
66 MHz
Main Clock
Generator
Hub I/F, processor I/F. AGP. Shut off during S3 or below.
ICH4
PCICLK
33 MHz
Main Clock
Generator
Free-running PCI Clock to ICH4. This clock remains on
during S0 and S1 state, and is expected to be shut off
during S3 or below .
System PCI
33 MHz
Main Clock
Generator
PCI Bus, LPC I/F. These only go to external PCI and LPC
devices.
ICH4
CLK48
48 MHz
Main Clock
Generator
Super I/O, USB controllers. Expected to be shut off during
S3 or below
ICH4
CLK14
14.31818 MHz
Main Clock
Generator
Used for ACPI timer. Expected to be shut off during S3 or
below
ICH4
AC_BIT_CLK
12.288 MHz
AC ’97 Codec
AC-link. Generated by AC ’97 Codec. Can be shut by
codec in D3. Expected to be shut off during S3 or below
ICH4
APICCLK
33 MHz
Main Clock
Generator
LAN_CLK
5 to 50 MHz
LAN Connect
Component
Intel® 82801DB ICH4 Datasheet
Used for ICH4-CPU interrupt messages. Runs up to
33 MHz. Expected to be shut off during S3 or below
Generated by the LAN Connect component. Expected to
be shut off during S3 or below
65
Intel® ICH4 and System Clock Domains
Figure 4-1. Conceptual System Clock Diagram
66 MHz
33 MHz
APIC CLK
Intel®
ICH4
14.31818 MHz
48 MHz
48 MHz
50 MHz
66
PCI Clocks
(33 MHz)
14.31818 MHz
12.288 MHz
32 kHz
XTAL
Clock
Gen.
AC ’97 Codec(s)
LAN Connect
SUSCLK# (32 kHz)
Intel® 82801DB ICH4 Datasheet
Functional Description
Functional Description
5
This chapter describes the functions and interfaces of the ICH4.
5.1
Hub Interface to PCI Bridge (D30:F0)
The hub interface to PCI Bridge resides in PCI Device 30, Function 0 on bus #0. This portion of the
ICH4 implements the buffering and control logic between PCI and the hub interface. The
arbitration for the PCI bus is handled by this PCI device. The PCI decoder in this device must
decode the ranges for the hub interface. All register contents will be lost when core well power is
removed.
5.1.1
PCI Bus Interface
The ICH4 PCI interface provides a 33 MHz, PCI Local Bus Specification, Revision 2.2-compliant
implementation. All PCI signals are 5 V tolerant. The ICH4 integrates a PCI arbiter that supports
up to six external PCI bus masters in addition to the internal ICH4 requests.
Note that most transactions targeted to the ICH4 will first appear on the external PCI bus before
being claimed back by the ICH4. The exceptions are I/O cycles involving USB, IDE, and AC ’97.
These transactions will complete over the hub interface without appearing on the external PCI bus.
Configuration cycles targeting USB, IDE or AC ’97 will appear on the PCI bus. If the ICH4 is
programmed for positive decode, the ICH4 will claim the cycles appearing on the external PCI bus
in medium decode time. If the ICH4 is programmed for subtractive decode, the ICH4 will claim
these cycles in subtractive time. If the ICH4 is programmed for subtractive decode, these cycles
can be claimed by another positive decode agent out on PCI. This architecture enables the ability to
boot off of a PCI card that positively decodes the boot cycles. In order to boot off a PCI card it is
necessary to keep the ICH4 in subtractive decode mode. When booting off a PCI card, the
BOOT_STS bit (bit 2, TCO2 Status Register) will be set.
Note:
The ICH4’s AC ’97, IDE and USB controllers cannot perform peer-to-peer traffic.
Note:
Poor performing PCI devices that cause long latencies (numerous retries) to processor-to-PCI
Locked cycles may starve isochronous transfers between USB or AC ’97 devices and memory.
This will result in overrun or underrun, causing reduced quality of the isochronous data
(e.g., audio).
Note:
PCI configuration write cycles, initiated by the processor, with the following characteristics will be
converted to a Special Cycle with the Shutdown message type.
• Device Number (AD[15:11]) = 11111
• Function Number (AD[10:8]) = 111
• Register Number (AD[7:2]) = 000000
• Data = 00h
• Bus number matches secondary bus number
Intel® 82801DB ICH4 Datasheet
67
Functional Description
5.1.2
Note:
If the processor issues a locked cycle to a resource that is too slow (e.g., PCI), the ICH4 will not
allow upstream requests to be performed until the cycle completion. This may be critical for
isochronous buses which assume certain timing for their data flow (e.g., AC ’97 or USB). Devices
on these buses may suffer from underrun if the asynchronous traffic is too heavy. Underrun means
that the same data is sent over the bus while ICH4 is not able to issue a request for the next data.
Snoop cycles are not permitted while the front side bus is locked.
Note:
Locked cycles are assumed to be rare. Locks by PCI targets are assumed to exist for a short
duration (a few microseconds at most). If a system has a very large number of locked cycles and
some that are very long, then the system will definitely experience underruns and overruns. The
units most likely to have problems are the AC ’97 controller and the USB controllers. Other units
could get underruns/overruns, but are much less likely. The IDE controller (due to its stalling
capability on the cable) should not get any underruns or overruns.
PCI-to-PCI Bridge Model
From a software perspective, the ICH4 contains a PCI-to-PCI bridge. This bridge connects the hub
interface to the PCI bus. By using the PCI-to-PCI bridge software model, the ICH4 can have its
decode ranges programmed by existing plug-and-play software such that PCI ranges do not
conflict with AGP and graphics aperture ranges in the host controller.
5.1.3
IDSEL to Device Number Mapping
When addressing devices on the external PCI bus (with the PCI slots) the ICH4 will assert one
address signal as an IDSEL. When accessing device 0, the ICH4 will assert AD16. When accessing
Device 1, the ICH4 will assert AD17. This mapping continues all the way up to device 15 where
the ICH4 asserts AD31. Note that the ICH4’s internal functions (AC ’97, IDE, USB, and PCI
Bridge) are enumerated like they are on a separate PCI bus (the hub interface) from the external
PCI bus. The integrated LAN controller is Device 8 on the ICH4’s PCI bus, and hence it uses
AD24 for IDSEL
5.1.4
SERR# Functionality
There are several internal and external sources that can cause SERR#. The ICH4 can be
programmed to cause an NMI based on detecting that an SERR# condition has occurred. The NMI
can also be routed to instead cause an SMI#. Note that the ICH4 does not drive the external PCI bus
SERR# signal active onto the PCI bus. The external SERR# signal is an input into the ICH4 driven
only by external PCI devices. The conceptual logic diagrams in Figure 5-1 and Figure 5-2 illustrate
all sources of SERR#, along with their respective enable and status bits. Figure 5-3 shows how the
ICH4 error reporting logic is configured for NMI# generation.
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Intel® 82801DB ICH4 Datasheet
Functional Description
Figure 5-1. Primary Device Status Register Error Reporting Logic
D30:F0 BRIDGE_CNT
[Parity Error Response Enable]
D30:F0 BRIDGE_CNT
[SERR# Enable]
AND
AND
PCI Address Parity Error
D30:F0 PD_STS
[SSE]
D30:F0 CMD
[SERR_EN]
OR
D30:F0 ERR_STS
[SERR_DTT]
D30:F0 CMD
[SERR_EN]
Delayed Transaction Timeout
D30:F0 ERR_CMD
[SERR_DTT_EN]
AND
AND
SERR# Pin
D30:F0 BRIDGE_CNT
[SERR# Enable]
D30:F0 ERR_CMD
[SERR_RTA_EN]
AND
OR
AND
Received Target Abort
D30:F0 ERR_STS
[SERR_RTA]
Figure 5-2. Secondary Status Register Error Reporting Logic
D30:F0 BRIDGE_CNT
[SERR# Enable]
AND
D30:F0 SECSTS
[SSE]
PCI Delayed Transaction Timeout
D31:F0 D31_ERR_CFG
[SERR_DTT_EN]
AND
LPC Device Signaling an Error
IOCHK# via SERIRQ
OR
TCO1_STS
[HUBERR_STS]
D31:F0 D31_ERR_CFG
[SERR_RTA_EN]
AND
Received Target Abort
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Functional Description
Figure 5-3. NMI# Generation Logic
NMI_SC
[IOCHK_NMI_STS]
IOCHK From SERIRQ Logic
AND
NMI_SC
[IOCHK_NMI_EN]
NMI_SC
[SERR#_NMI_STS]
NMI_SC
[PCI_SERR_EN]
AND
D30:F0 SECSTS
[SSE]
D30:F0 PDSTS
[SSE]
OR
TCO1_STS
[HUBNMI_STS]
TCO1_CNT
[NMI_NOW]
OR
AND
OR
Hub Interface Parity
Error Detected
To NMI#
Output
and
Gating
Logic
AND
D30:F0 CMD
[Parity Error Response]
D30:F0 PD_STS
[DPD]
PCI Parity Error detected
during AC'97, IDE or USB
Master Cycle
AND
D30:F0 BRIDGE_CNT
[Parity Error Response
Enable]
OR
D30:F0 SECSTS
[DPD]
NMI_EN
[NMI_EN]
PCI Parity Error detected
during LPC or Legacy DMA
Master Cycle
D31:F0 PCICMD
[PER]
5.1.5
AND
D31:F0 PCISTA
[DPED]
Parity Error Detection
The ICH4 can detect and report different parity errors in the system. The ICH4 can be programmed
to cause an NMI (or SMI# if NMI is routed to SMI#) based on detecting a parity error. The
conceptual logic diagram in Figure 5-3 details all the parity errors that the ICH4 can detect, along
with their respective enable bits, status bits, and the results.
Note:
70
If NMIs are enabled, and parity error checking on PCI is also enabled, then parity errors will cause
an NMI. Some operating systems will not attempt to recover from this NMI, since it considers the
detection of a PCI error to be a catastrophic event.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.1.6
Standard PCI Bus Configuration Mechanism
The PCI Bus defines a slot based “configuration space” that allows each device to contain up to
eight functions with each function containing up to 256, 8-bit configuration registers. The PCI
specification defines two bus cycles to access the PCI configuration space: Configuration Read and
Configuration Write. Memory and I/O spaces are supported directly by the processor.
Configuration space is supported by a mapping mechanism implemented within the ICH4. The PCI
specification defines two mechanisms to access configuration space, Mechanism #1 and
Mechanism #2. The ICH4 only supports Mechanism #1.
Configuration cycles for PCI Bus #0 devices #2 through #31, and for PCI Bus numbers greater than
0 will be sent towards the ICH4 from the host controller. The ICH4 compares the non-zero Bus
Number with the Secondary Bus Number and Subordinate Bus number registers of its PCI-to-PCI
bridge to determine if the configuration cycle is meant for Primary PCI or a downstream PCI bus.
Note:
5.1.6.1
Configuration writes to internal ICH4 USB EHCI (D29:F7) and AC ’97 (D31:F5, F6) devices
when disabled are illegal and may cause undefined results.
Type 0 to Type 0 Forwarding
When a Type 0 configuration cycle is received on hub interface to any function other than USB
EHCI or AC ’97, the ICH4 forwards these cycles to PCI and then reclaims them. The ICH4 uses
address bits AD[15:13] to communicate the ICH4 device numbers in Type 0 configuration cycles.
If the Type 0 cycle on hub interface specifies any device number other than 29, 30 or 31, the ICH4
will not set any address bits in the range AD[31:11] during the corresponding transaction on PCI.
Table 5-1 shows the device number translation.
Table 5-1. Type 0 Configuration Cycle Device Number Translation
Device # In Hub Interface Type 0 Cycle
AD[31:11] During Address Phase of Type 0 Cycle on PCI
0 through 28
0000000000000000_00000b
29
0000000000000000_00100b
30
0000000000000000_01000b
31
0000000000000000_10000b
The ICH4 logic will generate single DWord configuration read and write cycles on the PCI bus.
The ICH4 will generate a Type 0 configuration cycle for configurations to the bus number
matching the PCI bus. Type 1 configuration cycles will be converted to Type 0 cycles in this case.
If the cycle is targeting a device behind an external bridge, the ICH4 will run a Type 1 cycle on the
PCI bus.
5.1.6.2
Type 1 to Type 0 Conversion
When the bus number for the Type 1 configuration cycle matches the PCI (Secondary) bus number,
the ICH4 will convert the address as follows:
1. For device numbers 0 through 15, only one bit of the PCI address [31:16] will be set. If the
device number is 0, AD[16] is set; if the device number is 1, AD[17] is set; etc.
2. The ICH4 will always drive zeros on bits AD[15:11] when converting Type 1 configurations
cycles to Type 0 configuration cycles on PCI.
3. Address bits [10:1] will also be passed unchanged to PCI.
4. Address bit 0 will be changed to 0.
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Functional Description
5.1.7
PCI Dual Address Cycle (DAC) Support
The ICH4 supports Dual Address Cycle (DAC) format on PCI for cycles from PCI initiators to
main memory. This allows PCI masters to generate an address up to 44 bits. The size of the actual
supported memory space will be determined by the Memory controller and the processor.
The DAC mode is only supported for PCI adapters and USB EHCI, and is not supported for any of
the internal PCI masters (IDE, LAN, USB UHCI, AC ’97, 8237 DMA, etc.).
When a PCI master wants to initiate a cycle with an address above 4 GB, it follows the following
behavioral rules (See PCI Local Bus Specification, Revision 2.2, Section 3.9 for more details):
1. On the first clock of the cycle (when FRAME# is first active), the peripheral uses the DAC
encoding on the C/BE# signals. This unique encoding is: 1101.
2. Also during the first clock, the peripheral drives the AD[31:0] signals with the low address.
3. On the second clock, the peripheral drives AD[31:0] with the high address. The address is
right justified: A[43:32] appear on AD[12:0]. The value of AD[31:13] is expected to be 0,
however the ICH4 will ignore these bits. C/BE# indicate the bus command type (Memory
Read, Memory Write, etc.)
4. The rest of the cycle proceeds normally.
5.2
LAN Controller (B1:D8:F0)
The ICH4’s integrated LAN controller includes a 32-bit PCI controller that provides enhanced
scatter-gather bus mastering capabilities and enables the LAN controller to perform high-speed
data transfers over the PCI bus. Its bus master capabilities enable the component to process high
level commands and perform multiple operations, which lowers processor utilization by offloading communication tasks from the processor. Two large transmit and receive FIFOs of 3 KB
each help prevent data underruns and overruns while waiting for bus accesses. This enables the
integrated LAN controller to transmit data with minimum interframe spacing (IFS).
The ICH4 integrated LAN controller can operate in either full-duplex or half-duplex mode. In fullduplex mode the LAN controller adheres with the IEEE 802.3x Flow Control specification. Half
duplex performance is enhanced by a proprietary collision reduction mechanism.
The integrated LAN controller also includes an interface to a serial (4-pin) EEPROM. The
EEPROM provides power-on initialization for hardware and software configuration parameters.
From a software perspective, the integrated LAN controller appears to reside on the secondary side
of the ICH4’s virtual PCI-to-PCI Bridge (see Section 5.1.2). This is typically Bus 1, but may be
assigned a different number, depending on system configuration.
The following summarizes the ICH4 LAN controller features:
• Compliance with Advanced Configuration and Power Interface and PCI Power Management
•
•
•
•
•
•
•
72
standards
Support for wake-up on interesting packets and link status change
Support for remote power-up using Wake on LAN (WOL) technology
Deep power-down mode support
Support of Wired for Management (WfM) Rev 2.0
Backward compatible software with 82557, 82558 and 82559
TCP/UDP checksum off load capabilities
Support for Intel’s Adaptive Technology
Intel® 82801DB ICH4 Datasheet
Functional Description
5.2.1
LAN Controller Architectural Overview
Figure 5-4 is a high level block diagram of the ICH4 integrated LAN controller. It is divided into
four main subsystems: a Parallel subsystem, a FIFO subsystem and the Carrier-Sense Multiple
Access with Collision Detect (CSMA/CD) unit.
Figure 5-4. Integrated LAN Controller Block Diagram
EEPROM
Interface
PCI Target and
EEPROM Interface
3 Kbyte
Tx FIFO
Four Channel
Addressing Unit DMA
PCI
Interface
PCI Bus
Interface Unit
(BIU)
Micromachine
FIFO Control
Dual
Ported
FIFO
3 Kbyte
Rx FIFO
Data Interface Unit
(DIU)
5.2.1.1
CSMA/CD
Unit
LAN
Connect
Interface
Parallel Subsystem Overview
The parallel subsystem is broken down into several functional blocks: a PCI bus master interface, a
micromachine processing unit and its corresponding microcode ROM, and a PCI Target Control/
EEPROM/ interface. The parallel subsystem also interfaces to the FIFO subsystem, passing data
(such as transmit, receive, and configuration data) and command and status parameters between
these two blocks.
The PCI bus master interface provides a complete interface to the PCI bus and is compliant with
the PCI Local Bus Specification, Revision 2.2. The LAN controller provides 32 bits of addressing
and data, as well as the complete control interface to operate on the PCI bus. As a PCI target, it
follows the PCI configuration format which allows all accesses to the LAN controller to be
automatically mapped into free memory and I/O space upon initialization of a PCI system. For
processing of transmit and receive frames, the integrated LAN controller operates as a master on
the PCI bus, initiating zero wait-state transfers for accessing these data parameters.
The LAN controller Control/Status Register Block is part of the PCI target element. The Control/
Status Register block consists of the following LAN controller internal control registers: System
Control Block (SCB), PORT, EEPROM Control and Management Data Interface (MDI) Control.
The micromachine is an embedded processing unit contained in the LAN controller that enables
Adaptive Technology. The micromachine accesses the LAN controller’s microcode ROM, working
its way through the opcodes (or instructions) contained in the ROM to perform its functions.
Parameters accessed from memory (e.g., pointers to data buffers) are also used by the
micromachine during the processing of transmit or receive frames by the LAN controller. A typical
micromachine function is to transfer a data buffer pointer field to the LAN controller’s DMA unit
for direct access to the data buffer. The micromachine is divided into two units, Receive Unit and
Command Unit which includes transmit functions. These two units operate independently and
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73
Functional Description
concurrently. Control is switched between the two units according to the microcode instruction
flow. The independence of the Receive and Command units in the micromachine allows the LAN
controller to execute commands and receive incoming frames simultaneously, with no real-time
processor intervention.
The LAN controller contains an interface to an external serial EEPROM. The EEPROM is used to
store relevant information for a LAN connection such as node address, as well as board
manufacturing and configuration information. Both read and write accesses to the EEPROM are
supported by the LAN controller. Information on the EEPROM interface is detailed in
Section 5.2.3.
5.2.1.2
FIFO Subsystem Overview
The ICH4 LAN controller FIFO subsystem consists of a 3-KB transmit FIFO and 3-KB receive
FIFO. Each FIFO is unidirectional and independent of the other. The FIFO subsystem serves as the
interface between the LAN controller parallel side and the serial CSMA/CD unit. It provides a
temporary buffer storage area for frames as they are either being received or transmitted by the
LAN controller, which improves performance:
• Transmit frames can be queued within the transmit FIFO, allowing back-to-back transmission
within the minimum Interframe Spacing (IFS).
• The storage area in the FIFO allows the LAN controller to withstand long PCI bus latencies
without losing incoming data or corrupting outgoing data.
• The ICH4 LAN controller’s transmit FIFO threshold allows the transmit start threshold to be
tuned to eliminate underruns while concurrent transmits are being performed.
• The FIFO subsection allows extended PCI zero wait-state burst accesses to or from the LAN
controller for both transmit and receive frames since the transfer is to the FIFO storage area
rather than directly to the serial link.
• Transmissions resulting in errors (collision detection or data underrun) are retransmitted
directly from the LAN controller’s FIFO, increasing performance and eliminating the need to
re-access this data from the host system.
• Incoming runt receive frames (in other words, frames that are less than the legal minimum
frame size) can be discarded automatically by the LAN controller without transferring this
faulty data to the host system.
5.2.1.3
Serial CSMA/CD Unit Overview
The CSMA/CD unit of the ICH4 LAN controller allows it to be connected to the 82562ET/EM
10/100 Mbps Ethernet LAN Connect components. The CSMA/CD unit performs all of the
functions of the 802.3 protocol (e.g., frame formatting, frame stripping, collision handling, deferral
to link traffic, etc.). The CSMA/CD unit can also be placed in a full-duplex mode which allows
simultaneous transmission and reception of frames.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.2.2
LAN Controller PCI Bus Interface
As a Fast Ethernet controller, the role of the ICH4 integrated LAN controller is to access
transmitted data or deposit received data. The LAN controller, as a bus master device, will initiate
memory cycles via the PCI bus to fetch or deposit the required data.
To perform these actions, the LAN controller is controlled and examined by the processor via its
control and status structures and registers. Some of these control and status structures reside in the
LAN controller and some reside in system memory. For access to the LAN controller’s Control/
Status Registers (CSR), the LAN controller acts as a slave (in other words, a target device). The
LAN controller serves as a slave also while the processor accesses the EEPROM.
5.2.2.1
Bus Slave Operation
The ICH4 integrated LAN controller serves as a target device in one of the following cases:
• Processor accesses to the LAN controller System Control Block (SCB) Control/Status
Registers (CSR)
• Processor accesses to the EEPROM through its CSR
• Processor accesses to the LAN controller PORT address via the CSR
• Processor accesses to the MDI control register in the CSR
The size of the CSR memory space is 4 KB in the memory space and 64 bytes in the I/O space. The
LAN controller treats accesses to these memory spaces differently.
Control/Status Register (CSR) Accesses
The integrated LAN controller supports zero wait-state single cycle memory or I/O mapped
accesses to its CSR space. Separate BARs request 4 KB of memory space and 64 bytes of I/O space
to accomplish this. Based on its needs, the software driver will use either memory or I/O mapping
to access these registers. The LAN controller provides four valid Kbytes of CSR space, which
include the following elements:
•
•
•
•
•
System Control Block (SCB) registers
PORT register
EEPROM control register
MDI control register
Flow control registers
In the case of accessing the Control/Status Registers, the processor is the initiator and the LAN
controller is the target.
Read Accesses: The processor, as the initiator, drives address lines AD[31:0], the command and
byte enable lines C/BE[3:0]# and the control lines IRDY# and FRAME#. As a slave, the LAN
controller controls the TRDY# signal and provides valid data on each data access. The LAN
controller allows the processor to issue only one read cycle when it accesses the Control/Status
Registers, generating a disconnect by asserting the STOP# signal. The processor can insert waitstates by deasserting IRDY# when it is not ready.
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Functional Description
Write Accesses: The processor, as the initiator, drives the address lines AD[31:0], the command
and byte enable lines C/BE[3:0]# and the control lines IRDY# and FRAME#. It also provides the
LAN controller with valid data on each data access immediately after asserting IRDY#. The LAN
controller controls the TRDY# signal and asserts it from the data access. The LAN controller
allows the processor to issue only one I/O write cycle to the Control/Status Registers, generating a
disconnect by asserting the STOP# signal. This is true for both memory mapped and I/O mapped
accesses.
Retry Premature Accesses
The LAN controller responds with a Retry to any configuration cycle accessing the LAN controller
before the completion of the automatic read of the EEPROM. The LAN controller may continue to
retry any configuration accesses until the EEPROM read is complete. The LAN controller does not
enforce the rule that the retried master must attempt to access the same address again in order to
complete any delayed transaction. Any master access to the LAN controller after the completion of
the EEPROM read will be honored.
Error Handling
Data Parity Errors: The LAN controller checks for data parity errors while it is the target of the
transaction. If an error was detected, the LAN controller always sets the Detected Parity Error bit in
the PCI Configuration Status register, bit 15. The LAN controller also asserts PERR#, if the Parity
Error Response bit is set (PCI Configuration Command register, bit 6). The LAN controller does
not attempt to terminate a cycle in which a parity error was detected. This gives the initiator the
option of recovery.
Target-Disconnect: The LAN controller prematurely terminates a cycle in the following cases:
• After accesses to its CSR
• After accesses to the configuration space
System Error: The LAN controller reports parity error during the address phase using the SERR#
pin. If the SERR# Enable bit in the PCI Configuration Command register or the Parity Error
Response bit are not set, the LAN controller only sets the Detected Parity Error bit (PCI
Configuration Status register, bit 15). If SERR# Enable and Parity Error Response bits are both set,
the LAN controller sets the Signaled System Error bit (PCI Configuration Status register, bit 14) as
well as the Detected Parity Error bit and asserts SERR# for one clock.
The LAN controller, when detecting system error, will claim the cycle if it was the target of the
transaction and continue the transaction as if the address was correct.
Note:
76
The LAN controller reports a system error for any error during an address phase, whether or not it
is involved in the current transaction.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.2.2.2
Bus Master Operation
As a PCI Bus Master, the ICH4 integrated LAN controller initiates memory cycles to fetch data for
transmission or deposit received data and for accessing the memory resident control structures. The
LAN controller performs zero wait-state burst read and write cycles to the host main memory. For
bus master cycles, the LAN controller is the initiator and the host main memory (or the PCI host
bridge, depending on the configuration of the system) is the target.
The processor provides the LAN controller with action commands and pointers to the data buffers
that reside in host main memory. The LAN controller independently manages these structures and
initiates burst memory cycles to transfer data to and from them. The LAN controller uses the
Memory Read Multiple (MR Multiple) command for burst accesses to data buffers and the
Memory Read Line (MR Line) command for burst accesses to control structures. For all write
accesses to the control structure, the LAN controller uses the Memory Write (MW) command. For
write accesses to data structure, the LAN controller may use either the Memory Write or Memory
Write and Invalidate (MWI) commands.
Read Accesses: The LAN controller performs block transfers from host system memory in order
to perform frame transmission on the serial link. In this case, the LAN controller initiates zero
wait-state memory read burst cycles for these accesses. The length of a burst is bounded by the
system and the LAN controller’s internal FIFO. The length of a read burst may also be bounded by
the value of the Transmit DMA Maximum Byte Count in the Configure command. The Transmit
DMA Maximum Byte Count value indicates the maximum number of transmit DMA PCI cycles
that will be completed after an LAN controller internal arbitration.
The LAN controller, as the initiator, drives the address lines AD[31:0], the command and byte
enable lines C/BE[3:0]# and the control lines IRDY# and FRAME#. The LAN controller asserts
IRDY# to support zero wait-state burst cycles. The target signals the LAN controller that valid data
is ready to be read by asserting the TRDY# signal.
Write Accesses: The LAN controller performs block transfers to host system memory during
frame reception. In this case, the LAN controller initiates memory write burst cycles to deposit the
data, usually without wait-states. The length of a burst is bounded by the system and the LAN
controller’s internal FIFO threshold. The length of a write burst may also be bounded by the value
of the Receive DMA Maximum Byte Count in the Configure command. The Receive DMA
Maximum Byte Count value indicates the maximum number of receive DMA PCI transfers that
will be completed before the LAN controller internal arbitration.
The LAN controller, as the initiator, drives the address lines AD[31:0], the command and byte
enable lines C/BE[3:0]# and the control lines IRDY# and FRAME#. The LAN controller asserts
IRDY# to support zero wait-state burst cycles. The LAN controller also drives valid data on
AD[31:0] lines during each data phase (from the first clock and on). The target controls the length
and signals completion of a data phase by deassertion and assertion of TRDY#.
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Functional Description
Cycle Completion: The LAN controller completes (terminates) its initiated memory burst cycles
in the following cases:
• Normal Completion: All transaction data has been transferred to or from the target device
(for example, host main memory).
• Backoff: Latency Timer has expired and the bus grant signal (GNT#) was removed from the
LAN controller by the arbiter, indicating that the LAN controller has been preempted by
another bus master.
• Transmit or Receive DMA Maximum Byte Count: The LAN controller burst has reached
the length specified in the Transmit or Receive DMA Maximum Byte Count field in the
Configure command block.
• Target Termination: The target may request to terminate the transaction with a targetdisconnect, target-retry, or target-abort. In the first two cases, the LAN controller initiates the
cycle again. In the case of a target-abort, the LAN controller sets the Received Target Abort bit
in the PCI Configuration Status field (PCI Configuration Status register, bit 12) and does not
re-initiate the cycle.
• Master Abort: The target of the transaction has not responded to the address initiated by the
LAN controller (in other words, DEVSEL# has not been asserted). The LAN controller simply
deasserts FRAME# and IRDY# as in the case of normal completion.
• Error Condition: In the event of parity or any other system error detection, the LAN
controller completes its current initiated transaction. Any further action taken by the LAN
controller depends on the type of error and other conditions.
Memory Write and Invalidate
The LAN controller has four Direct Memory Access (DMA) channels. Of these four channels, the
Receive DMA is used to deposit the large number of data bytes received from the link into system
memory. The Receive DMA uses both the Memory Write (MW) and the Memory Write and
Invalidate (MWI) commands. To use MWI, the LAN controller must guarantee the following:
• Minimum transfer of one cache line.
• Active byte enable bits (or BE[3:0]# are all low) during MWI access.
• The LAN controller may cross the cache line boundary only if it intends to transfer the next
cache line too.
To ensure the above conditions, the LAN controller may use the MWI command only under the
following conditions:
• The Cache Line Size (CLS) written in the CLS register during PCI configuration is 8 or 16
DWords.
•
•
•
•
•
78
The accessed address is cache line aligned.
The LAN controller has at least 8 or 16 DWords of data in its receive FIFO.
There are at least 8 or 16 DWords of data space left in the system memory buffer.
The MWI Enable bit in the PCI Configuration Command register, bit 4, should is set to 1b.
The MWI Enable bit in the LAN controller Configure command should is set to 1b.
Intel® 82801DB ICH4 Datasheet
Functional Description
If any one of the above conditions does not hold, the LAN controller will use the MW command. If
a MWI cycle has started and one of the conditions is no longer valid (for example, the data space in
the memory buffer is now less than CLS), then the LAN controller terminates the MWI cycle at the
end of the cache line. The next cycle will be either a MW or MWI cycle depending on the
conditions listed above.
If the LAN controller started a MW cycle and reached a cache line boundary, it either continues or
terminates the cycle depending on the Terminate Write on Cache Line configuration bit of the LAN
controller Configure command (byte 3, bit 3). If this bit is set, the LAN controller terminates the
MW cycle and attempts to start a new cycle. The new cycle is a MWI cycle if this bit is set and all
of the above listed conditions are met. If the bit is not set, the LAN controller continues the MW
cycle across the cache line boundary if required.
Read Align
The Read Align feature enhances the LAN controller’s performance in cache line oriented systems.
In these particular systems, starting a PCI transaction on a non-cache line aligned address may
cause low performance.
In order to resolve this performance anomaly, the LAN controller attempts to terminate transmit
DMA cycles on a cache line boundary and start the next transaction on a cache line aligned
address. This feature is enabled when the Read Align Enable bit is set in the LAN controller
Configure command (byte 3, bit 2).
If this bit is set, the LAN controller operates as follows:
• When the LAN controller is almost out of resources on the transmit DMA (i.e., the transmit
FIFO is almost full), it attempts to terminate the read transaction on the nearest cache line
boundary when possible.
• When the arbitration counter’s feature is enabled (i.e., the Transmit DMA Maximum Byte
Count value is set in the Configure command), the LAN controller switches to other pending
DMAs on cache line boundary only.
Note:
1. This feature is not recommended for use in non-cache line oriented systems since it may cause
shorter bursts and lower performance.
2. This feature should be used only when the CLS register in PCI Configuration space is set to 8
or 16.
3. The LAN controller reads all control data structures (including Receive Buffer Descriptors)
from the first DWord (even if it is not required) in order to maintain cache line alignment.
Error Handling
Data Parity Errors: As an initiator, the LAN controller checks and detects data parity errors that
occur during a transaction. If the Parity Error Response bit is set (PCI Configuration Command
register, bit 6), the LAN controller also asserts PERR# and sets the Data Parity Detected bit (PCI
Configuration Status register, bit 8). In addition, if the error was detected by the LAN controller
during read cycles, it sets the Detected Parity Error bit (PCI Configuration Status register, bit 15).
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79
Functional Description
5.2.2.3
PCI Power Management
Enhanced support for the power management standard, PCI Local Bus Specification, Revision 2.2,
is provided in the ICH4 integrated LAN controller. The LAN controller supports a large set of
wake-up packets and the capability to wake the system from a low power state on a link status
change. The LAN controller enables the host system to be in a sleep state and remain virtually
connected to the network.
After a power management event or link status change is detected, the LAN controller will wake
the host system. The sections below describe these events, the LAN controller power states, and
estimated power consumption at each power state.
Power States
The LAN controller contains power management registers for PCI, and implements all four power
states as defined in the Power Management Network Device Class Reference Specification,
Revision 1.0. The four states (D0 through D3) vary from maximum power consumption at D0 to
the minimum power consumption at D3. PCI transactions are only allowed in the D0 state, except
for host accesses to the LAN controller’s PCI configuration registers. The D1 and D2 power
management states enable intermediate power savings while providing the system wake-up
capabilities. In the D3 cold state, the LAN controller can provide wake-up capabilities. Wake-up
indications from the LAN controller are provided by the Power Management Event (PME#) signal.
• D0 Power State
As defined in the Network Device Class Reference Specification, the device is fully functional
in the D0 power state. In this state, the LAN controller receives full power and should be
providing full functionality. In the LAN controller the D0 state is partitioned into two
substates, D0 Uninitialized (D0u) and D0 Active (D0a).
D0u is the LAN controller’s initial power state following a PCI RST#. While in the D0u state,
the LAN controller has PCI slave functionality to support its initialization by the host and
supports Wake on LAN mode. Initialization of the CSR, Memory, or I/O Base Address
Registers in the PCI Configuration space switches the LAN controller from the D0u state to
the D0a state.
In the D0a state, the LAN controller provides its full functionality and consumes its nominal
power. In addition, the LAN controller supports wake on link status change (see
Section 5.2.2.5). While it is active, the LAN controller requires a nominal PCI clock signal (in
other words, a clock frequency greater than 16 MHz) for proper operation. The LAN controller
supports a dynamic standby mode. In this mode, the LAN controller is able to save almost as
much power as it does in the static power-down states. The transition to or from standby is
done dynamically by the LAN controller and is transparent to the software.
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Intel® 82801DB ICH4 Datasheet
Functional Description
• D1 Power State
In order for a device to meet the D1 power state requirements, as specified in the Advanced
Configuration and Power Interface (ACPI) Specification, Revision 2.0, it must not allow bus
transmission or interrupts; however, bus reception is allowed. Therefore, device context may
be lost and the LAN controller does not initiate any PCI activity. In this state, the LAN
controller responds only to PCI accesses to its configuration space and system wake-up events.
The LAN controller retains link integrity and monitors the link for any wake-up events (e.g.,
wake-up packets or link status chang)e. Following a wake-up event, the LAN controller asserts
the PME# signal.
• D2 Power State
The ACPI D2 power state is similar in functionality to the D1 power state. In addition to D1
functionality, the LAN controller can provide a lower power mode with wake-on-link status
change capability. The LAN controller may enter this mode if the link is down while the LAN
controller is in the D2 state. In this state, the LAN controller monitors the link for a transition
from an invalid to a valid link.
The sub-10 mA state due to an invalid link can be enabled or disabled by a configuration bit in
the Power Management Driver Register (PMDR). The LAN controller will consume in D2
<10 mA, regardless of the link status. It is the LAN Connect component that consumes much
less power during link down, hence LAN controller in this state can consume <10 mA.
• D3 Power State
In the D3 power state, the LAN controller has the same capabilities and consumes the same
amount of power as it does in the D2 state. However, it enables the PCI system to be in the B3
state. If the PCI system is in the B3 state (in other words, no PCI power is present), the LAN
controller provides wake-up capabilities. If PME is disabled, the LAN controller does not
provide wake-up capability or maintain link integrity. In this mode the LAN controller
consumes its minimal power.
The LAN controller enables a system to be in a sub-5 Watt state (low power state) and still be
virtually connected. More specifically, the LAN controller supports full wake-up capabilities
while it is in the D3 cold state. The LAN controller is in the ICH4 resume well, and thus is
connected to an auxiliary power source (V AUX), which enables it to provide wake-up
functionality while the PCI power is off.
5.2.2.4
PCI Reset Signal
The PCIRST# signal may be activated in one of the following cases:
• During S3–S5 states
• Due to a CF9h reset
If PME# is enabled (in the PCI power management registers), PCIRST# assertion does not affect
any PME# related circuits (in other words, PCI power management registers and the wake-up
packet would not be affected). While PCIRST# is active, the LAN controller ignores other PCI
signals. The configuration of the LAN controller registers associated with ACPI wake events is not
affected by PCIRST#.
The integrated LAN controller uses the PCIRST# or the PWROK signal as an indication to ignore
the PCI interface. Following the deassertion of PCIRST#, the LAN controller PCI Configuration
Space, MAC configuration, and memory structure are initialized while preserving the PME# signal
and its context.
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Functional Description
5.2.2.5
Wake-Up Events
There are two types of wake-up events: “Interesting” Packets and Link Status Change. These two
events are detailed below.
Note:
If the Wake on LAN bit in the EEPROM is not set, wake-up events are supported only if the PME
Enable bit in the Power Management Control/Status Register (PMCSR) is set. However, if the
Wake on LAN bit in the EEPROM is set, and Wake on Magic Packet* or Wake on Link Status
Change are enabled, the Power Management Enable bit is ignored with respect to these events. In
the latter case, PME# would be asserted by these events.
"Interesting" Packet Event
In the power-down state, the LAN controller is capable of recognizing “interesting” packets. The
LAN controller supports pre-defined and programmable packets that can be defined as any of the
following:
•
•
•
•
•
•
ARP Packets (with Multiple IP addresses)
Direct Packets (with or without type qualification)
Magic Packet
Neighbor Discovery Multicast Address Packet (“ARP” in IPv6 environment)
NetBIOS over TCP/IP (NBT) Query Packet (under IPv4)
Internetwork Package Exchange* (IPX) Diagnostic Packet
This allows the LAN controller to handle various packet types. In general, the LAN controller
supports programmable filtering of any packet in the first 128 bytes.
When the LAN controller is in one of the low power states, it searches for a predefined pattern in
the first 128 bytes of the incoming packets. The only exception is the Magic Packet, which is
scanned for the entire frame. The LAN controller will classify the incoming packets as one of the
following categories:
• No Match: The LAN controller discards the packet and continues to process the incoming
packets.
• TCO Packet: The LAN controller implements perfect filtering of TCO packets. After a TCO
packet is processed, the LAN controller is ready for the next incoming packet. TCO packets
are treated as any other wake-up packet and may assert the PME# signal if configured to do so.
• Wake-up Packet: The LAN controller is capable of recognizing and storing the first
128 bytes of a wake-up packet. If a wake-up packet is larger than 128 bytes, its tail is discarded
by the LAN controller. After the system is fully powered-up, software has the ability to
determine the cause of the wake-up event via the PMDR and dump the stored data to the host
memory.
Magic Packets are an exception. The Magic Packets may cause a power management event
and set an indication bit in the PMDR; however, it is not stored by the LAN controller for use
by the system when it is woken up.
Link Status Change Event
The LAN controller link status indication circuit is capable of issuing a PME on a link status
change from a valid link to an invalid link condition or vice versa. The LAN controller reports a
PME link status event in all power states. If the Wake on LAN bit in the EEPROM is not set, the
PME# signal is gated by the PME Enable bit in the PMCSR and the CSMA Configure command.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.2.2.6
Wake on LAN* (Preboot Wake-Up)
The LAN controller enters Wake on LAN mode after reset if the Wake on LAN bit in the EEPROM
is set. At this point, the LAN controller is in the D0u state.
When the LAN controller is in Wake on LAN mode:
• The LAN controller scans incoming packets for a Magic Packet and asserts the PME# signal
for 52 ms when a one is detected in Wake on LAN mode.
• The Activity LED changes its functionality to indicates that the received frame passed
Individual Address (IA) filtering or broadcast filtering.
• The PCI Configuration registers are accessible to the host.
The LAN controller switches from Wake on LAN mode to the D0a power state following a setup of
the Memory or I/O Base Address Registers in the PCI Configuration space.
5.2.3
Serial EEPROM Interface
The serial EEPROM stores configuration data for the ICH4 integrated LAN controller and is a
serial in/serial out device. The LAN controller supports a 64 register or 256 register size EEPROM
and automatically detects the EEPROM’s size. The EEPROM should operate at a frequency of at
least 1 MHz.
All accesses, either read or write, are preceded by a command instruction to the device. The
address field is six bits for a 64-register EEPROM or eight bits for a 256-register EEPROM. The
end of the address field is indicated by a dummy zero bit from the EEPROM, which indicates the
entire address field has been transferred to the device. An EEPROM read instruction waveform is
shown in Figure 5-5.
Figure 5-5. 64-Word EEPROM Read Instruction Waveform
EE_SHCLKK
EE_CS
A5
A4
A3
A2
AA10
A0
EE_DIN
READ OP code
D15
D0
EE_DOUT
The LAN controller performs an automatic read of seven words (0h, 1h, 2h, Ah, Bh, Ch and Dh) of
the EEPROM after the deassertion of Reset.
Intel® 82801DB ICH4 Datasheet
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Functional Description
5.2.4
CSMA/CD Unit
The ICH4 integrated LAN controller CSMA/CD unit implements both the IEEE 802.3 Ethernet
10 Mbps and IEEE 802.3u Fast Ethernet 100 Mbps standards. It performs all the CSMA/CD
protocol functions (e.g., transmission, reception, collision handling, etc.). The LAN controller
CSMA/CD unit interfaces to the 82562ET/EM 10/100 Mbps Ethernet through the ICH4’s LAN
Connect interface signals.
5.2.4.1
Full Duplex
When operating in full-duplex mode, the LAN controller can transmit and receive frames
simultaneously. Transmission starts regardless of the state of the internal receive path. Reception
starts when the LAN Connect component detects a valid frame on its receive differential pair. The
ICH4 integrated LAN controller also supports the IEEE 802.3x flow control standard, when in fullduplex mode.
The LAN controller operates in either half-duplex mode or full-duplex mode. For proper operation,
both the LAN controller CSMA/CD module and the discrete LAN Connect component must be set
to the same duplex mode. The CSMA duplex mode is set by the LAN controller Configure
command or forced by automatically tracking the mode in the LAN Connect component.
Following reset, the CSMA defaults to automatically track the LAN Connect component duplex
mode.
The selection of duplex operation (full or half) and flow control is done in two levels: MAC and
LAN Connect.
5.2.4.2
Flow Control
The LAN controller supports IEEE 802.3x frame-based flow control frames only in both full
duplex and half duplex switched environments. The LAN controller flow control feature is not
intended to be used in shared media environments.
Flow control is optional in full-duplex mode and is selected through software configuration. There
are three modes of flow control that can be selected: frame-based transmit flow control, framebased receive flow control, and none.
5.2.4.3
Address Filtering Modifications
The LAN controller can be configured to ignore one bit when checking for its Individual Address
(IA) on incoming receive frames. The address bit, known as the Upper/Lower (U/L) bit, is the
second least significant bit of the first byte of the IA. This bit may be used, in some cases, as a
priority indication bit. When configured to do so, the LAN controller passes any frame that
matches all other 47 address bits of its IA, regardless of the U/L bit value.
This configuration only affects the LAN controller specific IA and not multicast, multi-IA, or
broadcast address filtering. The LAN controller does not attribute any priority to frames with this
bit set, it simply passes them to memory regardless of this bit.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.2.4.4
VLAN Support
The LAN controller supports the IEEE 802.1 standard VLAN. All VLAN flows will be
implemented by software. The LAN controller supports the reception of long frames, specifically
frames longer than 1518 bytes, including the CRC, if software sets the Long Receive OK bit in the
Configuration command. Otherwise, “long” frames are discarded.
5.2.5
Media Management Interface
The management interface allows the processor to control the LAN Connect component via a
control register in the ICH4 integrated LAN controller. This allows the software driver to place the
LAN Connect in specific modes (e.g., full duplex, loopback, power down, etc.) without the need
for specific hardware pins to select the desired mode. This structure allows the LAN controller to
query the LAN Connect component for status of the link. This register is the MDI Control Register
and resides at offset 10h in the LAN controller CSR. The MDI registers reside within the LAN
Connect component, and are described in detail in the LAN Connect component’s datasheet. The
processor writes commands to this register and the LAN controller reads or writes the control/
status parameters to the LAN Connect component through the MDI register.
5.2.6
TCO Functionality
The ICH4 integrated LAN controller supports management communication to reduce Total Cost of
Ownership (TCO). It has a System Management Bus (SMB) on which the LAN controller is a
slave device. The SMB is used as an interface between the LAN controller and the integrated host
controller. An EEPROM of 256 words is required to support the heartbeat command.
5.2.6.1
Receive Functionality
In the power-up state, the LAN controller transfers TCO packets to the host as any other packet.
These packets include a new status indication bit in the Receive Frame Descriptor (RFD) status
register and have a specific port number indicating TCO packet recognition. In the power-down
state, the TCO packets are treated as wake-up packets. The ICH4 integrated LAN controller asserts
the PME# signal and delivers the first 120 bytes of the packet to the host.
5.2.6.2
Transmit Functionality
The ICH4 integrated LAN controller supports the Heartbeat (HB) transmission command from the
SMB interface. The send HB packet command includes a system health status issued by the
integrated system controller. The LAN controller computes a matched checksum and CRC and will
transmit the HB packet from its serial EEPROM. The HB packet size and structure are not limited
as long as it fits within the EEPROM size. In this case, the EEPROM size is 256 words to enable
the storage of the HB packet (the first 64 words are used for driver specific data).
Note:
On the SMB, the send heartbeat packet command is not normally used in the D0 power state. The
one exception in which it is used in the D0 state is when the system is hung. In normal operating
mode, the heartbeat packets are transmitted through the ICH4 integrated LAN controller software
similar to other packets.
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85
Functional Description
5.3
LPC Bridge (w/ System and Management Functions)
(D31:F0)
The LPC Bridge function of the ICH4 resides in PCI Device 31:Function 0. In addition to the LPC
bridge function, D31:F0 contains other functional units including DMA, Interrupt controllers,
Timers, Power Management, System Management, GPIO, and RTC. In this chapter, registers and
functions associated with other functional units (power management, GPIO, USB, IDE, etc.) are
described in their respective sections.
5.3.1
LPC Interface
The ICH4 implements an LPC interface as described in the LPC 1.0 specification. The LPC
interface to the ICH4 is shown in Figure 5-6. Note that the ICH4 implements all of the signals that
are shown as optional, but peripherals are not required to do so.
Figure 5-6. LPC Interface Diagram
PCI Bus
PCI
CLK
PCI
RST#
PCI
SERIRQ
PCI
PME#
LAD[3:0]
LFRAME#
Intel® ICH4
LDRQ#
(optional)
86
SUS_STAT#
LPCPD#
(optional)
GPI
LSMI#
(optional)
Super I/O
Intel® 82801DB ICH4 Datasheet
Functional Description
5.3.1.1
LPC Cycle Types
The ICH4 implements all of the cycle types described in the Low Pin Count Interface
Specification, Revision 1.0. Table 5-2 shows the cycle types supported by the ICH4.
Table 5-2. LPC Cycle Types Supported
Cycle Type
Memory Read
Memory Write
Comment
Single: 1 byte only
Single: 1 byte only
I/O Read
1 byte only. Intel® ICH4 breaks up 16- and 32-bit processor cycles into multiple 8-bit
transfers. (See Note 1)
I/O Write
1 byte only. ICH4 breaks up 16- and 32-bit processor cycles into multiple 8-bit
transfers. (See Note 1)
DMA Read
Can be 1, or 2 bytes
DMA Write
Can be 1, or 2 bytes
Bus Master Read
Can be 1, 2, or 4 bytes. (See Note 2)
Bus Master Write
Can be 1, 2, or 4 bytes. (See Note 2)
NOTES:
1. For memory cycles below 16 MB which do not target enabled FWH ranges, the ICH4 performs standard LPC
memory cycles. It only attempts 8-bit transfers. If the cycle appears on PCI as a 16-bit transfer, it will appear
as two consecutive 8-bit transfers on LPC. Likewise, if the cycle appears as a 32-bit transfer on PCI, it will
appear as four consecutive 8-bit transfers on LPC. If the cycle is not claimed by any peripheral, it will be
subsequently aborted, and the ICH4 will return a value of all ones to the processor. This is done to maintain
compatibility with ISA memory cycles where pull-up resistors would keep the bus high if no device responds.
2. Bus Master Read or Write cycles must be naturally aligned. For example, a 1-byte transfer can be to any
address. However, the 2-byte transfer must be word aligned (i.e., with an address where A0=0). A DWord
transfer must be DWord aligned (i.e., with an address where A1and A0 are both 0).
5.3.1.2
Start Field Definition
Table 5-3. Start Field Bit Definitions
Bits[3:0]
Encoding
Definition
0000
Start of cycle for a generic target
0010
Grant for bus master 0
0011
Grant for bus master 1
1111
Stop/Abort: End of a cycle for a target.
NOTE: All other encodings are RESERVED.
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Functional Description
5.3.1.3
Cycle Type / Direction (CYCTYPE + DIR)
The ICH4 will always drive bit 0 of this field to 0. Peripherals running bus master cycles must also
drive bit 0 to 0. Table 5-4 shows the valid bit encodings:
Table 5-4. Cycle Type Bit Definitions
5.3.1.4
Bits[3:2]
Bit[1]
00
0
Definition
I/O Read
00
1
I/O Write
01
0
Memory Read
01
1
Memory Write
10
0
DMA Read
10
1
DMA Write
11
x
Reserved. If a peripheral performing a bus master cycle generates this value, the
Intel® ICH4 will abort the cycle.
Size
Bits[3:2] are reserved. The ICH4 always drives them to 00. Peripherals running bus master cycles
are also supposed to drive 00 for bits 3:2, however, the ICH4 will ignore those bits. Bits[1:0] are
encoded as shown in Table 5-5.
Table 5-5. Transfer Size Bit Definition
Bits[1:0]
5.3.1.5
Size
00
8-bit transfer (1 byte)
01
16-bit transfer (2 bytes)
10
Reserved. The Intel® ICH4 will never drive this combination. If a peripheral running a bus
master cycle drives this combination, the ICH4 may abort the transfer.
11
32-bit transfer (4 bytes)
SYNC
Valid values for the SYNC field are provided in Table 5-6.
Table 5-6. SYNC Bit Definition
Bits[3:0]
Indication
0000
Ready: SYNC achieved with no error. For DMA transfers, this also indicates DMA request
deassertion and no more transfers desired for that channel.
0101
Short Wait: Part indicating wait-states. For bus master cycles, the Intel® ICH4 will not use
this encoding. It will instead use the Long Wait encoding (see next encoding below).
0110
Long Wait: Part indicating wait-states, and many wait-states will be added. This encoding
driven by the ICH4 for bus master cycles, rather than the Short Wait (0101).
1001
Ready More (Used only by peripheral for DMA cycle): SYNC achieved with no error and
more DMA transfers desired to continue after this transfer. This value is valid only on DMA
transfers and is not allowed for any other type of cycle.
1010
Error: Sync achieved with error. This is generally used to replace the SERR# or IOCHK#
signal on the PCI/ISA bus. It indicates that the data is to be transferred, but there is a serious
error in this transfer. For DMA transfers, this not only indicates an error, but also indicates
DMA request deassertion and no more transfers desired for that channel.
NOTE: All other combinations are RESERVED.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.3.1.6
SYNC Time-Out
There are several error cases that can occur on the LPC interface. Table 5-7 indicates the failing
case and the ICH4 response.
Table 5-7. Intel® ICH4 Response to Sync Failures
Possible Sync Failure
Intel® ICH4 Response
Intel® ICH4 starts a Memory, I/O, or DMA cycle, but no device drives a valid
SYNC after 4 consecutive clocks. This could occur if the processor tries to
access an I/O location to which no device is mapped.
ICH4 aborts the cycle after
the fourth clock.
ICH4 drives a Memory, I/O, or DMA cycle, and a peripheral drives more than 8
consecutive valid SYNC to insert wait-states using the Short (0101b’) encoding
for SYNC. This could occur if the peripheral is not operating properly.
Continues waiting
ICH4 starts a Memory, I/O, or DMA cycle, and a peripheral drives an invalid
SYNC pattern. This could occur if the peripheral is not operating properly or if
there is excessive noise on the LPC interface.
ICH4 aborts the cycle when
the invalid Sync is
recognized.
There may be other peripheral failure conditions, however these are not handled by the ICH4.
5.3.1.7
SYNC Error Indication
The SYNC protocol allows the peripheral to report an error via the LAD[3:0] = 1010b encoding.
The intent of this encoding is to give peripherals a method of communicating errors to aid higher
layers with more robust error recovery.
If the ICH4 was reading data from a peripheral, data will still be transferred in the next two nibbles.
This data may be invalid, but it must be transferred by the peripheral. If the ICH4 was writing data
to the peripheral, the data had already been transferred.
In the case of multiple byte cycles (e.g., as for memory and DMA cycles) an error SYNC
terminates the cycle. Therefore, if the ICH4 is transferring 4 bytes from a device and the device
returns the error SYNC in the first byte, the other three bytes will not be transferred.
Upon recognizing the SYNC field indicating an error, the ICH4 will treat this the same as IOCHK#
going active on the ISA bus.
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Functional Description
5.3.1.8
LFRAME# Usage
Start of Cycle
For Memory, I/O, and DMA cycles, the ICH4 asserts LFRAME# for 1 clock at the beginning of the
cycle (Figure 5-7). During that clock, the ICH4 drives LAD[3:0] with the proper START field.
Figure 5-7. Typical Timing for LFRAME#
LCLK
LFRAME#
Start
ADDR
TAR
Sync
Data
1-8
Clocks
2
Clocks
1-n
Clocks
2
Clocks
LAD[3:0]
1
CYCTYPE
Clock Dir & Size
TAR
Start
2
Clocks
1
Clock
Abort Mechanism
When performing an Abort, the ICH4 drives LFRAME# active for four consecutive clocks. On the
fourth clock, it drives LAD[3:0] to 1111b.
Figure 5-8. Abort Mechanism
LCLK
LFRAME#
LAD[3:0]
Start
ADDR
CYCTYPE
Dir & Size
TAR
Sync
Peripheral must
stop driving
Chipset will
drive high
Too many
Syncs causes
timeout
The ICH4 performs an abort for the following cases (possible failure cases):
• ICH4 starts a Memory, I/O, or DMA cycle, but no device drives a valid SYNC after four
consecutive clocks.
• ICH4 starts a Memory, I/O, or DMA cycle, and the peripheral drives an invalid SYNC pattern.
• A peripheral drives an illegal address when performing bus master cycles.
• A peripheral drives an invalid value.
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Functional Description
5.3.1.9
I/O Cycles
For I/O cycles targeting registers specified in the ICH4’s decode ranges, the ICH4 performs I/O
cycles as defined in the LPC specification. These will be 8-bit transfers. If the processor attempts a
16-bit or 32-bit transfer, the ICH4 breaks the cycle up into multiple 8-bit transfers to consecutive
I/O addresses.
Note:
5.3.1.10
If the cycle is not claimed by any peripheral (and subsequently aborted), the ICH4 returns a value
of all ones (FFh) to the processor. This is to maintain compatibility with ISA I/O cycles where pullup resistors would keep the bus high if no device responds.
Bus Master Cycles
The ICH4 supports Bus Master cycles and requests (using LDRQ#) as defined in the LPC
specification. The ICH4 has two LDRQ# inputs, and thus, supports two separate bus master
devices. It uses the associated START fields for Bus Master 0 (0010b) or Bus Master 1 (0011b).
Note:
5.3.1.11
The ICH4 does not support LPC Bus Masters performing I/O cycles. LPC Bus Masters should only
perform memory read or memory write cycles.
LPC Power Management
LPCPD# Protocol
Same timings as for SUS_STAT#. Upon driving SUS_STAT# low, LPC peripherals will drive
LDRQ# low or tri-state it. ICH4 will shut off the LDRQ# input buffers. After driving SUS_STAT#
active, the ICH4 drives LFRAME# low, and tri-states (or drive low) LAD[3:0].
5.3.1.12
Configuration and Intel® ICH4 Implications
LPC Interface Decoders
To allow the I/O cycles and memory mapped cycles to go to the LPC interface, the ICH4 includes
several decoders. During configuration, the ICH4 must be programmed with the same decode ranges
as the peripheral. The decoders are programmed via the Device 31:Function 0 configuration space.
Note:
The ICH4 cannot accept PCI write cycles from PCI-to-PCI bridges or devices with similar
characteristics (specifically those with a “Retry Read” feature which is enabled) to an LPC device
if there is an outstanding LPC read cycle towards the same PCI device or bridge. These cycles are
not part of normal system operation, but may be encountered as part of platform validation testing
using custom test fixtures.
Bus Master Device Mapping and START Fields
Bus Masters must have a unique START field. In the case of the ICH4, which supports 2 LPC bus
masters, it will drive 0010 for the START field for grants to bus master #0 (requested via
LDRQ[0]#) and 0011 for grants to bus master #1 (requested via LDRQ[1]#.). Thus, no registers are
needed to configure the START fields for a particular bus master.
Intel® 82801DB ICH4 Datasheet
91
Functional Description
5.4
DMA Operation (D31:F0)
The ICH4 supports two types of DMA: LPC, and PC/PCI. DMA via LPC is similar to ISA DMA.
LPC DMA and PC/PCI DMA use the ICH4’s DMA controller. The DMA controller has registers
that are fixed in the lower 64 KB of I/O space. The DMA controller is configured using registers in
the PCI configuration space. These registers allow configuration of individual channels for use by
LPC or PC/PCI DMA.
The DMA circuitry incorporates the functionality of two 82C37 DMA controllers with seven
independently programmable channels (Figure 5-9). DMA controller 1 (DMA-1) corresponds to
DMA channels 0–3 and DMA controller 2 (DMA-2) corresponds to channels 5–7. DMA channel 4
is used to cascade the two controllers and defaults to cascade mode in the DMA Channel Mode
(DCM) Register. Channel 4 is not available for any other purpose. In addition to accepting requests
from DMA slaves, the DMA controller also responds to requests that software initiates. Software
may initiate a DMA service request by setting any bit in the DMA Channel Request Register to a 1.
Figure 5-9. Intel® ICH4 DMA Controller
Channel 4
Channel 0
Channel 1
Channel 5
DMA-1
Channel 2
Channel 6
Channel 3
Channel 7
DMA-2
Each DMA channel is hardwired to the compatible settings for DMA device size: channels 3–0 are
hardwired to 8-bit, count-by-bytes transfers, and channels 7–5 are hardwired to 16-bit, count-bywords (address shifted) transfers.
ICH4 provides 24-bit addressing in compliance with the ISA-Compatible specification. Each
channel includes a 16-bit ISA-Compatible Current Register which holds the 16 least-significant
bits of the 24-bit address, an ISA-Compatible Page Register which contains the eight next most
significant bits of address.
The DMA controller also features refresh address generation and autoinitialization following a
DMA termination.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.4.1
Channel Priority
For priority resolution, the DMA consists of two logical channel groups: channels 0–3 and
channels 4–7. Each group may be in either fixed or rotate mode, as determined by the DMA
Command Register.
DMA I/O slaves normally assert their DREQ line to arbitrate for DMA service. However, a
software request for DMA service can be presented through each channel's DMA Request Register.
A software request is subject to the same prioritization as any hardware request. See the detailed
register description for Request Register programming information in Section 9.2.
5.4.1.1
Fixed Priority
The initial fixed priority structure is as follows:
High priority.....Low priority
(0, 1, 2, 3)
(5, 6, 7)
The fixed priority ordering is 0, 1, 2, 3, 5, 6, and 7. In this scheme, channel 0 has the highest
priority, and channel 7 has the lowest priority. Channels 3–0 of DMA-1 assume the priority
position of channel 4 in DMA-2, thus taking priority over channels 5, 6, and 7.
5.4.1.2
Rotating Priority
Rotation allows for "fairness" in priority resolution. The priority chain rotates so that the last
channel serviced is assigned the lowest priority in the channel group (0–3, 5–7).
Channels 0–3 rotate as a group of 4. They are always placed between channel 5 and channel 7 in
the priority list.
Channel 5–7 rotate as part of a group of 4. That is, channels 5–7 form the first three positions in the
rotation, while channel group 0–3 comprises the fourth position in the arbitration.
5.4.2
Address Compatibility Mode
When the DMA is operating, the addresses do not increment or decrement through the High and
Low Page Registers. Therefore, if a 24-bit address is 01FFFFh and increments, the next address
will be 010000h, not 020000h. Similarly, if a 24-bit address is 020000h and decrements, the next
address will be 02FFFFh, not 01FFFFh. However, when the DMA is operating in 16-bit mode, the
addresses still do not increment or decrement through the High and Low Page Registers but the
page boundary is now 128 KB. Therefore, if a 24-bit address is 01FFFEh and increments, the next
address will be 000000h, not 010000h. Similarly, if a 24-bit address is 020000h and decrements,
the next address will be 03FFFEh, not 02FFFEh. This is compatible with the 82C37 and Page
Register implementation used in the PC-AT. This mode is set after CPURST is valid.
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Functional Description
5.4.3
Summary of DMA Transfer Sizes
Table 5-8 lists each of the DMA device transfer sizes. The column labeled “Current Byte/Word
Count Register” indicates that the register contents represents either the number of bytes to transfer
or the number of 16-bit words to transfer. The column labeled “Current Address Increment/
Decrement” indicates the number added to or taken from the Current Address register after each
DMA transfer cycle. The DMA Channel Mode Register determines if the Current Address Register
will be incremented or decremented.
5.4.3.1
Address Shifting When Programmed for 16-Bit I/O Count by Words
Table 5-8. DMA Transfer Size
Current Byte/Word Count
Register
Current Address
Increment/Decrement
8-Bit I/O, Count By Bytes
Bytes
1
16-Bit I/O, Count By Words (Address Shifted)
Words
1
DMA Device Date Size And Word Count
The ICH4 maintains compatibility with the implementation of the DMA in the PC AT which used
the 82C37. The DMA shifts the addresses for transfers to/from a 16-bit device count-by-words.
Note that the least significant bit of the Low Page Register is dropped in 16-bit shifted mode. When
programming the Current Address Register (when the DMA channel is in this mode), the Current
Address must be programmed to an even address with the address value shifted right by one bit.
The address shifting is shown in Table 5-9.
Table 5-9. Address Shifting in 16-bit I/O DMA Transfers
Output
Address
8-Bit I/O Programmed Address
(Ch 0–3)
16-Bit I/O Programmed Address
(Ch 5–7)
(Shifted)
A0
A[16:1]
A[23:17]
A0
A[16:1]
A[23:17]
0
A[15:0]
A[23:17]
NOTE: The least significant bit of the Page Register is dropped in 16-bit shifted mode.
5.4.4
Autoinitialize
By programming a bit in the DMA Channel Mode Register, a channel may be set up as an
autoinitialize channel. When a channel undergoes autoinitialization, the original values of the
Current Page, Current Address, and Current Byte/Word Count registers are automatically restored
from the Base Page, Address, and Byte/Word Count Registers of that channel following TC. The
Base registers are loaded simultaneously with the Current registers by the microprocessor when the
DMA channel is programmed and remain unchanged throughout the DMA service. The mask bit is
not set when the channel is in autoinitialize. Following autoinitialize, the channel is ready to
perform another DMA service, without processor intervention, as soon as a valid DREQ is
detected.
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Functional Description
5.4.5
Software Commands
There are three additional special software commands that the DMA controller can execute. The
three software commands are:
• Clear Byte Pointer Flip-Flop
• Master Clear
• Clear Mask Register
They do not depend on any specific bit pattern on the data bus.
5.4.5.1
Clear Byte Pointer Flip-Flop
This command is executed prior to writing or reading new address or word count information to/
from the DMA controller. This initializes the flip-flop to a known state so that subsequent accesses
to register contents by the microprocessor will address upper and lower bytes in the correct
sequence.
When the host processor is reading or writing DMA registers, two Byte Pointer flip-flops are used;
one for channels 0–3 and one for channels 4–7. Both of these act independently. There are separate
software commands for clearing each of them (0Ch for channels 0–3, 0D8h for channels 4–7).
5.4.5.2
DMA Master Clear
This software instruction has the same effect as the hardware reset. The Command, Status,
Request, and Internal First/Last Flip-Flop registers are cleared and the Mask register is set. The
DMA controller will enter the idle cycle.
There are two independent master clear commands; 0Dh which acts on channels 0–3, and 0DAh
which acts on channels 4–7.
5.4.5.3
Clear Mask Register
This command clears the mask bits of all four channels, enabling them to accept DMA requests.
I/O port 00Eh is used for channels 0–3 and I/O port 0DCh is used for channels 4–7.
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Functional Description
5.5
PCI DMA
ICH4 provides support for the PC/PCI DMA protocol. PC/PCI DMA uses dedicated REQUEST
and GRANT signals to permit PCI devices to request transfers associated with specific DMA
channels. Upon receiving a request and getting control of the PCI bus, the ICH4 performs a twocycle transfer. For example, if data is to be moved from the peripheral to main memory, the ICH4
will first read data from the peripheral and then write it to main memory. The location in main
memory is the Current Address registers in the 8237.
ICH4 supports up to 2 PC/PCI REQ/GNT pairs, REQ[A:B]# and GNT[A:B]#. A 16-bit register is
included in the ICH4 Function 0 configuration space at offset 90h. It is divided into seven 2-bit
fields that are used to configure the seven DMA channels. Each DMA channel can be configured to
one of two options:
• LPC DMA
• PC/PCI style DMA using the REQ/GNT signals
It is not possible for a particular DMA channel to be configured for more than one style of DMA;
however, the seven channels can be programmed independently. For example, channel 3 could be
set up for PC/PCI and channel 5 set up for LPC DMA.
The ICH4 REQ[A:B]# and GNT[A:B]# can be configured for support of a PC/PCI DMA
Expansion agent. The PCI DMA Expansion agent can then provide DMA service or ISA Bus
Master service using the ICH4 DMA controller. The REQ#/GNT# pair must follow the PC/PCI
serial protocol described below.
5.5.1
PCI DMA Expansion Protocol
The PCI expansion agent must support the PCI expansion Channel Passing Protocol defined in
Figure 5-10 for both the REQ# and GNT# pins.
Figure 5-10. DMA Serial Channel Passing Protocol
PCICLK
REQ#
GNT#
Start CH0 CH1 CH2 CH3 CH4 CH5 CH6 CH7
Start Bit0
Bit1
Bit2
The requesting device must encode the channel request information as shown above, where CH0–
CH7 are one clock active high states representing DMA channel requests 0–7.
ICH4 encodes the granted channel on the GNT# line as shown above, where the bits have the same
meaning as shown in Figure 5-10. For example, the sequence [start, bit 0, bit 1, bit 2]=[0,1,0,0]
grants DMA channel 1 to the requesting device, and the sequence [start, bit 0, bit 1, bit 2]=[0,0,1,1]
grants DMA channel 6 to the requesting device.
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Functional Description
All PCI DMA expansion agents must use the channel passing protocol described above. They must
also work as follows:
• If a PCI DMA expansion agent has more than one request active, it must resend the request
serial protocol after one of the requests has been granted the bus and it has completed its
transfer. The expansion device should drive its REQ# inactive for two clocks and then transmit
the serial channel passing protocol again, even if there are no new requests from the PCI
expansion agent to ICH4. For example: If a PCI expansion agent had active requests for DMA
channel 1 and channel 5, it would pass this information to ICH4 through the expansion
channel passing protocol. If after receiving GNT# (assume for CH5) and having the device
finish its transfer (device stops driving request to PCI expansion agent) it would then need to
re-transmit the expansion channel passing protocol to inform ICH4 that DMA channel 1 was
still requesting the bus, even if that was the only request the expansion device had pending.
• If a PCI DMA expansion agent has a request go inactive before ICH4 asserts GNT#, it must
resend the expansion channel passing protocol to update ICH4 with this new request
information. For example: If a PCI expansion agent has DMA channel 1 and 2 requests
pending it will send them serially to ICH4 using the expansion channel passing protocol. If,
however, DMA channel 1 goes inactive into the expansion agent before the expansion agent
receives a GNT# from ICH4, the expansion agent MUST pull its REQ# line high for ONE
clock and resend the expansion channel passing information with only DMA channel 2 active.
Note that ICH4 does not do anything special to catch this case because a DREQ going inactive
before a DACK# is received is not allowed in the ISA DMA protocol and, therefore, does not
need to work properly in this protocol either. This requirement is needed to be able to support
Plug-n-Play ISA devices that toggle DREQ# lines to determine if those lines are free in the
system.
• If a PCI expansion agent has sent its serial request information and receives a new DMA
request before receiving GNT#, the agent must resend the serial request with the new request
active. For example: If a PCI expansion agent has already passed requests for DMA channel 1
and 2 and sees DREQ 3 active before a GNT is received, the device must pull its REQ# line
high for one clock and resend the expansion channel passing information with all three
channels active.
The three cases above require the following functionality in the PCI DMA expansion device:
• Drive REQ# inactive for one clock to signal new request information.
• Drive REQ# inactive for two clocks to signal that a request that had been granted the bus has
gone inactive.
• The REQ# and GNT# state machines must run independently and concurrently (i.e., a GNT#
could be received while in the middle of sending a serial REQ# or a GNT# could be active
while REQ# is inactive).
5.5.2
PCI DMA Expansion Cycles
ICH4’s support of the PC/PCI DMA Protocol currently consists of four types of cycles: Memory to
I/O, I/O to Memory, Verify, and ISA Master cycles. ISA Masters are supported through the use of a
DMA channel that has been programmed for cascade mode.
The DMA controller does a two cycle transfer (a load followed by a store) as opposed to the ISA
"fly-by" cycle for PC/PCI DMA agents. The memory portion of the cycle generates a PCI memory
read or memory write bus cycle, its address representing the selected memory.
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Functional Description
The I/O portion of the DMA cycle generates a PCI I/O cycle to one of four I/O addresses
(Table 5-10). Note that these cycles must be qualified by an active GNT# signal to the requesting
device.
Table 5-10. DMA Cycle vs. I/O Address
5.5.3
DMA Cycle Type
DMA I/O Address
PCI Cycle Type
Normal
00h
I/O Read/Write
Normal TC
04h
I/O Read/Write
Verify
0C0h
I/O Read
Verify TC
0C4h
I/O Read
DMA Addresses
The memory portion of the cycle generates a PCI memory read or memory write bus cycle (its
address representing the selected memory). The I/O portion of the DMA cycle generates a PCI
I/O cycle to one of the four I/O addresses listed in Table 5-10.
5.5.4
DMA Data Generation
The data generated by PC/PCI devices on I/O reads when they have an active GNT# is on the lower
two bytes of the PCI AD bus. Table 5-11 lists the PCI pins that the data appears on for 8- and 16-bit
channels. Each I/O read results in one memory write, and each memory read results in one
I/O write. If the I/O device is 8 bit, the ICH4 performs an 8-bit memory write. The ICH4 does not
assemble the I/O read into a DWord for writing to memory. Similarly, the ICH4 does not
disassemble a DWord read from memory to the I/O device.
Table 5-11. PCI Data Bus vs. DMA I/O Port Size
5.5.5
PCI DMA I/O Port Size
PCI Data Bus Connection
Byte
AD[7:0]
Word
AD[15:0]
DMA Byte Enable Generation
The byte enables generated by the ICH4 on I/O reads and writes must correspond to the size of the
I/O device. Table 5-12 defines the byte enables asserted for 8- and 16-bit DMA cycles.
Table 5-12. DMA I/O Cycle Width vs. BE[3:0]#
BE[3:0]#
Description
1110b
8-bit DMA I/O Cycle: Channels 0-3
1100b
16-bit DMA I/O Cycle: Channels 5-7
NOTE: For verify cycles the value of the Byte Enables (BEs) is a “don’t care”.
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Functional Description
5.5.6
DMA Cycle Termination
DMA cycles are terminated when a terminal count is reached in the DMA controller and the
channel is not in autoinitialize mode, or when the PC/PCI device deasserts its request. The PC/PCI
device must follow explicit rules when deasserting its request, or the ICH4 may not see it in time
and run an extra I/O and memory cycle.
The PC/PCI device must deassert its request 7 PCICLKs before it generates TRDY# on the I/O
read or write cycle, or the ICH4 is allowed to generate another DMA cycle. For transfers to
memory, this means that the memory portion of the cycle is run without an asserted PC/PCI REQ#.
5.5.7
LPC DMA
DMA on LPC is handled through the use of the LDRQ# lines from peripherals and special
encodings on LAD[3:0] from the host. Single, Demand, Verify, and Increment modes are supported
on the LPC interface. Channels 0–3 are 8-bit channels. Channels 5–7 are 16-bit channels. Channel
4 is reserved as a generic bus master request.
5.5.8
Asserting DMA Requests
Peripherals that need DMA service encode their requested channel number on the LDRQ# signal.
To simplify the protocol, each peripheral on the LPC interface has its own dedicated LDRQ# signal
(they may not be shared between two separate peripherals). The ICH4 has two LDRQ# inputs,
allowing at least two devices to support DMA or bus mastering.
LDRQ# is synchronous with LCLK (PCI clock). As shown in Figure 5-11 the peripheral uses the
following serial encoding sequence:
• Peripheral starts the sequence by asserting LDRQ# low (start bit). LDRQ# is high during idle
conditions.
• The next 3 bits contain the encoded DMA channel number (MSB first).
• The next bit (ACT) indicates whether the request for the indicated DMA channel is active or
inactive. The ACT bit will be a 1(high) to indicate if it is active and 0 (low) if it is inactive.
The case where ACT is low is rare, and is only used to indicate that a previous request for that
channel is being abandoned.
• After the active/inactive indication, the LDRQ# signal must go high for at least 1 clock. After
that one clock, LDRQ# signal can be brought low to the next encoding sequence.
If another DMA channel also needs to request a transfer, another sequence can be sent on LDRQ#.
For example, if an encoded request is sent for channel 2 and then channel 3 needs a transfer before
the cycle for channel 2 is run on the interface, the peripheral can send the encoded request for
channel 3. This allows multiple DMA agents behind an I/O device to request use of the LPC
interface and the I/O device does not need to self-arbitrate before sending the message.
Figure 5-11. DMA Request Assertion Through LDRQ#
LCLK
LDRQ#
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Start
MSB
LSB
ACT
Start
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Functional Description
5.5.9
Abandoning DMA Requests
DMA Requests can be deasserted in two fashions: on error conditions by sending an LDRQ#
message with the “ACT” bit set to 0, or normally through a SYNC field during the DMA transfer.
This section describes boundary conditions where the DMA request needs to be removed prior to a
data transfer.
There may be some special cases where the peripheral desires to abandon a DMA transfer. The
most likely case of this occurring is due to a floppy disk controller which has overrun or underrun
its FIFO, or software stopping a device prematurely.
In these cases, the peripheral wishes to stop further DMA activity. It may do so by sending an
LDRQ# message with the ACT bit as 0. However, since the DMA request was seen by the ICH4,
there is no guarantee that the cycle has not been granted and will shortly run on LPC. Therefore,
peripherals must take into account that a DMA cycle may still occur. The peripheral can choose not
to respond to this cycle, in which case the host will abort it, or it can choose to complete the cycle
normally with any random data.
This method of DMA deassertion should be prevented whenever possible, to limit boundary
conditions both on the ICH4 and the peripheral.
5.5.10
General Flow of DMA Transfers
Arbitration for DMA channels is performed through the 8237 within the host. Once the host has
won arbitration on behalf of a DMA channel assigned to LPC, it asserts LFRAME# on the LPC
interface and begins the DMA transfer. The general flow for a basic DMA transfer is as follows:
1. ICH4 starts transfer by asserting 0000b on LAD[3:0] with LFRAME# asserted.
2. ICH4 asserts “cycle type” of DMA, direction based on DMA transfer direction.
3. ICH4 asserts channel number and, if applicable, terminal count.
4. ICH4 indicates the size of the transfer: 8 or 16 bits.
5. If a DMA read…
— The ICH4 drives the first 8 bits of data and turns the bus around.
— The peripheral acknowledges the data with a valid SYNC.
— If a 16-bit transfer, the process is repeated for the next 8 bits.
6. If a DMA write…
— The ICH4 turns the bus around and waits for data.
— The peripheral indicates data ready through SYNC and transfers the first byte.
— If a 16-bit transfer, the peripheral indicates data ready and transfers the next byte.
7. The peripheral turns around the bus.
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Functional Description
5.5.11
Terminal Count
Terminal count is communicated through LAD[3] on the same clock that DMA channel is
communicated on LAD[2:0]. This field is the CHANNEL field. Terminal count indicates the last
byte of transfer, based upon the size of the transfer.
For example, on an 88bit transfer size (SIZE field is 00b), if the TC bit is set, then this is the last
byte. On a 16-bit transfer (SIZE field is 01b), if the TC bit is set, then the second byte is the last
byte. The peripheral, therefore, must internalize the TC bit when the CHANNEL field is
communicated, and only signal TC when the last byte of that transfer size has been transferred.
5.5.12
Verify Mode
Verify mode is supported on the LPC interface. A verify transfer to the peripheral is similar to a
DMA write, where the peripheral is transferring data to main memory. The indication from the host
is the same as a DMA write, so the peripheral will be driving data onto the LPC interface.
However, the host will not transfer this data into main memory.
5.5.13
DMA Request Deassertion
An end of transfer is communicated to the ICH4 through a special SYNC field transmitted by the
peripheral. An LPC device must not attempt to signal the end of a transfer by deasserting
LDREQ#. If a DMA transfer is several bytes (e.g., a transfer from a demand mode device) the
ICH4 needs to know when to deassert the DMA request based on the data currently being
transferred.
The DMA agent uses a SYNC encoding on each byte of data being transferred, which indicates to
the ICH4 whether this is the last byte of transfer or if more bytes are requested. To indicate the last
byte of transfer, the peripheral uses a SYNC value of 0000b (ready with no error), or 1010b (ready
with error). These encodings tell the ICH4 that this is the last piece of data transferred on a DMA
read (ICH4 to peripheral), or the byte which follows is the last piece of data transferred on a DMA
write (peripheral to ICH4).
When the ICH4 sees one of these two encodings, it ends the DMA transfer after this byte and
deasserts the DMA request to the 8237. Therefore, if the ICH4 indicated a 16-bit transfer, the
peripheral can end the transfer after one byte by indicating a SYNC value of 0000b or 1010b. The
ICH4 will not attempt to transfer the second byte, and will deassert the DMA request internally.
If the peripheral indicates a 0000b or 1010b SYNC pattern on the last byte of the indicated size,
then the ICH4 will only deassert the DMA request to the 8237 since it does not need to end the
transfer.
If the peripheral wishes to keep the DMA request active, then it uses a SYNC value of 1001b
(ready plus more data). This tells the 8237 that more data bytes are requested after the current byte
has been transferred, so the ICH4 will keep the DMA request active to the 8237. Therefore, on an
8-bit transfer size, if the peripheral indicates a SYNC value of 1001b to the ICH4, the data will be
transferred and the DMA request will remain active to the 8237. At a later time, the ICH4 will then
come back with another START–CYCTYPE–CHANNEL–SIZE etc. combination to initiate
another transfer to the peripheral.
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Functional Description
The peripheral must not assume that the next START indication from the ICH4 is another grant to
the peripheral if it had indicated a SYNC value of 1001b. On a single mode DMA device, the 8237
will re-arbitrate after every transfer. Only demand mode DMA devices can be guaranteed that they
will receive the next START indication from the ICH4.
Note:
Indicating a 0000b or 1010b encoding on the SYNC field of an odd byte of a 16-bit channel (first
byte of a 16-bit transfer) is an error condition.
Note:
The host will stop the transfer on the LPC bus as indicated, fill the upper byte with random data on
DMA writes (peripheral to memory), and indicate to the 8237 that the DMA transfer occurred,
incrementing the 8237’s address and decrementing its byte count.
5.5.14
SYNC Field / LDRQ# Rules
Since DMA transfers on LPC are requested through an LDRQ# assertion message, and are ended
through a SYNC field during the DMA transfer, the peripheral must obey the following rule when
initiating back-to-back transfers from a DMA channel.
The peripheral must not assert another message for eight LCLKs after a deassertion is indicated
through the SYNC field. This is needed to allow the 8237, which typically runs off a much slower
internal clock, to see a message deasserted before it is re-asserted so that it can arbitrate to the next
agent.
Under default operation, the host will only perform 8-bit transfers on 8-bit channels and 16-bit
transfers on 16-bit channels.
The method by which this communication between host and peripheral through system BIOS is
performed is beyond the scope of this specification. Since the LPC host and LPC peripheral are
motherboard devices, no “plug-n-play” registry is required.
The peripheral must not assume that the host will be able to perform transfer sizes that are larger
than the size allowed for the DMA channel, and be willing to accept a SIZE field that is smaller
than what it may currently have buffered.
To that end, it is recommended that future devices which may appear on the LPC bus, which
require higher bandwidth than 8-bit or 16-bit DMA allow, do so with a bus mastering interface and
not rely on the 8237.
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5.6
8254 Timers (D31:F0)
The ICH4 contains three counters which have fixed uses. All registers and functions associated
with the 8254 timers are in the core well. The 8254 unit is clocked by a 14.31818 MHz clock.
Counter 0, System Timer
This counter functions as the system timer by controlling the state of IRQ0 and is typically
programmed for Mode 3 operation. The counter produces a square wave with a period equal to the
product of the counter period (838 ns) and the initial count value. The counter loads the initial
count value one counter period after software writes the count value to the counter I/O address. The
counter initially asserts IRQ0 and decrements the count value by two each counter period. The
counter negates IRQ0 when the count value reaches 0. It then reloads the initial count value and
again decrements the initial count value by two each counter period. The counter then asserts IRQ0
when the count value reaches 0, reloads the initial count value, and repeats the cycle, alternately
asserting and negating IRQ0.
Counter 1, Refresh Request Signal
This counter provides the refresh request signal and is typically programmed for Mode 2 operation.
The counter negates refresh request for one counter period (838 ns) during each count cycle. The
initial count value is loaded one counter period after being written to the counter I/O address. The
counter initially asserts refresh request, and negates it for 1 counter period when the count value
reaches 1. The counter then asserts refresh request and continues counting from the initial count
value.
Counter 2, Speaker Tone
This counter provides the speaker tone and is typically programmed for Mode 3 operation. The
counter provides a speaker frequency equal to the counter clock frequency (1.193 MHz) divided by
the initial count value. The speaker must be enabled by a write to port 061h (see NMI Status and
Control ports).
5.6.1
Timer Programming
The counter/timers are programmed in the following fashion:
1. Write a control word to select a counter.
2. Write an initial count for that counter.
3. Load the least and/or most significant bytes (as required by Control Word bits 5, 4) of the
16-bit counter.
4. Repeat with other counters.
Only two conventions need to be observed when programming the counters. First, for each counter,
the control word must be written before the initial count is written. Second, the initial count must
follow the count format specified in the control word (least significant byte only, most significant
byte only, or least significant byte and then most significant byte).
A new initial count may be written to a counter at any time without affecting the counter's
programmed mode. Counting will be affected as described in the mode definitions. The new count
must follow the programmed count format.
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Functional Description
If a counter is programmed to read/write two-byte counts, the following precaution applies: A
program must not transfer control between writing the first and second byte to another routine
which also writes into that same counter. Otherwise, the counter will be loaded with an incorrect
count.
The Control Word Register at port 43h controls the operation of all three counters. Several
commands are available:
• Control Word Command. Specifies which counter to read or write, the operating mode, and
the count format (binary or BCD).
• Counter Latch Command. Latches the current count so that it can be read by the system. The
countdown process continues.
• Read Back Command. Reads the count value, programmed mode, the current state of the
OUT pins, and the state of the Null Count Flag of the selected counter.
Table 5-13 lists the six operating modes for the interval counters.
Table 5-13. Counter Operating Modes
Mode
5.6.2
Function
Description
0
Out signal on end of count (=0)
Output is 0. When count goes to 0, output goes to 1 and
stays at 1 until counter is reprogrammed.
1
Hardware retriggerable one-shot
Output is 0. When count goes to 0, output goes to 1 for
one clock time.
2
Rate generator (divide by n counter)
Output is 1. Output goes to 0 for one clock time, then
back to 1 and counter is reloaded.
3
Square wave output
Output is 1. Output goes to 0 when counter rolls over, and
counter is reloaded. Output goes to 1 when counter rolls
over, and counter is reloaded, etc.
4
Software triggered strobe
Output is 1. Output goes to 0 when count expires for one
clock time.
5
Hardware triggered strobe
Output is 1. Output goes to 0 when count expires for one
clock time.
Reading from the Interval Timer
It is often desirable to read the value of a counter without disturbing the count in progress. There
are three methods for reading the counters: a simple read operation, counter Latch command, and
the Read-Back command. Each is explained below.
With the simple read and counter latch command methods, the count must be read according to the
programmed format; specifically, if the counter is programmed for two byte counts, two bytes must
be read. The two bytes do not have to be read one right after the other. Read, write, or programming
operations for other counters may be inserted between them.
5.6.2.1
Simple Read
The first method is to perform a simple read operation. The counter is selected through port 40h
(counter 0), 41h (counter 1), or 42h (counter 2).
Note:
104
Performing a direct read from the counter will not return a determinate value, because the counting
process is asynchronous to read operations. However, in the case of counter 2, the count can be
stopped by writing to the GATE bit in port 61h.
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Functional Description
5.6.2.2
Counter Latch Command
The Counter Latch Command, written to port 43h, latches the count of a specific counter at the
time the command is received. This command is used to ensure that the count read from the counter
is accurate, particularly when reading a two-byte count. The count value is then read from each
counter's Count Register as was programmed by the Control Register.
The count is held in the latch until it is read or the counter is reprogrammed. The count is then
unlatched. This allows reading the contents of the counters on the fly without affecting counting in
progress. Multiple Counter Latch Commands may be used to latch more than one counter. Counter
Latch commands do not affect the programmed mode of the counter in any way.
If a Counter is latched and then, some time later, latched again before the count is read, the second
Counter Latch command is ignored. The count read will be the count at the time the first Counter
Latch command was issued.
5.6.2.3
Read Back Command
The Read Back command, written to port 43h, latches the count value, programmed mode, and
current states of the OUT pin and Null Count flag of the selected counter or counters. The value of
the counter and its status may then be read by I/O access to the counter address.
The Read Back command may be used to latch multiple counter outputs at one time. This single
command is functionally equivalent to several counter latch commands, one for each counter
latched. Each counter's latched count is held until it is read or reprogrammed. Once read, a counter
is unlatched. The other counters remain latched until they are read. If multiple count Read Back
commands are issued to the same counter without reading the count, all but the first are ignored.
The Read Back command may additionally be used to latch status information of selected counters.
The status of a counter is accessed by a read from that counter's I/O port address. If multiple
counter status latch operations are performed without reading the status, all but the first are
ignored.
Both count and status of the selected counters may be latched simultaneously. This is functionally
the same as issuing two consecutive, separate Read Back commands. If multiple count and/or
status Read Back commands are issued to the same counters without any intervening reads, all but
the first are ignored.
If both count and status of a counter are latched, the first read operation from that counter will
return the latched status, regardless of which was latched first. The next one or two reads,
depending on whether the counter is programmed for one or two type counts, return the latched
count. Subsequent reads return unlatched count.
Intel® 82801DB ICH4 Datasheet
105
Functional Description
5.7
8259 Interrupt Controllers (PIC) (D31:F0)
The ICH4 incorporates the functionality of two 8259 interrupt controllers that provide system
interrupts for the ISA compatible interrupts. These interrupts are: system timer, keyboard
controller, serial ports, parallel ports, floppy disk, IDE, mouse, and DMA channels. In addition,
this interrupt controller can support the PCI based interrupts, by mapping the PCI interrupt onto the
compatible ISA interrupt line. Each 8259 core supports eight interrupts, numbered 0–7. Table 5-14
shows how the cores are connected.
.
Table 5-14. Interrupt Controller Core Connections
8259
8259
Input
Typical Interrupt
Source
Connected Pin / Function
0
Internal
Internal Timer / Counter 0 output
1
Keyboard
IRQ1 via SERIRQ
2
Internal
Slave Controller INTR output
3
Serial Port A
IRQ3 via SERIRQ
4
Serial Port B
IRQ4 via SERIRQ
5
Parallel Port / Generic
IRQ5 via SERIRQ
6
Floppy Disk
IRQ6 via SERIRQ
7
Parallel Port / Generic
IRQ7 via SERIRQ
0
Internal Real Time Clock
Internal RTC
1
Generic
IRQ9 via SERIRQ
2
Generic
IRQ10 via SERIRQ
3
Generic
IRQ11 via SERIRQ
4
PS/2 Mouse
IRQ12 via SERIRQ
5
Internal
State Machine output based on processor FERR#
assertion.
6
Primary IDE cable
IRQ14 from input signal (primary IDE in legacy mode
only) or via SERIRQ
7
Secondary IDE Cable
IRQ15 from input signal (secondary IDE in legacy mode
only) or via SERIRQ
Master
Slave
The ICH4 cascades the slave controller onto the master controller through master controller
interrupt input 2. This means there are only 15 possible interrupts for the ICH4 PIC.
Interrupts can individually be programmed to be edge or level, except for IRQ0, IRQ2, IRQ8#, and
IRQ13.
Note that previous PIIXn devices internally latched IRQ12 and IRQ1 and required a port 60h read
to clear the latch. The ICH4 can be programmed to latch IRQ12 or IRQ1 (see bit 11 and bit 12 in
General Control Register, D31:F0, offset D0h).
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.7.1
Interrupt Handling
5.7.1.1
Generating Interrupts
The PIC interrupt sequence involves three bits, from the IRR, ISR, and IMR, for each interrupt
level. These bits are used to determine the interrupt vector returned, and status of any other pending
interrupts. Table 5-15 defines the IRR, ISR and IMR.
Table 5-15. Interrupt Status Registers
Bit
5.7.1.2
Description
IRR
Interrupt Request Register. This bit is set on a low-to-high transition of the interrupt line in edge
mode, and by an active high level in level mode. This bit is set whether or not the interrupt is
masked. However, a masked interrupt will not generate INTR.
ISR
Interrupt Service Register. This bit is set, and the corresponding IRR bit cleared, when an interrupt
acknowledge cycle is seen, and the vector returned is for that interrupt.
IMR
Interrupt Mask Register. This bit determines whether an interrupt is masked. Masked interrupts will
not generate INTR.
Acknowledging Interrupts
The processor generates an interrupt acknowledge cycle which is translated by the host bridge into
a PCI Interrupt Acknowledge Cycle to the ICH4. The PIC translates this command into two
internal INTA# pulses expected by the 8259 cores. The PIC uses the first internal INTA# pulse to
freeze the state of the interrupts for priority resolution. On the second INTA# pulse, the master or
slave will sends the interrupt vector to the processor with the acknowledged interrupt code. This
code is based upon bits [7:3] of the corresponding ICW2 register, combined with three bits
representing the interrupt within that controller.
Table 5-16. Content of Interrupt Vector Byte
Master, Slave Interrupt
Bits [7:3]
IRQ7,15
Bits [2:0]
111
IRQ6,14
110
IRQ5,13
101
IRQ4,12
100
ICW2[7:3]
Intel® 82801DB ICH4 Datasheet
IRQ3,11
011
IRQ2,10
010
IRQ1,9
001
IRQ0,8
000
107
Functional Description
5.7.1.3
Hardware/Software Interrupt Sequence
1. One or more of the Interrupt Request lines (IRQ) are raised high in edge mode, or seen high in
level mode, setting the corresponding IRR bit.
2. The PIC sends INTR active to the processor if an asserted interrupt is not masked.
3. The processor acknowledges the INTR and responds with an interrupt acknowledge cycle. The
cycle is translated into a PCI interrupt acknowledge cycle by the host bridge. This command is
broadcast over PCI by the ICH4.
4. Upon observing its own interrupt acknowledge cycle on PCI, the ICH4 converts it into the two
cycles that the internal 8259 pair can respond to. Each cycle appears as an interrupt
acknowledge pulse on the internal INTA# pin of the cascaded interrupt controllers.
5. Upon receiving the first internally generated INTA# pulse, the highest priority ISR bit is set
and the corresponding IRR bit is reset. On the trailing edge of the first pulse, a slave
identification code is broadcast by the master to the slave on a private, internal three bit wide
bus. The slave controller uses these bits to determine if it must respond with an interrupt vector
during the second INTA# pulse.
6. Upon receiving the second internally generated INTA# pulse, the PIC returns the interrupt
vector. If no interrupt request is present because the request was too short in duration, the PIC
will return vector 7 from the master controller.
7. This completes the interrupt cycle. In AEOI mode the ISR bit is reset at the end of the second
INTA# pulse. Otherwise, the ISR bit remains set until an appropriate EOI command is issued
at the end of the interrupt subroutine.
5.7.2
Initialization Command Words (ICWx)
Before operation can begin, each 8259 must be initialized. In the ICH4, this is a four byte
sequence. The four initialization command words are referred to by their acronyms: ICW1, ICW2,
ICW3, and ICW4.
The base address for each 8259 initialization command word is a fixed location in the I/O memory
space: 20h for the master controller, and A0h for the slave controller.
5.7.2.1
ICW1
An I/O write to the master or slave controller base address with data bit 4 equal to 1 is interpreted
as a write to ICW1. Upon sensing this write, the ICH4 PIC expects three more byte writes to 21h
for the master controller, or A1h for the slave controller, to complete the ICW sequence.
A write to ICW1 starts the initialization sequence during which the following automatically occur:
1. Following initialization, an interrupt request (IRQ) input must make a low-to-high transition to
generate an interrupt.
2. The Interrupt Mask Register is cleared.
3. IRQ7 input is assigned priority 7.
4. The slave mode address is set to 7.
5. Special mask mode is cleared and Status Read is set to IRR.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.7.2.2
ICW2
The second write in the sequence (ICW2) is programmed to provide bits [7:3] of the interrupt
vector that will be released during an interrupt acknowledge. A different base is selected for each
interrupt controller.
5.7.2.3
ICW3
The third write in the sequence (ICW3) has a different meaning for each controller.
• For the master controller, ICW3 is used to indicate which IRQ input line is used to cascade the
slave controller. Within the ICH4, IRQ2 is used. Therefore, bit 2 of ICW3 on the master
controller is set to a 1, and the other bits are set to zeros.
• For the slave controller, ICW3 is the slave identification code used during an interrupt
acknowledge cycle. On interrupt acknowledge cycles, the master controller broadcasts a code
to the slave controller if the cascaded interrupt won arbitration on the master controller. The
slave controller compares this identification code to the value stored in its ICW3, and if it
matches, the slave controller assumes responsibility for broadcasting the interrupt vector.
5.7.2.4
ICW4
The final write in the sequence, ICW4, must be programmed both controllers. At the very least,
bit 0 must be set to a 1 to indicate that the controllers are operating in an Intel Architecture-based
system.
5.7.3
Operation Command Words (OCW)
These command words reprogram the Interrupt controller to operate in various interrupt modes.
• OCW1 masks and unmasks interrupt lines.
• OCW2 controls the rotation of interrupt priorities when in rotating priority mode and controls
the EOI function.
• OCW3 is sets up ISR/IRR reads, enables/disables the special mask mode (SMM) and enables/
disables polled interrupt mode.
5.7.4
Modes of Operation
5.7.4.1
Fully Nested Mode
In this mode, interrupt requests are ordered in priority from 0 through 7, with 0 being the highest.
When an interrupt is acknowledged, the highest priority request is determined and its vector placed
on the bus. Additionally, the ISR for the interrupt is set. This ISR bit remains set until: the
processor issues an EOI command immediately before returning from the service routine; or if in
AEOI mode, on the trailing edge of the second INTA#. While the ISR bit is set, all further
interrupts of the same or lower priority are inhibited, while higher levels will generate another
interrupt. Interrupt priorities can be changed in the rotating priority mode.
Intel® 82801DB ICH4 Datasheet
109
Functional Description
5.7.4.2
Special Fully-Nested Mode
This mode will be used in the case of a system where cascading is used, and the priority has to be
conserved within each slave. In this case, the special fully-nested mode will be programmed to the
master controller. This mode is similar to the fully-nested mode with the following exceptions:
• When an interrupt request from a certain slave is in service, this slave is not locked out from
the master's priority logic and further interrupt requests from higher priority interrupts within
the slave will be recognized by the master and will initiate interrupts to the processor. In the
normal-nested mode, a slave is masked out when its request is in service.
• When exiting the Interrupt Service routine, software has to check whether the interrupt
serviced was the only one from that slave. This is done by sending a Non-Specific EOI
command to the slave and then reading its ISR. If it is 0, a non-specific EOI can also be sent to
the master.
5.7.4.3
Automatic Rotation Mode (Equal Priority Devices)
In some applications, there are a number of interrupting devices of equal priority. Automatic
rotation mode provides for a sequential 8-way rotation. In this mode, a device receives the lowest
priority after being serviced. In the worst case, a device requesting an interrupt will have to wait
until each of seven other devices are serviced at most once.
There are two ways to accomplish automatic rotation using OCW2; the Rotation on Non-Specific
EOI Command (R=1, SL=0, EOI=1) and the rotate in automatic EOI mode which is set by
(R=1, SL=0, EOI=0).
5.7.4.4
Specific Rotation Mode (Specific Priority)
Software can change interrupt priorities by programming the bottom priority. For example, if IRQ5
is programmed as the bottom priority device, then IRQ6 will be the highest priority device. The Set
Priority Command is issued in OCW2 to accomplish this, where: R=1, SL=1, and LO-L2 is the
binary priority level code of the bottom priority device.
In this mode, internal status is updated by software control during OCW2. However, it is
independent of the EOI command. Priority changes can be executed during an EOI command by
using the Rotate on Specific EOI Command in OCW2 (R=1, SL=1, EOI=1 and LO-L2=IRQ level
to receive bottom priority.
5.7.4.5
Poll Mode
Poll mode can be used to conserve space in the interrupt vector table. Multiple interrupts that can
be serviced by one interrupt service routine do not need separate vectors if the service routine uses
the poll command. Poll mode can also be used to expand the number of interrupts. The polling
interrupt service routine can call the appropriate service routine, instead of providing the interrupt
vectors in the vector table. In this mode the INTR output is not used and the microprocessor
internal Interrupt Enable flip-flop is reset, disabling its interrupt input. Service to devices is
achieved by software using a Poll command.
The Poll command is issued by setting P=1 in OCW3. The PIC treats its next I/O read as an
interrupt acknowledge, sets the appropriate ISR bit if there is a request, and reads the priority level.
Interrupts are frozen from the OCW3 write to the I/O read. The byte returned during the I/O read
will contain a 1 in bit 7 if there is an interrupt, and the binary code of the highest priority level in
bits 2:0.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.7.4.6
Cascade Mode
The PIC in the ICH4 has one master 8259 and one slave 8259 cascaded onto the master through
IRQ2. This configuration can handle up to 15 separate priority levels. The master controls the
slaves through a three bit internal bus. In the ICH4, when the master drives 010b on this bus, the
slave controller takes responsibility for returning the interrupt vector. An EOI command must be
issued twice: once for the master and once for the slave.
5.7.4.7
Edge and Level Triggered Mode
In ISA systems this mode is programmed using bit 3 in ICW1, which sets level or edge for the
entire controller. In the ICH4, this bit is disabled and a new register for edge and level triggered
mode selection, per interrupt input, is included. This is the Edge/Level control Registers ELCR1
and ELCR2.
If an ELCR bit is 0, an interrupt request will be recognized by a low-to-high transition on the
corresponding IRQ input. The IRQ input can remain high without generating another interrupt. If
an ELCR bit is 1, an interrupt request will be recognized by a high level on the corresponding IRQ
input and there is no need for an edge detection. The interrupt request must be removed before the
EOI command is issued to prevent a second interrupt from occurring.
In both the edge and level triggered modes, the IRQ inputs must remain active until after the falling
edge of the first internal INTA#. If the IRQ input goes inactive before this time, a default IRQ7
vector will be returned.
5.7.4.8
End of Interrupt Operations
An EOI can occur in one of two fashions: by a command word write issued to the PIC before
returning from a service routine, the EOI command; or automatically when AEOI bit in ICW4 is
set to 1.
5.7.4.9
Normal End of Interrupt
In Normal EOI, software writes an EOI command before leaving the interrupt service routine to
mark the interrupt as completed. There are two forms of EOI commands: Specific and NonSpecific. When a Non-Specific EOI command is issued, the PIC will clear the highest ISR bit of
those that are set to 1. Non-Specific EOI is the normal mode of operation of the PIC within the
ICH4, as the interrupt being serviced currently is the interrupt entered with the interrupt
acknowledge. When the PIC is operated in modes which preserve the fully nested structure,
software can determine which ISR bit to clear by issuing a Specific EOI. An ISR bit that is masked
will not be cleared by a Non-Specific EOI if the PIC is in the special mask mode. An EOI
command must be issued for both the master and slave controller.
5.7.4.10
Automatic End of Interrupt Mode
In this mode, the PIC will automatically perform a Non-Specific EOI operation at the trailing edge
of the last interrupt acknowledge pulse. From a system standpoint, this mode should be used only
when a nested multi-level interrupt structure is not required within a single PIC. The AEOI mode
can only be used in the master controller and not the slave controller.
Intel® 82801DB ICH4 Datasheet
111
Functional Description
5.7.5
Masking Interrupts
5.7.5.1
Masking on an Individual Interrupt Request
Each interrupt request can be masked individually by the Interrupt Mask Register (IMR). This
register is programmed through OCW1. Each bit in the IMR masks one interrupt channel. Masking
IRQ2 on the master controller will mask all requests for service from the slave controller.
5.7.5.2
Special Mask Mode
Some applications may require an interrupt service routine to dynamically alter the system priority
structure during its execution under software control. For example, the routine may wish to inhibit
lower priority requests for a portion of its execution but enable some of them for another portion.
The special mask mode enables all interrupts not masked by a bit set in the Mask Register.
Normally, when an interrupt service routine acknowledges an interrupt without issuing an EOI to
clear the ISR bit, the interrupt controller inhibits all lower priority requests. In the special mask
mode, any interrupts may be selectively enabled by loading the Mask Register with the appropriate
pattern. The special mask mode is set by OCW3 where: SSMM=1, SMM=1, and cleared where
SSMM=1, SMM=0.
5.7.6
Steering PCI Interrupts
The ICH4 can be programmed to allow PIRQA#-PIRQH# to be internally routed to interrupts 3-7,
9-12, 14 or 15. The assignment is programmable through the PIRQx Route Control registers,
located at 60-63h and 68-6Bh in function 0. One or more PIRQx# lines can be routed to the same
IRQx input. If interrupt steering is not required, the Route Registers can be programmed to disable
steering.
The PIRQx# lines are defined as active low, level sensitive to allow multiple interrupts on a PCI
Board to share a single line across the connector. When a PIRQx# is routed to specified IRQ line,
software must change the IRQ's corresponding ELCR bit to level sensitive mode. The ICH4 will
internally invert the PIRQx# line to send an active high level to the PIC. When a PCI interrupt is
routed onto the PIC, the selected IRQ can no longer be used by an ISA device (through SERIRQ).
However, active low non-ISA interrupts can share their interrupt with PCI interrupts.
Internal sources of the PIRQs, including SCI and TCO interrupts, cause the external PIRQ to be
asserted. The ICH4 receives the PIRQ input, like all of the other external sources, and routes it
accordingly.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.8
Advanced Interrupt Controller (APIC) (D31:F0)
In addition to the standard ISA-compatible Programmable Interrupt Controller (PIC) described in
Section 5.7, the ICH4 incorporates the Advanced Programmable Interrupt Controller (APIC).
While the standard interrupt controller is intended for use in a uni-processor system, APIC can be
used in either a uni-processor or multi-processor system.
5.8.1
Interrupt Handling
The I/O APIC handles interrupts very differently than the 8259. Briefly, these differences are:
• Method of Interrupt Transmission. The I/O APIC transmits interrupts through a three wire
bus, and interrupts are handled without the need for the processor to run an interrupt
acknowledge cycle.
• Interrupt Priority. The priority of interrupts in the I/O APIC is independent of the interrupt
number. For example, interrupt 10 can be given a higher priority than interrupt 3.
• More Interrupts. The I/O APIC in the ICH4 supports a total of 24 interrupts.
• Multiple Interrupt Controllers. The I/O APIC interrupt transmission protocol has an
arbitration phase, which allows for multiple I/O APICs in the system with their own interrupt
vectors. The ICH4 I/O APIC must arbitrate for the APIC bus before transmitting its interrupt
message.
5.8.2
Interrupt Mapping
The I/O APIC within the ICH4 supports 24 APIC interrupts. Each interrupt has its own unique
vector assigned by software. The interrupt vectors are mapped as follows, and match “Config 6” of
the Multi-Processor Specification.
Table 5-17. APIC Interrupt Mapping (Sheet 1 of 2)
IRQ #
Via
SERIRQ
Direct from
pin
Via PCI
message
0
No
No
No
1
Yes
No
Yes
2
No
No
No
3
Yes
No
Yes
4
Yes
No
Yes
5
Yes
No
Yes
6
Yes
No
Yes
7
Yes
No
Yes
8
No
No
No
RTC
9
Yes
No
Yes
Option for SCI, TCO
10
Yes
No
Yes
Option for SCI, TCO
11
Yes
No
Yes
Option for SCI, TCO
12
Yes
No
Yes
Intel® 82801DB ICH4 Datasheet
Internal Modules
Cascade from 8259 #1
8254 Counter 0
113
Functional Description
Table 5-17. APIC Interrupt Mapping (Sheet 2 of 2)
IRQ #
Via
SERIRQ
Direct from
pin
Via PCI
message
13
No
No
No
1
Internal Modules
FERR# logic
14
Yes
Yes
Yes
15
Yes
Yes1
Yes
16
PIRQ[A]#
PIRQ[A]#
No
USB UHCI controller #1
17
PIRQ[B]#
PIRQ[B]#
No
AC ’97 Audio, Modem, option for SMbus
18
PIRQ[C]#
PIRQ[C]#
No
USB UHCI controller #3, Native IDE
19
PIRQ[D]#
PIRQ[D]#
No
USB UHCI controller #2
20
N/A
PIRQ[E]#
Yes
LAN, option for SCI, TCO
21
N/A
PIRQ[F]#
Yes
Option for SCI, TCO
22
N/A
PIRQ[G]#
Yes
Option for SCI, TCO
23
N/A
PIRQ[H]#
Yes
USB EHCI controller, option for SCI, TCO
NOTES:
1. IRQ 14 and 15 can only be driven directly from the pins when in legacy IDE mode.
2. When programming the polarity of internal interrupt sources on the APIC, interrupts 0 through 15 receive
active-high internal interrupt sources, while interrupts 16 through 23 receive active-low internal interrupt
sources.
5.8.3
APIC Bus Functional Description
5.8.3.1
Physical Characteristics of APIC
The APIC bus is a 3-wire synchronous bus connecting all I/O and local APICs. Two of these wires
are used for data transmission, and one wire is a clock. For bus arbitration, the APIC uses only one
of the data wires. The bus is logically a wire-OR and electrically an open-drain connection
providing for both bus use arbitration and arbitration for lowest priority. The APIC bus speed can
run from 16.67 MHz to 33 MHz.
5.8.3.2
APIC Bus Arbitration
The I/O APIC uses one wire arbitration to win bus ownership. A rotating priority scheme is used
for APIC bus arbitration. The winner of the arbitration becomes the lowest priority agent and
assumes an arbitration ID of 0. All other agents, except the agent whose arbitration ID is 15,
increment their Arbitration IDs by one. The agent whose ID was 15 will take the winner's
arbitration ID and will increment it by one. Arbitration IDs are changed only for messages that are
transmitted successfully (except for the Low Priority messages). A message is transmitted
successfully if no CS error or acceptance error was reported for that message.
An APIC agent can use two different priority schemes: Normal or EOI. EOI has the highest
priority. EOI priority is used to send EOI messages for level interrupts from a local APIC to an I/O
APIC. When an agent requests the bus with EOI priority, all other agents requesting the bus with
normal priorities will back off.
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Intel® 82801DB ICH4 Datasheet
Functional Description
When ICH4 detects a bus idle condition on the APIC Bus, and it has an interrupt to send over the
APIC bus, it drives a start cycle to begin arbitration by driving bit 0 to a 0 on an APICCLK rising
edge. It then samples bit 1. If Bit 1 was a 0, then a local APIC started arbitration for an EOI
message on the same clock edge that the ICH4 started arbitration. The ICH4 has, thus, lost
arbitration and will stop driving the APIC bus.
If the ICH4 did not see an EOI message start, it will start transferring its arbitration ID, located in
bits [27:24] of its Arbitration ID register (ARBID). Starting in Cycle 2, through Cycle 5, it will tristate bit 0, and drive bit 1 to a 0 if ARBID[27] is a 1. If ARBID[27] is a 0, it will also tri-state bit 1.
At the end of each cycle, the ICH4 will sample the state of Bit 1 on the APIC bus. If the ICH4 did
not drive Bit 1 (ARBID[27] = 0), and it samples a 0, then another APIC agent started arbitration for
the APIC bus at the same time as the ICH4, and it has higher priority. The ICH4 will stop driving
the APIC bus. Table 5-18 describes the arbitration cycles.
Table 5-18. Arbitration Cycles
5.8.3.3
Cycle
Bit 1
Bit 0
1
EOI
0
2
NOT (ARBID[27])
1
3
NOT (ARBID[26])
1
4
NOT (ARBID[25])
1
5
NOT (ARBID[24])
1
Comment
Bit 1 = 1: Normal, Bit 1 = 0: EOI
Arbitration ID. If ICH4 samples a different value than it sent, it
lost arbitration.
Bus Message Formats
After bus arbitration, the winner is granted exclusive use of the bus and will drive its message.
APIC messages come in four formats, determined by the Delivery Mode bits. These four messages
are of different length, and are known by all APICs on the bus through the transmission of the
Delivery Mode bits.
Table 5-19. APIC Message Formats
Message
# of
Cycles
Delivery Mode
Bits
Comments
EOI
14
xxx
End of Interrupt transmission from Local APIC to I/O APIC
on Level interrupts. EOI is known by the EOI bit at the start
of arbitration.
Short
21
001, 010, 100,
101, 111
I/O APIC delivery on Fixed, NMI, SMI, Reset, ExtINT, and
Lowest Priority with focus processor messages.
Lowest Priority
33
001
Transmission of Lowest Priority interrupts when the status
field indicates that the processor does not have focus.
Remote Read
39
011
Message from one Local APIC to another to read registers.
Intel® 82801DB ICH4 Datasheet
115
Functional Description
EOI Message for Level Triggered Interrupts
EOI messages are used by local APICs to send an EOI cycle occurring for a level-triggered
interrupt to an I/O APIC. This message is needed so that the I/O APIC can differentiate between a
new interrupt on the interrupt line versus the same interrupt on the interrupt line. The target of the
EOI is given by the local APIC through the transmission of the priority vector (V7 through V0) of
the interrupt. Upon receiving this message, the I/O APIC resets the Remote IRR bit for that
interrupt. If the interrupt signal is still active after the IRR bit is reset, the I/O APIC will treat it as a
new interrupt.
Table 5-20. EOI Message
116
Cycle
Bit 1
Bit 0
Comments
1
0
0
EOI message
2–5
ARBID
1
Arbitration ID
6
NOT(V7)
NOT(V6)
7
NOT(V5)
NOT(V4)
8
NOT(V3)
NOT(V2)
9
NOT(V1)
NOT(V0)
10
NOT(C1)
NOT(C0)
11
1
1
Interrupt vector bits V7 - V0 from redirection table
register
Check Sum from Cycles 6–9
Postamble
12
NOT(A)
NOT(A)
Status Cycle 0
13
NOT(A1)
NOT(A1)
Status Cycle 1
14
1
1
Idle
Intel® 82801DB ICH4 Datasheet
Functional Description
Short Message
Short messages are used for the delivery of Fixed, NMI, SMI, Reset, ExtINT, and Lowest Priority
with Focus processor interrupts. The Delivery Mode bits (M2–M0) specify the message. All short
messages take 21 cycles including the idle cycle.
Table 5-21. Short Message
Cycle
Bit 1
Bit 0
Comments
1
1
0
Normal Arbitration
2–5
ARBID
1
Arbitration ID
6
NOT(DM)
NOT(M2)
DM1 = Destination Mode from bit 11 of the redirection table
register
7
NOT(M1)
NOT(M0)
M2-M0 = Delivery Mode from bits 10:8 of the redirection table
register
8
NOT(L)
NOT(TM)
L = Level, TM = Trigger Mode
9
NOT(V7)
NOT(V6)
10
NOT(V5)
NOT(V4)
11
NOT(V3)
NOT(V2)
12
NOT(V1)
NOT(V0)
13
NOT(D7)
NOT(D6)
14
NOT(D5)
NOT(D4)
15
NOT(D3)
NOT(D2)
16
NOT(D1)
NOT(D0)
17
NOT(C1)
NOT(C0)
18
1
1
19
NOT(A)
NOT(A)
Status Cycle 0. See Table 5-22.
20
NOT(A1)
NOT(A1)
Status Cycle 1. See Table 5-22.
21
1
1
Interrupt vector bits V7 - V0 from redirection table register
Destination field from bits 63:56 of redirection table register1
Checksum for Cycles 6–162
Postamble3
Idle
NOTES:
1. If DM is 0 (physical mode), cycles 15 and 16 are the APIC ID and cycles 13 and 14 are sent as 1. If DM is 1
(logical mode), cycles 13 through 16 are the 8-bit Destination field. The interpretation of the logical mode 8-bit
Destination field is performed by the local units using the Destination Format Register. Shorthands of “all-inclself” and “all-excl-self” both use physical destination mode and a destination field containing APIC ID value of
all ones. The sending APIC knows whether it should (incl) or should not (excl) respond to its own message.
2. The checksum field is the cumulative add (mod 4) of all data bits (DM, M0–3, L, TM, V0–7, D0–7). The APIC
driving the message provides this checksum. This, in essence, is the lower two bits of an adder at the end of
the message.
3. This cycle allows all APICs to perform various internal computations based on the information contained in
the received message. One of the computations takes the checksum of the data received in cycles 6 through
16 and compares it with the value in cycle 18. If any APIC computes a different checksum than the one
passed in cycle 17, then that APIC will signal an error on the APIC bus (“00”) in cycle 19. If this happens, all
APICs will assume the message was never sent and the sender must try sending the message again, which
includes re-arbitrating for the APIC bus. In lowest priority delivery when the interrupt has a focus processor,
the focus processor will signal this by driving a 01 during cycle 19. This tells all the other APICs that the
interrupt has been accepted, the arbitration is preempted, and short message format is used. Cycle 19 and
20 indicates the status of the message (i.e., accepted, check sum error, retry, or error). Table 5-22 shows the
status signal combinations and their meanings for all delivery modes.
Intel® 82801DB ICH4 Datasheet
117
Functional Description
Table 5-22. APIC Bus Status Cycle Definition
Delivery Mode
A
11
Comments
Checksum OK
A1
Comments
1x
Error
01
Accepted
00
Retry
Fixed, EOI
10
NMI, SMM, Reset,
ExtINT
Error
xx
01
Error
xx
00
Checksum Error
xx
11
Checksum OK
1x
Error
01
Accepted
00
Error
10
Error
xx
01
Error
xx
00
Checksum Error
xx
11
Checksum OK: No Focus
Processor
1x
Error
01
End and Retry
00
Go for Low Priority Arbitration
Lowest Priority
10
Error
xx
01
Checksum OK: Focus
Processor
xx
00
Checksum Error
xx
11
Checksum OK
xx
10
Error
xx
01
Error
xx
00
Checksum Error
xx
Remote Read
118
Intel® 82801DB ICH4 Datasheet
Functional Description
Lowest Priority without Focus Processor (FP) Message
This message format is used to deliver an interrupt in the lowest priority mode in which it does not
have a Focus Process. Cycles 1 through 21 for this message is same as for the short message
discussed above. Status cycle 19 identifies if there is a Focus processor (10) and a status value of 11
in cycle 20 indicates the need for lowest priority arbitration.
Table 5-23. Lowest Priority Message (Without Focus Processor)
Cycle
Bit 1
Bit 0
1
1
0
Comments
Normal Arbitration
2–5
ARBID
1
6
NOT(DM)
NOT(M2)
DM = Destination Mode from bit 11 of the redirection table register
7
NOT(M1)
NOT(M0)
M2-M0 = Delivery Mode from bits 10:8 of the redirection table
register
8
NOT(L)
NOT(TM)
L = Level, TM = Trigger Mode
9
NOT(V7)
NOT(V6)
10
NOT(V5)
NOT(V4)
11
NOT(V3)
NOT(V2)
Arbitration ID
Interrupt vector bits V7–V0 from redirection table register
12
NOT(V1)
NOT(V0)
13
NOT(D7)
NOT(D6)
14
NOT(D5)
NOT(D4)
15
NOT(D3)
NOT(D2)
16
NOT(D1)
NOT(D0)
17
NOT(C1)
NOT(C0)
18
1
1
19
NOT(A)
NOT(A)
Status Cycle 0.
20
NOT(A1)
NOT(A1)
Status Cycle 1.
21
P7
1
22
P6
1
23
P5
1
24
P4
1
25
P3
1
26
P2
1
27
P1
1
Destination field from bits 63:56 of redirection table register
Checksum for Cycles 6–16
Postamble
Inverted Processor Priority P7–P0
28
P0
1
29
ArbID3
1
30
ArbID2
1
31
ArbID1
1
32
ArbID0
1
33
S
S
Status
34
1
1
Idle
NOTES:
1. Cycle 21 through 28 are used to arbitrate for the lowest priority processor. The processor that takes part in
the arbitration drives the processor priority on the bus. Only the local APICs that have "free interrupt slots" will
participate in the lowest priority arbitration.
2. Cycles 29 through 32 are used to break a tie in case two more processors have lowest priority. The bus
arbitration IDs are used to break the tie.
Intel® 82801DB ICH4 Datasheet
119
Functional Description
Remote Read Message
Remote read message is used when a local APIC wishes to read the register in another local APIC.
The I/O APIC in the ICH4 neither generates or responds to this cycle. The message format is same
as short message for the first 21 cycles.
Table 5-24. Remote Read Message
Cycle
Bit 1
Bit 0
Comments
1
1
0
Normal Arbitration
2–5
ARBID
1
Arbitration ID
6
NOT(DM)
NOT(M2)
DM = Destination Mode from bit 11 of the redirection table register
7
NOT(M1)
NOT(M0)
M2-M0 = Delivery Mode from bits 10:8 of the redirection table
register
8
NOT(L)
NOT(TM)
L = Level, TM = Trigger Mode
9
NOT(V7)
NOT(V6)
10
NOT(V5)
NOT(V4)
11
NOT(V3)
NOT(V2)
12
NOT(V1)
NOT(V0)
13
NOT(D7)
NOT(D6)
14
NOT(D5)
NOT(D4)
15
NOT(D3)
NOT(D2)
Interrupt vector bits V7–V0 from redirection table register
Destination field from bits 63:56 of redirection table register
16
NOT(D1)
NOT(D0)
17
NOT(C1)
NOT(C0)
18
1
1
19
NOT(A)
NOT(A)
Status Cycle 0.
20
NOT(A1)
NOT(A1)
Status Cycle 1.
21
d31
d30
22
d29
d28
23
d27
d26
24
d25
d24
25
d23
d22
26
d21
d20
27
d19
d18
28
d17
d16
29
d15
d14
30
d13
d12
31
d11
d10
32
d09
d08
33
d07
d06
34
d05
d04
35
d03
d02
36
d01
d00
37
S
S
Data Status: 00 = valid, 11 = invalid
38
C
C
Check Sum for data d31-d00
39
1
1
Idle
Checksum for Cycles 6–16
Postamble
Remote register data 31-0
NOTE: Cycle 21 through 36 contain the remote register data. The status information in cycle 37 specifies if the
data is good or not. Remote read cycle is always successful (although the data may be valid or invalid)
in that it is never retried. The reason for this is that Remote Read is a debug feature, and a "hung"
remote APIC that is unable to respond should not cause the debugger to hang.
120
Intel® 82801DB ICH4 Datasheet
Functional Description
5.8.4
PCI Message-Based Interrupts
5.8.4.1
Theory of Operation
The following scheme is only supported when the internal I/O(x) APIC is used (rather than just the
8259).
The ICH4 supports the new method for PCI devices to deliver interrupts as write cycles, rather than
using the traditional PIRQ[A:D] signals. Essentially, the PCI devices are given a write path directly
to a register that will cause the desired interrupt. This mode is only supported when the ICH4’s
internal I/O APIC is enabled. Upon recognizing the write from the peripheral, the ICH4 sends the
interrupt message to the processor using the I/O APIC’s serial bus.
The interrupts associated with the PCI Message-based interrupt method must be set up for edge
triggered mode, rather than level triggered, since the peripheral only does the write to indicate the
edge.
The following sequence is used:
1. During PCI PnP, the PCI peripheral is first programmed with an address
(MESSAGE_ADDRESS) and data value (MESSAGE_DATA) that will be used for the
interrupt message delivery. For the ICH4, the MESSAGE_ADDRESS is the IRQ Pin
Assertion Register, which is mapped to memory location FEC0_0020h.
2. To cause the interrupt, the PCI peripheral requests the PCI bus and when granted, writes the
MESSAGE_DATA value to the location indicated by the MESSAGE_ADDRESS. The
MESSAGE_DATA value indicates which interrupt occurred. This MESSAGE_DATA value is
a binary encoded. For example, to indicate that interrupt 7 should go active, the peripheral
writes a binary value of 0000111. The MESSAGE_DATA is a 32-bit value, although only the
lower 5 bits are used.
3. If the PRQ bit in the APIC Version register is set, the ICH4 positively decodes the cycles (as a
slave) in medium time.
4. The ICH4 decodes the binary value written to MESSAGE_ADDRESS and sets the appropriate
IRR bit in the internal I/O APIC. The corresponding interrupt must be set up for edgetriggered interrupts. The ICH4 supports interrupts 00h through 23h. Binary values outside this
range will not cause any action.
5. After sending the interrupt message to the processor, the ICH4 automatically clears the
interrupt.
Because they are edge-triggered, the interrupts that are allocated to the PCI bus for this scheme
may not be shared with any other interrupt (e.g., the standard PCI PIRQ[A:D], those received via
SERIRQ#, or the internal level-triggered interrupts such as SCI or TCO).
The ICH4 ignores interrupt messages sent by PCI masters that attempt to use IRQ0, 2, 8, or 13.
Intel® 82801DB ICH4 Datasheet
121
Functional Description
5.8.4.2
Registers and Bits Associated with PCI Interrupt Delivery
Capabilities Indication
The capability to support PCI interrupt delivery is indicated via ACPI configuration techniques.
This involves the BIOS creating a data structure that gets reported to the ACPI configuration
software. The OS reads the PRQ bit in the APIC Version Register to see if the ICH4 is capable of
support PCI-based interrupt messages. As a precaution, the PRQ bit is not set if the XAPIC_EN bit
is not set.
Interrupt Message Register
The PCI devices all write their message into the IRQ Pin Assertion Register, which is a memoryMapped register located at the APIC base memory location + 20h.
5.8.5
Processor System Bus Interrupt Delivery
5.8.5.1
Theory of Operation
For processors that support Processor System Bus interrupt delivery, the ICH4 has an option to let
the integrated I/O APIC behave as an I/O (x) APIC. In this case, it will deliver interrupt messages
to the processor in a parallel manner, rather than using the I/O APIC serial scheme. The ICH4 is
intended to be compatible with the I/O (x) APIC specification, Rev 1.1.
This is done by the ICH4 writing (via the Hub Interface) to a memory location that is snooped by
the processor(s). The processor(s) snoop the cycle to know which interrupt goes active.
The processor enables the mode by setting the I/O APIC Enable (APIC_EN) bit and by setting the
DT bit in the I/O APIC ID register.
The following sequence is used:
1. When the ICH4 detects an interrupt event (active edge for edge-triggered mode or a change for
level-triggered mode), it sets or resets the internal IRR bit associated with that interrupt.
2. Internally, the ICH4 requests to use the bus in a way that automatically flushes upstream
buffers. This can be internally implemented similar to a DMA device request.
3. The ICH4 then delivers the message by performing a write cycle to the appropriate address
with the appropriate data. The address and data formats are described below in Section 5.8.5.5.
Note:
5.8.5.2
PSB Interrupt Delivery compatibility with processor clock control depends on the processor, not
the ICH4.
Edge-Triggered Operation
In this case, the “Assert Message” is sent when there is an inactive-to-active edge on the interrupt.
5.8.5.3
Level-Triggered Operation
In this case, the Assert Message is sent when there is an inactive-to-active edge on the interrupt. If
after the EOI the interrupt is still active, then another Assert Message is sent to indicate that the
interrupt is still active.
122
Intel® 82801DB ICH4 Datasheet
Functional Description
5.8.5.4
Registers Associated with Processor System Bus Interrupt Delivery
Capabilities Indication
The capability to support Processor System Bus interrupt delivery is indicated via ACPI
configuration techniques. This involves the BIOS creating a data structure that gets reported to the
ACPI configuration software.
DT Bit in the Boot Configuration Register
This enables the ICH4 to deliver interrupts as memory writes. This bit is ignored if the APIC mode
is not enabled.
5.8.5.5
Interrupt Message Format
The ICH4 writes the message to PCI (and to the Host controller) as a 32-bit memory write cycle. It
uses the formats shown in Table 5-25 and Table 5-26 for the Address and Data.
The local APIC (in the processor) has a delivery mode option to interpret Processor System Bus
messages as a SMI in which case the processor treats the incoming interrupt as a SMI instead of as
an interrupt. This does not mean that the ICH4 has any way to have a SMI source from ICH4 power
management logic cause the I/OAPIC to send an SMI message (there is no way to do this). The
ICH4’s I/OAPIC can only send interrupts due to interrupts which do not include SMI, NMI or
INIT. This means that in IA32/IA64 based platforms, Processor System Bus interrupt message
format delivery modes 010 (SMI/PMI), 100 (NMI), and 101 (INIT) as indicated in this section,
must not be used and is not supported. Only the hardware pin connection is supported by ICH4.
:
Table 5-25. Interrupt Message Address Format
Bit
Description
31:20
Will always be FEEh
19:12
Destination ID: This will be the same as bits 63:56 of the I/O Redirection Table entry for the
interrupt associated with this message.
11:4
Extended Destination ID: This will be the same as bits 55:48 of the I/O Redirection Table entry for
the interrupt associated with this message.
3
Redirection Hint: This bit is used by the processor host bridge to allow the interrupt message to be
redirected.
0 = The message will be delivered to the agent (processor) listed in bits 19:12.
1 = The message will be delivered to an agent with a lower interrupt priority This can be derived
from bits 10:8 in the Data Field (see below).
The Redirection Hint bit will be a 1 if bits 10:8 in the delivery mode field associated with
corresponding interrupt are encoded as 001 (Lowest Priority). Otherwise, the Redirection Hint bit
will be 0.
2
Destination Mode: This bit is used only when the Redirection Hint bit is set to 1. If the Redirection
Hint bit and the Destination Mode bit are both set to 1, then the logical destination mode is used,
and the redirection is limited only to those processors that are part of the logical group as based on
the logical ID.
1:0
Will always be 00.
Intel® 82801DB ICH4 Datasheet
123
Functional Description
Table 5-26. Interrupt Message Data Format
Bit
31:16
Will always be 0000h.
15
Trigger Mode: 1 = Level, 0 = Edge. Same as the corresponding bit in the I/O Redirection Table for
that interrupt.
14
Delivery Status: 1 = Assert, 0 = Deassert.
If using edge-triggered interrupts, then bit will always be 1, since only the assertion is sent.
If using level-triggered interrupts, then this bit indicates the state of the interrupt input.
13:12
11
5.9
Description
Will always be 00.
Destination Mode: 1 = Logical. 0 = Physical. Same as the corresponding bit in the I/O Redirection
Table for that interrupt.
10:8
Delivery Mode: This is the same as the corresponding bits in the I/O Redirection Table for that
interrupt.
000 = Fixed 100 = NMI
001 = Lowest Priority 101 = INIT
010 = SMI/PMI 110 = Reserved
011 = Reserved 111 = ExtINT
7:0
Vector: This is the same as the corresponding bits in the I/O Redirection Table for that interrupt.
Serial Interrupt (D31:F0)
The ICH4 supports a serial IRQ scheme. This allows a single signal to be used to report interrupt
requests. The signal used to transmit this information is shared between the host, the ICH4, and all
peripherals that support serial interrupts. The signal line, SERIRQ, is synchronous to PCI clock,
and follows the sustained tri-state protocol that is used by all PCI signals. This means that if a
device has driven SERIRQ low, it will first drive it high synchronous to PCI clock and release it the
following PCI clock. The serial IRQ protocol defines this sustained tri-state signaling in the
following fashion:
• S - Sample Phase. Signal driven low
• R - Recovery Phase. Signal driven high
• T - Turn-around Phase. Signal released
The ICH4 supports a message for 21 serial interrupts. These represent the 15 ISA interrupts
(IRQ[0:1, 2:15]), the four PCI interrupts, and the control signals SMI# and IOCHK#. The serial
IRQ protocol does not support the additional APIC interrupts (20–23).
Note:
124
When the IDE primary and secondary controllers are configured for native IDE mode, the only
way to use the internal IRQ14 and IRQ15 connections to the Interrupt controllers is through the
Serial Interrupt pin.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.9.1
Start Frame
The serial IRQ protocol has two modes of operation which affect the start frame. These two modes
are: Continuous, where the ICH4 is solely responsible for generating the start frame; and Quiet,
where a serial IRQ peripheral is responsible for beginning the start frame.
The mode that must first be entered when enabling the serial IRQ protocol is continuous mode. In
this mode, the ICH4 asserts the start frame. This start frame is 4-, 6-, or 8-PCI clocks wide, based
upon the Serial IRQ Control Register (bits 1:0 at 64h in Device 31:Function 0 configuration space).
This is a polling mode.
When the serial IRQ stream enters quiet mode (signaled in the Stop Frame), the SERIRQ line
remains inactive and pulled up between the Stop and Start Frame until a peripheral drives the
SERIRQ signal low. The ICH4 senses the line low and continues to drive it low for the remainder
of the Start Frame. Since the first PCI clock of the start frame was driven by the peripheral in this
mode, the ICH4 drives the SERIRQ line low for 1 PCI clock less than in continuous mode. This
mode of operation allows for a quiet, and, therefore, lower power operation.
5.9.2
Data Frames
Once the Start frame has been initiated, all of the SERIRQ peripherals must start counting frames
based on the rising edge of SERIRQ. Each of the IRQ/DATA frames has exactly three phases of
one clock each:
• Sample Phase. During this phase, the SERIRQ device drives SERIRQ low if the
corresponding interrupt signal is low. If the corresponding interrupt is high, then the SERIRQ
devices will tri-state the SERIRQ signal. The SERIRQ line will remain high due to pull-up
resistors (there is no internal pull-up resistor on this signal, an external pull-up resistor is
required). A low level during the IRQ0-1 and IRQ2-15 frames indicates that an active-high
ISA interrupt is not being requested, but a low level during the PCI INT[A:D], SMI#, and
IOCHK# frame indicates that an active-low interrupt is being requested.
• Recovery Phase. During this phase, the device drives the SERIRQ line high if in the Sample
Phase it was driven low. If it was not driven in the sample phase, it will be tri-stated in this
phase.
• Turn-around Phase. The device will tri-state the SERIRQ line
5.9.3
Stop Frame
After all data frames, a Stop Frame are driven by the ICH4. The SERIRQ signal is driven low by
the ICH4 for 2 or 3 PCI clocks. The number of clocks is determined by the SERIRQ configuration
register. The number of clocks determines the next mode:
Table 5-27. Stop Frame Explanation
Stop Frame Width
Next Mode
2 PCI clocks
Quiet Mode. Any SERIRQ device may initiate a Start Frame
3 PCI clocks
Continuous Mode. Only the host (ICH4) may initiate a Start Frame
Intel® 82801DB ICH4 Datasheet
125
Functional Description
5.9.4
Specific Interrupts Not Supported via SERIRQ
There are three interrupts seen through the serial stream which are not supported by the ICH4.
These interrupts are generated internally and are not sharable with other devices within the system.
These interrupts are:
• IRQ0. Heartbeat interrupt generated off of the internal 8254 counter 0.
• IRQ8#. RTC interrupt can only be generated internally.
• IRQ13. Floating point error interrupt generated off of the processor assertion of FERR#.
The ICH4 ignores the state of these interrupts in the serial stream, and does not adjust their level
based on the level seen in the serial stream. In addition, the interrupts IRQ14 and IRQ15 from the
serial stream are treated differently than their ISA counterparts. These two frames are not passed to
the Bus Master IDE logic. The Bus Master IDE logic expects IDE to be behind the ICH4.
5.9.5
Data Frame Format
Table 5-28 shows the format of the data frames. For the PCI interrupts (A–D), the output from the
ICH4 is ANDed with the PCI input signal. This way, the interrupt can be signaled via both the PCI
interrupt input signal and via the SERIRQ signal (they are shared).
Table 5-28. Data Frame Format
126
Data
Frame #
Interrupt
Clocks Past
Start Frame
1
IRQ0
2
2
IRQ1
5
3
SMI#
8
4
IRQ3
11
5
IRQ4
14
6
IRQ5
17
7
IRQ6
20
8
IRQ7
23
9
IRQ8
26
10
IRQ9
29
11
IRQ10
32
12
IRQ11
35
Comment
Ignored. IRQ0 can only be generated via the internal 8524
Causes SMI# if low. Will set the SERIRQ_SMI_STS bit.
Ignored. IRQ8# can only be generated internally or on ISA.
13
IRQ12
38
14
IRQ13
41
Ignored. IRQ13 can only be generated from FERR#
15
IRQ14
44
Do not include in BM IDE interrupt logic
16
IRQ15
47
Do not include in BM IDE interrupt logic
17
IOCHCK#
50
Same as ISA IOCHCK# going active.
18
PCI INTA#
53
Drive PIRQA#
19
PCI INTB#
56
Drive PIRQB#
20
PCI INTC#
59
Drive PIRQC#
21
PCI INTD#
62
Drive PIRQD#
Intel® 82801DB ICH4 Datasheet
Functional Description
5.10
Real Time Clock (D31:F0)
The Real Time Clock (RTC) module provides a battery backed-up date and time keeping device
with two banks of static RAM with 128 bytes each, although the first bank has 114 bytes for
general purpose usage. Three interrupt features are available: time of day alarm with once a second
to once a month range, periodic rates of 122 µs to 500 ms, and end of update cycle notification.
Seconds, minutes, hours, days, day of week, month, and year are counted. Daylight savings
compensation is optional. The hour is represented in twelve or twenty-four hour format, and data
can be represented in BCD or binary format. The design is meant to be functionally compatible
with the Motorola MS146818B. The time keeping comes from a 32.768 kHz oscillating source,
which is divided to achieve an update every second. The lower 14 bytes on the lower RAM block
has very specific functions. The first ten are for time and date information. The next four (0Ah to
0Dh) are registers, which configure and report RTC functions.
The time and calendar data should match the data mode (BCD or binary) and hour mode
(12 or 24 hour) as selected in register B. It is up to the programmer to make sure that data stored in
these locations is within the reasonable values ranges and represents a possible date and time. The
exception to these ranges is to store a value of C0–FF in the Alarm bytes to indicate a don’t care
situation. All Alarm conditions must match to trigger an Alarm Flag, which could trigger an Alarm
Interrupt if enabled. The SET bit must be one while programming these locations to avoid clashes
with an update cycle. Access to time and date information is done through the RAM locations. If a
RAM read from the ten time and date bytes is attempted during an update cycle, the value read will
not necessarily represent the true contents of those locations. Any RAM writes under the same
conditions will be ignored.
Note:
The ICH4 supports the ability to generate an SMI# based on Year 2000 rollover. See Section 5.10.4
for more information on the century rollover.
The ICH4 does not implement month/year alarms.
5.10.1
Update Cycles
An update cycle occurs once a second, if the SET bit of register B is not asserted and the divide
chain is properly configured. During this procedure, the stored time and date will be incremented,
overflow will be checked, a matching alarm condition will be checked, and the time and date will
be rewritten to the RAM locations. The update cycle will start at least 488 µs after the UIP bit of
register A is asserted, and the entire cycle will not take more than 1984 µs to complete. The time
and date RAM locations (0–9) will be disconnected from the external bus during this time.
To avoid update and data corruption conditions, external RAM access to these locations can safely
occur at two times. When a updated-ended interrupt is detected, almost 999 ms is available to read
and write the valid time and date data. If the UIP bit of Register A is detected to be low, there is at
least 488 µs before the update cycle begins.
Warning:
The overflow conditions for leap years and daylight savings adjustments are based on more than
one date or time item. To ensure proper operation when adjusting the time, the new time and data
values should be set at least two seconds before one of these conditions (leap year, daylight savings
time adjustments) occurs.
Intel® 82801DB ICH4 Datasheet
127
Functional Description
5.10.2
Interrupts
The real-time clock interrupt is internally routed within the ICH4 both to the I/O APIC and the
8259. It is mapped to interrupt vector 8. This interrupt does not leave the ICH4, nor is it shared with
any other interrupt. IRQ8# from the SERIRQ stream is ignored.
5.10.3
Lockable RAM Ranges
The RTC’s battery-backed RAM supports two, 8-byte ranges that can be locked via the
configuration space. If the locking bits are set, the corresponding range in the RAM will not be
readable or writable. A write cycle to those locations will have no effect. A read cycle to those
locations will not return the location’s actual value (may be all zeros or all ones).
Once a range is locked, the range can be unlocked only by a hard reset, which will invoke the BIOS
and allow it to relock the RAM range.
5.10.4
Century Rollover
The ICH4 detects a rollover when the Year byte (RTC I/O space, index offset 09h) transitions form
99 to 00. Upon detecting the rollover, the ICH4 will set the NEWCENTURY_STS bit
(TCOBASE + 04h, bit 7). If the system is in an S0 state, this will cause an SMI#. The SMI#
handler can update registers in the RTC RAM that are associated with century value. If the system
is in a sleep state (S1–S5) when the century rollover occurs, the ICH4 will also set the
NEWCENTURY_STS bit, but no SMI# is generated. When the system resumes from the sleep
state, BIOS should check the NEWCENTURY_STS bit and update the century value in the RTC
RAM.
5.10.5
Clearing Battery-Backed RTC RAM
Clearing CMOS RAM in an ICH4-based platform can be done by using a jumper on RTCRST# or
GPI, or using SAFEMODE strap. Implementations should not attempt to clear CMOS by using a
jumper to pull VccRTC low.
Using RTCRST# to clear CMOS
A jumper on RTCRST# can be used to clear CMOS values, as well as reset to default, the state of
those configuration bits that reside in the RTC power well. When the RTCRST# is strapped to
ground, the RTC_PWR_STS bit (D31:F0:A4h bit 2) is set and those configuration bits in the RTC
power well will be set to their default state. BIOS can monitor the state of this bit and manually
clear the RTC CMOS array once the system is booted. The normal position would cause RTCRST#
to be pulled up through a weak pull-up resistor. Table 5-29 shows which bits are set to their default
state when RTCRST# is asserted.
128
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-29. Configuration Bits Reset By RTCRST# Assertion
Bit Name
Default State
Register
Location
Bit(s)
FREQ_STRAP[3:0]
GEN_STS
D31:F0:D4h
11:8
1111b
AIE
RTC Reg B
I/O space
5
0
AF
RTC Reg C
I/O space
5
0
PWR_FLR
GEN_PMCON_3
D31:F0:A4h
1
0
AFTERG3_EN
GEN_PMCON_3
D31:F0:A4h
0
0
RTC_PWR_STS
GEN_PMCON_3
D31:F0:A4h
2
1
PRBTNOR_STS
PM1_STS
PMBase + 00h
11
0
PME_EN
GPE0_EN
PMBase + 2Ah
11
0
RI_EN
GPE0_EN
PMBase + 2Ah
8
0
NEW_CENTURY_STS
TCO1_STS
TCOBase + 04h
7
0
INTRD_DET
TCO2_STS
TCOBase + 06h
0
0
TOP_SWAP
GEN_STS
D31:F0:D4h
13
0
RTC_EN
PM1_EN
PMBase + 02h
10
0
Using a GPI to Clear CMOS
A jumper on a GPI can also be used to clear CMOS values. BIOS would detect the setting of this
GPI on system boot-up, and manually clear the CMOS array.
Using the SAFEMODE Strap to Clear CMOS
A jumper on AC_SDOUT (SAFEMODE strap) can also be used to clear CMOS values. BIOS
would detect the setting of the SAFE_MODE status bit (D31:F0: Offset D4h bit 2) on system bootup, and manually clear the CMOS array.
Note:
Both the GPI and SAFEMODE strap techniques to clear CMOS require multiple steps to
implement. The system is booted with the jumper in new position, then powered back down. The
jumper is replaced back to the normal position, then the system is rebooted again. The RTCRST#
jumper technique allows the jumper to be moved and then replaced, all while the system is
powered off. Then, once booted, the RTC_PWR_STS can be detected in the set state.
Note:
Clearing CMOS, using a jumper on VccRTC, must not be implemented.
Intel® 82801DB ICH4 Datasheet
129
Functional Description
5.11
Processor Interface (D31:F0)
The ICH4 interfaces to the processor with a variety of signals
• Standard Outputs to processor: A20M#, SMI#, NMI, INIT#, INTR, STPCLK#, IGNNE#,
CPUSLP#
• Standard Input from processor: FERR#
Most ICH4 outputs to the processor use standard buffers. The ICH4 has a separate VCC signal
which is pulled up at the system level to the processor voltage, and thus determines VOH for the
outputs to the processor. Note that this is different than previous generations of chips, that have
used open-drain outputs. This new method saves up to 12 external pull-up resistors.
The ICH4 also handles the speed setting for the processor by holding specific signals at certain
states just prior to CPURST going inactive. This avoids the glue often required with other chipsets.
The ICH4 does not support the processor’s FRC mode.
5.11.1
Processor Interface Signals
This section describes each of the signals that interface between the ICH4 and the processor(s).
Note that the behavior of some signals may vary during processor reset, as the signals are used for
frequency strapping.
5.11.1.1
A20M#
The A20M# signal will be active (low) when both of the following conditions are true:
• The ALT_A20_GATE bit (Bit 1 of PORT92 register) is a 0
• The A20GATE input signal is a 0
The A20GATE input signal is expected to be generated by the external microcontroller (KBC).
5.11.1.2
INIT#
The INIT# signal will be active (driven low) based on any one of several events described in
Table 5-30. When any of these events occur, INIT# will be driven low for 16 PCI clocks, then
driven high.
Note:
130
The 16-clock counter for INIT# assertion will halt while STPCLK# is active. Therefore, if INIT# is
supposed to go active while STPCLK# is asserted, it will actually go active after STPCLK# goes
inactive.
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-30. INIT# Going Active
Cause of INIT# Going Active
Comment
Shutdown special cycle from processor.
PORT92 write, where INIT_NOW (bit 0) transitions
from a 0 to a 1.
PORTCF9 write, where RST_CPU (bit 2) was a 0 and
SYS_RST(bit 1) transitions from 0 to 1.
5.11.1.3
RCIN# input signal goes low. RCIN# is expected to be
driven by the external microcontroller (KBC).
0 to 1 transition on RCIN# must occur before the
ICH4 will arm INIT# to be generated again.
NOTE: RCIN# signal is expected to be low during
S3, S4, and S5 states. Transition on the
RCIN# signal in those states (or the
transition to those states) may not
necessarily cause the INIT# signal to be
generated to the processor.
CPU BIST
To enter BIST, the software sets CPU_BIST_EN bit
and then does a full processor reset using the CF9
register.
FERR#/IGNNE# (Coprocessor Error)
The ICH4 supports the coprocessor error function with the FERR#/IGNNE# pins. The function is
enabled via the COPROC_ERR_EN bit (Device 31:Function 0, Offset D0, bit 13). FERR# is tied
directly to the Coprocessor Error signal of the processor. If FERR# is driven active by the
processor, IRQ13 goes active (internally). When it detects a write to the COPROC_ERR register,
the ICH4 negates the internal IRQ13 and drives IGNNE# active. IGNNE# remains active until
FERR# is driven inactive. IGNNE# is never driven active unless FERR# is active.
Figure 5-12. Coprocessor Error Timing Diagram
FERR#
Internal IRQ13
I/O Write to F0h
IGNNE#
If COPROC_ERR_EN is not set, then the assertion of FERR# will have not generate an internal
IRQ13, nor will the write to F0h generate IGNNE#.
Intel® 82801DB ICH4 Datasheet
131
Functional Description
5.11.1.4
NMI
Non-Maskable Interrupts (NMIs) can be generated by several sources, as described in Table 5-31.
Table 5-31. NMI Sources
5.11.1.5
Cause of NMI
Comment
SERR# goes active (either internally, externally
via SERR# signal, or via message from the MCH)
Can instead be routed to generate an SCI, through the
NMI2SCI_EN bit (Device 31:Function 0, offset 4E, bit 11).
IOCHK# goes active via SERIRQ# stream
(ISA system Error)
Can instead be routed to generate an SCI, through the
NMI2SCI_EN bit (Device 31:Function 0, offset 4E, bit 11).
STPCLK# and CPUSLP# Signals
The ICH4 power management logic controls these active-low signals. Refer to Section 5.12 for
more information on the functionality of these signals.
5.11.1.6
CPUPWRGOOD Signal
This signal is connected to the processor’s PWRGOOD input. This is an open-drain output signal
(external pull-up resistor required) that represents a logical AND of the ICH4’s PWROK and
VRMPWRGD signals.
5.11.2
Dual-Processor Designs
5.11.2.1
Signal Differences
In dual-processor (DP) designs, some of the processor signals are unused or used differently than
for uniprocessor designs.
Table 5-32. DP Signal Differences
Signal
132
Difference
A20M# / A20GATE
Generally not used, but still supported by Intel® ICH4.
STPCLK#
Used for S1 State as well as preparation for entry to S3–S5
Also allows for THERM# based throttling (not via ACPI control methods).
Should be connected to both processors.
FERR# / IGNNE#
Generally not used, but still supported by ICH4.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.11.2.2
Power Management
Attempting clock control with more than one processor is not feasible, because the Host controller
does not provide any indication as to which processor is executing a particular Stop-Grant cycle.
Without this information, there is no way for the ICH4 to know when it is safe to deassert
STPCLK#.
Because the S1 state will have the STPCLK# signal active, the STPCLK# signal can be connected
to both processors. However, for ACPI implementations, the ICH4 does not support the C2 state
for both processors, since there are not two processor control blocks. The BIOS must indicate that
the ICH4 only supports the C1 state for dual-processor designs. However, the THRM# signal can
be used for overheat conditions to activate thermal throttling.
When entering S1, the ICH4 asserts STPCLK# to both processors. To meet the processor
specifications, the CPUSLP# signal will have to be delayed until the second Stop-Grant cycle
occurs. To ensure this, the ICH4 waits a minimum or 60 PCI clocks after receipt of the first StopGrant cycle before asserting CPUSLP# (if the SLP_EN bit is set to 1).
Both processors must immediately respond to the STPCLK# assertion with stop grant
acknowledge cycles before the ICH4 asserts CPUSLP# in order to meet the processor setup time
for CPUSLP#. Meeting the processor setup time for CPUSLP# is not an issue if both processors are
idle when the system is entering S1. If you cannot guarantee that both processors will be idle, do
not enable the SLP_EN bit. Note that setting SLP_EN to 1 is not required to support S1 in a dualprocessor configuration.
In going to the S3, S4, or S5 states, the system will appear to pass through the S1 state, and thus
STPCLK# and SLP# are also used. During the S3, S4, and S5 states, both processors will lose
power. Upon exit from those states, the processors will have their power restored.
Intel® 82801DB ICH4 Datasheet
133
Functional Description
5.11.3
Speed Strapping for Processor
The ICH4 directly sets the speed straps for the processor, saving the external logic that has been
needed with prior PCIsets. Refer to processor specification for speed strapping definition.
The ICH4 performs the following to set the speed straps for the processor:
1. While PCIRST# is active, the ICH4 drives A20M#, IGNNE#, NMI, and INTR high.
2. As soon as PWROK goes active, the ICH4 reads the FREQ_STRAP field contents.
3. The next step depends on the power state being exited as described in Table 5-33.
Table 5-33. Frequency Strap Behavior Based on Exit State
State
Exiting
ICH4
S1
There is no processor reset, so no frequency strap logic is used.
S3, S4, S5,
or G3
Based on PWROK going active, the ICH4 will deassert PCIRST#, and based on the value of the
FREQ_STRAP field (D31:F0,Offset D4), the Intel® ICH4 will drive the intended core frequency
values on A20M#, IGNNE#, NMI, and INTR. The ICH4 will hold these signals for 120 ns after
CPURST# is deasserted by the Host controller.
Table 5-34. Frequency Strap Bit Mapping
FREQ_STRAP Bits [3:0]
Sets High/Low Level for the Corresponding Signal
3
NMI
2
INTR
1
IGNNE#
0
A20M#
NOTE: The FREQ_STRAP register is in the RTC well. The value in the register can be forced to 1111h via a
pinstrap (AC_SDOUT signal), or the ICH4 can automatically force the speed strapping to 1111h if the
processor fails to boot.
Figure 5-13. Signal Strapping
Processor
A20M#, IGNNE#,
INTR, NMI
CPURST#
Host Controller
INIT#
ICH4
PCIRST#
4x 2 to 1
Mux
Frequency
Strap Register
PWROK
134
Intel® 82801DB ICH4 Datasheet
Functional Description
5.12
Power Management (D31:F0)
The power management features include:
• ACPI Power and Thermal Management Support
•
•
•
•
5.12.1
— ACPI 24-Bit Timer
— Software initiated throttling of processor performance for Thermal and Power Reduction
— Hardware Override to throttle processor performance if system too hot
— SCI and SMI# Generation
PCI PME# Signal for Wake Up from Low-Power states
System Clock Control
— ACPI C2 state: Stop-Grant state (using STPCLK# signal) halts processor’s instruction
stream
System Sleeping State Control
— ACPI S1 state: Like C2 state (only STPCLK# active, and SLP# optional)
— ACPI S3 state: Suspend to RAM (STR)
— ACPI S4 state: Suspend-to-Disk (STD)
— ACPI G2/S5 state: Soft Off (SOFF)
— Power Failure Detection and Recovery
Streamlined Legacy Power Management Support for APM-Based Systems
Intel® ICH4 and System Power States
Table 5-35 shows the power states defined for ICH4-based platforms. The state names generally
match the corresponding ACPI states.
Table 5-35. General Power States for Systems Using Intel® ICH4
State/
Substates
Legacy Name / Description
G0/S0/C0
Full On: Processor operating. Individual devices may be shut down to save power. The different
processor operating levels are defined by Cx states, as shown in Table 5-36. Within the C0 state, the
Intel® ICH4 can throttle the STPCLK# signal to reduce power consumption. The throttling can be
initiated by software or by the THRM# input signal.
G0/S0/C1
Auto-Halt: Processor has executed a AutoHalt instruction and is not executing code. The processor
snoops the bus and maintains cache coherency.
G0/S0/C2
Stop-Grant: The STPCLK# signal goes active to the processor. The processor performs a StopGrant cycle, halts its instruction stream, and remains in that state until the STPCLK# signal goes
inactive. In the Stop-Grant state, the processor snoops the bus and maintains cache coherency.
G1/S1
Stop-Grant: Similar to G0/S0/C2 state. ICH4 also has the option to assert the CPUSLP# signal to
further reduce processor power consumption.
NOTE: The behavior for this state is slightly different when supporting iA64 processors.
G1/S3
Suspend-To-RAM (STR): The system context is maintained in system DRAM, but power is shut off
to non-critical circuits. Memory is retained, and refreshes continue. All clocks stop except RTC clock.
G1/S4
Suspend-To-Disk (STD): The context of the system is maintained on the disk. All power is then shut
off to the system except for the logic required to resume.
G2/S5
Soft Off (SOFF): System context is not maintained. All power is shut off except for the logic required
to restart. A full boot is required when waking.
G3
Mechanical OFF (MOFF): System context not maintained. All power is shut off except for the RTC.
No “Wake” events are possible, because the system does not have any power. This state occurs if
the user removes the batteries, turns off a mechanical switch, or if the system power supply is at a
level that is insufficient to power the “waking” logic. When system power returns, transition will
depends on the state just prior to the entry to G3 and the AFTERG3 bit in the GEN_PMCON3 register
(D31:F0, offset A4). Refer to Table 5-43 for more details.
Intel® 82801DB ICH4 Datasheet
135
Functional Description
Table 5-36 shows the transitions rules among the various states. Note that transitions among the
various states may appear to temporarily transition through intermediate states. For example, in
going from S0 to S1, it may appear to pass through the G0/S0/C2 states. These intermediate
transitions and states are not listed in the table.
Table 5-36. State Transition Rules for Intel® ICH4
Present
State
Transition Trigger
• Processor halt instruction
• Level 2 Read
Next State
• SLP_EN bit set
• Power Button Override
• Mechanical Off/Power Failure
•
•
•
•
•
•
G0/S0/C1
G0/S0/C2
G0/S0/C3
G1/Sx or G2/S5state
G2/S5
G3
G0/S0/C1
•
•
•
•
•
•
•
•
G0/S0/C0
G0/S0/C2
G2/S5
G3
• G0/S0/C0
• G0/S0/C1
G0/S0/C2
• Any Enabled Break Event
• STPCLK# goes inactive and previously
in C1
• Power Button Override
• Power Failure
G1/S1,
G1/S3, or
G1/S4
• Any Enabled Wake Event
• Power Button Override
• Power Failure
• G0/S0/C0
• G2/S5
• G3
G2/S5
• Any Enabled Wake Event
• Power Failure
• G0/S0/C0
• G3
• Power Returns
• Optional to go to S0/C0 (reboot) or G2/S5
(stay off until power button pressed or other
wake event).
(See Note 1)
G0/S0/C0
G3
Any Enabled Break Event
STPCLK# goes active
Power Button Override
Power Failure
• G2/S5
• G3
NOTES:
1. Some wake events can be preserved through power failure.
136
Intel® 82801DB ICH4 Datasheet
Functional Description
5.12.2
System Power Planes
The system has several independent power planes, as described in Table 5-37. Note that when a
particular power plane is shut off, it should go to a 0 V level.
s
Table 5-37. System Power Plane
5.12.3
Plane
Controlled
By
Processor
SLP_S3#
signal
The SLP_S3# signal can be used to cut the processor’s power completely
MAIN
SLP_S3#
signal
When SLP_S3# goes active, power can be shut off to any circuit not required
to wake the system from the S3 state. Since the S3 state requires that the
memory context be preserved, power must be retained to the main memory.
The processor, devices on the PCI bus, LPC interface downstream hub
interface and AGP will typically be shut off when the Main power plane is
shut, although there may be small subsections powered.
MEMORY
SLP_S4#
signal
When the SLP_S4# goes active, power can be shut off to any circuit not
required to wake the system from the S4. Since the memory context does
not need to be preserved in the S4 state, the power to the memory can also
be shut down.
DEVICE[n]
GPIO
Individual subsystems may have their own power plane. For example, GPIO
signals may be used to control the power to disk drives, audio amplifiers, or
the display screen.
Description
Intel® ICH4 Power Planes
The ICH4 power planes are defined in Section 4.1. Although there are not specific power planes
within the ICH4, there are many interface signals that go to devices that may be powered down.
These include:
• IDE: ICH4 can tri-state or drive low all IDE output signals and shut off input buffers.
• USB: ICH4 can tri-state USB output signals and shut off input buffers if USB wakeup is not
desired
• AC ’97: ICH4 can drive low the outputs and shut off inputs
5.12.4
SMI#/SCI Generation
Upon any SMI# event taking place, ICH4 asserts SMI# to the processor which causes it to enter
SMM space. SMI# remains active until the EOS bit is set. When the EOS bit is set, SMI# goes
inactive for a minimum of 4 PCICLK. If another SMI event occurs, SMI# is driven active again.
The SCI is a level-mode interrupt that is typically handled by an ACPI-aware operating system. In
non-APIC systems (which is the default), the SCI IRQ is routed to one of the 8259 interrupts
(IRQ 9, 10, or 11). The 8259 interrupt controller must be programmed to level mode for that
interrupt.
In systems using the APIC, the SCI can be routed to interrupts 9, 10, 11, 20, 21, 22, or 23. The
interrupt polarity changes depending on whether it is on an interrupt shareable with a PIRQ or not;
(see Section 9.1.11 ACPI Control Register for details.) The interrupt will remain asserted until all
SCI sources are removed.
Intel® 82801DB ICH4 Datasheet
137
Functional Description
Table 5-38 shows which events can cause an SMI# and SCI. Note that some events can be
programmed to cause either an SMI# or SCI. The usage of the event for SCI (instead of SMI#) is
typically associated with an ACPI-based system. Each SMI# or SCI source has a corresponding
enable and status bit.
Table 5-38. Causes of SMI# and SCI (Sheet 1 of 2)
Cause
138
SCI
SMI
Additional Enables
Where Reported
PME#
Yes
Yes
PME_EN=1
PME_STS
PME_B0 (internal EHCI controller)
Yes
Yes
PME_B0_EN=1
PME_B0_STS
Power Button Press
Yes
Yes
PWRBTN_EN=1
PWRBTN_STS
RTC Alarm
Yes
Yes
RTC_EN=1
RTC_STS
Ring Indicate
Yes
Yes
RI_EN=1
RI_STS
AC ’97 wakes
Yes
Yes
AC ’97_EN=1
AC ’97_STS
USB UHCI #1 wakes
Yes
Yes
USB1_EN=1
USB1_STS
USB UHCI #2 wakes
Yes
Yes
USB2_EN=1
USB2_STS
USB UHCI #3 wakes
Yes
Yes
USB3_EN=1
USB3_STS
THRM# pin active
Yes
Yes
THRM_EN=1
THRM_STS
ACPI Timer overflow (2.34 sec.)
Yes
Yes
TMROF_EN=1
TMROF_STS
Any GPI
Yes
Yes
GPI[x]_Route=10 (SCI)
GPI[x]_Route=01 (SMI)
GPE0[x]_EN=1
GPI[x]_STS
GPE0_STS
TCO SCI Logic
Yes
No
TCOSCI_EN=1
TCOSCI_STS
TCO SCI message from MCH
Yes
No
none
MCHSCI_STS
TCO SMI Logic
No
Yes
TCO_EN=1
TCO_STS
TCO SMI -Year 2000 Rollover
No
Yes
none
NEWCENTURY_STS
TCO SMI -TCO TIMEROUT
No
Yes
none
TIMEOUT
TCO SMI - OS writes to
TCO_DAT_IN register
No
Yes
none
OS_TCO_SMI
TCO SMI -Message from MCH
No
Yes
none
MCHSMI_STS
TCO SMI - NMI occurred (and
NMIs mapped to SMI)
No
Yes
NMI2SMI_EN=1
NMI2SMI_STS
TCO SMI -INTRUDER# signal
goes active
No
Yes
INTRD_SEL=10
INTRD_DET
TCO SMI - Change of the BIOSWP
bit from 0 to 1
No
Yes
BLD=1
BIOSWR_STS
TCO SMI -Write attempted to BIOS
No
Yes
BIOSWP=1
BIOSWR_STS
BIOS_RLS written to
Yes
No
GBL_EN=1
GBL_STS
GBL_RLS written to
No
Yes
BIOS_EN=1
BIOS_STS
Write to B2h register
No
Yes
none
APM_STS
Periodic timer expires
No
Yes
PERIODIC_EN=1
PERIODIC_STS
64 ms timer expires
No
Yes
SWSMI_TMR_EN=1
SWSMI_TMR_STS
Enhanced USB Legacy Support
Event
No
Yes
LEGACY_USB2_EN = 1
LEGACY_USB2_STS
Enhanced USB Intel Specific Event
No
Yes
INTEL_USB2_EN = 1
INTEL_USB2_STS
Classic USB Legacy logic
No
Yes
LEGACY_USB_EN=1
LEGACY_USB_STS
Serial IRQ SMI reported
No
Yes
none
SERIRQ_SMI_STS
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-38. Causes of SMI# and SCI (Sheet 2 of 2)
Cause
SCI
SMI
Additional Enables
Where Reported
Device monitors match address in
its range
No
Yes
DEV[n]_TRAP_EN=1
DEVMON_STS,
DEV[n]_TRAP_STS
SMBus Host controller
No
Yes
SMB_SMI_EN
Host Controller Enabled
SMBus host status reg.
SMBus Slave SMI message
No
Yes
none
SMBUS_SMI_STS
SMBus SMBALERT# signal active
No
Yes
none
SMBUS_SMI_STS
SMBus Host Notify message
received
No
Yes
HOST_NOTIFY_INTREN
SMBUS_SMI_STS
HOST_NOTIFY_STS
Access microcontroller 62h/66h
No
Yes
MCSMI_EN
MCSMI_STS
SLP_EN bit written to 1
No
Yes
SMI_ON_SLP_EN=1
SMI_ON_SLP_EN_STS
NOTES:
1. SCI_EN must be 1 to enable SCI. SCI_EN must be 0 to enable SMI.
2. SCI can be routed to cause interrupt 9:11 or 20:23 (20:23 only available in APIC mode).
3. GBL_SMI_EN must be 1 to enable SMI.
4. EOS must be written to 1 to re-enable SMI for the next one.
5.12.5
Dynamic Processor Clock Control
The ICH4 has extensive control for dynamically starting and stopping system clocks. The clock
control is used for transitions among the various S0/Cx states, and processor throttling. Each
dynamic clock control method is described in this section. The various Sleep states may also
perform types of non-dynamic clock control.
The ICH4 supports the ACPI C0, C1, and C2 states.
The Dynamic processor clock control is handled using the following signals:
• STPCLK#: Used to halt processor instruction stream.
The C1 state is entered based on the processor performing an auto halt instruction. The C2 state is
entered based on the processor reading the Level 2 register in the ICH4.
A C1, C2 state ends due to a Break event. Based on the break event, the ICH4 returns the system to
C0 state. Table 5-39 lists the possible break events from C2 . The break events from C1 are
indicated in the processor’s datasheet.
Table 5-39. Break Events
Event
Breaks from
Comment
Any unmasked interrupt goes active
C2
IRQ[0:15] when using the 8259s, IRQ[0:23] for
I/O APIC. Since SCI is an interrupt, any SCI will
also be a break event.
Any internal event that will cause an
NMI or SMI#
C2
Many possible sources
Any internal event that will cause
INIT# to go active
C2
Could be indicated by the keyboard controller
via the RCIN input signal.
Processor Pending Break Event
Indication
C2
Only available if FERR# enabled for break event
indication (See GEN_CNTL.FERR# Mux-En bit
in Section 9.1.22).
Intel® 82801DB ICH4 Datasheet
139
Functional Description
The ICH4 supports the Pending Break Event (PBE) indication from the processor using the FERR#
signal. The following rules apply:
1. When STPCLK# is detected active by the processor, the FERR# signal from the processor will
be redefined to indicate whether an interrupt is pending. The signal is active low (i.e., FERR#
will be low to indicate a pending interrupt).
2. When the ICH4 asserts STPCLK#, it will latch the current state of the FERR# signal and
continue to present this state to the FERR# state machine (independent of what the FERR# pin
does after the latching).
3. When the ICH4 detects the Stop-Grant cycle, it will start looking at the FERR# signal as a
break event indication. If FERR# is sampled low, a break event is indicated. This will force a
transition to the C0 state.
4. When the processor detects the deassertion of STPCLK#, the processor will start driving the
FERR# signal with the natural value (i.e., the value it would do if the pin was not muxed). The
time from STPCLK# inactive to the FERR# signal transition back to the native function must
be less than 120 ns.
5. The ICH4 waits at least 180 ns after deasserting STPCLK# and then starts using the FERR#
signal for an indication of a floating point error. The maximum time that the ICH4 may wait is
bounded such that it must have a chance to look at the FERR# signal before reasserting
STPCLK#. Based on current implementation, that maximum time would be 240 ns (8 PCI
clocks).
The break event associated with this new mechanism does not need to set any particular status bit,
since the pending interrupt will be serviced by the processor after returning to the C0 state.
5.12.5.1
Throttling Using STPCLK#
Throttling is used to lower power consumption or reduce heat. The ICH4 asserts STPCLK# to
throttle the processor clock and the processor appears to temporarily enter a C2 state. After a
programmable time, the ICH4 deasserts STPCLK# and the processor appears to return to the C0
state. This allows the processor to operate at reduced average power, with a corresponding decrease
in performance. Two methods are included to start throttling:
1. Software enables a timer with a programmable duty cycle. The duty cycle is set by the
THTL_DTY field and the throttling is enabled using the THTL_EN field. This is known as
Manual Throttling. The period is fixed to be in the non-audible range, due to the nature of
switching power supplies.
2. A Thermal Override condition (THRM# signal active for >2 seconds) occurs that
unconditionally forces throttling, independent of the THTL_EN bit. The throttling due to
Thermal Override has a separate duty cycle (THRM_DTY) which may vary by field and
system. The Thermal Override condition will end when THRM# goes inactive.
Throttling due to the THRM# signal has higher priority than the software-initiated throttling.
Throttling does not occur when the system is in a C2, even if Thermal override occurs.
140
Intel® 82801DB ICH4 Datasheet
Functional Description
5.12.5.2
Transition Rules among S0/Cx and Throttling States
The following priority rules and assumptions apply among the various S0/Cx and throttling states:
• Entry to any S0/Cx state is mutually exclusive with entry to any S1–S5 state. This is because
the processor can only perform one register access at a time and Sleep states have higher
priority than thermal throttling.
• When the SLP_EN bit is set (system going to a sleep state (S1–S5), the THTL_EN bit can be
internally treated as being disabled (no throttling while going to sleep state). Note that thermal
throttling (based on THRM# signal) cannot be disabled in an S0 state. However, once the
SLP_EN bit is set, the thermal throttling is shut off (since STPCLK# will be active in S1–S5
states).
• If the THTL_EN bit is set, and a Level 2read then occurs, the system should immediately go
and stay in a C2state until a break event occurs. A Level 2read has higher priority than the
software initiated throttling or thermal throttling.
• If Thermal Override is causing throttling, and a Level 2read then occurs, the system will stay
in a C2 state until a break event occurs. A Level 2read has higher priority than the Thermal
Override.
• After an exit from a C2state (due to a Break event), and if the THTL_EN bit is still set, or if a
Thermal Override is still occurring, the system will continue to throttle STPCLK#. Depending
on the time of break event, the first transition on STPCLK# active can be delayed by up to one
THRM period (1024 PCI clocks=30.72 microseconds).
• The Host controller must post Stop-Grant cycles in such a way that the processor gets an
indication of the end of the special cycle prior to the ICH4 observing the Stop-Grant cycle.
This ensures that the STPCLK# signals stays active for a sufficient period after the processor
observes the response phase.
• If in the C1 state and the STPCLK# signal goes active, the processor will generate a StopGrant cycle, and the system should go to the C2 state. When STPCLK# goes inactive, it should
return to the C1 state.
5.12.6
Sleep States
5.12.6.1
Sleep State Overview
The ICH4 directly supports different sleep states (S1–S5), which are entered by setting the
SLP_EN bit, or due to a Power Button press. The entry to the Sleep states are based on several
assumptions:
• Entry to a Cx state is mutually exclusive with entry to a Sleep state. This is because the
processor can only perform one register access at a time. A request to Sleep always has higher
priority than throttling.
• Prior to setting the SLP_EN bit, the software turns off processor-controlled throttling. Note
that thermal throttling cannot be disabled, but setting the SLP_EN bit disables thermal
throttling (since S1–S5 sleep state has higher priority).
• The G3 state cannot be entered via any software mechanism. The G3 state indicates a
complete loss of power.
Intel® 82801DB ICH4 Datasheet
141
Functional Description
5.12.6.2
Initiating Sleep State
Sleep states (S1–S5) are initiated by:
• Masking interrupts, turning off all bus master enable bits, setting the desired type in the
SLP_TYP field, and then setting the SLP_EN bit. The hardware will then attempt to gracefully
put the system into the corresponding Sleep state by first going to a C2 state. See
Section 5.12.5 for details on going to the C2 state.
• Pressing the PWRBTN# signal for more than 4 seconds to cause a Power Button Override
event. In this case the transition to the S5 state will be less graceful, since there will be no
dependencies on observing Stop-Grant cycles from the processor or on clocks other than the
RTC clock.
Table 5-40. Sleep Types
Sleep Type
Comment
®
5.12.6.3
S1
Intel ICH4 asserts the STPCLK# signal. It also has the option to assert the CPUSLP# signal.
This lowers the processor’s power consumption. No snooping is possible in this state.
S3
ICH4 asserts SLP_S3#. The SLP_S3# signal will control the power to non-critical circuits.
Power will only be retained to devices needed to wake from this sleeping state, as well as to
the memory.
S4
ICH4 asserts SLP_S3# and SLP_S4#. The SLP_S4# signal will shut off the power to the
memory subsystem. Only devices needed to wake from this state should be powered.
S5
Same power state as S4. ICH4 asserts SLP_S3#, SLP_S4# and SLP_S5#.
Exiting Sleep States
Sleep states (S1–S5) are exited based on Wake events. The Wake events force the system to a full
on state (S0), although some non-critical subsystems might still be shut off and have to be brought
back manually. For example, the hard disk may be shut off during a sleep state, and have to be
enabled via a GPIO pin before it can be used.
Upon exit from the ICH4-controlled Sleep states, the WAK_STS bit is set. The possible causes of
Wake Events (and their restrictions) are shown in Table 5-41.
142
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-41. Causes of Wake Events
Cause
RTC Alarm
Power Button
States Can Wake
From
S1–S5 (1)
S1–S5
How Enabled
Set RTC_EN bit in PM1_EN register
Always enabled as Wake event
GPI[0:n]
S1–S5 (1)
GPE0_EN register
USB
S1–S5 (3)
Set USB1_EN, USB 2_EN and USB3_EN bits in GPE0_EN
register
LAN
S1–S5
S1–S5
RI#
(1)
Will use PME#. Wake enable set with LAN logic.
Set RI_EN bit in GPE0_EN register
AC ’97
S1–S5
Set AC ’97_EN bit in GPE0_EN register
Primary PME#
S1–S5
PME_B0_EN bit in GPE0_EN register
Secondary PME#
S1–S5
(1)
Set PME_EN bit in GPE0_EN Register.
SMBALERT#
S1–S5
Always enabled as Wake event
SMBus Slave
Message
S1–S5
Wake/SMI# command always enabled as a Wake Event.
NOTE: SMBus Slave Message can wake the system from S1–
S5, as well as from S5 due to Power Button Override.
SMBus Host Notify
message received
S1–S5
HOST_NOTIFY_WKEN bit SMBus Slave Command register.
Reported in the SMB_WAK_STS bit in the GPEO_STS register.
PME_B0 (internal USB
EHCI controller)
S1–S5 (1)
Set PME_B0_EN bit in GPE0_EN register.
NOTES:
1. This will be a wake event from S5 only if the sleep state was entered by setting the SLP_EN and SLP_TYP
bits via software.
2. If in the S5 state due to a powerbutton override, the possible wake events are due to Power Button, Hard
Reset Without Cycling (See Command Type 3 in Table 5-95), and Hard Reset System (See Command
Type 4 in Table 5-95).
3. The entry for USB changes from being able to wake from S1–S4 to being able to wake from S1–S5. Previous
designs actively blocked wake events while in S5. There is no need to do this as software already disables
waking from USB on S5 (so the wake bits are masked), and in the future power buttons will move to USB
keyboards, and a wake from S5 will be necessary.
It is important to understand that the various GPIs have different levels of functionality when used
as wake events. The GPIs that reside in the core power well can only generate wake events from an
S1 state. Also only certain GPIs are “ACPI Compliant,” meaning that their Status and Enable bits
reside in ACPI I/O space. Table 5-42 summarizes the use of GPIs as wake events.
Table 5-42. GPI Wake Events
GPI
Power Well
Wake From
GPI[7:0]
Core
S1
GPI[13:11], GPI[8]
Resume
S1–S5
Notes
ACPI Compliant
The latency to exit the various Sleep states varies greatly and is heavily dependent on power supply
design, so much so that the exit latencies due to the ICH4 are insignificant.
Intel® 82801DB ICH4 Datasheet
143
Functional Description
5.12.6.4
Sx-G3-Sx, Handling Power Failures
In desktop systems, power failures can occur if the AC power is cut (a real power failure) or if the
system is unplugged. In either case, PWROK and RSMRST# are assumed to go low.
Depending on when the power failure occurs and how the system is designed, different transitions
could occur due to a power failure.
The AFTER_G3 bit provides the ability to program whether or not the system should boot once
power returns after a power loss event. If the policy is to not boot, the system will remain in an S5
state (unless previously in S4). There are only three possible events that will wake the system after
a power failure.
1. PWRBTN#: PWRBTN# is always enabled as a wake event. When RSMRST# is low
(G3 state), the PWRBTN_STS bit is reset. When the ICH4 exits G3 after power returns
(RSMRST# goes high), the PWRBTN# signal is already high (because VCC-standby goes
high before RSMRST# goes high) and the PWRBTN_STS bit is 0.
2. RI#: RI# does not have an internal pull-up. Therefore, if this signal is enabled as a wake event,
it is important to keep this signal powered during the power loss event. If this signal goes low
(active), when power returns, the RI_STS bit will be set and the system will interpret that as a
wake event.
3. RTC Alarm: The RTC_EN bit is in the RTC well and is preserved after a power loss. Like
PWRBTN_STS, the RTC_STS bit is cleared when RSMRST# goes low.
The ICH4 monitors both PWROK and RSMRST# to detect for power failures. If PWROK goes
low, the PWROK_FLR bit is set. If RSMRST# goes low, PWR_FLR is set.
Note:
Although PME_EN is in the RTC well, this signal cannot wake the system after a power loss.
PME_EN is cleared by RTCRST# and PME_STS is cleared by RSMRST#.
Table 5-43. Transitions Due to Power Failure
144
State at Power Failure
AFTERG3_EN bit
Transition When Power Returns
S0, S1, S3
1
0
S5
S0
S4
1
0
S4
S0
S5
1
0
S5
S0
Intel® 82801DB ICH4 Datasheet
Functional Description
5.12.7
Thermal Management
The ICH4 has mechanisms to assist with managing thermal problems in the system.
5.12.7.1
THRM# Signal
The THRM# signal is used as a status input for a thermal sensor. Based on the THRM# signal
going active, the ICH4 generates an SMI# or SCI (depending on SCI_EN).
If the THRM_POL bit is set low, when the THRM# signal goes low, the THRM_STS bit will be
set. This is an indicator that the thermal threshold has been exceeded. If the THRM_EN bit is set,
then when THRM_STS goes active, either an SMI# or SCI is generated (depending on the SCI_EN
bit being set).
The power management software (BIOS or ACPI) can then take measures to start reducing the
temperature. Examples include shutting off unwanted subsystems, or halting the processor.
By setting the THRM_POL bit to high, another SMI# or SCI can optionally be generated when the
THRM# signal goes back high. This allows the software (BIOS or ACPI) to turn off the cooling
methods.
Note:
5.12.7.2
THRM# assertion does not cause a TCO event message in S3, or S4. The level of the signal will
not be reported in the heartbeat message.
THRM# Initiated Passive Cooling
If the THRM# signal remains active for some time greater than 2 seconds and the ICH4 is in the
S0/G0/C0 state, then the ICH4 enters an auto-throttling mode in which it provides a duty cycle on
the STPCLK# signal. This reduces the overall power consumption by the system and should cool
the system. The intended result of the cooling is that the THRM# signal should go back inactive.
For all programmed values (001–111), THRM# going active results in STPCLK# active for a
minimum time of 12.5% and a maximum of 87.5%. The period is 1024 PCI clocks. Thus, the
STPCLK# signal can be active for as little as 128 PCI clocks or as much as 896 PCI clocks. The
actual slowdown (and cooling) of the processor depends on the instruction stream, because the
processor is allowed to finish the current instruction. Furthermore, the ICH4 waits for the STOPGRANT cycle before starting the count of the time the STPCLK# signal is active.
When THRM# goes inactive, the throttling will stop. In case the ICH4 is already attempting
throttling because the THTL_EN bit is set, the duty cycle associated with the THRM# signal will
have higher priority. If the ICH4 is in the C2 or S1–S5 states, then no throttling will be caused by
the THRM# signal being active.
5.12.7.3
THRM# Override Software Bit
The FORCE_THTL bit allows the BIOS to force passive cooling, just as if the THRM# signal had
been active for two seconds. If this bit is set, the ICH4 starts throttling using the ratio in the
THRM_DTY field.
When this bit is cleared, the ICH4 stops throttling, unless the THRM# signal has been active for
two seconds or if the THTL_EN bit is set (indicating that ACPI software is attempting throttling).
Intel® 82801DB ICH4 Datasheet
145
Functional Description
5.12.7.4
Processor-Initiated Passive Cooling (Via Programmed Duty Cycle on
STPCLK#)
Using the THTL_EN and THTL_DTY bits, the ICH4 can force a programmed duty cycle on the
STPCLK# signal. This reduces the effective instruction rate of the processor and cut its power
consumption and heat generation.
5.12.7.5
Active Cooling
Active cooling involves fans. The GPIO signals from the ICH4 can be used to turn on/off a fan.
5.12.8
Event Input Signals and Their Usage
The ICH4 has various input signals that trigger specific events. This section describes those signals
and how they should be used.
5.12.8.1
PWRBTN# - Power Button
The ICH4 PWRBTN# signal operates as a “Fixed Power Button” as described in the ACPI
specification. PWRBTN# signal has a 16 ms de-bounce on the input. The state transition
descriptions are included in Table 5-44. Note that the transitions start as soon as the PWRBTN# is
pressed (but after the debounce logic), and does not depend on when the Power Button is released.
Table 5-44. Transitions Due to Power Button
Present
State
Event
Transition/Action
S0/Cx
PWRBTN# goes low
SMI# or SCI generated
(depending on SCI_EN)
S1–S5
PWRBTN# goes low
Wake Event. Transitions to
S0 state.
G3
PWRBTN# pressed
None
S0–S4
PWRBTN# held low for
at least 4 consecutive
seconds
Unconditional transition to S5
state.
Comment
Software will typically initiate a
Sleep state.
Standard wakeup
No effect since no power.
Not latched nor detected.
No dependence on processor
(e.g., Stop-Grant cycles) or any
other subsystem.
Power Button Override Function
If PWRBTN# is observed active for at least four consecutive seconds, then the state machine
should unconditionally transition to the G2/S5 state, regardless of present state (S0–S4). In this
case, the transition to the G2/S5 state should not depend on any particular response from the
processor (e.g., a Stop-Grant cycle), nor any similar dependency from any other subsystem.
New: A power button override will force a transition to S5, even if PWROK is not active.
The PWRBTN# status is readable to check if the button is currently being pressed or has been
released. The status is taken after the de-bounce, and is readable via the PWRBTN_LVL bit.
Note:
146
The 4-second PWRBTN# assertion should only be used if a system lock-up has occurred. The
4-second timer starts counting when the ICH4 is in a S0 state. If the PWRBTN# signal is asserted
and held active when the system is in a suspend state (S1–S5), the assertion causes a wake event.
Once the system has resumed to the S0 state, the 4-second timer starts.
Intel® 82801DB ICH4 Datasheet
Functional Description
Sleep Button
The ACPI specification defines an optional Sleep button. It differs from the power button in that it
only is a request to go from S0 to S1–S4 (not S5). Also, in an S5 state, the Power Button can wake
the system, but the Sleep Button cannot.
Although the ICH4 does not include a specific signal designated as a Sleep Button, one of the
GPIO signals can be used to create a “Control Method” Sleep Button. See the ACPI specification
for implementation details.
5.12.8.2
Ring Indicate (RI#)
The Ring Indicator can cause a wake event (if enabled) from the S1–S5 states. Table 5-45 shows
when the wake event is generated or ignored in different states. If in the G0/S0/Cx states, the ICH4
will generate an interrupt based on RI# active and the interrupt will be set up as a Break event.
Table 5-45. Transitions Due to RI# Signal
Note:
5.12.8.3
Present State
Event
RI_EN
Event
S0
RI# Active
X
Ignored
S1–S5
RI# Active
0
1
Ignored
Wake Event
Filtering/Debounce on RI# will not be done in the ICH4. It can be in modem or external.
PCI Power Management Event (PME#)
The PME# signal comes from a PCI device to request that the system be restarted. The PME#
signal can generate an SMI#, SCI, or optionally a Wake event. The event occurs when the PME#
signal goes from high-to-low. No event is caused when it goes from low-to-high.
In the EHCI controller, there is an internal PME_B0 bit. This is separate from the external PME#
signal and can cause the same effect.
5.12.8.4
SYS_RESET# Signal
SYS_RESET# is a new pin on the ICH4 that is used to eliminate extra glue logic on the board.
Before the addition of this pin, a system reset was activated by external glue forcing the PWROK
signal low after the reset button was pressed. This pin eliminates the need for that glue. As such, a
SYS_RESET# event should look internally to our chip and externally to the system as if PWROK
had gone low.
When the SYS_RESET# pin is detected as active after the 16 ms debounce logic, the ICH4
attempts to perform a “graceful” reset, by waiting up to 25 ms for the SMBus to go idle. If the
SMBus is idle when the pin is detected active, the reset occurs immediately, otherwise the counter
starts. If at any point during the count the SMBus goes idle, the reset occurs. If, however, the
counter expires and the SMBus is still active, a reset is forced upon the system even though activity
is still occurring.
Once a reset of this type has occurred, it cannot occur again until SYS_RESET# has been detected
inactive after the debounce logic, and the system is back to a full S0 state as indicated by all of the
PWROK inputs being active.
Intel® 82801DB ICH4 Datasheet
147
Functional Description
5.12.8.5
THRMTRIP# Signal
If THRMTRIP# goes active, the processor is indicating an overheat condition, and the ICH4
immediately transitions to an S5 state. However, since the processor has overheated, it does not
respond to the ICH4’s STPCLK# pin with a stop grant special cycle. Therefore, the ICH4 does not
wait for one. Immediately upon seeing THRMTRIP# low, the ICH4 initiates a transition to the S5
state, drives SLP_S3#, SLP_S4#, SLP_S5# low, and sets the CTS bit. The transition looks like a
power button override.
It is extremely important that when a THRMTRIP# event occurs, the ICH4 power down
immediately without following the normal S0 -> S5 path. This path may be taken in parallel, but
ICH4 must immediately enter a power down state. It will do this by driving SLP_S3#, SLP_S4#,
and SLP_S5# immediately after sampling THRMTRIP# active.
If the processor is running extremely hot and is heating up, it is possible (although very unlikely)
that components around it (e.g., the ICH4, are no longer executing cycles properly). Therefore, if
THRMTRIP# fires, and the ICH4 is relying on state machine logic to perform the power down, the
state machine may not be working, and the system will not power down.
The ICH4 follows this flow for THRMTRIP#.
1. At boot (PCIRST# low), THRMTRIP# ignored.
2. After power-up (PCIRST# high), if THRMTRIP# sampled active, SLP_S3#, SLP_S4#, and
SLP_S5# fire, and normal sequence of sleep machine starts.
3. Until sleep machine enters the S5 state, SLP_S3#, SLP_S4#, and SLP_S5# stay active, even if
THRMTRIP# is now inactive. This is the equivalent of “latching” the thermal trip event.
4. If S5 state reached, go to step #1, otherwise stay here. If the ICH4 never reaches S5, ICH4 will
not reboot until power is cycled.
5.12.9
ALT Access Mode
Before entering a low power state, several registers from powered down parts may need to be
saved. In the majority of cases, this is not an issue, as registers have read and write paths. However,
several of the ISA compatible registers are either read only or write only. To get data out of writeonly registers, and to restore data into read-only registers, the ICH4 implements an ALT access
mode.
If the ALT access mode is entered and exited after reading the registers of the ICH4 timer (8254),
the timer starts counting faster (13.5 ms). The following steps listed below can cause problems:
• BIOS enters ALT access mode for reading the ICH4 timer related registers.
• BIOS exits ALT access mode.
• BIOS continues through the execution of other needed steps and passes control to the OS.
After getting control in step #3, if the OS does not reprogram the system timer again, the timer
ticks may be happening faster than expected. For example DOS and its associated software assume
that the system timer is running at 54.6 ms and as a result the timeouts in the software may be
happening faster than expected.
Operating systems (e.g., Microsoft Windows* 98, Windows* 2000 and Windows NT*) reprogram
the system timer and, therefore, will not run into this problem.
148
Intel® 82801DB ICH4 Datasheet
Functional Description
For other operating systems (e.g., MS-DOS) the BIOS should restore the timer back to 54.6 ms
before passing control to the OS. If the BIOS is entering ALT access mode before entering the
suspend state it is not necessary to restore the timer contents after the exit from ALT access mode.
5.12.9.1
Write Only Registers with Read Paths in ALT Access Mode
The registers described in Table 5-46 have read paths in ALT access mode. The access number
field in the table indicates which register will be returned per access to that port.
Table 5-46. Write Only Registers with Read Paths in ALT Access Mode (Sheet 1 of 2)
Restore Data
I/O
Addr
# of
Rds
00h
2
01h
02h
03h
04h
05h
06h
07h
Restore Data
I/O
Addr
Data
1
DMA Chan 0 base address low byte
1
Timer Counter 0 status, bits [5:0]
2
DMA Chan 0 base address high
byte
2
Timer Counter 0 base count low byte
Access
Data
1
DMA Chan 0 base count low byte
2
DMA Chan 0 base count high byte
1
3
Timer Counter 0 base count high byte
4
Timer Counter 1 base count low byte
DMA Chan 1 base address low byte
5
Timer Counter 1 base count high byte
2
DMA Chan 1 base address high
byte
6
Timer Counter 2 base count low byte
1
DMA Chan 1 base count low byte
7
Timer Counter 2 base count high byte
2
DMA Chan 1 base count high byte
41h
1
Timer Counter 1 status, bits [5:0]
1
DMA Chan 2 base address low byte
42h
1
Timer Counter 2 status, bits [5:0]
2
DMA Chan 2 base address high
byte
70h
1
Bit 7 = NMI Enable,
Bits [6:0] = RTC Address
1
DMA Chan 2 base count low byte
C4h
2
2
2
40h
7
2
2
2
1
DMA Chan 5 base address low byte
2
DMA Chan 2 base count high byte
2
DMA Chan 5 base address high byte
1
DMA Chan 3 base address low byte
1
DMA Chan 5 base count low byte
2
DMA Chan 5 base count high byte
1
DMA Chan 6 base address low byte
2
DMA Chan 6 base address high byte
2
2
DMA Chan 3 base address high
byte
1
DMA Chan 3 base count low byte
2
C6h
C8h
2
2
2
1
DMA Chan 0–3 Command
2
DMA Chan 0–3 Request
3
DMA Chan 0 Mode: Bits(1:0) = “00”
CCh
6
4
2
DMA Chan 3 base count high byte
CAh
08h
# of
Rds
Access
5
DMA Chan 2 Mode: Bits(1:0) = “10”
DMA Chan 3 Mode: Bits(1:0) = “11”.
CEh
Intel® 82801DB ICH4 Datasheet
DMA Chan 6 base count low byte
DMA Chan 6 base count high byte
1
DMA Chan 7 base address low byte
2
DMA Chan 7 base address high byte
2
DMA Chan 1 Mode: Bits(1:0) = “01”
6
1
2
2
1
DMA Chan 7 base count low byte
2
DMA Chan 7 base count high byte
2
149
Functional Description
Table 5-46. Write Only Registers with Read Paths in ALT Access Mode (Sheet 2 of 2)
Restore Data
I/O
Addr
20h
# of
Rds
Access
Restore Data
I/O
Addr
Data
# of
Rds
Access
Data
1
PIC ICW2 of Master controller
1
DMA Chan 4–7 Command2
2
PIC ICW3 of Master controller
2
DMA Chan 4–7 Request
3
PIC ICW4 of Master controller
3
DMA Chan 4 Mode: Bits(1:0) = 00
1
D0h
6
4
PIC OCW1 of Master controller
4
DMA Chan 5 Mode: Bits(1:0) = 01
5
PIC OCW2 of Master controller
5
DMA Chan 6 Mode: Bits(1:0) = 10
6
PIC OCW3 of Master controller
6
DMA Chan 7 Mode: Bits(1:0) = 11.
7
PIC ICW2 of Slave controller
8
PIC ICW3 of Slave controller
12
9
PIC ICW4 of Slave controller
10
PIC OCW1 of Slave controller1
11
PIC OCW2 of Slave controller
12
PIC OCW3 of Slave controller
NOTES:
1. The OCW1 register must be read before entering ALT access mode.
2. Bits 5, 3, 1, and 0 return 0.
5.12.9.2
PIC Reserved Bits
Many bits within the PIC are reserved, and must have certain values written in order for the PIC to
operate properly. Therefore, there is no need to return these values in ALT access mode. When
reading PIC registers from 20h and A0h, the reserved bits shall return the values listed in
Table 5-47.
Table 5-47. PIC Reserved Bits Return Values
150
PIC Reserved Bits
Value Returned
ICW2[2:0]
000
ICW4[7:5]
000
ICW4[3:2]
00
ICW4[0]
0
OCW2[4:3]
00
OCW3[7]
0
OCW3[5]
Reflects bit 6
OCW3[4:3]
01
Intel® 82801DB ICH4 Datasheet
Functional Description
5.12.9.3
Read Only Registers with Write Paths in ALT Access Mode
The registers described in Table 5-48 have write paths to them in ALT access mode. Software
restores these values after returning from a powered down state. These registers must be handled
special by software. When in normal mode, writing to the base address/count register also writes to
the current address/count register. Therefore, the base address/count must be written first, then the
part is put into ALT access mode and the current address/count register is written.
Table 5-48. Register Write Accesses in ALT Access Mode
I/O Address
Register Write Value
08h
DMA Status Register for channels 0–3.
D0h
DMA Status Register for channels 4–7.
5.12.10
System Power Supplies, Planes, and Signals
5.12.10.1
Power Plane Control with SLP_S3#, SLP_S4# and SLP_S5#
The SLP_S3# output signal can be used to cut power to the system core supply, since it only goes
active for the STR state (typically mapped to ACPI S3). Power must be maintained to the ICH4
resume well, and to any other circuits that need to generate Wake signals from the STR state.
Cutting power to the core may be done via the power supply, or by external FETs to the
motherboard. The SLP_S4# or SLP_S5# output signal can be used to cut power to the system core
supply, as well as power to the system memory, since the context of the system is saved on the disk.
Cutting power to the memory may be done via the power supply, or by external FETs to the
motherboard.
5.12.10.2
PWROK Signal
The PWROK input should go active based on the core supply voltages becoming valid. PWROK
should go active no sooner than 10 ms after Vcc3_3 and Vcc1_5 have reached their nominal
values.
Note:
1. Traditional designs have a reset button logically ANDs with the PWROK signal from the
power supply and the processor’s voltage regulator module. If this is done with the ICH4, the
PWROK_FLR bit will be set. The ICH4 treats this internally as if the RSMRST# signal had
gone active. However, it is not treated as a full power failure. If PWROK goes inactive and
then active (but RSMRST# stays high), then the ICH4 will reboot (regardless of the state of
the AFTERG3 bit). If the RSMRST# signal also goes low before PWROK goes high, then this
is a full power failure, and the reboot policy is controlled by the AFTERG3 bit.
2. PWROK and RSMRST# are sampled using the RTC clock. Therefore, low times that are less
than one RTC clock period may not be detected by the ICH4.
3. In the case of true PWROK failure, PWROK will go low first before the VRMPWRGD.
5.12.10.3
VRMPWRGD Signal
This signal is connected to the processor’s VRM and is internally AND’d with the PWROK signal
that comes from the system power supply. This saves the external AND gate found in desktop
systems.
Intel® 82801DB ICH4 Datasheet
151
Functional Description
5.12.10.4
Controlling Leakage and Power Consumption during Low-Power
States
To control leakage in the system, various signals tri-state or go low during some low-power states.
General principles:
• All signals going to powered down planes (either internally or externally) must be either tristated or driven low.
• Signals with pull-up resistors should not be low during low-power states. This is to avoid the
power consumed in the pull-up resistor.
• Buses should be halted (and held) in a known state to avoid a floating input (perhaps to some
other device). Floating inputs can cause extra power consumption.
Based on the above principles, the following measures are taken:
• During S3 (STR), all signals attached to powered down planes will be tri-stated or driven low.
5.12.11
Clock Generators
The clock generator is expected to provide the frequencies shown in Table 5-49.
Table 5-49. Intel® ICH4 Clock Inputs
152
Clock
Domain
Frequency
Source
Usage
CLK66
66 MHz
Main Clock
Generator
Should be running in all Cx states. Stopped in S3 ~ S5 based on
SLP_S3# assertion.
PCICLK
33 MHz
Main Clock
Generator
Free-running PCI Clock to ICH4. Stopped in S3 ~ S5 based on
SLP_S3# assertion.
CLK48
48 MHz
Main Clock
Generator
Used by USB controllers. Stopped in S3 ~ S5 based on
SLP_S3# assertion.
CLK14
14.318 MHz
Main Clock
Generator
Used by ACPI timers. Stopped in S3 ~ S5 based on SLP_S3#
assertion.
AC_BIT_CLK
12.288 MHz
AC ’97
Codec
AC-link. Control policy is determined by the clock source.
APICCLK
16.67 MHz
or 33 MHz
Main Clock
Generator
Used for ICH4-processor interrupt messages. Should be
running in C0, C1 and C2. Stopped in S3 ~ S5 based on
SLP_S3# assertion.
LAN_CLK
0.8 to
50 MHz
LAN
Connect
LAN Connect link. Control policy is determined by the clock
source.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.12.12
Legacy Power Management Theory of Operation
Instead of relying on ACPI software, legacy power management uses BIOS and various hardware
mechanisms. ICH4 has a greatly simplified method for legacy power management compared with
previous generations (e.g., the PIIX4).
The scheme relies on the concept of detecting when individual subsystems are idle, detecting when
the whole system is idle, and detecting when accesses are attempted to idle subsystems.
However, the OS is assumed to be at least APM enabled. Without APM calls, there is no quick way
to know when the system is idle between keystrokes. The ICH4 does not support the burst modes
found in previous components (e.g., the PIIX4).
5.12.12.1
Desktop APM Power Management
The ICH4 has a timer that, when enabled by the 1MIN_EN bit in the SMI Control and Enable
register, generates an SMI# once per minute. The SMI handler can check for system activity by
reading the DEVACT_STS register. If none of the system bits are set, the SMI handler can
increment a software counter. When the counter reaches a sufficient number of consecutive
minutes with no activity, the SMI handler can then put the system into a lower power state.
If there is activity, various bits in the DEVACT_STS register will be set. Software clears the bits by
writing a 1 to the bit position.
The DEVACT_STS register allows for monitoring various internal devices, or Super I/O devices
(SP, PP, FDC) on LPC or PCI, keyboard controller accesses, or audio functions on LPC or PCI.
Other PCI activity can be monitored by checking the PCI interrupts.
Intel® 82801DB ICH4 Datasheet
153
Functional Description
5.13
System Management (D31:F0)
The ICH4 provides various functions to make a system easier to manage and to lower the Total
Cost of Ownership (TCO) of the system. Features and functions can be augmented via external
A/D converters and GPIO, as well as an external microcontroller.
The following features and functions are supported by the ICH4:
• Processor present detection
— Detects if processor fails to fetch the first instruction after reset
• Various Error detection (e.g., ECC Errors) Indicated by Host controller
— Can generate SMI#, SCI, SERR, NMI, or TCO interrupt
• Intruder Detect input
— Can generate TCO interrupt or SMI# when the system cover is remove
— INTRUDER# allowed to go active in any power state, including G3
• Detection of bad FWH programming
— Detects if data on first read is FFh (indicates unprogrammed FWH)
• Ability to hide a PCI device
— Allows software to hide a PCI device in terms of configuration space through the use of a
device hide register (See Section 8.1.26)
Note:
5.13.1
Voltage ID from the processor can be read via GPI signals.
Theory of Operation
The System Management functions are designed to allow the system to diagnose failing
subsystems. The intent of this logic is that some of the system management functionality be
provided without the aid of an external microcontroller.
5.13.1.1
Detecting a System Lockup
When the processor is reset, it is expected to fetch its first instruction. If the processor fails to fetch
the first instruction after reset, the TCO timer times out twice and the ICH4 asserts PCIRST#.
5.13.1.2
Handling an Intruder
The ICH4 has an input signal, INTRUDER#, that can be attached to a switch that is activated by
the system’s case being open. This input has a two RTC clock debounce. If INTRUDER# goes
active (after the debouncer), this will set the INTRD_DET bit in the TCO_STS register. The
INTRD_SEL bits in the TCO_CNT register can enable the ICH4 to cause an SMI# or interrupt.
The BIOS or interrupt handler can then cause a transition to the S5 state by writing to the SLP_EN
bit.
The software can also directly read the status of the INTRUDER# signal (high or low) by clearing
and then reading the INTRD_DET bit. This allows the signal to be used as a GPI if the intruder
function is not required.
154
Intel® 82801DB ICH4 Datasheet
Functional Description
If the INTRUDER# signal goes inactive some point after the INTRD_DET bit is written as a 1,
then the INTRD_DET signal will go to a 0 when INTRUDER# input signal goes inactive. Note
that this is slightly different than a classic sticky bit, since most sticky bits would remain active
indefinitely when the signal goes active and would immediately go inactive when a 1 is written to
the bit.
Note:
The INTRD_DET bit resides in the ICH4’s RTC well, and is set and cleared synchronously with
the RTC clock. Thus, when software attempts to clear INTRD_DET (by writing a 1 to the bit
location) there may be as much as two RTC clocks (about 65 µs) delay before the bit is actually
cleared. Also, the INTRUDER# signal should be asserted for a minimum of 1 ms to guarantee that
the INTRD_DET bit will be set.
Note:
If the INTRUDER# signal is still active when software attempts to clear the INTRD_DET bit, the
bit will remain set and the SMI will be generated again immediately. The SMI handler can clear the
INTRD_SEL bits to avoid further SMIs. However, if the INTRUDER# signal goes inactive and
then active again, there will not be further SMIs, since the INTRD_SEL bits would select that no
SMI# be generated.
5.13.1.3
Detecting Improper FWH Programming
The ICH4 can detect the case where the FWH is not programmed. This results in the first
instruction fetched to have a value of FFh. If this occurs, the ICH4 sets the BAD_BIOS bit, which
can then be reported via the Heartbeat and Event reporting using an external, Alert on LAN
enabled LAN controller (See Section 5.13.2).
5.13.1.4
Handling an ECC Error or Other Memory Error
The Host controller provides a message to indicate that it would like to cause an SMI#, SCI,
SERR#, or NMI. The software must check the Host controller as to the exact cause of the error.
5.13.2
Alert on LAN*
The ICH4 integrated LAN controller supports Alert on LAN functionality when used with the
82562EM Platform LAN Connect component. This allows the integrated LAN controller to report
messages to a network management console without the aid of the system processor. This is crucial
in cases where the processor is malfunctioning or cannot function due to being in a low-power
state.
The ICH4 also features an independent, dedicated SMBus interface, referred to as the SMLINK
interface that can be used with an external Alert on LAN (or Alert on LAN 2) enabled LAN
controller. This separate interface is required, since devices on the system SMBus will be powered
down during some low power states.
The basic scheme is for the ICH4 integrated LAN controller to send a prepared Ethernet message
to a network management console. The prepared message is stored in the non-volatile EEPROM
that is connected to the ICH4.
Messages will be sent by the LAN controller either because a specific event has occurred, or they
will be sent periodically (also known as a heartbeat). The event and heartbeat messages have the
exact same format. The event messages are sent based on events occurring. The heartbeat messages
is sent every 30 to 32 seconds. When an event occurs, the ICH4 sends a new message and
increments the SEQ[3:0] field. For heartbeat messages, the sequence number does not increment.
Intel® 82801DB ICH4 Datasheet
155
Functional Description
The following rules/steps apply if the system is in a G0 state and the policy is for the ICH4 to
reboot the system after a hardware lockup:
1. Upon detecting the lockup the SECOND_TO_STS bit will be set. The ICH4 may send up to 1
Event message to the D110. The ICH4 then attempts to reboot the processor.
2. If the reboot at step 1 is successful, BIOS should clear the SECOND_TO_STS bit. This
prevents any further Heartbeats from being sent. The BIOS may then perform addition
recovery/boot steps. (See note 2.)
3. If the reboot attempt in step 1 is not successful, then the timer will timeout a third time. At this
point the system has locked up and was unsuccessful in rebooting. The ICH4 does not attempt
to automatically reboot again. The ICH4 starts sending a message every heartbeat period
(30–32 seconds). The heartbeats continue until some external intervention occurs (reset, power
failure, etc.).
4. After step 3 (unsuccessful reboot after third timeout), if the user does a Power Button
Override, the system goes to an S5 state. The ICH4 continues sending the messages every
heartbeat period.
5. After step 4 (power button override after unsuccessful reboot) if the user presses the Power
Button again, the system should wake to an S0 state and the processor should start executing
the BIOS.
6. If step 5 (power button press) is successful in waking the system, the ICH4 continues sending
messages every heartbeat period until the BIOS clears the SECOND_TO_STS bit. (See note 2)
7. If step 5 (power button press) is unsuccessful in waking the system, the ICH4 continues
sending a message every heartbeat period. The ICH4 does not attempt to automatically reboot
again. The ICH4 will start sending a message every heartbeat period (30–32 seconds). The
heartbeats continue until some external intervention occurs (reset, power failure, etc.).
(See note 3)
8. After step 3 (unsuccessful reboot after third timeout), if a reset is attempted (using a button
that pulses PWROK low or via the message on the SMBus slave interface), the ICH4 attempts
to reset the system.
9. After step 8 (reset attempt) if the reset is successful, BIOS is run. The ICH4 continues sending
a message every heartbeat period until the BIOS clears the SECOND_TO_STS bit.
(See note 2)
10. After step 8 (reset attempt), if the reset is unsuccessful, then the ICH4 continues sending a
message every heartbeat period. The ICH4 does not attempt to reboot the system again without
external intervention. (See note 3)
The following rules/steps apply if the system is in a G0 state and the policy is for the ICH4 to not
reboot the system after a hardware lockup.
1. Upon detecting the lockup the SECOND_TO_STS bit is set. The ICH4 sends a message with
the Watchdog (WD) Event status bit set (and any other bits that must also be set). This
message is sent as soon as the lockup is detected, and is sent with the next (incremented)
sequence number.
2. After step 1, the ICH4 sends a message every heartbeat period until some external intervention
occurs.
3. Rules/steps 4–10 apply if no user intervention (resets, power button presses, SMBus reset
messages) occur after a third timeout of the watchdog timer. If the intervention occurs before
the third timeout, then jump to rule/step11.
4. After step 3 (third timeout), if the user does a Power Button Override, the system goes to an S5
state. The ICH4 continues sending heartbeats at this point.
156
Intel® 82801DB ICH4 Datasheet
Functional Description
5. After step 4 (power button override), if the user presses the power button again, the system
should wake to an S0 state and the processor should start executing the BIOS.
6. If step 5 (power button press) is successful in waking the system, the ICH4 continues sending
heartbeats until the BIOS clears the SECOND_TO_STS bit. (See note 2)
7. If step 5 (power button press) is unsuccessful in waking the system, the ICH4 continues
sending heartbeats. The ICH4 does not attempt to reboot the system again until some external
intervention occurs (reset, power failure, etc.). (See note 3)
8. After step 3 (3rd timeout), if a reset is attempted (using a button that pulses PWROK low or via
the message on the SMBus slave interface), the ICH4 attempts to reset the system.
9. If step 8 (reset attempt) is successful, then the BIOS will be run. The ICH4 continues sending
heartbeats until the BIOS clears the SECOND_TO_STS bit. (See note 2)
10. If step 8 (reset attempt), is unsuccessful, the ICH4 continues sending heartbeats. The ICH4
does not attempt to reboot the system again without external intervention. Note: A system that
has locked up and can not be restarted with power button press is probably broken (bad power
supply, short circuit on some bus, etc.).
11. This and the following rules/steps apply if the user intervention (power button press, reset,
SMBus message, etc.) occur prior to the third timeout of the watchdog timer.
12. After step 1 (second timeout), if the user does a Power Button Override, the system goes to an
S5 state. The ICH4 continues sending heartbeats at this point.
13. After step 12 (power button override), if the user presses the power button again, the system
should wake to an S0 state and the processor should start executing the BIOS.
14. If step 13 (power button press) is successful in waking the system, the ICH4 will continue
sending heartbeats until the BIOS clears the SECOND_TO_STS bit. (See note 2)
15. If step 13 (power button press) is unsuccessful in waking the system, the ICH4 will continue
sending heartbeats. The ICH4 will not attempt to reboot the system again until some external
intervention occurs (reset, power failure, etc.). (See note 3)
16. After step 1 (second timeout), if a reset is attempted (using a button that pulses PWROK low
or via the message on the SMBus slave interface), the ICH4 will attempt to reset the system.
17. If step 16 (reset attempt) is successful, then the BIOS will be run. The ICH4 will continue
sending heartbeats until the BIOS clears the SECOND_TO_STS bit. (See note 2)
18. If step 16 (reset attempt), is unsuccessful, then the ICH4 will continue sending heartbeats. The
ICH4 will not attempt to reboot the system again without external intervention. (See note 3)
If the system is in a G1 (S1–S4) state, the ICH4 will send a heartbeat message every
30–32 seconds. If an event occurs prior to the system being shutdown, the ICH4 will immediately
send an event message with the next incremented sequence number. After the event message, the
ICH4 will resume sending heartbeat messages.
Note:
Notes for Previous two numbered lists.
1. Normally, the ICH4 does not send heartbeat messages while in the G0 state (except in the case
of a lockup). However, if a hardware event (or heartbeat) occurs just as the system is
transitioning into a G0 state, the hardware will continue to send the message even though the
system will be in a G0 state (and the status bits may indicate this).
When used with an external Alert on LAN enabled LAN controller, the ICH4 sends these
messages via the SMLINK signals. When sending messages via these signals, the ICH4 abides
by the SMBus rules associated with collision detection. It delays starting a message until the
bus is idle, and will detect collisions. If a collision is detected, the ICH4 waits until the bus is
idle and tries again.
Intel® 82801DB ICH4 Datasheet
157
Functional Description
2. WARNING: It is important that the BIOS clears the SECOND_TO_STS bit, as the alerts will
interfere with the LAN device driver from working properly. The alerts reset part of the D110
and would prevent an operating system’s device driver from sending or receiving some
messages.
3. A system that has locked up and can not be restarted with power button press is assumed to
have broken hardware (bad power supply, short circuit on some bus, etc.), and is beyond
ICH4’s recovery mechanisms.
4. A spurious alert could occur in the following sequence:
— The processor has initiated an alert using the SEND_NOW bit.
— During the alert, the THRM#, INTRUDER# or GPI[11] changes state.
— The system then goes to a non-S0 state.
Once the system transitions to the non-S0 state, it may send a single alert with an incremental
SEQUENCE number.
5. An inaccurate alert message can be generated in the following scenario.
— The system successfully boots after a second watchdog Timeout occurs.
— PWROK goes low (typically, due to a reset button press) or a power button override
occurs (before the SECOND_TO_STS bit is cleared).
— An alert message indicating that the processor is missing or locked up is generated with a
new sequence number.
Table 5-50 shows the data included in the Alert on LAN messages.
Table 5-50. Alert on LAN* Message Data
Field
158
Comment
Cover Tamper Status
1 = This bit will be set if the intruder detect bit is set (INTRD_DET).
Temp Event Status
1 = This bit will be set if the ICH4THERM# input signal is asserted.
Processor Missing Event Status
1 = This bit will be set if the processor failed to fetch the first instruction.
TCO Timer Event Status
1 = This bit is set when the TCO timer expires.
Software Event Status
1 = This bit is set when software writes a 1 to the SEND_NOW bit.
Unprogrammed FWH Event Status
1 = First BIOS fetch returned a value of FFh, indicating that the FWH has
not yet been programmed (still erased).
GPIO Status
1 = This bit is set when GPIO[11] signal is high.
0 = This bit is cleared when GPIO[11] signal is low.
An event message is triggered on an transition of GPIO[11].
SEQ[3:0]
This is a sequence number. It is initially 0, and increments each time the
Intel® ICH4 sends a new message. Upon reaching 1111, the sequence
number rolls over to 0000. MSB (SEQ3) sent first.
System Power State
00 = G0, 01 = G1, 10 = G2, 11 = Pre-Boot. MSB sent first
MESSAGE1
Will be the same as the MESSAGE1 Register. MSB sent first.
MESSAGE2
Will be the same as the MESSAGE2 Register. MSB sent first.
WDSTATUS
Will be the same as the WDSTATUS Register. MSB sent first.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.14
General Purpose I/O
5.14.1
GPIO Mapping
Table 5-51. GPIO Implementation (Sheet 1 of 2)
GPIO
GPI[0]
GPI[1]
Type
Input
Only
Input
Only
Alternate
Function (1)
REQ[A]#
REQ[B]# or
REQ[5]#
Power
Well
Tolerant
Notes
5.0 V
• GPIO_USE_SEL bit 0 enables REQ/
GNT[A]# pair.
• Input active status read from
GPE0_STS register bit 0.
• Input active high/low set through
GPI_INV register bit 0.
5.0 V
• GPIO_USE_SEL bit 1 enables REQ/
GNT[B]# pair (3).
• Input active status read from
GPE0_STS register bit 1.
• Input active high/low set through
GPI_INV register bit 1.
5.0 V
• GPIO_USE_SEL bits [2:5] enable
PIRQ[E:H]#.
• Input active status read from
GPE0_STS register bits [2:5].
• Input active high/low set through
GPI_INV register bits [2:5].
Core
5.0 V
• Input active status read from
GPE0_STS register bit 6.
• Input active high/low set through
GPI_INV register bit 6.
Core
5.0 V
• Input active status read from
GPE0_STS register bit 7.
• Input active high/low set through
GPI_INV register bit 7
3.3 V
• Input active status read from
GPE0_STS register bit 8.
• Input active high/low set through
GPI_INV register bit 8.
Core
Core
GPI[2:5]
Input
Only
GPI[6]
Input
Only
GPI[7]
Input
Only
GPI[8]
Input
Only
Unmuxed
Resume
GPIO[9:10]
N/A
N/A
N/A
PIRQ[E:H]#
Unmuxed
Core
• Not implemented
GPI[11]
Input
Only
SMBALERT#
Resume
3.3 V
• GPIO_USE_SEL bit 11 enables
SMBALERT#
• Input active status read from
GPE0_STS register bit 11.
• Input active high/low set through
GPI_INV register bit 11.
GPI[12]
Input
Only
Unmuxed
Resume
3.3 V
• Input active status read from
GPE0_STS register bit 12.
• Input active high/low set through
GPI_INV register bit 12.
GPI[13]
Input
Only
Unmuxed
Resume
3.3 V
• Input active status read from
GPE0_STS register bit 13.
• Input active high/low set through
GPI_INV register bit 13.
GPIO[14:15]
N/A
N/A
N/A
Intel® 82801DB ICH4 Datasheet
• Not Implemented
159
Functional Description
Table 5-51. GPIO Implementation (Sheet 2 of 2)
GPIO
Type
Alternate
Function (1)
Power
Well
Tolerant
Notes
GPO[16]
Output
Only
GNT[A]#
Core
3.3 V
• Output controlled via GP_LVL register
bit 16.
• TTL driver output
GPO[17]
Output
Only
GNT[B]# or
GNT[5]#
Core
3.3 V
• Output controlled via GP_LVL register
bit 17.
• TTL driver output
GPO[18]
Output
Only
N/A
Core
3.3 V
• Output controlled via GP_LVL register
bits [18:19].
• TTL driver output
GPO[19]
Output
Only
N/A
Core
3.3 V
• Output controlled via GP_LVL register
bits [18:19].
• TTL driver output
GPO[20]
Output
Only
N/A
Core
3.3 V
• Output controlled via GP_LVL register
bit 20.
• TTL driver output
GPO[21]
Output
Only
N/A
Core
3.3 V
• This GPO defaults high.
• Output controlled via GP_LVL register
bit 21.
• TTL driver output
GPO[22]
Output
Only
N/A
Core
3.3 V
• Output controlled via GP_LVL register
bit [22].
• Open-drain output
GPIO[23
Output
Only
N/A
Core
3.3 V
• Output controlled via GP_LVL register
bit [23].
• TTL driver output
3.3 V
• Input active status read from GP_LVL
register bit 24.
• Output controlled via GP_LVL register
bit 24.
• TTL driver output
3.3 V
• Blink enabled via GPO_BLINK register
bit 25.
• Input active status read from GP_LVL
register bit 25
• Output controlled via GP_LVL register
bit 25.
• TTL driver output
3.3 V
• Input active status read from GP_LVL
register bits [27:28]
• Output controlled via GP_LVL register
bits [27:28]
• TTL driver output
GPIO[24]
I/O
N/A
Resume
GPIO[25]
I/O
Unmuxed
Resume
GPIO[26]
N/A
N/A
N/A
GPIO[27:28]
I/O
Unmuxed
Resume
GPIO[29:31]
N/A
N/A
N/A
GPIO[32:43]
I/O
Unmuxed
Core
• Not implemented
• Not implemented
3.3 V
NOTES:
1. All GPIOs default to their alternate function.
2. All inputs are sticky. The status bit remains set as long as the input was asserted for 2 clocks. GPIs are
sampled on PCI clocks in S0/S1. GPIs are sampled on RTC clocks in S3/S4/S5 .
3. GPIO[0:7] are 5 V tolerant, and all GPIs can be routed to cause an SCI or SMI#.
4. If GPIO_USE_SEL bit 1 is set to 1 and GEN_CNT bit 25 is also set to 1 then REQ/GNT[5]# is enabled. See
Section 9.1.22.
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Functional Description
5.14.2
Power Wells
Some GPIOs exist in the resume power plane. Care must be taken to make sure GPIO signals are
not driven high into powered-down planes.
Some ICH4 GPIOs may be connected to pins on devices that exist in the core well. If these GPIOs
are outputs, there is a danger that a loss of core power (PWROK low) or a Power Button Override
event will result in the ICH4 driving a pin to a logic 1 to another device that is powered down.
GPIO[1:15] have “sticky” bits on the input. Refer to the GPE0_STS register. As long as the signal
goes active for at least 2 clocks, the ICH4 will keep the sticky status bit active. The active level can
be selected in the GP_LVL register.
If the system is in an S0 or an S1 state, the GPI inputs are sampled at 33 MHz, so the signal only
needs to be active for about 60 ns to be latched. In the S3–S5 states, the GPI inputs are sampled at
32.768 kHz, and thus must be active for at least 61 microseconds to be latched.
If the input signal is still active when the latch is cleared, it will again be set. Another edge trigger
is not required. This makes these signals “level” triggered inputs.
5.14.3
SMI# and SCI Routing
The routing bits for GPIO[0:15] allow an input to be routed to SMI# or SCI, or neither. Note that a
bit can be routed to either an SMI# or an SCI, but not both.
5.15
IDE Controller (D31:F1)
The ICH4 IDE controller features two sets of interface signals (Primary and Secondary) that can be
independently enabled, tri-stated or driven low. The ICH4 IDE controller supports both legacy
mode and native mode IDE interface. In native mode, the IDE controller is a fully PCI compliant
software interface and does not use any legacy I/O or interrupt resources. The IDE interfaces of the
ICH4 can support several types of data transfers:
• Programmed I/O (PIO): Processor is in control of the data transfer.
• 8237 style DMA: DMA protocol that resembles the DMA on the ISA bus, although it does not
use the 8237 in the ICH4. This protocol off loads the processor from moving data. This allows
higher transfer rate of up to 16 MB/s.
• Ultra ATA/33: DMA protocol that redefines signals on the IDE cable to allow both host and
target throttling of data and transfer rates of up to 33 MB/s.
• Ultra ATA/66: DMA protocol that redefines signals on the IDE cable to allow both host and
target throttling of data and transfer rates of up to 66 MB/s.
• Ultra ATA/100: DMA protocol that redefines signals on the IDE cable to allow both host and
target throttling of data and transfer rates of up to 100 MB/s.
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Functional Description
5.15.1
PIO Transfers
The ICH4 IDE controller includes both compatible and fast timing modes. The fast timing modes
can be enabled only for the IDE data ports. All other transactions to the IDE registers are run in
single transaction mode with compatible timings.
Up to two IDE devices may be attached per IDE connector (drive 0 and drive 1). The IDETIM and
SIDETIM Registers permit different timing modes to be programmed for drive 0 and drive 1 of the
same connector.
The Ultra ATA/33/66/100 synchronous DMA timing modes can also be applied to each drive by
programming the IDE I/O Configuration register and the Synchronous DMA Control and Timing
registers. When a drive is enabled for synchronous DMA mode operation, the DMA transfers are
executed with the synchronous DMA timings. The PIO transfers are executed using compatible
timings or fast timings if also enabled.
5.15.1.1
IDE Port Decode
The Command and Control Block registers are accessed differently depending on the decode
mode, which is selected by the Programming Interface configuration register (Offset 09h).
Note:
5.15.1.2
The primary and secondary channels are controlled by separate bits, allowing one to be in native
mode and the other in legacy mode simultaneously.
IDE Legacy Mode and Native Mode
The ICH4 IDE controller supports both legacy mode and PCI native mode. In legacy mode, the
Command and Control Block registers are accessible at fixed I/O addresses. While in legacy mode,
the ICH4 does not decode any of the native mode ranges. Likewise, in native mode the ICH4 does
not decode any of the legacy mode ranges.
The IDE I/O ports involved in PIO transfers are decoded by the ICH4 to the IDE interface when
D31:F1 I/O space is enabled and IDE decode is enabled through the IDE_TIMx registers. The IDE
registers are implemented in the drive itself. An access to the IDE registers results in the assertion
of the appropriate IDE chip select for the register, and the IDE command strobes (PDIOR#/
SDIOR#, PDIOW#/SDIOW#).
There are two I/O ranges for each IDE cable: the Command Block, which corresponds to the
PCS1#/SCS1# chip select, and the Control Block, which corresponds to the PCS3#/SCS3# chip
select. The Command Block is an 8-byte range, while the control block is a 4-byte range.
— Command Block Offset: 01F0h for primary, 0170h for secondary
— Control Block Offset: 03F4h for primary, 0374h for secondary
Table 5-52 and Table 5-53 specify the registers as they affect the ICH4 hardware definition.
Note:
162
The Data Register (I/O Offset 00h) should be accessed using 16-bit or 32-bit I/O instructions. All
other registers should be accessed using 8-bit I/O instructions.
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-52. IDE Legacy I/O Ports: Command Block Registers (CS1x# Chip Select)
I/O Offset
Register Function (Read)
Register Function (Write)
00h
Data
Data
01h
Error
Features
02h
Sector Count
Sector Count
03h
Sector Number
Sector Number
04h
Cylinder Low
Cylinder Low
05h
Cylinder High
Cylinder High
06h
Drive
Head
07h
Status
Command
NOTE: For accesses to the Alt Status register in the Control Block, the ICH4 must always force the upper
address bit (PDA[2] or SDA[2]) to 1 in order to guarantee proper native mode decode by the IDE device.
Unlike the legacy mode fixed address location, the native mode address for this register may contain a 0
in address bit 2 when it is received by the ICH4.
In native mode, the ICH4 does not decode the legacy ranges. The same offsets are used as in
Table 5-52 and Table 5-53 above. However, the base addresses are selected using the PCI BARs,
rather than fixed I/O locations.
5.15.1.3
PIO IDE Timing Modes
IDE data port transaction latency consists of startup latency, cycle latency, and shutdown latency.
Startup latency is incurred when a PCI master cycle targeting the IDE data port is decoded and the
DA[2:0] and CSxx# lines are not set up. Startup latency provides the setup time for the DA[2:0]
and CSxx# lines prior to assertion of the read and write strobes (DIOR# and DIOW#).
Cycle latency consists of the I/O command strobe assertion length and recovery time. Recovery
time is provided so that transactions may occur back-to-back on the IDE interface (without
incurring startup and shutdown latency) without violating minimum cycle periods for the IDE
interface. The command strobe assertion width for the enhanced timing mode is selected by the
IDE_TIM Register and may be set to 2, 3, 4, or 5 PCI clocks. The recovery time is selected by the
IDE_TIM Register and may be set to 1, 2, 3, or 4 PCI clocks.
If IORDY is asserted when the initial sample point is reached, no wait-states are added to the
command strobe assertion length. If IORDY is negated when the initial sample point is reached,
additional wait-states are added. Since the rising edge of IORDY must be synchronized, at least
two additional PCI clocks are added.
Shutdown latency is incurred after outstanding scheduled IDE data port transactions (either a nonempty write post buffer or an outstanding read prefetch cycles) have completed and before other
transactions can proceed. It provides hold time on the DA[2:0] and CSxx# lines with respect to the
read and write strobes (DIOR# and DIOW#). Shutdown latency is two PCI clocks in duration.
The IDE timings for various transaction types are shown in Table 5-53. Note that bit 2 (16-bit I/O
recovery enable) of the ISA I/O Recovery Timer Register does not add wait-states to IDE data port
read accesses when any of the fast timing modes are enabled.
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Functional Description
Table 5-53. IDE Transaction Timings (PCI Clocks)
IDE Transaction Type
Non-Data Port Compatible
5.15.1.4
Startup
Latency
IORDY Sample
Point (ISP)
Recovery Time
(RCT)
Shutdown
Latency
4
11
22
2
Data Port Compatible
3
6
14
2
Fast Timing Mode
2
2–5
1–4
2
IORDY Masking
The IORDY signal can be ignored and assumed asserted at the first IORDY Sample Point (ISP) on
a drive by drive basis via the IDETIM Register.
5.15.1.5
PIO 32-Bit IDE Data Port Accesses
A 32-bit PCI transaction run to the IDE data address (01F0h primary, 0170h secondary) results in
two back-to-back 16-bit transactions to the IDE data port. The 32-bit data port feature is enabled
for all timings, not just enhanced timing. For compatible timings, a shutdown and startup latency is
incurred between the two, 16-bit halves of the IDE transaction. This guarantees that the chip selects
will be deasserted for at least two PCI clocks between the two cycles.
5.15.1.6
PIO IDE Data Port Prefetching and Posting
The ICH4 can be programmed via the IDETIM registers to allow data to be posted to and
prefetched from the IDE data ports. Data prefetching is initiated when a data port read occurs. The
read prefetch eliminates latency to the IDE data ports and allows them to be performed back to
back for the highest possible PIO data transfer rates. The first data port read of a sector is called the
demand read. Subsequent data port reads from the sector are called prefetch reads. The demand
read and all prefetch reads must be the same size (16 or 32 bits).
Data posting is performed for writes to the IDE data ports. The transaction is completed on the PCI
bus after the data is received by the ICH4. The ICH4 will then run the IDE cycle to transfer the data
to the drive. If the ICH4 write buffer is non-empty and an unrelated (non-data or opposite channel)
IDE transaction occurs, that transaction will be stalled until all current data in the write buffer is
transferred to the drive.
5.15.2
Bus Master Function
The ICH4 can act as a PCI Bus master on behalf of an IDE slave device. Two PCI Bus master
channels are provided, one channel for each IDE connector (primary and secondary). By
performing the IDE data transfer as a PCI Bus master, the ICH4 off-loads the processor and
improves system performance in multitasking environments. Both devices attached to a connector
can be programmed for bus master transfers, but only one device per connector can be active at a
time.
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Functional Description
5.15.2.1
Physical Region Descriptor Format
The physical memory region to be transferred is described by a Physical Region Descriptor (PRD).
The PRDs are stored sequentially in a Descriptor Table in memory. The data transfer proceeds until
all regions described by the PRDs in the table have been transferred. Note that the ICH4 bus master
IDE function does not support memory regions or Descriptor tables located on ISA.
Descriptor Tables must not cross a 64-KB boundary. Each PRD entry in the table is 8 bytes in
length. The first 4 bytes specify the byte address of a physical memory region. This memory region
must be DWord aligned and must not cross a 64-KB boundary. The next two bytes specify the size
or transfer count of the region in bytes (64-KB limit per region). A value of zero in these two bytes
indicates 64 KB (thus, the minimum transfer count is 1). If bit 7 (EOT) of the last byte is a 1, it
indicates that this is the final PRD in the Descriptor table. Bus master operation terminates when
the last descriptor has been retired.
When the Bus Master IDE controller is reading data from the memory regions, bit 1 of the Base
Address is masked and byte enables are asserted for all read transfers. When writing data, bit 1 of
the Base Address is not masked and if set, causes the lower Word byte enables to be deasserted for
the first DWord transfer. The write to PCI typically consists of a 32-byte cache line. If valid data
ends prior to end of the cache line, the byte enables are deasserted for invalid data.
The total sum of the byte counts in every PRD of the descriptor table must be equal to or greater
than the size of the disk transfer request. If greater than the disk transfer request, the driver must
terminate the bus master transaction (by setting bit 0 in the Bus Master IDE Command Register to
0) when the drive issues an interrupt to signal transfer completion.
Figure 5-14. Physical Region Descriptor Table Entry
Main Memory
Byte 3
Byte 2
Byte 1
Memory Region Physical Base Address [31:1]
EOT
Reserved
Memory
Region
Byte 0
Byte Count [15:1]
0
0
051910_3.drw
5.15.2.2
Line Buffer
A single line buffer exists for the ICH4 Bus master IDE interface. This buffer is not shared with
any other function. The buffer is maintained in either the read state or the write state. Memory
writes are typically 4-DWord bursts and invalid DWords have C/BE[3:0]#=0Fh. The line buffer
allows burst data transfers to proceed at peak transfer rates.
The Bus Master IDE Active bit in Bus Master IDE Status register is reset automatically when the
controller has transferred all data associated with a Descriptor Table (as determined by EOT bit in
last PRD). The IDE Interrupt Status bit is set when the IDE device generates an interrupt. These
events may occur prior to line buffer emptying for memory writes. If either of these conditions
exist, all PCI Master non-memory read accesses to ICH4 are retried until all data in the line buffers
has been transferred to memory.
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Functional Description
5.15.2.3
Bus Master IDE Timings
The timing modes used for Bus Master IDE transfers are identical to those for PIO transfers. The
DMA Timing Enable Only bits in the IDE Timing register can be used to program fast timing mode
for DMA transactions only. This is useful for IDE devices whose DMA transfer timings are faster
that its PIO transfer timings. The IDE device DMA request signal is sampled on the same PCI
clock that DIOR# or DIOW# is deasserted. If inactive, the DMA Acknowledge signal is deasserted
on the next PCI clock and no more transfers take place until DMA request is asserted again.
5.15.2.4
Interrupts
Legacy Mode
The ICH4 is connected to IRQ14 for the primary interrupt and IRQ15 for the secondary interrupt.
This connection is done from the ISA pin, before any mask registers. This implies the following:
• Bus Master IDE devices are connected directly off of ICH4. IDE interrupts cannot be
communicated through PCI devices or the serial stream.
Warning:
In this mode, the ICH4 does not drive the PCI Interrupt associated with this function. That is only
used in native mode.
Native Mode
In this case both the primary and secondary channels share an interrupt. It will be internally
connected to PIRQ[C]# (IRQ18 in APIC mode). The interrupt will be active-low and shared.
Behavioral notes in native mode are:
• The IRQ14 and IRQ15 pins do not affect the internal IRQ14 and IRQ15 inputs to the interrupt
•
•
•
5.15.2.5
controllers. The IDE logic forces these signals inactive in such a way that the Serial IRQ
source may be used.
The IRQ14 and IRQ15 inputs (not external IRQ[14:15] pins) to the interrupt controller can
come from other sources (Serial IRQ, PIRQx).
The IRQ14 and IRQ15 pins are inverted from active-high to the active-low PIRQ.
When switching the IDE controller to native mode, the IDE Interrupt Pin register (see
Section 10.1.19) will be masked. If an interrupt occurs while the masking is in place and the
interrupt is still active when the masking ends, the interrupt will be allowed to be asserted.
Bus Master IDE Operation
To initiate a bus master transfer between memory and an IDE device, the following steps are
required:
1. Software prepares a PRD Table in system memory. The PRD Table must be DWord-aligned
and must not cross a 64-KB boundary.
2. Software provides the starting address of the PRD Table by loading the PRD Table Pointer
Register. The direction of the data transfer is specified by setting the Read/Write Control bit.
The interrupt bit and Error bit in the Status register are cleared.
3. Software issues the appropriate DMA transfer command to the disk device.
4. The bus master function is engaged by software writing a 1 to the Start bit in the Command
Register. The first entry in the PRD table is fetched and loaded into two registers which are not
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Functional Description
visible by software, the Current Base and Current Count registers. These registers hold the
current value of the address and byte count loaded from the PRD table. The value in these
registers is only valid when there is an active command to an IDE device.
5. Once the PRD is loaded internally, the IDE device receives a DMA acknowledge.
6. The controller transfers data to/from memory responding to DMA requests from the IDE
device. The IDE device and the host controller may or may not throttle the transfer several
times. When the last data transfer for a region has been completed on the IDE interface, the
next descriptor is fetched from the table. The descriptor contents are loaded into the Current
Base and Current Count registers.
7. At the end of the transfer the IDE device signals an interrupt.
8. In response to the interrupt, software resets the Start/Stop bit in the command register. It then
reads the controller status followed by the drive status to determine if the transfer completed
successfully.
The last PRD in a table has the End of List (EOL) bit set. The PCI bus master data transfers will
terminate when the physical region described by the last PRD in the table has been completely
transferred. The active bit in the Status Register will be reset and the DDRQ signal will be masked.
The buffer is flushed (when in the write state) or invalidated (when in the read state) when a
terminal count condition exists; that is, the current region descriptor has the EOL bit set and that
region has been exhausted. The buffer is also flushed (write state) or invalidated (read state) when
the Interrupt bit in the Bus Master IDE Status register is set. Software that reads the status register
and finds the Error bit reset, and either the Active bit reset or the Interrupt bit set, can be assured
that all data destined for system memory has been transferred and that data is valid in system
memory. Table 5-54 describes how to interpret the Interrupt and Active bits in the Status Register
after a DMA transfer has started.
During concurrent DMA or Ultra ATA transfers, the ICH4 IDE interface arbitrates between the
primary and secondary IDE cables when a PRD expires.
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Functional Description
Table 5-54. Interrupt/Active Bit Interaction Definition
5.15.2.6
Interrupt
Active
Description
0
1
DMA transfer is in progress. No interrupt has been generated by the IDE device.
1
0
The IDE device generated an interrupt. The controller exhausted the Physical Region
Descriptors. This is the normal completion case where the size of the physical memory
regions was equal to the IDE device transfer size.
1
1
The IDE device generated an interrupt. The controller has not reached the end of the
physical memory regions. This is a valid completion case where the size of the physical
memory regions was larger than the IDE device transfer size.
0
0
This bit combination signals an error condition. If the Error bit in the status register is set,
then the controller has some problem transferring data to/from memory. Specifics of the
error have to be determined using bus-specific information. If the Error bit is not set, then
the PRD's specified a smaller size than the IDE transfer size.
Error Conditions
IDE devices are sector-based mass storage devices. The drivers handle errors on a sector basis;
either a sector is transferred successfully or it is not. A sector is 512 bytes.
If the IDE device does not complete the transfer due to a hardware or software error, the command
will eventually be stopped by the driver setting Command Start bit to 0 when the driver times out
the disk transaction. Information in the IDE device registers help isolate the cause of the problem.
If the controller encounters an error while doing the bus master transfers it will stop the transfer
(i.e., reset the Active bit in the Command register) and set the Error bit in the Bus Master IDE
Status register. The controller does not generate an interrupt when this happens. The device driver
can use device specific information (PCI Configuration Space Status register and IDE Drive
Register) to determine what caused the error.
When a requested transfer does not complete properly, information in the IDE device registers
(Sector Count) can be used to determine how much of the transfer was completed and to construct
a new PRD table to complete the requested operation. In most cases the existing PRD table can be
used to complete the operation.
5.15.2.7
8237-Like Protocol
The 8237 mode DMA is similar in form to DMA used on the ISA bus. This mode uses pins
familiar to the ISA bus, namely a DMA Request, a DMA Acknowledge, and I/O read/write strobes.
These pins have similar characteristics to their ISA counterparts in terms of when data is valid
relative to strobe edges, and the polarity of the strobes; however, the ICH4 does not use the 8237
for this mode.
5.15.3
Ultra ATA/33 Protocol
Ultra ATA/33 is enabled through configuration register 48h in Device 31:Function 1 for each IDE
device. The IDE signal protocols are significantly different under this mode than for 8237 mode.
Ultra ATA/33 is a physical protocol used to transfer data between a Ultra ATA/33 capable IDE
controller (e.g., the ICH4) and one or more Ultra ATA/33 capable IDE devices. It utilizes the
standard Bus Master IDE functionality and interface to initiate and control the transfer.
Ultra ATA/33 utilizes a “source synchronous” signaling protocol to transfer data at rates up to
33 MB/s. The Ultra ATA/33 definition also incorporates a Cyclic Redundancy Checking (CRC-16)
error checking protocol.
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Functional Description
5.15.3.1
Signal Descriptions
The Ultra ATA/33 protocol requires no extra signal pins on the IDE connector. It does redefine a
number of the standard IDE control signals when in Ultra ATA/33 mode. These redefinitions are
shown in Table 5-55. Read cycles are defined as transferring data from the IDE device to the ICH4.
Write cycles are defined as transferring data from ICH4 to IDE device.
Table 5-55. UltraATA/33 Control Signal Redefinitions
Standard IDE
Signal Definition
Ultra ATA/33 Read
Cycle Definition
Ultra ATA/33 Write
Cycle Definition
ICH4 Primary
Channel Signal
ICH4 Secondary
Channel Signal
DIOW#
STOP
STOP
PDIOW#
SDIOW#
DIOR#
DMARDY#
STROBE
PDIOR#
SDIOR#
IORDY
STROBE
DMARDY#
PIORDY
SIORDY
The DIOW# signal is redefined as STOP for both read and write transfers. This is always driven by
the ICH4 and is used to request that a transfer be stopped or as an acknowledgment to stop a
request from the IDE device.
The DIOR# signal is redefined as DMARDY# for transferring data from the IDE device to the
ICH4 (read). It is used by the ICH4 to signal when it is ready to transfer data and to add wait-states
to the current transaction. The DIOR# signal is redefined as STROBE for transferring data from the
ICH4 to the IDE device (write). It is the data strobe signal driven by the ICH4 on which data is
transferred during each rising and falling edge transition.
The IORDY signal is redefined as STROBE for transferring data from the IDE device to the ICH4
(read). It is the data strobe signal driven by the IDE device on which data is transferred during each
rising and falling edge transition. The IORDY signal is redefined as DMARDY# for transferring
data from the ICH4 to the IDE device (write). It is used by the IDE device to signal when it is ready
to transfer data and to add wait-states to the current transaction.
All other signals on the IDE connector retain their functional definitions during Ultra ATA/33
operation.
5.15.3.2
Operation
Initial setup programming consists of enabling and performing the proper configuration of ICH4
and the IDE device for Ultra ATA/33 operation. For ICH4, this consists of enabling synchronous
DMA mode and setting up appropriate Synchronous DMA timings.
When ready to transfer data to or from an IDE device, the Bus Master IDE programming model is
followed. Once programmed, the drive and ICH4 control the transfer of data via the Ultra ATA/33
protocol. The actual data transfer consists of three phases, a start-up phase, a data transfer phase,
and a burst termination phase.
The IDE device begins the start-up phase by asserting DMARQ signal. When ready to begin the
transfer, the ICH4 asserts DMACK# signal. When DMACK# signal is asserted, the host controller
drives CS0# and CS1# inactive, DA0–DA2 low. For write cycles, the ICH4 deasserts STOP, waits
for the IDE device to assert DMARDY#, and then drives the first data word and STROBE signal.
For read cycles, the ICH4 tri-states the DD lines, deasserts STOP, and asserts DMARDY#. The
IDE device then sends the first data word and STROBE.
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Functional Description
The data transfer phase continues the burst transfers with the data transmitter (ICH4 - writes, IDE
device - reads) providing data and toggling STROBE. Data is transferred (latched by receiver) on
each rising and falling edge of STROBE. The transmitter can pause the burst by holding STROBE
high or low, resuming the burst by again toggling STROBE. The receiver can pause the burst by
deasserting DMARDY# and resumes the transfers by asserting DMARDY#. The ICH4 pauses a
burst transaction to prevent an internal line buffer over or under flow condition, resuming once the
condition has cleared. It may also pause a transaction if the current PRD byte count has expired,
resuming once it has fetched the next PRD.
The current burst can be terminated by either the transmitter or receiver. A burst termination
consists of a Stop Request, Stop Acknowledge and transfer of CRC data. The ICH4 can stop a burst
by asserting STOP, with the IDE device acknowledging by deasserting DMARQ. The IDE device
stops a burst by deasserting DMARQ and the ICH4 acknowledges by asserting STOP. The
transmitter then drives the STROBE signal to a high level. The ICH4 then drives the CRC value
onto the DD lines and deasserts DMACK#. The IDE device latches the CRC value on the rising
edge of DMACK#. The ICH4 terminates a burst transfer if it needs to service the opposite IDE
channel, if a Programmed I/O (PIO) cycle is executed to the IDE channel currently running the
burst, or upon transferring the last data from the final PRD.
5.15.3.3
CRC Calculation
Cyclic Redundancy Checking (CRC-16) is used for error checking on Ultra ATA/33 transfers. The
CRC value is calculated for all data by both the ICH4 and the IDE device over the duration of the
Ultra ATA/33 burst transfer segment. This segment is defined as all data transferred with a valid
STROBE edge from DDACK# assertion to DDACK# deassertion. At the end of the transfer burst
segment, the ICH4 drives the CRC value onto the DD[15:0] signals. It is then latched by the IDE
device on deassertion of DDACK#. The IDE device compares the ICH4 CRC value to its own and
reports an error if there is a mismatch.
5.15.4
Ultra ATA/66 Protocol
In addition to Ultra ATA/33, the ICH4 supports the Ultra ATA/66 protocol. The Ultra ATA/66
protocol is enabled via configuration bits 3:0 at offset 54h. The two protocols are similar, and are
intended to be device driver compatible. The Ultra ATA/66 logic can achieve transfer rates of up to
66 MB/s.
To achieve the higher data rate, the timings are shortened and the quality of the cable is improved
to reduce reflections, noise, and inductive coupling. Note that the improved cable is required and
will still plug into the standard IDE connector. The Ultra ATA/66 protocol also supports a 44 MB/s
mode.
5.15.5
Ultra ATA/100 Protocol
When the ATA_FAST bit is set for any of the four IDE devices, then the timings for the transfers to
and from the corresponding device run at a higher rate. The ICH4 Ultra ATA/100 logic can achieve
read transfer rates up to 100MB/s, and write transfer rates up to 88.9MB/s.
The cable improvements required for Ultra ATA/66 are sufficient for Ultra ATA/100, so no further
cable improvements are required when implementing Ultra ATA/100.
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Functional Description
5.15.6
Ultra ATA/33/66/100 Timing
The timings for Ultra ATA/33/66/100 modes are programmed via the Synchronous DMA Timing
Register and the IDE Configuration Register. Different timings can be programmed for each drive
in the system. The Base Clock frequency for each drive is selected in the IDE Configuration
Register. The Cycle Time (CT) and Ready to Pause (RP) time (defined as multiples of the Base
Clock) are programmed in the Synchronous DMA Timing Register. The Cycle Time represents the
minimum pulse width of the data strobe (STROBE) signal. The Ready to Pause time represents the
number of Base Clock periods that the ICH4 will wait from deassertion of DMARDY# to the
assertion of STOP when it desires to stop a burst read transaction.
Note:
5.15.7
The internal Base Clock for Ultra ATA/100 (Mode 5) runs at 133 MHz, and the Cycle Time (CT)
must be set for three Base Clocks. The ICH4 will thus toggle the write strobe signal every 22.5 ns,
transferring two bytes of data on each strobe edge. This means that the ICH4 will perform Mode 5
write transfers at a maximum rate of 88.9 MB/s. For read transfers, the read strobe will be driven
by the ATA/100 device, and the ICH4 supports reads at the maximum rate of 100 MB/s.
IDE Swap Bay
To support a swap bay, the ICH4 allows the IDE output signals to be tri-stated and input buffers to
be turned off. This should be done prior to the removal of the drive. The output signals can also be
driven low. This can be used to remove charge built up on the signals. Configuration bits are
included in the IDE I/O Configuration Register, offset 54h in the IDE PCI configuration space.
In an IDE Hot Swap Operation, an IDE device is removed and a new one inserted while the IDE
interface is powered down and the rest of the system is in a fully powered-on state (SO). During an
IDE Hot Swap, if the operating system executes cycles to the IDE interface after it has been
powered down, it will cause the ICH4 to hang the system that is waiting for IORDY to be asserted
from the drive. To correct this issue, the following BIOS procedures are required for performing an
IDE hot swap.
1. Program IDE SIG_MODE (offset 54h) to 10b (drive low mode).
2. Clear IORDY Sample Point Enable (bits 1 or 5 of IDE Timing register). This prevents ICH4
from waiting for IORDY assertion when the operating system accesses the IDE device after
the IDE drive powers down, and ensures that zeros will always be returned for read cycles that
occur during hot swap operation.
Warning:
The software should not attempt to control the outputs (either tri-state or driving low), while an
IDE transfer is in progress. Unpredictable results could occur, including a system lockup.
Intel® 82801DB ICH4 Datasheet
171
Functional Description
5.16
USB UHCI Controllers (D29:F0, F1 and F2)
The ICH4 contains three USB UHCI Host controllers. Each Host controller includes a root hub
with two separate USB ports each, for a total of 6 USB ports. The ICH4 Host controllers support
the standard Universal Host Controller Interface (UHCI) Specification, Revision 1.1.
• Overcurrent detection on all six USB ports is supported. The overcurrent inputs are 5 Vtolerant, and can be used as GPIs if not needed.
• The ICH4’s USB UHCI controllers are arbitrated differently than standard PCI devices to
improve arbitration latency.
• The USB UHCI controllers use the Analog Front End (AFE) embedded cell that allows
support for USB High-speed signaling rates, instead of USB I/O buffers.
5.16.1
Data Structures in Main Memory
This section describes the details of the data structures used to communicate control, status, and
data between software and the ICH4: Frame Lists, Transfer Descriptors, and Queue Heads. Frame
Lists are aligned on 4-KB boundaries. Transfer Descriptors and Queue Heads are aligned on
16-byte boundaries.
5.16.1.1
Frame List Pointer
The frame list pointer contains a link pointer to the first data object to be processed in the frame, as
well as the control bits defined in Table 5-56.
Table 5-56. Frame List Pointer Bit Description
Bit
172
Description
31:4
Frame List Pointer (FLP). This field contains the address of the first data object to be processed in
the frame and corresponds to memory address signals [31:4], respectively.
3:2
Reserved. These bits must be written as 0.
1
QH/TD Select (Q). This bit indicates to the hardware whether the item referenced by the link pointer
is a TD (Transfer Descriptor) or a QH (Queue Head). This allows the Intel® ICH4 to perform the proper
type of processing on the item after it is fetched.
0 = TD
1 = QH
0
Terminate (T). This bit indicates to the ICH4 whether the schedule for this frame has valid entries in
it.
0 = Pointer is valid (points to a QH or TD).
1 = Empty Frame (pointer is invalid).
Intel® 82801DB ICH4 Datasheet
Functional Description
5.16.1.2
Transfer Descriptor (TD)
Transfer Descriptors (TDs) express the characteristics of the transaction requested on USB by a
client. TDs are always aligned on 16-byte boundaries, and the elements of the TD are shown in
Figure 5-15. The 4 different USB transfer types are supported by a small number of control bits in
the descriptor that the ICH4 interprets during operation. All Transfer Descriptors have the same
basic, 32-byte structure. During operation, the ICH4 hardware performs consistency checks on
some fields of the TD. If a consistency check fails, the ICH4 halts immediately and issues an
interrupt to the system. This interrupt cannot be masked within the ICH4.
Figure 5-15. Transfer Descriptor
31 30 29 28
27 26 25 24 23
21 20 19 18
16 15 14
11 10
8 7
4 3
2
1
0
0
Vf
Q
T
Link Pointer
R
SPD C_ERR
LS ISO ISC
MaxLen
Status
R
D
R
EndPt
Device Address
ActLen
PID
Buffer Pointer
R = Reserved
Intel® ICH4 Read/Write
ICH4 Read Only
Table 5-57. TD Link Pointer
Bit
Description
31:4
Link Pointer (LP). Bits [31:4] Correspond to memory address signals [31:4], respectively. This field
points to another TD or QH.
3
Reserved. Must be 0 when writing this field.
2
Depth/Breadth Select (VF). This bit is only valid for queued TDs and indicates to the hardware
whether it should process in a depth first or breadth first fashion. When set to depth first, it informs
the Intel® ICH4 to process the next transaction in the queue rather than starting a new queue.
0 = Breadth first
1 = Depth first
1
QH/TD Select (Q). This bit informs the ICH4 whether the item referenced by the link pointer is
another TD or a QH. This allows the ICH4 to perform the proper type of processing on the item after
it is fetched.
0 = TD
1 = QH
0
Terminate (T). This bit informs the ICH4 that the link pointer in this TD does not point to another
valid entry. When encountered in a queue context, this bit indicates to the ICH4 that there are no
more valid entries in the queue. A TD encountered outside of a queue context with the T bit set
informs the ICH4 that this is the last TD in the frame.
0 = Link Pointer field is valid.
1 = Link Pointer field not valid.
Intel® 82801DB ICH4 Datasheet
173
Functional Description
Table 5-58. TD Control and Status (Sheet 1 of 2)
Bit
31:30
Description
Reserved.
29
Short Packet Detect (SPD). When a packet has this bit set to 1 and the packet is an input packet, is
in a queue; and successfully completes with an actual length less than the maximum length, then
the TD is marked inactive, the Queue Header is not updated, and the USBINT status bit (Status
Register) is set at the end of the frame. In addition, if the interrupt is enabled, the interrupt will be
sent at the end of the frame.
Note that any error (e.g., babble or FIFO error) prevents the short packet from being reported. The
behavior is undefined when this bit is set with output packets or packets outside of queues.
0 = Disable
1 = Enable
28:27
Error Counter (C_ERR). This field is a 2-bit down counter that keeps track of the number of Errors
detected while executing this TD. If this field is programmed with a non zero value during setup, the
ICH4 decrements the count and writes it back to the TD if the transaction fails. If the counter counts
from one to zero, the Intel® ICH4 marks the TD inactive, sets the “STALLED” and error status bit for
the error that caused the transition to zero in the TD. An interrupt will be generated to Host controller
Driver (HCD) if the decrement to zero was caused by Data Buffer error, Bit stuff error, or if enabled,
a CRC or Timeout error. If HCD programs this field to zero during setup, the ICH4 will not count
errors for this TD and there will be no limit on the retries of this TD.
Bits[28:27]
Interrupt After
00
No Error Limit
01
1 Error
10
2 Errors
11
3 Errors
Error
Decrement Counter
Error
Decrement Counter
CRC Error
Yes
Data Buffer Error Yes
Timeout Error
Yes
Stalled
No1
NAK Received
No
Bit stuff Error
Yes
Babble Detected No1
NOTE 1. Detection of Babble or Stall automatically deactivates the TD. Thus, count is not
decremented.
26
Low Speed Device (LS). This bit indicates that the target device (USB data source or sink) is a low
speed device, running at 1.5 Mb/s, instead of at full speed (12 Mb/sec). There are special
restrictions on schedule placement for low speed TDs. If an ICH4 root hub port is connected to a full
speed device and this bit is set to a 1 for a low speed transaction, the ICH4 sends out a low speed
preamble on that port before sending the PID. No preamble is sent if an ICH4 root hub port is
connected to a low speed device.
0 = Full-Speed Device
1 = Low-Speed Device
25
Isochronous Select (IOS). The field specifies the type of the data structure. If this bit is set to a 1,
the TD is an isochronous transfer. Isochronous TDs are always marked inactive by the hardware
after execution, regardless of the results of the transaction.
0 = Non-isochronous Transfer Descriptor
1 = Isochronous Transfer Descriptor
24
Interrupt on Complete (IOC). This specifies that the ICH4 should issue an interrupt on completion
of the frame in which this Transfer Descriptor is executed. Even if the Active bit in the TD is already
cleared when the TD is fetched (no transaction will occur on USB), an IOC interrupt is generated at
the end of the frame.
1 = Issue IOC
Active. For ICH4 schedule execution operations, see Section 5.16.2, Data Transfers to/from Main
Memory.
23
174
0 = When the transaction associated with this descriptor is completed, the ICH4 sets this bit to 0
indicating that the descriptor should not be executed when it is next encountered in the
schedule. The Active bit is also set to 0 if a stall handshake is received from the endpoint.
1 = Set to 1 by software to enable the execution of a message transaction by the ICH4.
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-58. TD Control and Status (Sheet 2 of 2)
Bit
Description
22
Stalled.
1 = Set to a 1 by the ICH4 during status updates to indicate that a serious error has occurred at the
device/endpoint addressed by this TD. This can be caused by babble, the error counter
counting down to zero, or reception of the STALL handshake from the device during the
transaction. Any time that a transaction results in the Stalled bit being set, the Active bit is also
cleared (set to 0). If a STALL handshake is received from a SETUP transaction, a Time Out
Error will also be reported.
21
Data Buffer Error (DBE).
1 = Set to a 1 by the ICH4 during status update to indicate that the ICH4 is unable to keep up with
the reception of incoming data (overrun) or is unable to supply data fast enough during
transmission (underrun). When this occurs, the actual length and Max Length field of the TD
will not match. In the case of an underrun, the ICH4 will transmit an incorrect CRC (thus
invalidating the data at the endpoint) and leave the TD active (unless error count reached zero).
If a overrun condition occurs, the ICH4 will force a timeout condition on the USB, invalidating
the transaction at the source.
20
Babble Detected (BABD).
1 = Set to a 1 by the ICH4 during status update when “babble” is detected during the transaction
generated by this descriptor. Babble is unexpected bus activity for more than a preset amount
of time. In addition to setting this bit, the ICH4 also sets the” STALLED” bit (bit 22) to a 1. Since
“babble” is considered a fatal error for that transfer, setting the” STALLED” bit to a 1 insures that
no more transactions occur as a result of this descriptor. Detection of babble causes immediate
termination of the current frame. No further TDs in the frame are executed. Execution resumes
with the next frame list index.
19
Negative Acknowledgment (NAK) Received (NAKR).
1 = Set to a 1 by the ICH4 during status update when the ICH4 receives a “NAK” packet during the
transaction generated by this descriptor. If a NAK handshake is received from a SETUP
transaction, a Time Out Error will also be reported.
CRC/Time Out Error (CRC_TOUT).
1 = Set to a 1 by the ICH4 as follows:
18
17
16
• During a status update in the case that no response is received from the target device/endpoint
within the time specified by the protocol chapter of the USB specification.
• During a status update when a Cycli Redundancy Check (CRC) error is detected during the
transaction associated with this transfer descriptor.
In the transmit case (OUT or SETUP Command), this is in response to the ICH4 detecting a timeout
from the target device/endpoint.
In the receive case (IN Command), this is in response to the ICH4’s CRC checker circuitry detecting
an error on the data received from the device/endpoint or a NAK or STALL handshake being
received in response to a SETUP transaction.
Bit stuff Error (BSE).
1 = This bit is set to a 1 by the ICH4 during status update to indicate that the receive data stream
contained a sequence of more than 6 ones in a row.
Bus Turn Around Time-out (BTTO).
1 = This bit is set to a 1 by the ICH4 during status updates to indicate that a bus time-out condition
was detected for this USB transaction. This time-out is specially defined as not detecting an
IDLE-to ‘K’ state Start of Packet (SOP) transition from 16 to 18-bit times after the SE0-to-IDE
transition of previous End of Packet (EOP).
15:11
Reserved
10:0
Actual Length (ACTLEN). The Actual Length field is written by the ICH4 at the conclusion of a USB
transaction to indicate the actual number of bytes that were transferred. It can be used by the
software to maintain data integrity. The value programmed in this register is encoded as n-1 (see
Maximum Length field description in the TD Token).
Intel® 82801DB ICH4 Datasheet
175
Functional Description
Table 5-59. TD Token
Bit
Description
31:21
Maximum Length (MAXLEN). The Maximum Length field specifies the maximum number of data
bytes allowed for the transfer. The Maximum Length value does not include protocol bytes, such as
Packet ID (PID) and CRC. The maximum data packet is 1280 bytes. The 1280 packet length is the
longest packet theoretically guaranteed to fit into a frame. Actual packet maximum lengths are set
by HCD according to the type and speed of the transfer. Note that the maximum length allowed by
the USB specification is 1023 bytes. The valid encodings for this field are:
0x000 = 1 byte
0x001 = 2 bytes
....
0x3FE = 1023 bytes
0x3FF = 1024 bytes
....
0x4FF = 1280 bytes
0x7FF = 0 bytes (null data packet)
Note that values from 500h to 7FEh are illegal and cause a consistency check failure.
In the transmit case, the Intel® ICH4 uses this value as a terminal count for the number of bytes it
fetches from host memory. In most cases, this is the number of bytes it will actually transmit. In rare
cases, the ICH4 may be unable to access memory (e.g., due to excessive latency) in time to avoid
underrunning the transmitter. In this instance the ICH4 would transmit fewer bytes than specified in
the Maximum Length field.
20
Reserved.
19
Data Toggle (D). This bit is used to synchronize data transfers between a USB endpoint and the
host. This bit determines which data PID is sent or expected (0=DATA0 and 1=DATA1). The Data
Toggle bit provides a 1-bit sequence number to check whether the previous packet completed. This
bit must always be 0 for Isochronous TDs.
18:15
Endpoint (ENDPT). This 4-bit field extends the addressing internal to a particular device by
providing 16 endpoints. This permits more flexible addressing of devices in which more than one
sub-channel is required.
14:8
Device Address. This field identifies the specific device serving as the data source or sink.
7:0
Packet Identification (PID). This field contains the Packet ID to be used for this transaction. Only
the IN (69h), OUT (E1h), and SETUP (2Dh) tokens are allowed. Any other value in this field causes
a consistency check failure resulting in an immediate halt of the ICH4. Bits [3:0] are complements of
bits [7:4].
Table 5-60. TD Buffer Pointer
Bit
31:0
176
Description
Buffer Pointer (BUFF_PNT). Bits [31:0] corresponds to memory address [31:0], respectively. It
points to the beginning of the buffer that will be used during this transaction. This buffer must be at
least as long as the value in the Maximum Length field described int the TD token. The data buffer
may be byte-aligned.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.16.1.3
Queue Head (QH)
Queue heads are special structures used to support the requirements of Control, Bulk, and Interrupt
transfers. Since these TDs are not automatically retired after each use, their maintenance
requirements can be reduced by putting them into a queue. Queue Heads must be aligned on a
16-byte boundary, and the elements are shown in Table 5-61.
Table 5-61. Queue Head Block
Bytes
Description
Attributes
00–03
Queue Head Link Pointer
RO
04–07
Queue Element Link Pointer
R/W
Table 5-62. Queue Head Link Pointer
Bit
Description
31:4
Queue Head Link Pointer (QHLP). This field contains the address of the next data object to be
processed in the horizontal list and corresponds to memory address signals [31:4], respectively.
3:2
Reserved. These bits must be written as zeros.
1
QH/TD Select (Q). This bit indicates to the hardware whether the item referenced by the link pointer
is another TD or a QH.
0 = TD
1 = QH
0
Terminate (T). This bit indicates to the Intel® ICH4 that this is the last QH in the schedule. If there are
active TDs in this queue, they are the last to be executed in this frame.
0 = Pointer is valid (points to a QH or TD).
1 = Last QH (pointer is invalid).
Table 5-63. Queue Element Link Pointer
Bit
Description
31:4
Queue Element Link Pointer (QELP). This field contains the address of the next TD or QH to be
processed in this queue and corresponds to memory address signals [31:4], respectively.
3:2
Reserved.
1
QH/TD Select (Q). This bit indicates to the hardware whether the item referenced by the link pointer
is another TD or a QH. For entries in a queue, this bit is typically set to 0.
0 = TD
1 = QH
0
Terminate (T). This bit indicates to the Intel® ICH4 that there are no valid TDs in this queue. When
HCD has new queue entries it overwrites this value with a new TD pointer to the queue entry.
0 = Pointer is valid.
1 = Terminate (No valid queue entries).
Intel® 82801DB ICH4 Datasheet
177
Functional Description
5.16.2
Data Transfers to/from Main Memory
The following sections describe the details on how HCD and the ICH4 communicate via the
Schedule data structures. The discussion is organized in a top-down manner, beginning with the
basics of walking the Frame List, followed by a description of generic processing steps common to
all transfer descriptors, and finally a discussion on Transfer Queuing.
5.16.2.1
Executing the Schedule
Software programs the ICH4 with the starting address of the Frame List and the Frame List index,
then causes the ICH4 to execute the schedule by setting the Run/Stop bit in the Control register to
Run. The ICH4 processes the schedule one entry at a time: the next element in the frame list is not
fetched until the current element in the frame list is retired.
Schedule execution proceeds in the following fashion:
• The ICH4 first fetches an entry from the Frame List. This entry has three fields. Bit 0 indicates
whether the address pointer field is valid. Bit 1 indicates whether the address points to a
Transfer Descriptor or to a queue head. The third field is the pointer itself.
• If isochronous traffic is to be moved in a given frame, the Frame List entry points to a Transfer
Descriptor. If no isochronous data is to be moved in that frame, the entry points to a queue
head or the entry is marked invalid and no transfers are initiated in that frame.
• If the Frame List entry indicates that it points to a Transfer Descriptor, the ICH4 fetches the
entry and begins the operations necessary to initiate a transaction on USB. Each TD contains a
link field that points to the next entry, as well as indicating whether it is a TD or a QH.
• If the Frame List entry contains a pointer to a QH, the ICH4 processes the information from
the QH to determine the address of the next data object that it should process.
• The TD/QH process continues until the millisecond allotted to the current frame expires. At
this point, the ICH4 fetches the next entry from the Frame List. If the ICH4 is not able to
process all of the transfer descriptors during a given frame, those descriptors are retired by
software without having been executed.
178
Intel® 82801DB ICH4 Datasheet
Functional Description
5.16.2.2
Processing Transfer Descriptors
The ICH4 executes a TD using the following generalized algorithm. These basic steps are common
across all modes of TDs. Subsequent sections present processing steps unique to each TD mode.
1. ICH4 fetches TD or QH from the current Link Pointer.
2. If a QH, go to 1 to fetch from the Queue Element Link Pointer. If inactive, go to 12
3. Build token, actual bits are in TD token.
4. If (Host-to-Function) then
[PCI Access] issue request for data, (referenced through TD.BufferPointer)
wait for first chunk data arrival
end if
5. [Begin USB Transaction] Issue token (from token built in 2, above) and begin data transfer.
if (Host-to-Function) then Go to 6
else Go to 7
end if
6. Fetch data from memory (via TD BufferPointer) and transfer over USB until TD Max-Length
bytes have been read and transferred. [Concurrent system memory and USB Accesses]. Go to
8.
7. Wait for data to arrive (from USB). Write incoming bytes into memory beginning at TD
BufferPointer. Internal HC buffer should signal end of data packet. Number of bytes received
must be (TD Max-Length; The length of the memory area referenced by TD BufferPointer
must be (TD Max-Length. [Concurrent system memory and USB Accesses].
8. Issue handshake based on status of data received (Ack or Time-out). Go to 10.
9. Wait for handshake, if required [End of USB Transaction].
10. Update Status [PCI Access] (TD.Status and TD.ActualLength).
If the TD was an isochronous TD, mark the TD inactive. Go to 12.
If not an isochronous TD, and the TD completed successfully, mark the TD inactive. Go to 11.
If not successful, and the error count has not been reached, leave the TD active. If the error
count has been reached, mark the TD inactive. Go to 12.
11. Write the link pointer from the current TD into the element pointer field of the QH structure. If
the Vf bit is set in the TD link pointer, go to 2.
12. Proceed to next entry.
Intel® 82801DB ICH4 Datasheet
179
Functional Description
5.16.2.3
Command Register, Status Register, and TD Status Bit Interaction
Table 5-64. Command Register, Status Register, and TD Status Bit Interaction
Condition
Intel® ICH4 USB Status Register Actions
TD Status Register Actions
CRC/Time Out Error
Set USB Error Int bit1, Clear HC Halted bit
Clear Active bit1 and set Stall bit1
Illegal PID, PID Error,
Max Length (illegal)
Clear Run/Stop bit in Command register
Set HC Process Error and HC Halted bits
PCI Master/Target Abort
Clear Run/Stop bit in Command register
Set Host System Error and HC Halted bits
Suspend Mode
Clear Run/Stop bit in Command register2
Set HC Halted bit
Resume Received and
Suspend Mode = 1
Set Resume received bit
Run/Stop = 0
Clear Run/Stop bit in command register
Set HC Halted bit
Configuration Flag Set
Set Configuration Flag in Command
register
HC Reset/Global Reset
Clear Run/Stop and Configuration Flag in
Command register
Clear USB Int, USB Error Int, Resume
received, Host System Error, HC Process
Error, and HC Halted bits
IOC = 1 in TD Status
Set USB Int bit
Stall
Set USB Error Int bit
Clear Active bit1 and set Stall bit
Bit Stuff/Data Buffer Error
Set USB Error Int bit1
Clear Active bit1 and set Stall bit1
Short Packet Detect
Set USB Int bit
Clear Active bit
NOTES:
1. Only If error counter counted down from 1 to 0
2. Suspend mode can be entered only when Run/Stop bit is 0
Note that if a NAK or STALL response is received from a SETUP transaction, a Time Out Error
will be reported. This causes the Error counter to decrement and the CRC/Time-out Error status bit
to be set within the TD Control and Status DWord during write back. If the Error counter changes
from 1 to 0, the Active bit is reset to 0 and Stalled bit to 1 as normal.
180
Intel® 82801DB ICH4 Datasheet
Functional Description
5.16.2.4
Transfer Queuing
Transfer Queues are used to implement a guaranteed data delivery stream to a USB Endpoint.
Transfer Queues are composed of two parts: a Queue Header (QH) and a linked list. The linked list
of TDs and QHs has an indeterminate length (0 to n).
The QH contains two link pointers and is organized as two contiguous DWords. The first DWord is
a horizontal pointer (Queue Head Link Pointer), used to link a single transfer queue with either
another transfer queue, or a TD (target data structure depends on Q bit). If the T bit is set, this QH
represents the last data structure in the current Frame. The T bit informs the ICH4 that no further
processing is required until the beginning of the next frame. The second DWord is a vertical pointer
(Queue Element Link Pointer) to the first data structure (TD or QH) being managed by this QH. If
the T bit is set, the queue is empty. This pointer may reference a TD or another QH.
Figure 5-16 illustrates four example queue conditions. The first QH (on far left) is an example of
an “empty” queue; the termination bit (T Bit) in the vertical link pointer field is set to 1. The
horizontal link pointer references another QH. The next queue is the expected typical
configuration. The horizontal link pointer references another QH, and the vertical link pointer
references a valid TD.
Typically, the vertical pointer in a QH points to a TD. However, as shown in Figure 5-16 (third
example from left side of figure) the vertical pointer could point to another QH. When this occurs,
a new Q Context is entered and the Q Context just exited is NULL (ICH4 will not update the
vertical pointer field).
The far right QH is an example of a frame “termination” node. Since its horizontal link pointer has
its termination bit set, the ICH4 assumes there is no more work to complete for the current Frame.
Figure 5-16. Example Queue Conditions
31
2 1 0
Frame List Pointer
31
QH
Q T
2 1 0
Indicates 'Nil' Next Pointer
31
QH
2 1 0
31
QH
2 1 0
31
QH
2 1 0
Link Pointer (Horiz) Q T
Link Pointer (Horiz) Q T
Link Pointer (Horiz) Q T
Link Pointer (Horiz) Q T
Link Pointer (Vert)
Link Pointer (Vert)
Q T
Link Pointer (Vert)
Link Pointer (Vert)
Link Pointer
Q T
Q T
Indicates 'NULL' Queue Head
Q T
Indicates 'Nil' Next Pointer
TD
Link Pointer
31
Link Pointer
Q T
Q T
QH
2 1 0
Q T
TD
Link Pointer (Horiz) Q T
Link Pointer (Vert)
Q T
Link Pointer
Q T
TD
Link Pointer (Horz)=Queue Head Link Pointer
field in QH DWord
z0
Link Pointer (Vert)=Queue Element Link Pointer
field in QH DWord 1
TD
Link Pointer
Q T
TD
Intel® 82801DB ICH4 Datasheet
181
Functional Description
Transfer Queues are based on the following characteristics:
• A QH’s vertical link pointer (Queue Element Link Pointer) references the “Top” queue
member. A QH’s horizontal link pointer (Queue Head Link Pointer) references the “next”
work element in the Frame.
• Each queue member’s link pointer references the next element within the queue.
In the simplest model, the ICH4 follows vertical link point to a queue element, then executes the
element. If the completion status of the TD satisfies the advance criteria as shown in Table 5-65,
the ICH4 advances the queue by writing the just-executed TD’s link pointer back into the QH’s
Queue Element link pointer. The next time the queue head is traversed, the next queue element will
be the Top element.
The traversal has two options: Breadth first, or Depth first. A flag bit in each TD (Vf - Vertical
Traversal Flag) controls whether traversal is Breadth or Depth first. The default mode of traversal
is Breadth-First. For Breadth-First, the ICH4 only executes the top element from each queue. The
execution path is shown below:
1. QH (Queue Element Link Pointer)
2. TD
3. Write-Back to QH (Queue Element Link Pointer)
4. QH (Queue Head Link pointer).
Breadth-First is also performed for every transaction execution that fails the advance criteria. This
means that if a queued TD fails, the queue does not advance, and the ICH4 traverses the QH’s
Queue Head Link Pointer.
In a Depth-first traversal, the top queue element must complete successfully to satisfy the advance
criteria for the queue. If the ICH4 is currently processing a queue, and the advance criteria are met,
and the Vf bit is set, the ICH4 follows the TD’s link pointer to the next schedule work item.
Note that regardless of traversal model, when the advance criteria are met, the successful TD’s link
pointer is written back to the QH’s Queue Element link pointer. When the ICH4 encounters a QH,
it caches the QH internally, and sets internal state to indicate it is in a Q-context. It needs this state
to update the correct QH (for auto advancement) and also to make the correct decisions on how to
traverse the Frame List.
Restricting the advancement of queues to advancement criteria implements a guaranteed data
delivery stream. A queue is never advanced on an error completion status (even in the event the
error count was exhausted). Table 5-65 lists the general queue advance criteria, which are based on
the execution status of the TD at the “Top” of a currently “active” queue.
Table 5-65. Queue Advance Criteria
Function-to-Host (IN)
Host-to-Function (OUT)
Non-NULL
NULL
Error/NAK
Non-NULL
NULL
Error/NAK
Advance Q
Advance Q
Retry Q Element
Advance Q
Advance Q
Retry Q Element
Table 5-66 is a decision table illustrating the valid combinations of link pointer bits and the valid
actions taken when advancement criteria for a queued transfer descriptor are met. The column
headings for the link pointer fields are encoded, based on the following list:
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Intel® 82801DB ICH4 Datasheet
Functional Description
TD
QHLP
QH
Q
QELP
QE
Vf
T
TDLP
Vf Q T
Q T
Legends:
QH.LP = Queue Head Link Pointer (or Horizontal Link Pointer)
QE.LP = Queue Element Link Pointer (or Vertical Link Pointer)
TD.LP = TD Link Pointer
QH.Q = Q bit in QH
QH.T = T bit in QH
QE.Q = Q bit in QE
QE.T = T bit in QE
TD. Vf = Vf bit in TD
TD.Q = Q bit in TD
TD. T = T bit in TD
Table 5-66. USB Schedule List Traversal Decision Table
Q
Context
QH.Q
QH.T
QE.Q
QE.T
TD.Vf
TD.Q
TD.T
0
—
—
—
—
x
0
0
• Not in Queue - execute TD.
• Use TD.LP to get next TD
0
—
—
—
—
x
x
1
• Not in Queue - execute TD. End of Frame
0
—
—
—
—
x
1
0
• Not in Queue - execute TD.
• Use TD.LP to get next (QH+QE).
• Set Q Context to 1.
1
0
0
0
0
0
x
x
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use QH.LP to get next TD.
1
x
x
0
0
1
0
0
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use TD.LP to get next TD.
1
x
x
0
0
1
1
0
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use TD.LP to get next (QH+QE).
1
0
0
x
1
x
x
x
• In Queue. Empty queue.
• Use QH.LP to get next TD
1
x
x
1
0
—
—
—
• In Queue. Use QE.LP to get (QH+QE)
1
x
1
0
0
0
x
x
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• End of Frame
1
x
1
x
1
x
x
x
• In Queue. Empty queue. End of Frame
1
1
0
0
0
0
x
x
• In Queue. Use QE.LP to get TD.
• Execute TD. Update QE.LP with TD.LP.
• Use QH.LP to get next (QH+QE).
1
1
0
x
1
x
x
x
• In Queue. Empty queue.
• Use QH.LP to get next (QH+QE)
Intel® 82801DB ICH4 Datasheet
Description
183
Functional Description
5.16.3
Data Encoding and Bit Stuffing
The USB employs NRZI data encoding (Non-Return to Zero Inverted) when transmitting packets.
In NRZI encoding; a one is represented by no change in level, and a zero is represented by a change
in level. A string of zeros causes the NRZI data to toggle each bit time. A string of ones causes long
periods with no transitions in the data. To ensure adequate signal transitions, bit stuffing is
employed by the transmitting device when sending a packet on the USB. A zero is inserted after
every six, consecutive ones in the data stream before the data is NRZI encoded to force a transition
in the NRZI data stream. This gives the receiver logic a data transition at least once every seven bit
times to guarantee the data and clock lock. A waveform of the data encoding is shown in
Figure 5-17.
Figure 5-17. USB Data Encoding
CLOCK
Data
Bit Stuffed Data
NRZI Data
Bit stuffing is enabled beginning with the Sync Pattern and throughout the entire transmission. The
data “one” that ends the Sync Pattern is counted as the first one in a sequence. Bit stuffing is always
enforced, without exception. If required by the bit stuffing rules, a zero bit will be inserted even if
it is the last bit before the end-of-packet (EOP) signal.
5.16.4
Bus Protocol
5.16.4.1
Bit Ordering
Bits are sent out onto the bus least significant bit (LSb) first, followed by next LSb, through to the
most significant bit (MSb) last.
5.16.4.2
SYNC Field
All packets begin with a synchronization (SYNC) field, which is a coded sequence that generates a
maximum edge transition density. The SYNC field appears on the bus as IDLE followed by the
binary string “KJKJKJKK,” in its NRZI encoding. It is used by the input circuitry to align
incoming data with the local clock and is defined to be eight bits in length. SYNC serves only as a
synchronization mechanism and is not shown in the following packet diagrams. The last two bits in
the SYNC field are a marker that is used to identify the first bit of the PID. All subsequent bits in
the packet must be indexed from this point.
5.16.4.3
Packet Field Formats
Field formats for the token, data, and handshake packets are described in the following section. The
effects of NRZI coding and bit stuffing have been removed for the sake of clarity. All packets have
distinct start and end of packet delimiters.
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Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-67. PID Format
Bit
Data Sent
Bit
Data Sent
0
PID 0
4
NOT(PID 0)
1
PID 1
5
NOT(PID 1)
2
PID 2
6
NOT(PID 2)
3
PID 3
7
NOT(PID 3)
Packet Identifier Field
A packet identifier (PID) immediately follows the SYNC field of every USB packet. A PID
consists of a four bit packet type field followed by a four-bit check field as shown in Table 5-67.
The PID indicates the type of packet and, by inference, the format of the packet and the type of
error detection applied to the packet. The four-bit check field of the PID insures reliable decoding
of the PID so that the remainder of the packet is interpreted correctly. The PID check field is
generated by performing a ones complement of the packet type field.
Any PID received with a failed check field or which decodes to a non-defined value is assumed to
be corrupted and the remainder of the packet is assumed to be corrupted and is ignored by the
receiver. PID types, codes, and descriptions are listed in Table 5-68.
Table 5-68. PID Types
PID Type
Token
PID Name
PID[3:0]
Description
OUT
b0001
Address + endpoint number in host -> function transaction
IN
b1001
Address + endpoint number in function -> host transaction
SOF
b0101
Start of frame marker and frame number
SETUP
b1101
Address + endpoint number in host -> function transaction for
setup to a control endpoint
DATA0
b0011
Data packet PID even
Data
Handshake
Special
DATA1
b1011
Data packet PID odd
ACK
b0010
Receiver accepts error free data packet
NAK
b1010
Rx device cannot accept data or Tx device cannot send data
STALL
b1110
Endpoint is stalled
PRE
b1100
Host-issued preamble. Enables downstream bus traffic to
low speed devices.
PIDs are divided into four coding groups: token, data, handshake, and special, with the first two
transmitted PID bits (PID[1:0]) indicating which group. This accounts for the distribution of PID
codes.
Intel® 82801DB ICH4 Datasheet
185
Functional Description
5.16.4.4
Address Fields
Function endpoints are addressed using two fields: the function address field and the endpoint
field.
Table 5-69. Address Field
Bit
Data Sent
Bit
Data Sent
0
ADDR 0
4
ADDR 4
1
ADDR 1
5
ADDR 5
2
ADDR 2
6
ADDR 6
3
ADDR 3
Address Field
The function address (ADDR) field specifies the function, via its address, that is either the source
or destination of a data packet, depending on the value of the token PID. As shown in Table 5-69, a
total of 128 addresses are specified as ADDR[6:0]. The ADDR field is specified for IN, SETUP,
and OUT tokens.
Endpoint Field
An additional four-bit endpoint (ENDP) field, shown in Table 5-70, permits more flexible
addressing of functions in which more than one sub-channel is required. Endpoint numbers are
function specific. The endpoint field is defined for IN, SETUP, and OUT token PIDs only.
Table 5-70. Endpoint Field
5.16.4.5
Bit
Data Sent
0
ENDP 0
1
ENDP 1
2
ENDP 2
3
ENDP 3
Frame Number Field
The frame number field is an 11-bit field that is incremented by the host on a per-frame basis. The
frame number field rolls over upon reaching its maximum value of x7FFh, and is sent only for SOF
tokens at the start of each frame.
5.16.4.6
Data Field
The data field may range from 0 to 1023 bytes and must be an integral numbers of bytes. Data bits
within each byte are shifted out LSB first.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.16.4.7
Cyclic Redundancy Check (CRC)
CRC is used to protect the all non-PID fields in token and data packets. In this context, these fields
are considered to be protected fields. The PID is not included in the CRC check of a packet
containing CRC. All CRCs are generated over their respective fields in the transmitter before bit
stuffing is performed. Similarly, CRCs are decoded in the receiver after stuffed bits have been
removed. Token and data packet CRCs provide 100% coverage for all single and double bit errors.
A failed CRC is considered to indicate that one or more of the protected fields is corrupted and
causes the receiver to ignore those fields, and, in most cases, the entire packet.
5.16.5
Packet Formats
5.16.5.1
Token Packets
Table 5-71 shows the field formats for a token packet. A token consists of a PID, specifying either
IN, OUT, or SETUP packet type, and ADDR and ENDP fields. For OUT and SETUP transactions,
the address and endpoint fields uniquely identify the endpoint that will receive the subsequent data
packet. For IN transactions, these fields uniquely identify which endpoint should transmit a data
packet. Only the ICH4 can issue token packets. IN PIDs define a data transaction from a function
to the ICH4. OUT and SETUP PIDs define data transactions from the ICH4 to a function.
Token packets have a five-bit CRC that covers the address and endpoint fields as shown above. The
CRC does not cover the PID, which has its own check field. Token and SOF packets are delimited
by an EOP after three bytes of packet field data. If a packet decodes as an otherwise valid token or
SOF but does not terminate with an EOP after three bytes, it must be considered invalid and
ignored by the receiver.
Table 5-71. Token Format
5.16.5.2
Packet
Width
PID
8 bits
ADDR
7 bits
ENDP
4 bits
CRC5
5 bits
Start of Frame Packets
Table 5-72 shows a start of frame (SOF) packet. SOF packets are issued by the host at a nominal
rate of once every 1.00 ms 0.05. SOF packets consist of a PID indicating packet type followed by
an 11-bit frame number field.
The SOF token comprises the token-only transaction that distributes a start of frame marker and
accompanying frame number at precisely timed intervals corresponding to the start of each frame.
All full speed functions, including hubs, must receive and decode the SOF packet. The SOF token
does not cause any receiving function to generate a return packet; therefore, SOF delivery to any
given function cannot be guaranteed. The SOF packet delivers two pieces of timing information. A
function is informed that a start of frame has occurred when it detects the SOF PID. Frame timing
sensitive functions, which do not need to keep track of frame number, need only decode the SOF
PID; they can ignore the frame number and its CRC. If a function needs to track frame number, it
must comprehend both the PID and the time stamp.
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187
Functional Description
Table 5-72. SOF Packet
Packet
5.16.5.3
Width
PID
8 bits
Frame Number
11 bits
CRC5
5 bits
Data Packets
A data packet consists of a PID, a data field, and a CRC as shown in Table 5-73. There are two
types of data packets, identified by differing PIDs: DATA0 and DATA1. Two data packet PIDs are
defined to support data toggle synchronization.
Data must always be sent in integral numbers of bytes. The data CRC is computed over only the
data field in the packet and does not include the PID, which has its own check field.
Table 5-73. Data Packet Format
5.16.5.4
Packet
Width
PID
8 bits
DATA
0–1023 bytes
CRC16
16 bits
Handshake Packets
Handshake packets consist of only a PID. Handshake packets are used to report the status of a data
transaction and can return values indicating successful reception of data, flow control, and stall
conditions. Only transaction types that support flow control can return handshakes. Handshakes are
always returned in the handshake phase of a transaction and may be returned, instead of data, in the
data phase. Handshake packets are delimited by an EOP after one byte of packet field. If a packet is
decoded as an otherwise valid handshake but does not terminate with an EOP after one byte, it
must be considered invalid and ignored by the receiver.
There are three types of handshake packets:
• ACK indicates that the data packet was received without bit stuff or CRC errors over the data
field and that the data PID was received correctly. An ACK handshake is applicable only in
transactions in which data has been transmitted and where a handshake is expected. ACK can
be returned by the host for IN transactions and by a function for OUT transactions.
• NAK indicates that a function was unable to accept data from the host (OUT) or that a
function has no data to transmit to the host (IN). NAK can only be returned by functions in the
data phase of IN transactions or the handshake phase of OUT transactions. The host can never
issue a NAK. NAK is used for flow control purposes to indicate that a function is temporarily
unable to transmit or receive data, but will eventually be able to do so without need of host
intervention. NAK is also used by interrupt endpoints to indicate that no interrupt is pending.
• STALL is returned by a function in response to an IN token or after the data phase of an OUT.
STALL indicates that a function is unable to transmit or receive data, and that the condition
requires host intervention to remove the stall. Once a function’s endpoint is stalled, the
function must continue returning STALL until the condition causing the stall has been cleared
through host intervention. The host is not permitted to return a STALL under any condition.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.16.5.5
Handshake Responses
IN Transaction
A function may respond to an IN transaction with a STALL or NAK. If the token received was
corrupted, the function will issue no response. If the function can transmit data, it will issue the
data packet. The ICH4, as the USB host, can return only one type of handshake on an IN
transaction, an ACK. If it receives a corrupted data, or cannot accept data due to a condition such as
an internal buffer overrun, it discards the data and issues no response.
OUT Transaction
A function may respond to an OUT transaction with a STALL, ACK, or NAK. If the transaction
contained corrupted data, it will issue no response.
SETUP Transaction
Setup defines a special type of host to function data transaction which permits the host to initialize
an endpoint’s synchronization bits to those of the host. Upon receiving a Setup transaction, a
function must accept the data. Setup transactions cannot be STALLed or NAKed and the receiving
function must accept the Setup transfer’s data. If a non-control endpoint receives a SETUP PID, it
must ignore the transaction and return no response.
5.16.6
USB Interrupts
There are two general groups of USB interrupt sources, those resulting from execution of
transactions in the schedule, and those resulting from an ICH4 operation error. All transactionbased sources can be masked by software through the ICH4’s Interrupt Enable register.
Additionally, individual transfer descriptors can be marked to generate an interrupt on completion.
When the ICH4 drives an interrupt for USB, it internally drives the PIRQ[A]# pin for USB
function #0, PIRQ[D]# pin for USB function #1, and the PIRQ[C]# pin for USB function #2, until
all sources of the interrupt are cleared. To accommodate some operating systems, the Interrupt Pin
register must contain a different value for each function of this new multi-function device.
5.16.6.1
Transaction Based Interrupts
These interrupts are not signaled until after the status for the last complete transaction in the frame
has been written back to host memory. This guarantees that software can safely process through
(Frame List Current Index -1) when it is servicing an interrupt.
CRC Error / Time-Out
A CRC/Time-Out error occurs when a packet transmitted from the ICH4 to a USB device or a
packet transmitted from a USB device to the ICH4 generates a CRC error. The ICH4 is informed of
this event by a time-out from the USB device or by the ICH4’s CRC checker generating an error on
reception of the packet. Additionally, a USB bus time-out occurs when USB devices do not
respond to a transaction phase within 19-bit times of an EOP. Either of these conditions will cause
the C_ERR field of the TD to decrement.
Intel® 82801DB ICH4 Datasheet
189
Functional Description
When the C_ERR field decrements to zero, the following occurs:
•
•
•
•
The Active bit in the TD is cleared
The Stalled bit in the TD is set
The CRC/Time-out bit in the TD is set.
At the end of the frame, the USB Error Interrupt bit is set in the HC status register.
If the CRC/Time out interrupt is enabled in the Interrupt Enable register, a hardware interrupt will
be signaled to the system.
Interrupt on Completion
Transfer Descriptors contain a bit that can be set to cause an interrupt on their completion. The
completion of the transaction associated with that block causes the USB Interrupt bit in the HC
Status Register to be set at the end of the frame in which the transfer completed. When a TD is
encountered with the IOC bit set to 1, the IOC bit in the HC Status register is set to 1 at the end of
the frame if the active bit in the TD is set to 0 (even if it was set to zero when initially read).
If the IOC Enable bit of Interrupt Enable register (bit 2 of I/O offset 04h) is set, a hardware
interrupt is signaled to the system. The USB Interrupt bit in the HC status register is set either when
the TD completes successfully or because of errors. If the completion is because of errors, the USB
Error bit in the HC status register is also set.
Short Packet Detect
A transfer set is a collection of data which requires more than 1 USB transaction to completely
move the data across the USB. An example might be a large print file which requires numerous
TDs in multiple frames to completely transfer the data. Reception of a data packet that is less than
the endpoint’s Max Packet size during Control, Bulk or Interrupt transfers signals the completion
of the transfer set, even if there are active TDs remaining for this transfer set. Setting the SPD bit in
a TD indicates to the HC to set the USB Interrupt bit in the HC status register at the end of the
frame in which this event occurs. This feature streamlines the processing of input on these transfer
types. If the Short Packet Interrupt Enable bit in the Interrupt Enable register is set, a hardware
interrupt is signaled to the system at the end of the frame where the event occurred.
Serial Bus Babble
When a device transmits on the USB for a time greater than its assigned Max Length, it is said to
be babbling. Since isochrony can be destroyed by a babbling device, this error results in the Active
bit in the TD being cleared to 0 and the Stalled and Babble bits being set to one. The C_ERR field
is not decremented for a babble. The USB Error Interrupt bit in the HC Status register is set to 1 at
the end of the frame. A hardware interrupt is signaled to the system.
If an EOF babble was caused by the ICH4 (due to incorrect schedule for instance), the ICH4 will
force a bit stuff error followed by an EOP and the start of the next frame.
Stalled
This event indicates that a device/endpoint returned a STALL handshake during a transaction or
that the transaction ended in an error condition. The TDs Stalled bit is set and the Active bit is
cleared. Reception of a STALL does not decrement the error counter. A hardware interrupt is
signaled to the system.
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Intel® 82801DB ICH4 Datasheet
Functional Description
Data Buffer Error
This event indicates that an overrun of incoming data or a under-run of outgoing data has occurred
for this transaction. This would generally be caused by the ICH4 not being able to access required
data buffers in memory within necessary latency requirements. Either of these conditions will
cause the C_ERR field of the TD to be decremented.
When C_ERR decrements to zero, the Active bit in the TD is cleared, the Stalled bit is set, the USB
Error Interrupt bit in the HC Status register is set to 1 at the end of the frame and a hardware
interrupt is signaled to the system.
Bit Stuff Error
A bit stuff error results from the detection of a sequence of more than 6 ones in a row within the
incoming data stream. This will cause the C_ERR field of the TD to be decremented. When the
C_ERR field decrements to zero, the Active bit in the TD is cleared to 0, the Stalled bit is set to 1,
the USB Error Interrupt bit in the HC Status register is set to 1 at the end of the frame and a
hardware interrupt is signaled to the system.
5.16.6.2
Non-Transaction Based Interrupts
If an ICH4 process error or system error occur, the ICH4 halts and immediately issues a hardware
interrupt to the system.
Resume Received
This event indicates that the ICH4 received a RESUME signal from a device on the USB bus
during a global suspend. If this interrupt is enabled in the Interrupt Enable register, a hardware
interrupt will be signaled to the system allowing the USB to be brought out of the suspend state and
returned to normal operation.
Intel® ICH4 Process Error
The HC monitors certain critical fields during operation to ensure that it does not process corrupted
data structures. These include checking for a valid PID and verifying that the MaxLength field is
less than 1280. If it detects a condition that would indicate that it is processing corrupted data
structures, it immediately halts processing, sets the HC Process Error bit in the HC Status register
and signals a hardware interrupt to the system.
This interrupt cannot be disabled through the Interrupt Enable register.
Host System Error
The ICH4 sets this bit to 1 when a PCI Parity error, PCI Master Abort, or PCI Target Abort occur.
When this error occurs, the ICH4 clears the Run/Stop bit in the Command register to prevent
further execution of the scheduled TDs. This interrupt cannot be disabled through the Interrupt
Enable register.
Intel® 82801DB ICH4 Datasheet
191
Functional Description
5.16.7
USB Power Management
The Host controller can be put into a suspended state and its power can be removed. This requires
that certain bits of information are retained in the resume power plane of the ICH4 so that a device
on a port may wake the system. Such a device may be a fax-modem, which will wake up the
machine to receive a fax or take a voice message. The settings of the following bits in I/O space
will be maintained when the ICH4 enters the S3, S4 or S5 states:
Table 5-74. Bits Maintained in Low Power States
Register
Offset
Bit
Command
00h
3
Enter Global Suspend Mode (EGSM)
Status
02h
2
Resume Detect
2
Port Enabled/Disabled
6
Resume Detect
8
Low Speed Device Attached
12
Suspend
Port Status and Control
Description
10h & 12h
When the ICH4 detects a resume event on any of its ports, it will set the corresponding USB_STS
bit in ACPI space. If USB is enabled as a wake/break event, the system will wake up and an SCI
will be generated.
5.16.8
USB Legacy Keyboard Operation
When a USB keyboard is plugged into the system, and a standard keyboard is not, the system may
not boot, and DOS legacy software will not run, because the keyboard will not be identified. The
ICH4 implements a series of trapping operations which will snoop accesses that go to the keyboard
controller, and put the expected data from the USB keyboard into the keyboard controller.
Note:
The scheme described below assumes that the keyboard controller (8042 or equivalent) is on the
LPC bus.
This legacy operation is performed through SMM space. Figure 5-18 shows the Enable and Status
path. The latched SMI source (60R, 60W, 64R, 64W) is available in the Status Register. Because
the enable is after the latch, it is possible to check for other events that didn't necessarily cause an
SMI. It is the software's responsibility to logically AND the value with the appropriate enable bits.
Note also that the SMI is generated before the PCI cycle completes (e.g., before TRDY# goes
active) to ensure that the processor does not complete the cycle before the SMI is observed. This
method is used on MPIIX and has been validated.
The logic will also need to block the accesses to the 8042. If there is an external 8042, then this is
simply accomplished by not activating the 8042 CS. This is simply done by logically ANDing the
4 enables (60R, 60W, 64R, 64W) with the 4 types of accesses to determine if 8042CS should go
active. An additional term is required for the “Pass-through” case.
The state table for the diagram is shown in Table 5-75.
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Intel® 82801DB ICH4 Datasheet
Functional Description
Figure 5-18. USB Legacy Keyboard Enable and Status Paths
To Individual
"Caused By"
"Bits"
60 READ
KBC Accesses
S
D
PCI Config
Comb.
Decoder
Clear SMI_60_R
R
EN_SMI_ON_60R
Read, Write
AND
SMI
Same for 60W, 64R, 64W
OR
EN_PIRQD#
AND
To PIRQD#
To "Caused By" Bit
USB_IRQ
S
Clear USB_IRQ
D
R
AND
EN_SMI_ON_IRQ
Intel® 82801DB ICH4 Datasheet
193
Functional Description
Table 5-75. USB Legacy Keyboard State Transitions
Current State
Action
Data Value
Next State
Comment
IDLE
64h / Write
D1h
GateState1
Standard D1 command. Cycle passed through to
8042. SMI# doesn't go active. PSTATE (offset C0,
bit 6) goes to 1.
IDLE
64h / Write
Not D1h
IDLE
Bit 3 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
IDLE
64h / Read
N/A
IDLE
Bit 2 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
IDLE
60h / Write
Don't Care
IDLE
Bit 1 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
IDLE
60h / Read
N/A
IDLE
Bit 0 in configuration register determines if cycle
passed through to 8042 and if SMI# generated.
GateState1
60h / Write
XXh
GateState2
Cycle passed through to 8042, even if trap enabled
in Bit 1 in configuration register. No SMI#
generated. PSTATE remains 1. If data value is not
DFh or DDh, then the 8042 may chose to ignore it.
GateState1
64h / Write
D1h
GateState1
Cycle passed through to 8042, even if trap enabled
via Bit 3 in configuration register. No SMI#
generated. PSTATE remains 1. Stay in GateState1
because this is part of the double-trigger
sequence.
GateState1
64h / Write
Not D1h
ILDE
Bit 3 in configuration space determines if cycle
passed through to 8042 and if SMI# generated.
PSTATE goes to 0. If Bit 7 in Configuration register
is set, then SMI# should be generated.
GateState1
60h / Read
N/A
IDLE
This is an invalid sequence. Bit 0 in configuration
register determines if cycle passed through to 8042
and if SMI# generated. PSTATE goes to 0. If Bit 7
in configuration register is set, then SMI# should be
generated.
GateState1
64h / Read
N/A
GateState1
Just stay in same state. Generate an SMI# if
enabled in Bit 2 of configuration register. PSTATE
remains 1.
GateState2
64 / Write
FFh
IDLE
Standard end of sequence. Cycle passed through
to 8042. PSTATE goes to 0. Bit 7 in configuration
space determines if SMI# should be generated.
GateState2
64h / Write
Not FFh
IDLE
Improper end of sequence. Bit 3 in the
configuration register determines if cycle passed
through to 8042 and if SMI# generated. PSTATE
goes to 0. If Bit 7 in the configuration register is set,
then SMI# should be generated.
GateState2
64h / Read
N/A
GateState2
Just stay in same state. Generate an SMI# if
enabled in Bit 2 of configuration register. PSTATE
remains 1.
IDLE
Improper end of sequence. Bit 1 in the
configuration register determines if cycle passed
through to 8042 and if SMI# generated. PSTATE
goes to 0. If Bit 7 in configuration register is set,
then SMI# should be generated.
IDLE
Improper end of sequence. Bit 0 in the
configuration register determines if cycle passed
through to 8042 and if SMI# generated. PSTATE
goes to 0. If Bit 7 in configuration register is set,
then SMI# should be generated.
GateState2
GateState2
194
60h / Write
60h / Read
XXh
N/A
Intel® 82801DB ICH4 Datasheet
Functional Description
5.17
USB EHCI Controller (D29:F7)
The ICH4 contains an Enhanced Host Controller Interface (EHCI) compliant host controller which
supports up to six, high-speed USB 2.0 Specification compliant root ports. High-speed USB 2.0
allows data transfers up to 480 Mbps using the same pins as the 6 Full-speed/Low-speed USB
UHCI ports. The ICH4 contains port-routing logic that determines whether a USB port is
controlled by one of the UHCI controllers or by the EHCI controller. A USB 2.0 based Debug Port
is also implemented in the ICH4.
A summary of the key architectural differences between the USB UHCI host controllers and the
USB EHCI host controller are shown in Table 5-66.
Table 5-76. UHCI vs. EHCI
USB UHCI
Accessible by
5.17.1
I/O space
USB EHCI
Memory Space
Memory Data Structure
Single linked list
Separated in to Periodic and Asynchronous lists
Differential Signaling Voltage
3.3 V
400 mV
Ports per Controller
2
6
EHC Initialization
The following descriptions step through the expected ICH4 Enhanced Host Controller (EHC)
initialization sequence in chronological order, beginning with a complete power cycle in which the
suspend well and core well have been off.
5.17.1.1
Power On
The suspend well is a “deeper” power plane than the core well, which means that the suspend well
is always functional when the core well is functional but the core well may not be functional when
the suspend well is. Therefore, the suspend well reset pin (RSMRST#) deasserts before the core
well reset pin (PWROK) rises.
1. The suspend well reset deasserts, leaving all registers and logic in the suspend well in the
default state. However, it is not possible to read any registers until after the core well reset
deasserts. Note that normally the suspend well reset will only occur when a system is
unplugged. In other words, suspend well resets are not easily achieved by software or the enduser. This step will typically not occur immediately before the remaining steps.
2. The core well reset deasserts, leaving all registers and logic in the core well in the default state.
The EHC configuration space is accessible at this point. Note that the core well reset can (and
typically does) occur without the suspend well reset asserting. This means that all of the
Configure Flag and Port Status and Control bits (and any other suspend-well logic) may be in
any valid state at this time.
5.17.1.2
BIOS Initialization
BIOS performs a number of platform customization steps after the core well has powered up.
Contact your intel field sales representative for the latest BIOS information.
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Functional Description
5.17.1.3
Driver Initialization
See Chapter 4 of the Enhanced Host Controller Interface Specification for Universal Serial Bus.
5.17.1.4
EHC Resets
In addition to the standard ICH4 hardware resets, portions of the EHC are reset by the HCRESET
bit and the transition from the D3hot device power management state to the D0 state. The effects of
each of these resets are listed in the following table.
Reset
Does Reset
Does not Reset
Comments
HCRESET bit set
Memory space
registers except
Structural Parameters
(which is written by
BIOS)
Configuration
registers
The HCRESET must only affect
registers that the EHCI driver controls.
PCI Configuration space and BIOSprogrammed parameters can not be
reset.
Software writes the
Device Power State
from D3hot (11b) to
D0 (00b)
Core well registers
(except BIOSprogrammed registers)
Suspend well
registers; BIOSprogrammed core
well registers
The D3-to-D0 transition must not cause
wake information (suspend well) to be
lost. It also must not clear BIOSprogrammed registers because BIOS
may not be invoked following the D3-toD0 transition.
If the detailed register descriptions give exceptions to these rules, those exceptions override these
rules. This summary is provided to help explain the reasons for the reset policies.
5.17.2
Data Structures in Main Memory
See Chapter 3 and Appendix B of the Enhanced Host Controller Interface Specification for
Universal Serial Bus for details.
5.17.3
USB 2.0 Enhanced Host Controller DMA
The ICH4 USB 2.0 EHC implements three sources of USB packets. They are, in order of priority
on USB during each microframe,
1. the USB 2.0 Debug Port (see Section USB 2.0 EHCI Based Debug Port),
2. the Periodic DMA engine, and
3. the Asynchronous DMA engine.
The ICH4 always performs any currently-pending debug port transaction at the beginning of a
microframe, followed by any pending periodic traffic for the current microframe. If there is time
left in the microframe, then the EHC performs any pending asynchronous traffic until the end of
the microframe (EOF1). Note that the debug port traffic is only presented on one port (Port #0),
while the other ports are idle during this time.
The following subsections describe the policies of the periodic and asynchronous DMA engines.
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Functional Description
5.17.3.1
Periodic List Execution
The Periodic DMA engine contains buffering for two control structures (two transactions). By
implementing two entries, the EHC is able to pipeline the memory accesses for the next transaction
while executing the current transaction on the USB ports. Note that a multiple-packet, HighBandwidth transaction occupies one of these buffer entries, which means that up to six, 1-KB data
packets may be associated with the two buffered control structures.
5.17.3.1.1 Read Policies for Periodic DMA
The Periodic DMA engine performs reads for the following structures.
Memory Structure
Size (DWords)
Comments
Periodic Frame List entry
1
The EHC reads the entry for each microframe. The frame list is
not internally cached across microframes.
iTD
23
Only the 64-bit addressing format is supported.
siTD
9
Only the 64-bit addressing format is supported.
qTD
13
Only the 64-bit addressing format is supported.
Queue Head
17
Only the 64-bit addressing format is supported.
Out Data
Frame Span Transversal
Node
Up to 257
The ICH4 breaks large read requests down into smaller aligned
read requests based on the setting of the Read Request Max
Length field.
2
The EHC Periodic DMA Engine (PDE) does not generate accesses to main memory unless all three
of the following conditions are met.
— The HCHalted bit is 0 (memory space, offset 24h, bit 12). Software clears this bit
indirectly by setting the RUN/STOP bit to 1.
— The Periodic Schedule Status bit is 1 (memory space, offset 24h, bit 14). Software sets this
bit indirectly by setting the Periodic Schedule Enable Bit to 1.
— The Bus Master Enable bit is 1 (configuration space, offset 04h, bit 2).
Note:
Prefetching is limited to the current and next microframes only.
Note:
Once the PDE checks the length of a periodic packet against the remaining time in the microframe
(late-start check) and decides that there is not enough time to run it on the wire, then the EHC
switches over to run asynchronous traffic.
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Functional Description
5.17.3.1.2 Write Policies for Periodic DMA
The Periodic DMA engine performs writes for the following reasons.
Memory Structure
Size
(DWords)
Comments
iTD Status Write
1
Only the DWord that corresponds to the just-executed microframe’s
status is written. All bytes of the DWord are written.
siTD Status Write
3
DWords 0C:17h are written. IOC and Buffer Pointer fields are rewritten with the original value.
Interrupt Queue Head
Overlay
14
Only the 64-bit addressing format is supported. DWords 0C:43h are
written.
Interrupt Queue Head
Status Write
54
DWords 14:27h are written.
Interrupt qTD Status
Write
3
DWords 04:0Fh are written. PID Code, IOC, Buffer Pointers, and Alt.
Next qTD Pointers are re-written with the original value.
In Data
Up to 257
The ICH4 breaks data writes down into 16-DWord aligned chunks.
NOTES:
1. The Periodic DMA Engine (PDE) will only generate writes after a transaction is executed on USB.
2. Status writes are always performed after In Data writes for the same transaction.
5.17.3.2
Asynchronous List Execution
The Asynchronous DMA engine contains buffering for two control structures (two transactions).
By implementing two entries, the EHC is able to pipeline the memory accesses for the next
transaction while executing the current transaction on the USB ports.
5.17.3.2.1 Read Policies for Asynchronous DMA
The Asynchronous DMA engine performs reads for the following structures.
Memory Structure
Size (DW)
Comments
qTD
13
Only the 64-bit addressing format is supported.
Queue Head
17
Only the 64-bit addressing format is supported.
Out Data
Up to 129
The ICH4 breaks large read requests down in to smaller aligned
read requests based on the setting of the Read Request Max
Length field.
The EHC Asynchronous DMA Engine (ADE) does not generate accesses to main memory unless
all four of the following conditions are met. (Note that the ADE may be active when the periodic
schedule is actively executed, unlike the description in the EHCI specification; since the EHC
contains independent DMA engines, the ADE may perform memory accesses interleaved with the
PDE accesses.)
• The HCHalted bit is 0 (memory space, offset 24h, bit 12). Software clears this bit indirectly by
•
•
•
198
setting the RUN/STOP bit to 1.
The Asynchronous Schedule Status bit is 1 (memory space, offset 24h, bit 14). Software sets
this bit indirectly by setting the Asynchronous Schedule Enable Bit to 1.
The Bus Master Enable bit is 1 (configuration space, offset 04h, bit 2).
The ADE is not sleeping due to the detection of an empty schedule. There is not one single bit
that indicates this state. However, the sleeping state is entered when the Queue Head with the
H bit set is encountered when the Reclamation bit in the USB EHCI Status register is 0.
Intel® 82801DB ICH4 Datasheet
Functional Description
Note:
The ADE does not fetch data when a QH is encountered in the Ping state. An Ack handshake in
response to the Ping results in the ADE writing the QH to the Out state, which results in the
fetching and delivery of the Out Data on the next iteration through the asynchronous list.
Note:
Once the ADE checks the length of an asynchronous packet against the remaining time in the
microframe (late-start check) and decides that there is not enough time to run it on the wire, then
the EHC stops all activity on the USB ports for the remainder of that microframe.
Note:
Once the ADE detects an “empty” asynchronous schedule as described in Chapter 4 of the
Enhanced Host Controller Interface (EHCI) Specification for Universal Serial Bus, it implements
a waking mechanism like the one in the example. The amount of time that the ADE “sleeps” is
10 µs ± 30 ns.
5.17.3.2.2 Write Policies for Asynchronous DMA
The Asynchronous DMA engine performs writes for the following reasons.
Memory Structure
Size
(DWords)
Asynchronous
Queue Head Overlay
14
Only the 64-bit addressing format is supported. DWords 0C:43h are
written.
Asynchronous
Queue Head Status
Write
34
DWords 14:1Fh are written.
Asynchronous qTD
Status Write
3
DWords 04:0Fh are written. PID Code, IOC, Buffer Pointer (Page 0),
and Alt. Next qTD Pointers are re-written with the original value.
In Data
Up to 1297
Comments
The Intel® ICH4 breaks data writes down into 16 DWord aligned
chunks.
NOTES:
1. The Asynchronous DMA Engine (ADE) will only generate writes after a transaction is executed on USB.
2. Status writes are always performed after In Data writes for the same transaction.
5.17.4
Data Encoding and Bit Stuffing
See Chapter 8 of the Universal Serial Bus (USB) Specification, Revision 2.0.
5.17.5
Packet Formats
See Chapter 8 of the Universal Serial Bus (USB) Specification, Revision 2.0.
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Functional Description
5.17.6
USB EHCI Interrupts and Error Conditions
Section 4 of the EHCI specification goes into detail on the EHC interrupts and the error conditions
that cause them. All error conditions that the EHC detects can be reported through the EHCI
Interrupt status bits. Only ICH4-specific interrupt and error-reporting behavior is documented in
this section. The EHCI Interrupts Section must be read first, followed by this section of the
datasheet to fully comprehend the EHC interrupt and error-reporting functionality.
— Based on the EHC’s buffer sizes and buffer management policies, the Data Buffer Error
can never occur on the ICH4.
— Master Abort and Target Abort responses from hub interface on EHC-initiated read
packets will be treated as Fatal Host Errors. The EHC halts when these conditions are
encountered.
— The ICH4 may assert the interrupts which are based on the interrupt threshold as soon as
the status for the last complete transaction in the interrupt interval has been posted in the
internal write buffers. The requirement in the EHCI Specification (that the status is
written to memory) is met internally, even though the write may not be seen on the hub
interface before the interrupt is asserted.
— Since the ICH4 supports the 1024-element Frame List size, the Frame List Rollover
interrupt occurs every 1024 milliseconds.
— The ICH4 delivers interrupts using PIRQ#[H].
— The ICH4 does not modify the CERR count on an Interrupt IN when the “Do CompleteSplit” execution criteria are not met.
— For complete-split transactions in the Periodic list, the “Missed Microframe” bit does not
get set on a control-structure-fetch that fails the late-start test. If subsequent accesses to
that control structure do not fail the late-start test, then the “Missed Microframe” bit will
get set and written back.
5.17.6.1
Aborts on USB EHCI-Initiated Memory Reads
If a read initiated by the EHC is aborted, the EHC treats it as a fatal host error. The following
actions are taken when this occurs:
•
•
•
•
•
•
200
The Host System Error status bit is set
The DMA engines are halted after completing up to one more transaction on the USB interface
If enabled (by the Host System Error Enable), an interrupt is generated
If the status is Master Abort, the Received Master Abort bit in configuration space is set
If the status is Target Abort, the Received Target Abort bit in configuration space is set
If enabled (by the SERR Enable bit in the function’s configuration space), the Signaled System
Error bit in configuration bit is set.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.17.7
USB EHCI Power Management
5.17.7.1
Pause Feature
This feature allows platforms (especially mobile systems) to dynamically enter low-power states
during brief periods when the system is idle (i.e., between keystrokes). This is useful for enabling
power management features like C3, C4, and Intel SpeedStep technology in the ICH4. The policies
for entering these states typically are based on the recent history of system bus activity to
incrementally enter deeper power management states. Normally, when the EHC is enabled, it
regularly accesses main memory while traversing the DMA schedules looking for work to do; this
activity is viewed by the power management software as a non-idle system, thus preventing the
power managed states to be entered. Suspending all of the enabled ports can prevent the memory
accesses from occurring, but there is an inherent latency overhead with entering and exiting the
suspended state on the USB ports that makes this unacceptable for the purpose of dynamic power
management. As a result, the EHCI software drivers are allowed to pause the EHC’s DMA engines
when it knows that the traffic patterns of the attached devices can afford the delay. The pause only
prevents the EHC from generating memory accesses; the SOF packets continue to be generated on
the USB ports (unlike the suspended state).
5.17.7.2
Suspend Feature
The Enhanced Host Controller Interface (EHCI) for Universal Serial Bus Specification describes
the details of Port Suspend and Resume in detail in Section 4.3.
5.17.7.3
ACPI Device States
The USB EHCI function only supports the D0 and D3 PCI Power Management states. Notes
regarding the ICH4 implementation of the Device States:
• The EHC hardware does not inherently consume any more power when it is in the D0 state
than it does in the D3 state. However, software is required to suspend or disable all ports prior
to entering the D3 state such that the maximum power consumption is reduced.
• In the D0 state, all implemented EHC features are enabled.
• In the D3 state, accesses to the EHC memory-mapped I/O range will master abort. Note that,
since the Debug Port uses the same memory range, the Debug Port is only operational when
the EHC is in the D0 state.
• In the D3 state, the EHC interrupt must never assert for any reason. The internal PME# signal
is used to signal wake events, etc.
• When the Device Power State field is written to D0 from D3, an internal reset is generated. See
section EHC Resets for general rules on the effects of this reset.
• Attempts to write any other value into the Device Power State field other than 00b (D0 state)
and 11b (D3 state) will complete normally without changing the current value in this field.
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Functional Description
5.17.7.4
ACPI System States
The EHC behavior as it relates to other power management states in the system is summarized in
the following list:
• The System is always in the S0 state when the EHC is in the D0 state. However, when the
EHC is in the D3 state, the system may be in any power management state (including S0).
• When in D0, the Pause feature (See Section 5.17.7.1) enables dynamic processor low-power
states to be entered.
• The PLL in the EHC is disabled when entering the S3/S4/S5 states (core power turns off).
• All core well logic is reset in the S3/S4/S5 states (core power turns off).
5.17.8
Interaction with Classic Host Controllers
The EHC shares the six USB ports with three UHCI Host controllers in the ICH4. The USB UHCI
controller at D29:F0 shares ports 0 and 1; the USB UHCI controller at D29:F1 shares ports 2 and 3;
and the USB UHCI controller at D29:F2 shares ports 4 and 5 with the EHCI controller. There is
very little interaction between the USB EHCI and the USB UHCI controllers other than the muxing
control which is provided as part of the EHCI controller.
Figure 5-19 depicts the USB Port Connections at a conceptual level. The dashed rectangle
indicates all of the logic that is part of the EHC cluster.
Figure 5-19. Intel® ICH4 USB Port Connections
UHCI #3
(D29:F2)
UHCI #2
(D29:F1)
UHCI #1
(D29:F0)
Port 5
Port 4
Port 3
Port 2
Port 1
Port 0
Debug
Port
5.17.8.1
EHCI (D29:F7)
Port-Routing Logic
Integrated into the EHC functionality is port-routing logic, which performs the muxing between the
USB UHCI and USB EHCI host controllers. The ICH4 conceptually implements this logic as
described in Section 4.2 of the Enhanced Host Controller Interface (EHCI) for Universal Serial
Bus Specification. If a device is connected that is not capable of USB 2.0’s high-speed signaling
protocol or if the EHCI software drivers are not present as indicated by the Configured Flag, then
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Functional Description
the USB UHCI controller owns the port. Owning the port means that the differential output is
driven by the owner and the input stream is only visible to the owner. The host controller that is not
the owner of the port internally sees a disconnected port.
Note that the port-routing logic is the only block of logic within the ICH4 that observes the
physical (real) connect/disconnect information. The port status logic inside each of the host
controllers observes the electrical connect/disconnect information that is generated by the portrouting logic.
Only the differential signal pairs are muxed/demuxed between the USB UHCI and USB EHCI host
controllers. The other USB functional signals are handled as follows:
• The Overcurrent inputs (OC#[5:0]) are directly routed to both controllers. An overcurrent
event is recorded in both controller’s status registers.
The Port-Routing logic is implemented in the Suspend power well so that re-enumeration and remapping of the USB ports is not required following entering and exiting a system sleep state in
which the core power is turned off.
The ICH4 also allows the USB Debug Port traffic to be routed in and out of Port #0. When in this
mode, the EHC is the owner of Port #0.
5.17.8.2
Device Connects
Section 4.2 of the Enhanced Host Controller Interface (EHCI) for Universal Serial Bus
Specification describes the details of handling Device Connects. There are four general scenarios
that are summarized below.
1. Configure Flag = 0 and a USB Full-speed/Low-speed -only Device is connected
— In this case, the USB UHCI controller is the owner of the port both before and after the
connect occurs. The EHC (except for the port-routing logic) never sees the connect occur.
The UHCI driver handles the connection and initialization process.
2. Configure Flag = 0 and an USB High-speed-capable Device is connected
— In this case, the USB UHCI controller is the owner of the port both before and after the
connect occurs. The EHC (except for the port-routing logic) never sees the connect occur.
The UHCI driver handles the connection and initialization process. Since the USB UHCI
controller does not perform the high-speed chirp handshake, the device operates in
compatible mode.
3. Configure Flag = 1 and a USB Full-speed/Low-speed-only Device is connected
— In this case, the USB EHCI controller is the owner of the port before the connect occurs.
The EHCI driver handles the connection and performs the port reset. After the reset
process completes, the EHC hardware has cleared (not set) the Port Enable bit in the
EHC’s PORTSC register. The EHCI driver then writes a 1 to the Port Owner bit in the
same register, causing the USB UHCI controller to see a connect event and the EHC to see
an “electrical” disconnect event. The UHCI driver and hardware handle the connection
and initialization process from that point on. The EHCI driver and hardware handle the
perceived disconnect.
4. Configure Flag = 1 and an USB High-speed-capable Device is connected
— In this case, the USB EHCI controller is the owner of the port before, and remains the
owner after, the connect occurs. The EHCI driver handles the connection and performs the
port reset. After the reset process completes, the EHC hardware has set the Port Enable bit
in the EHC’s PORTSC register. The port is functional at this point. The USB UHCI
controller continues to see an unconnected port.
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Functional Description
5.17.8.3
Device Disconnects
Section 4.2 of the Enhanced Host Controller Interface (EHCI) for Universal Serial Bus
Specification describes the details of handling Device Connects. There are three general scenarios
that are summarized below.
1. Configure Flag = 0 and the device is disconnected
— In this case, the USB UHCI controller is the owner of the port both before and after the
disconnect occurs. The EHC (except for the port-routing logic) never sees a device
attached. The UHCI driver handles disconnection process.
2. Configure Flag = 1 and a USB Full-speed/Low-speed-capable Device is disconnected
— In this case, the USB UHCI controller is the owner of the port before the disconnect
occurs. The disconnect is reported by the USB UHCI controller and serviced by the
associated UHCI driver. The port-routing logic in the EHC cluster forces the Port Owner
bit to 0, indicating that the EHC owns the unconnected port.
3. Configure Flag = 1 and a USB High-speed-capable Device is disconnected
— In this case, the USB EHCI controller is the owner of the port before, and remains the
owner after, the disconnect occurs. The EHCI hardware and driver handle the
disconnection process. The USB UHCI controller never sees a device attached.
5.17.8.4
Effect of Resets on Port-Routing Logic
As mentioned above, the Port Routing logic is implemented in the Suspend power well so that reenumeration and re-mapping of the USB ports is not required following entering and exiting a
system sleep state in which the core power is turned off.
Reset Event
Suspend Well Reset
Effect on Port Owner Bits
cleared (0)
set (1)
Core Well Reset
no effect
no effect
D3-to-D0 Reset
no effect
no effect
cleared (0)
set (1)
HCRESET
5.17.9
Effect on Configure Flag
USB 2.0 Legacy Keyboard Operation
The ICH4 must support the possibility of a keyboard downstream from either a USB UHCI or a
USB EHCI port. The description of the legacy keyboard support is unchanged from USB UHCI
(See Section 5.16.8).
The EHC provides the basic ability to generate SMIs on an interrupt event, along with more
sophisticated control of the generation of SMIs.
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Functional Description
5.17.10
USB 2.0 EHCI Based Debug Port
The ICH4 supports the elimination of the legacy COM ports by providing the ability for new
debugger software to interact with devices on a USB EHCI port. High-level restrictions and
features are:
• Must be operational before USB EHCI drivers are loaded.
• Must work even when the port is disabled.
• Must work even though non-configured port is default-routed to the classic controller. Note
•
•
•
•
that the Debug Port can not be used to debug an issue that requires a classic USB device on
Port #0 using the UHCI drivers.
Must allow normal system USB EHCI traffic in a system that may only have one USB port.
Debug Port device (DPD) must be High-Speed capable and connect to a High-Speed port on
ICH4 systems.
Debug Port FIFO must always make forward progress (a bad status on USB is simply
presented back to software)
The Debug Port FIFO is only given one USB access per microframe
The Debug port facilitates OS and device driver debug. It allows the software to communicate with
an external console using a USB EHCI connection. Because the interface to this link does not go
through the normal USB EHCI stack, it allows communication with the external console during
cases where the OS is not loaded, the USB EHCI software is broken, or where the USB EHCI
software is being debugged. Specific features of this implementation of a debug port are:
•
•
•
•
5.17.10.1
Only works with an external USB 2.0 debug device (console)
Implemented for a specific port on the host controller
Operational anytime the port is not suspended AND the host controller is in D0 power state.
Capability is interrupted when port is driving USB RESET
Theory of Operation
There are two operational modes for the USB debug port:
• Mode 1 is when the USB port is in a disabled state from the viewpoint of a standard host
controller driver. In Mode 1, the Debug Port controller is required to generate a “keepalive”
packets less than 2 ms apart to keep the attached debug device from suspending. The keepalive
packet should be a standalone 32-bit SYNC field.
• Mode 2 is when the host controller is running (i.e., Host controller’s Run/Stop# bit is 1). In
Mode 2, the normal transmission of SOF packets will keep the debug device from suspending.
Behavioral Rules
1. In both modes 1 and 2, the Debug Port controller must check for software requested debug
transactions at least every 125 microseconds.
2. If the debug port is enabled by the debug driver, and the standard host controller driver resets
the USB port, USB debug transactions are held off for the duration of the reset and until after
the first SOF is sent.
3. If the standard host controller driver suspends the USB port, then USB debug transactions are
held off for the duration of the suspend/resume sequence and until after the first SOF is sent.
4. The ENABLED_CNT bit in the debug register space is independent of the similar port control
bit in the associated Port Status and Control register.
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Functional Description
Table 5-77 shows the debug port behavior related to the state of bits in the debug registers as well
as bits in the associated Port Status and Control register.
Table 5-77. Debug Port Behavior
OWNER_CNT
ENABLED_CT
Port
Enable
Run /
Stop
Suspend
0
X
X
X
X
Debug port is not being used.
Normal operation.
1
0
X
X
X
Debug port is not being used.
Normal operation.
1
1
0
0
X
Debug port in Mode 1. SYNC
keepalives sent plus debug traffic
X
Debug port in Mode 2. SOF (and
only SOF) is sent as keepalive.
Debug traffic is also sent. Note that
no other normal traffic is sent out
this port, because the port is not
enabled.
1
1
0
1
Debug Port Behavior
1
1
1
0
0
Illegal. Host controller driver should
never put controller into this state
(enabled, not running and not
suspended).
1
1
1
0
1
Port is suspended. No debug traffic
sent.
1
1
1
1
0
Debug port in Mode 2. Debug
traffic is interspersed with normal
traffic.
1
1
1
1
1
Port is suspended. No debug traffic
sent.
5.17.10.1.1OUT Transactions
An Out transaction sends data to the debug device. It can occur only when the following are true:
• The debug port is enabled
• The debug software sets the GO_CNT bit
• The WRITE_READ#_CNT bit is set
The sequence of the transaction is:
1. Software sets the appropriate values in the following bits:
— USB_ADDRESS_CNF
— USB_ENDPOINT_CNF
— DATA_BUFFER[63:0]
— TOKEN_PID_CNT[7:0]
— SEND_PID_CNT[15:8]
— DATA_LEN_CNT
— WRITE_READ#_CNT (note: this will always be 1 for OUT transactions)
— GO_CNT (note: this will always be 1 to initiate the transaction)
206
Intel® 82801DB ICH4 Datasheet
Functional Description
2. The debug port controller sends a token packet consisting of
— SYNC
— TOKEN_PID_CNT field
— USB_ADDRESS_CNT field
— USB_ENDPOINT_CNT field
— 5-bit CRC field
3. After sending the token packet, the debug port controller sends a data packet consisting of
— SYNC
— SEND_PID_CNT field
— The number of data bytes indicated in DATA_LEN_CNT from the DATA_BUFFER
— 16-bit CRC
Note: A DATA_LEN_CNT value of zero is valid in which case no data bytes would be
included in the packet.
4. After sending the data packet, the controller waits for a handshake response from the debug
device.
• If a handshake is received, the debug port controller:
— a. Places the received PID in the RECEIVED_PID_STS field
— b. Resets the ERROR_GOOD#_STS bit
— c. Sets the DONE_STS bit
• If no handshake PID is received, the debug port controller:
— a. Sets the EXCEPTION_STS field to 001b
— b. Sets the ERROR_GOOD#_STS bit
— c. Sets the DONE_STS bit
5.17.10.1.2 IN Transactions
An IN transaction receives data from the debug device. It can occur only when the following are
true:
• The debug port is enabled
• The debug software sets the GO_CNT bit
• The WRITE_READ#_CNT bit is reset
The sequence of the transaction is:
1. Software sets the appropriate values in the following bits:
— USB_ADDRESS_CNF
— USB_ENDPOINT_CNF
— TOKEN_PID_CNT[7:0]
— DATA_LEN_CNT
— WRITE_READ#_CNT (note: this will always be 0 for IN transactions)
— GO_CNT (note: this will always be 1 to initiate the transaction)
Intel® 82801DB ICH4 Datasheet
207
Functional Description
2. The debug port controller sends a token packet consisting of:
— SYNC
— TOKEN_PID_CNT field
— USB_ADDRESS_CNT field
— USB_ENDPOINT_CNT field
— 5-bit CRC field.
3. After sending the token packet, the debug port controller waits for a response from the debug
device.
If a response is received:
— The received PID is placed into the RECEIVED_PID_STS field
— Any subsequent bytes are placed into the DATA_BUFFER
— The DATA_LEN_CNT field is updated to show the number of bytes that were received
after the PID.
4. If valid packet was received from the device that was one byte in length (indicating it was a
handshake packet), then the debug port controller:
— Resets the ERROR_GOOD#_STS bit
— Sets the DONE_STS bit
5. If valid packet was received from the device that was more than one byte in length (indicating
it was a data packet), then the debug port controller:
— Transmits an ACK handshake packet
— Resets the ERROR_GOOD#_STS bit
— Sets the DONE_STS bit
6. If no valid packet is received, then the debug port controller:
— Sets the EXCEPTION_STS field to 001b
— Sets the ERROR_GOOD#_STS bit
— Sets the DONE_STS bit.
5.17.10.1.3 Debug Software
Enabling the Debug Port
There are two mutually exclusive conditions that debug software must address as part of its startup
processing:
• The EHCI has been initialized by system software
• The EHCI has not been initialized by system software
Debug software can determine the current “initialized” state of the EHCI by examining the
Configure Flag in the EHCI USB 2.0 Command Register. If this flag is set, then system software
has initialized the EHCI. Otherwise, the EHCI should not be considered initialized. Debug
software will initialize the debug port registers depending on the state the EHCI. However, before
this can be accomplished, debug software must determine which root USB port is designated as the
debug port.
208
Intel® 82801DB ICH4 Datasheet
Functional Description
Determining the Debug Port
Debug software can easily determine which USB root port has been designated as the debug port
by examining bits 20:23 of the EHCI Host controller Structural Parameters register. This 4-bit field
represents the numeric value assigned to the debug port (i.e., 0000=port 0).
Debug Software Startup with Non-Initialized EHCI
Debug software can attempt to use the debug port if after setting the OWNER_CNT bit, the
Current Connect Status bit in the appropriate (See Determining the Debug Port) PORTSC register
is set. If the Current Connect Status bit is not set, then debug software may choose to terminate or it
may choose to wait until a device is connected.
If a device is connected to the port, then debug software must reset/enable the port. Debug software
does this by setting and then clearing the Port Reset bit the PORTSC register. To guarantee a
successful reset, debug software should wait at least 50 ms before clearing the Port Reset bit. Due
to possible delays, this bit may not change to 0 immediately; reset is complete when this bit reads
as 0. Software must not continue until this bit reads 0.
If a high-speed device is attached, the EHCI will automatically set the Port Enabled/Disabled bit in
the PORTSC register and the debug software can proceed. Debug software should set the
ENABLED_CNT bit in the Debug Port Control/Status register, and then reset (clear) the Port
Enabled/Disabled bit in the PORTSC register (so that the system host controller driver does not see
an enabled port when it is first loaded).
Debug Software Startup with Initialized EHCI
Debug software can attempt to use the debug port if the Current Connect Status bit in the
appropriate (See Determining the Debug Port) PORTSC register is set. If the Current Connect
Status bit is not set, then debug software may choose to terminate or it may choose to wait until a
device is connected.
If a device is connected, then debug software must set the OWNER_CNT bit and then the
ENABLED_CNT bit in the Debug Port Control/Status register.
Determining Debug Peripheral Presence
After enabling the debug port functionality, debug software can determine if a debug peripheral is
attached by attempting to send data to the debug peripheral. If all attempts result in an error
(Exception bits in the Debug Port Control/Status register indicates a Transaction Error), then the
attached device is not a debug peripheral. If the debug port peripheral is not present, then debug
software may choose to terminate or it may choose to wait until a debug peripheral is connected.
Intel® 82801DB ICH4 Datasheet
209
Functional Description
5.18
SMBus Controller Functional Description (D31:F3)
The ICH4 provides an SMBus 2.0 compliant Host controller as well as an SMBus Slave Interface.
The Host controller provides a mechanism for the processor to initiate communications with
SMBus peripherals (slaves). The ICH4 is also capable of operating in a mode in which it can
communicate with I2C compatible devices.
The ICH4 can perform SMBus messages with either packet error checking (PEC) enabled or
disabled. The actual PEC calculation and checking is performed in hardware by the ICH4.
The Slave Interface allows an external master to read from or write to the ICH4. Write cycles can
be used to cause certain events or pass messages, and the read cycles can be used to determine the
state of various status bits. The ICH4’s internal Host controller cannot access the ICH4’s internal
Slave Interface.
The ICH4 SMBus logic exists in Device 31:Function 3 configuration space, and consists of a
transmit data path and host controller. The transmit data path provides the data flow logic needed to
implement the seven different SMBus command protocols and is controlled by the host controller.
The ICH4 SMBus controller logic is clocked by RTC clock.
The SMBus Address Resolution Protocol (ARP) is supported by using the existing host controller
commands through software, except for the new Host Notify command (which is actually a
received message).
The programming model of the host controller is combined into two portions: a PCI configuration
portion and a system I/O mapped portion. All static configuration (e.g., the I/O base address) is
done via the PCI configuration space. Real-time programming of the Host interface is done in
system I/O space.
5.18.1
Host Controller
The SMBus Host controller is used to send commands to other SMBus slave devices. Software sets
up the host controller with an address, command, and, for writes, data and optional PEC; and then
tells the controller to start. When the controller has finished transmitting data on writes, or
receiving data on reads, it will generate an SMI# or interrupt, if enabled.
The host controller supports eight command protocols of the SMBus interface (see System
Management Bus Specification): Quick Command, Send Byte, Receive Byte, Write Byte/Word,
Read Byte/Word, Process Call, Block Read/Write, and Host Notify.
The SMBus Host controller requires that the various data and command fields be setup for the type
of command to be sent. When software sets the START bit, the SMBus Host controller performs
the requested transaction and interrupts the processor (or generate an SMI#) when the transaction is
completed. Once a START command has been issued, the values of the “active registers” (Host
Control, Host Command, Transmit Slave Address, Data 0, Data 1) should not be changed or read
until the interrupt status bit (INTR) has been set (indicating the completion of the command). Any
register values needed for computation purposes should be saved prior to issuing of a new
command, as the SMBus Host controller will update all registers while completing the new
command.
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Intel® 82801DB ICH4 Datasheet
Functional Description
Using the SMB Host controller to send commands to the ICH4’s SMB slave port is supported. The
ICH4 supports slave functionality, including the Host Notify protocol, on the SMLink pins.
Therefore, to be fully compliant with the SMBus 2.0 specification (which requires the Host Notify
protocol), the SMLink and SMBus signals should be tied together externally.
5.18.1.1
Command Protocols
In all of the following commands, the Host Status Register (offset 00h) is used to determine the
progress of the command. While the command is in operation, the HOST_BUSY bit is set. If the
command completes successfully, the INTR bit will be set in the Host Status Register. If the device
does not respond with an acknowledge, and the transaction times out, the DEV_ERR bit is set. If
software sets the KILL bit in the Host Control Register while the command is running, the
transaction will stop and the FAILED bit will be set.
Quick Command
When programmed for a Quick Command, the Transmit Slave Address Register is sent. The PEC
byte is never appended to the Quick Protocol. Software should force the PEC_EN bit to 0 when
performing the Quick Command. Software must force the I2C_EN bit to 0 when running this
command.The format of the protocol is shown in Table 5-78.
Table 5-78. Quick Protocol
Bit
Description
1
Start Condition
2–8
Slave Address - 7 bits
9
Read / Write Direction
10
Acknowledge from slave
11
Stop
Send Byte / Receive Byte
For the Send Byte command, the Transmit Slave Address and Device Command Registers are sent
For the Receive Byte command, the Transmit Slave Address Register is sent. The data received is
stored in the DATA0 register. Software must force the I2C_EN bit to 0 when running this
command.
The Receive Byte is similar to a Send Byte, the only difference is the direction of data transfer. The
format of the protocol is shown in Table 5-79. and Table 5-80
Table 5-79. Send / Receive Byte Protocol without PEC
Send Byte Protocol
Bit
1
2–8
9
Description
Start
Slave Address - 7 bits
Write
Receive Byte Protocol
Bit
1
2–8
9
10
Acknowledge from slave
10
11–18
Command code - 8 bits
11–18
Description
Start
Slave Address - 7 bits
Read
Acknowledge from slave
Data byte from slave
19
Acknowledge from slave
19
NOT Acknowledge
20
Stop
20
Stop
Intel® 82801DB ICH4 Datasheet
211
Functional Description
Table 5-80. Send/Receive Byte Protocol with PEC
Send Byte Protocol
Bit
1
2–8
9
Description
Start
Receive Byte Protocol
Bit
1
Slave Address - 7 bits
Write
Start
2–8
9
10
Acknowledge from slave
10
Command code - 8 bits
11–18
19
Acknowledge from slave
19
PEC
Slave Address - 7 bits
Read
11–18
20–27
Description
20–27
Acknowledge from slave
Data byte from slave
Acknowledge
PEC from slave
28
Acknowledge from slave
28
Not Acknowledge
29
Stop
29
Stop
Write Byte/Word
The first byte of a Write Byte/Word access is the command code. The next 1 or 2 bytes are the data
to be written. When programmed for a Write Byte/Word command, the Transmit Slave Address,
Device Command, and Data0 Registers are sent. In addition, the Data1 Register is sent on a Write
Word command. Software must force the I2C_EN bit to 0 when running this command. The format
of the protocol is shown in Table 5-81 and Table 5-82.
Table 5-81. Write Byte/Word Protocol without PEC
Write Byte Protocol
Bit
1
2–8
9
Start
Slave Address - 7 bits
Write
Bit
1
2–8
Description
Start
Slave Address - 7 bits
9
Write
10
Acknowledge from slave
10
Acknowledge from slave
11–18
Command code - 8 bits
11–18
Command code - 8 bits
19
Acknowledge from slave
19
Acknowledge from slave
20–27
212
Description
Write Word Protocol
Data Byte - 8 bits
28
Acknowledge from Slave
29
Stop
20–27
28
29–36
Data Byte Low - 8 bits
Acknowledge from Slave
Data Byte High - 8 bits
37
Acknowledge from slave
38
Stop
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-82. Write Byte/Word Protocol with PEC
Write Byte Protocol
Bit
1
2–8
9
Description
Start
Slave Address - 7 bits
Write
Write Word Protocol
Bit
1
2–8
9
Description
Start
Slave Address - 7 bits
Write
10
Acknowledge from slave
10
Acknowledge from slave
11–18
Command code - 8 bits
11–18
Command code - 8 bits
19
Acknowledge from slave
19
Acknowledge from slave
20–27
28
29–36
Data Byte - 8 bits
Acknowledge from Slave
PEC
37
Acknowledge from Slave
38
Stop
20–27
28
29–36
37
38–45
Data Byte Low - 8 bits
Acknowledge from Slave
Data Byte High - 8 bits
Acknowledge from slave
PEC
46
Acknowledge from slave
47
Stop
Read Byte/Word
Reading data is slightly more complicated than writing data. First the ICH4 must write a command
to the slave device. Then it must follow that command with a repeated start condition to denote a
read from that device’s address. The slave then returns 1 or 2 bytes of data. Software must force the
I2C_EN bit to 0 when running this command.
When programmed for the read byte/word command, the Transmit Slave Address and Device
Command Registers are sent. Data is received into the DATA0 on the read byte, and the DAT0 and
DATA1 registers on the read word. The format of the protocol is shown in Table 5-83 and
Table 5-84.
Intel® 82801DB ICH4 Datasheet
213
Functional Description
Table 5-83. Read Byte/Word Protocol without PEC
Read Byte Protocol
Bit
1
2–8
Description
Start
Read Word Protocol
Bit
1
Slave Address - 7 bits
2–8
Description
Start
Slave Address - 7 bits
9
Write
9
Write
10
Acknowledge from slave
10
Acknowledge from slave
11–18
Command code - 8 bits
11–18
Command code - 8 bits
19
Acknowledge from slave
19
Acknowledge from slave
20
21–27
Repeated Start
Slave Address - 7 bits
20
21–27
Repeated Start
Slave Address - 7 bits
28
Read
28
Read
29
Acknowledge from slave
29
Acknowledge from slave
30–37
Data from slave - 8 bits
30–37
38
NOT acknowledge
39
Stop
38
39–46
Data Byte Low from slave - 8 bits
Acknowledge
Data Byte High from slave - 8 bits
47
NOT acknowledge
48
Stop
Table 5-84. Read Byte/Word Protocol with PEC
Read Byte Protocol
Bit
1
2–8
9
Start
Slave Address - 7 bits
Write
Bit
1
2–8
Description
Start
Slave Address - 7 bits
9
Write
10
Acknowledge from slave
10
Acknowledge from slave
11–18
Command code - 8 bits
11–18
Command code - 8 bits
19
Acknowledge from slave
19
Acknowledge from slave
20
Repeated Start
20
Repeated Start
21–27
Slave Address - 7 bits
21–27
Slave Address - 7 bits
28
Read
28
Read
29
Acknowledge from slave
29
Acknowledge from slave
30–37
Data from slave - 8 bits
30–37
38
39–46
214
Description
Read Word Protocol
Acknowledge
PEC from slave
47
NOT Acknowledge
48
Stop
38
39–46
47
48–55
Data Byte Low from slave - 8 bits
Acknowledge
Data Byte High from slave - 8 bits
Acknowledge
PEC from slave
56
NOT acknowledge
57
Stop
Intel® 82801DB ICH4 Datasheet
Functional Description
Process Call
The process call is so named because a command sends data and waits for the slave to return a
value dependent on that data. The protocol is simply a Write Word followed by a Read Word, but
without a second command or stop condition.
When programmed for the Process Call command, the ICH4 transmits the Transmit Slave Address,
Host Command, DATA0 and DATA1 registers. Data received from the device is stored in the
DATA0 and DATA1 registers. The Process Call command with I2C_EN set and the PEC_EN bit
set produces undefined results. Software must force either I2C_EN or PEC_EN to 0 when running
this command. The format of the protocol is shown in Table 5-85 and Table 5-86.
Note:
For process call command, the value written into bit 0 of the Transmit Slave Address Register
(SMB I/O register, offset 04h) needs to be 0.
Table 5-85. Process Call Protocol without PEC
Bit
1
2–8
Description
Start
Slave Address - 7 bits
9
Write
10
Acknowledge from Slave
11–18
(Skip This step if I2C_EN bit set)
Command code - 8 bits
19
(Skip This step if I2C_EN bit set)
Acknowledge from slave
20–27
28
29–36
Data byte Low - 8 bits
Acknowledge from slave
Data Byte High - 8 bits
37
Acknowledge from slave
38
Repeated Start
39–45
46
47
48–55
56
57–64
Slave Address - 7 bits
Read
Acknowledge from slave
Data Byte Low from slave - 8 bits
Acknowledge
Data Byte High from slave - 8 bits
65
NOT acknowledge
66
Stop
Intel® 82801DB ICH4 Datasheet
215
Functional Description
Table 5-86. Process Call Protocol with PEC
Bit
1
2–8
Description
Start
Slave Address - 7 bits
9
Write
10
Acknowledge from Slave
11–18
Command code - 8 bits
19
Acknowledge from slave
20–27
28
29–36
Data byte Low - 8 bits
Acknowledge from slave
Data Byte High - 8 bits
37
Acknowledge from slave
38
Repeated Start
39–45
Slave Address - 7 bits
46
Read
47
Acknowledge from slave
48–55
56
57–64
65
66–73
Data Byte Low from slave - 8 bits
Acknowledge
Data Byte High from slave - 8 bits
Acknowledge
PEC from slave
74
NOT acknowledge
75
Stop
Block Read/Write
The ICH4 contains a 32-byte buffer for read and write data which can be enabled by setting bit 1 of
the Auxiliary Control register at offset 0Dh in I/O space, as opposed to a single byte of buffering.
This 32-byte buffer is filled with write data before transmission, and filled with read data on
reception. In the ICH4, the interrupt is generated only after a transmission or reception of 32 bytes,
or when the entire byte count has been transmitted/received.
This requires the ICH4 to check the byte count field. Currently, the byte count field is transmitted
but ignored by the hardware as software will end the transfer after all bytes it cares about have been
sent or received.
For a Block Write software must either force the I2C_EN bit or both the PEC_EN and AAC bits to
0 when running this command.
SMBus mode: The block write begins with a slave address and a write condition. After the
command code the ICH4 issues a byte count describing how many more bytes will follow in the
message. If a slave had 20 bytes to send, the first byte would be the number 20 (14h), followed by
20 bytes of data. The byte count may not be 0. A Block Read or Write is allowed to transfer a
maximum of 32 data bytes.
216
Intel® 82801DB ICH4 Datasheet
Functional Description
When programmed for a block write command, the Transmit Slave Address, Device Command,
and Data0 (count) registers are sent. Data is then sent from the Block Data Byte register; the total
data sent being the value stored in the Data0 Register. On block read commands, the first byte
received is stored in the Data0 register, and the remaining bytes are stored in the Block Data Byte
register.
The format of the Block Read/Write protocol is shown in Table 5-87 and Table 5-88.
Note:
For Block Write, if the I2C_EN bit is set, the format of the command changes slightly. The ICH4
will still send the number of bytes (on writes) or receive the number of bytes (on reads) indicated in
the DATA0 register. However, it will not send the contents of the DATA0 register as part of the
message.
l
Table 5-87. Block Read/Write Protocol without PEC
Block Write Protocol
Bit
1
2–8
Description
Start
Slave Address - 7 bits
Block Read Protocol
Bit
1
2–8
Description
Start
Slave Address - 7 bits
9
Write
9
Write
10
Acknowledge from slave
10
Acknowledge from slave
11–18
Command code - 8 bits
11–18
Command code - 8 bits
19
Acknowledge from slave
19
Acknowledge from slave
20–27
28
29–36
37
38–45
Byte Count - 8 bits
Acknowledge from Slave
20
21–27
Repeated Start
Slave Address - 7 bits
Data Byte 1 - 8 bits
28
Read
Acknowledge from Slave
29
Acknowledge from slave
Data Byte 2 - 8 bits
30–37
46
Acknowledge from slave
...
Data Bytes / Slave
Acknowledges...
39–46
...
Data Byte N - 8 bits
47
...
Acknowledge from Slave
...
Stop
Intel® 82801DB ICH4 Datasheet
38
48–55
Byte Count from slave - 8 bits
Acknowledge
Data Byte 1 from slave - 8 bits
Acknowledge
Data Byte 2 from slave - 8 bits
56
Acknowledge
...
Data Bytes from slave/Acknowledge
...
Data Byte N from slave - 8 bits
...
NOT Acknowledge
...
Stop
217
Functional Description
Table 5-88. Block Read/Write Protocol with PEC
Block Write Protocol
Bit
1
2–8
Description
Start
Slave Address - 7 bits
Block Read Protocol
Bit
1
2–8
Description
Start
Slave Address - 7 bits
9
Write
9
Write
10
Acknowledge from slave
10
Acknowledge from slave
11–18
Command code - 8 bits
11–18
Command code - 8 bits
19
Acknowledge from slave
19
Acknowledge from slave
20–27
Byte Count - 8 bits
(Skip this step if I2C_EN bit set)
20
Repeated Start
28
Acknowledge from Slave
(Skip this step if I2C_EN bit set)
21–27
29–36
37
38–45
Data Byte 1 - 8 bits
Acknowledge from Slave
Data Byte 2 - 8 bits
46
Acknowledge from slave
...
Data Bytes / Slave
Acknowledges...
Slave Address - 7 bits
28
Read
29
Acknowledge from slave
30–37
38
39–46
47
Byte Count from slave - 8 bits
Acknowledge
Data Byte 1 from slave - 8 bits
...
Data Byte N - 8 bits
...
Acknowledge from Slave
...
PEC - 8 bits
56
Acknowledge
...
Acknowledge from Slave
...
Data Bytes from slave/Acknowledge
...
Stop
48–55
Acknowledge
Data Byte 2 from slave - 8 bits
...
Data Byte N from slave - 8 bits
...
Acknowledge
...
PEC from slave - 8 bits
...
NOT Acknowledge
...
Stop
I2C Read
This command allows the ICH4 to perform block reads to certain I2C devices (e.g., serial
E2PROMs) in 10-bit addressing mode only. The SMBus Block Read sends both the 7-bit address,
as well as the Command field. This command field could be used as the extended 10-bit address for
accessing I2C devices that use 10-bit addressing.
However, this does not allow access to devices using the I2C “Combined Format” that has data
bytes after the address. Typically these data bytes correspond to an offset (address) within the serial
memory chips.
Note:
218
This command is supported independent of the setting of the I2C_EN bit. The I2C Read command
with the PEC_EN bit set produces undefined results. Software must force both the PEC_EN and
AAC bit to 0 when running this command.
Intel® 82801DB ICH4 Datasheet
Functional Description
For I2C Read command, the value written into bit 0 of the Transmit Slave Address Register (SMB
I/O register, offset 04h) needs to be 0. The format that is used for the new command is shown in
Table 5-89.
Table 5-89. I2C Block Read
Bit
1
2–8
9
Description
Start
Slave Address - 7 bits
Write
10
Acknowledge from slave
11–18
Command code - 8 bits
19
20–27
28
29–36
Acknowledge from slave
Send DATA0 register
Acknowledge from slave
Send DATA1 register
37
Acknowledge from slave
38
Repeated start
39–45
46
47
48–55
56
57–64
Slave Address - 7 bits
Read
Acknowledge from slave
Data byte from slave
Acknowledge
Data byte 2 from slave - 8 bits
65
Acknowledge
—
Data bytes from slave / Acknowledge
—
Data byte N from slave - 8 bits
—
NOT Acknowledge
—
Stop
The ICH4 will continue reading data from the peripheral until the NAK is received.
5.18.1.2
I2C Behavior
When the I2C_EN bit is set, the ICH4 SMBus logic will instead be set to communicate with I2C
devices. This forces the following changes:
• The Process Call command will skip the Command code (and its associated acknowledge)
• The Block Write command will skip sending the Byte Count (DATA0)
In addition, the ICH4 will support the new I2C Read command. This is independent of the I2C_EN
bit.
Note:
When operating in I2C mode the ICH4 will not use the 32-byte buffer for block commands.
Intel® 82801DB ICH4 Datasheet
219
Functional Description
5.18.1.3
Heartbeat for Use with the External LAN Controller
This method allows the ICH4 to send messages to an external LAN controller when the processor
is otherwise unable to do so. It uses the SMLINK interface between the ICH4 and the external
LAN controller. The actual Heartbeat message is a Block Write. Only 8 bytes are sent.
5.18.2
Bus Arbitration
Several masters may attempt to get on the bus at the same time by driving the SMBDATA line low
to signal a start condition. The ICH4 must continuously monitor the SMBDATA line. When the
ICH4 is attempting to drive the bus to a 1 by letting go of the SMBDATA line, and it samples
SMBDATA low, some other master is driving the bus and the ICH4 must stop transferring data.
If the ICH4 sees that it has lost arbitration, the condition is called a collision. The ICH4 will set the
BUS_ERR bit in the Host Status Register, and if enabled, generate an interrupt or SMI#. The
processor is responsible for restarting the transaction.
When the ICH4 is a SMBus master, it will drive the clock. When the ICH4 is sending address or
command as an SMBus master, or data bytes as a master on writes, it will drive data relative to the
clock it is also driving. It will not start toggling the clock until the start or stop condition meets
proper setup and hold time. The ICH4 will also guarantee minimum time between SMBus
transactions as a master.
Note:
The ICH4 supports the same arbitration protocol for both the SMBus and the System Management
(SMLINK) interfaces.
5.18.3
Bus Timing
5.18.3.1
Clock Stretching
Some devices may not be able to handle their clock toggling at the rate that the ICH4 as an SMBus
master would like. They have the capability of stretching the low time of the clock. When the ICH4
attempts to release the clock (allowing the clock to go high), the clock will remain low for an
extended period of time.
The ICH4 must monitor the SMBus clock line after it releases the bus to determine whether to
enable the counter for the high time of the clock. While the bus is still low, the high time counter
must not be enabled. Similarly, the low period of the clock can be stretched by an SMBus master if
it is not ready to send or receive data.
5.18.3.2
Bus Time Out (ICH4 as SMBus Master)
If there is an error in the transaction such that an SMBus device does not signal an acknowledge or
holds the clock lower than the allowed time-out time, the transaction will time out. The ICH4
discards the cycle and sets the DEV_ERR bit. The time-out minimum is 25 ms. The time-out
counter inside the ICH4 will start after the last bit of data is transferred by the ICH4 and it is
waiting for a response. The 25 ms is a count of 800 RTC clocks.
220
Intel® 82801DB ICH4 Datasheet
Functional Description
5.18.4
Interrupts / SMI#
The ICH4 SMBus controller uses PIRQB# as its interrupt pin. However, the system can
alternatively be set up to generate SMI# instead of an interrupt, by setting the SMBUS_SMI_EN
bit.
Table 5-91 and Table 5-92 specify how the various enable bits in the SMBus function control the
generation of the interrupt, Host and Slave SMI, and Wake internal signals. The rows in the tables
are additive, which means that if more than one row is true for a particular scenario then the Results
for all of the activated rows will occur.
Table 5-90. Enable for SMBALERT#
Event
INTREN (Host
Control I/O
Register, Offset
02h, Bit 0)
SMB_SMI_EN
(Host Configuration Register,
D31:F3:Offset 40h,
Bit 1)
SMBALERT_DIS
(Slave Command I/O
Register, Offset 11h,
Bit 2)
X
X
X
Wake generated
X
1
0
Slave SMI# generated
(SMBUS_SMI_STS)
1
0
0
Interrupt generated
SMBALERT#
asserted low
(always
reported in
Host Status
Register, Bit 5)
Result
Table 5-91. Enables for SMBus Slave Write and SMBus Host Events
INTREN (Host Control
I/O Register, Offset
02h, Bit 0)
SMB_SMI_EN (Host
Configuration
Register,
D31:F3:Offset 40h,
Bit1)
Slave Write to Wake/
SMI# Command
X
X
Wake generated when asleep.
Slave SMI# generated when
awake (SMBUS_SMI_STS).
Slave Write to
SMLINK_SLAVE_SMI
Command
X
X
Slave SMI# generated when in
the S0 state (SMBUS_SMI_STS)
0
X
None
1
0
Interrupt generated
1
1
Host SMI# generated
Event
Any combination of
Host Status Register
[4:1] asserted
Event
Table 5-92. Enables for the Host Notify Command
HOST_NOTIFY_INTREN
(Slave Control I/O
Register, Offset 11h, bit 0)
SMB_SMI_EN (Host
Configuration Register,
D31:F3:Off40h, Bit 1)
HOST_NOTIFY_WKEN
(Slave Control I/O
Register, Offset 11h, bit 1)
Result
0
X
0
None
X
X
1
Wake generated
1
0
X
Interrupt generated
1
1
X
Slave SMI#
generated
(SMBUS_SMI_STS)
Intel® 82801DB ICH4 Datasheet
221
Functional Description
5.18.5
SMBALERT#
SMBALERT# is multiplexed with GPIO[11]. When enable and the signal is asserted, The ICH4
can generate an interrupt, an SMI# or a wake event from S1–S5.
Note:
5.18.6
Any event on SMBALERT# (regardless whether it is programmed as a GPIO or not), causes the
event message to be sent in “heartbeat mode.”
SMBus CRC Generation and Checking
If the AAC bit is set in the Auxiliary Control register, the ICH4 automatically calculates and drives
CRC at the end of the transmitted packet for write cycles and checks the CRC for read cycles. It
will not transmit the contents of the PEC register for CRC. The PEC bit must not be set in the Host
Control register if this bit is set, or unspecified behavior will result.
If the read cycle results in a CRC error, the DEV_ERR bit and the CRCE bit in the Auxiliary Status
register at offset 0Ch will be set.
5.18.7
SMBus Slave Interface
The ICH4’s SMBus Slave interface is accessed via the SMLINK[1:0] signals. The SMBus slave
logic does not generate or handle receiving the PEC byte and only acts as a Legacy Alerting
Protocol (Alert on LAN) device. The slave interface allows the ICH4 to decode cycles, and allows
an external microcontroller to perform specific actions. Key features and capabilities include:
• Supports decode of three types of messages: Byte Write, Byte Read, and Host Notify
• Receive Slave Address register: This is the address that the ICH4 decodes. A default value is
provided so that the slave interface can be used without the processor having to program this
register.
• Receive Slave Data register in the SMBus I/O space that includes the data written by the
external microcontroller
• Registers that the external microcontroller can read to get the state of the ICH4. See Table 5-97
• Status bits to indicate that the SMLink/SMBus slave logic caused an interrupt or SMI# due to
the reception of a message that matched the slave address.
— Bit 0 of the Slave Status Register for the Host Notify command
— Bit 16 of the SMI Status Register (Section 9.8.3.10) for all others
If a master leaves the clock and data bits of the SMLink interface at 1 for 50 µs or more in the
middle of a cycle, the ICH4 slave logic’s behavior is undefined. This is interpreted as an
unexpected idle and should be avoided when performing management activities to the slave logic.
Note:
222
When an external microcontroller accesses the SMBus Slave Interface over the SMLink a
translation in the address is needed to accommodate the least significant bit used for read/write
control. For example, if the ICH4 slave address (RCV_SLVA) is left at 44h (default), the external
microcontroller would use an address of 88h/89h (write/read).
Intel® 82801DB ICH4 Datasheet
Functional Description
5.18.7.1
Format of Slave Write Cycle
The external master performs Byte Write commands to the ICH4 SMBus Slave interface. The
“Command” field (bits 11–18) indicate which register is being accessed. The Data field
(bits 20–27) indicate the value that should be written to that register.
The Write Cycle format is shown in Table 5-93. Table 5-94 provides the values associated with the
registers.
Table 5-93. Slave Write Cycle Format
Bits
Description
1
2–8
9
10
11–18
19
20–27
Driven by
Comment
Start Condition
External Microcontroller
Slave Address - 7 bits
External Microcontroller
Must match value in Receive Slave Address
register
Write
External Microcontroller
Always 0
®
ACK
Intel ICH4
Command
External Microcontroller
ACK
ICH4
Register Data
External Microcontroller
28
ACK
ICH4
29
Stop
External Microcontroller
This field indicates which register will be
accessed.
See Table 5-94 below for the register definitions
See Table 5-94 below for the register definitions
Table 5-94. Slave Write Registers
Register
0
1–3
Function
Command Register. See Table 5-95 for legal values written to this register.
Reserved
4
Data Message Byte 0
5
Data Message Byte 1
6–7
8
9–FFh
Reserved
Frequency Straps will be written on bits 3:0. Bits 7:4 should be 0, but will be ignored.
Reserved
NOTE: The external microcontroller is responsible to make sure that it does not update the contents of the data
byte registers until they have been read by the system processor. The ICH4 will overwrite the old value
with any new value received. A race condition is possible where the new value is being written to the
register just at the time it is being read. ICH4 will not attempt to cover this race condition
(i.e., unpredictable results in this case).
Intel® 82801DB ICH4 Datasheet
223
Functional Description
.
Table 5-95. Command Types
Command
Type
0
Reserved
1
WAKE/SMI#: Wake system if it is not already awake. If system is already awake, then an
SMI# will be generated.
NOTE: The SMB_WAK_STS bit will be set by this command, even if the system is already
awake. The SMI handler should then clear this bit.
2
Unconditional Powerdown: This command sets the PWRBTNOR_STS bit, and has the
same effect as the Powerbutton Override occurring.
3
HARD RESET WITHOUT CYCLING: The will cause a hard reset of the system (does not
include cycling of the power supply). This is equivalent to a write to the CF9h register with
bits 2:1 set to 1, but bit 3 set to 0.
4
HARD RESET SYSTEM: The will cause a hard reset of the system (including cycling of the
power supply). This is equivalent to a write to the CF9h register with bits 3:1 set to 1.
5
Disable the TCO Messages: This command will disable the Intel® ICH4 from sending
Heartbeat and Event messages (as described in Section 5.13.2). Once this command has
been executed, Heartbeat and Event message reporting can only be re-enabled by
assertion and deassertion of the RSMRST# signal.
6
WD RELOAD: Reload watchdog timer.
7
Reserved
8
SMLINK_SLV_SMI: When ICH4 detects this command type while in the S0 state, it sets the
SMLINK_SLV_SMI_STS bit (see Section 9.9.7). This command should only be used if the
system is in an S0 state. If the message is received during S1–S5 states, the ICH4
acknowledges it, but the SMLINK_SLV_SMI_STS bit does not get set.
NOTE: It is possible that the system transitions out of the S0 state at the same time that the
SMLINK_SLV_SMI command is received. In this case, the SMLINK_SLV_SMI_STS
bit may get set but not serviced before the system goes to sleep. Once the system
returns to S0, the SMI associated with this bit would then be generated. Software
must be able to handle this scenario.
9–FFh
5.18.7.2
Description
Reserved
Format of Read Command
The external master performs Byte Read commands to the ICH4 SMBus Slave interface. The
“Command” field (bits 11–18) indicate which register is being accessed. The Data field (bits 3037) contain the value that should be read from that register. Table 5-96 shows the Read Cycle
format. Table 5-97 shows the register mapping for the data byte.
224
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-96. Read Cycle Format
Bit
1
2–8
9
Description
Driven by:
Comment:
Start
External Microcontroller
Slave Address – 7 bits
External Microcontroller
Must match value in Receive Slave Address
register
Write
External Microcontroller
Always 0
®
ACK
Intel ICH4
Command code – 8 bits
External Microcontroller
19
ACK
ICH4
20
Repeated Start
External Microcontroller
Slave Address - 7 bits
External Microcontroller
Must match value in Receive Slave Address
register
28
Read
External Microcontroller
Always 1
29
ACK
ICH4
30–37
Data Byte
ICH4
38
NOT ACK
External Microcontroller
39
Stop
External Microcontroller
10
11–18
21–27
Indicates which register is being accessed.
See Table 5-97.
Value depends on register being accessed.
See Table 5-97.
Table 5-97. Data Values for Slave Read Registers (Sheet 1 of 2)
Register
Bits
0
7:0
Reserved.
1
2:0
System Power State
• 000 = S0
• 001 = S1
• 010 = Reserved
• 011 = S3
• 100 = S4
• 101 = S5
• 110 = Reserved
• 111 = Reserved
1
7:3
Reserved
2
3:0
Frequency Strap Register
2
7:4
Reserved
3
5:0
Watchdog Timer current value
3
7:6
Reserved
4
0
1 = The Intruder Detect (INTRD_DET) bit is set. This indicates that the system cover has
probably been opened.
4
1
1 = BTI Temperature Event occurred. This bit will be set if the Intel® ICH4’s THRM# input
signal is active. Need to take after polarity control.
4
2
Boot-Status. This bit will be 1 when the processor does not fetch the first instruction.
Intel® 82801DB ICH4 Datasheet
Description
225
Functional Description
Table 5-97. Data Values for Slave Read Registers (Sheet 2 of 2)
Register
Bits
4
3
4
6:4
Description
This bit will be set after the TCO timer times out a second time (Both TIMEOUT and
SECOND_TO_STS bits set).
Reserved.
4
7
The bit will reflect the state of the GPI[11]/SMBALERT# signal, and will depend on the
GP_INV[11] bit. It does not matter if the pin is configured as GPI[11] or SMBALERT#.
• If the GP_INV[11] bit is 1 then the value of register 4 bit 7 will equal the level of the
GPI[11]/SMBALERT# pin (high = 1, low = 0).
• If the GP_INV[11] bit is 0 then the value of register 4 bit 7 will equal the inverse of the
level of the GPI[11]/SMBALERT# pin (high = 1, low = 0).
5
0
Unprogrammed FWH bit. This bit will be 1 to indicate that the first BIOS fetch returned FFh,
which indicates that the FWH is probably blank.
5
1
Reserved
5
2
CPU Power Failure Status: 1 if the CPUPWR_FLR bit in the GEN_PMCON_2 register is
set.
5
7:3
Reserved
6
7:0
Contents of the Message 1 register. See Section 9.9.9.
7
7:0
Contents of the Message 2 register. See Section 9.9.9.
8
7:0
Contents of the WDSTATUS register. See Section 9.9.10.
9–FFh
7:0
Reserved
5.18.7.2.1 Behavioral Notes
According to SMBus protocol, Read and Write messages always begin with a Start bit–Address–
Write bit sequence. When the ICH4 detects that the address matches the value in the Receive Slave
Address register, it will assume that the protocol is always followed and ignore the Write bit (bit 9)
and signal an Acknowledge during bit 10 (See Table 5-93 and Table 5-96). In other words, if a
Start–Address–Read occurs (which is illegal for SMBus Read or Write protocol) and the address
matches the ICH4’s Slave Address, the ICH4 will still grab the cycle.
Also according to SMBus protocol, a Read cycle contains a Repeated Start–Address–Read
sequence beginning at bit 20 (See Table 5-96). Once again, if the Address matches the ICH4’s
Receive Slave Address, it will assume that the protocol is followed, ignore bit 28, and proceed with
the Slave Read cycle.
Note:
5.18.7.3
An external microcontroller must not attempt to access the ICH4’s SMBus Slave logic until at least
1 second after both RTCRST# and RSMRST# are deasserted (high).
Format of Host Notify Command
The ICH4 tracks and responds to the standard Host Notify command as specified in the SMBus 2.0
specification. The host address for this command is fixed to 0001000b. If the ICH4 already has
data for a previously-received host notify command which has not been serviced yet by the host
software (as indicated by the HOST_NOTIFY_STS bit), then it will NACK following the host
address byte of the protocol. This allows the host to communicate non-acceptance to the master and
retain the host notify address and data values for the previous cycle until host software completely
services the interrupt. Table 5-98 shows the Host Notify format.
Note:
226
Host software must always clear the HOST_NOTIFY_STS bit after completing any necessary
reads of the address and data registers.
Intel® 82801DB ICH4 Datasheet
Functional Description
Table 5-98. Host Notify Format
Bit
1
2–8
9
10
Driven by
Comment
Start
External Master
SMB Host Address – 7 bits
External Master
Always 0001_000
Write
External Master
Always 0
®
ACK (or NACK)
Intel ICH4
ICH4 NACKs if HOST_NOTIFY_STS is 1
Device Address – 7 bits
External Master
Indicates the address of the master; loaded
into the Notify Device Address Register
18
Unused – Always 0
External Master
7-bit-only address; this bit is inserted to
complete the byte
19
ACK
ICH4
Data Byte Low – 8 bits
External Master
ACK
ICH4
Data Byte High – 8 bits
External Master
37
ACK
ICH4
38
Stop
External Master
11–17
20–27
28
29–36
5.19
Description
Loaded into the Notify Data Low Byte
Register
Loaded into the Notify Data High Byte
Register
AC ’97 Controller Functional Description (Audio
D31:F5, Modem D31:F6)
All references to AC ’97 in this document refer to the Audio Codec ’97 Component Specification,
Revision 2.3. For further information on the operation of the AC-link protocol, see the AC ’97
specification.
The ICH4 AC ’97 controller features include:
• Independent PCI functions for audio and modem.
• Independent bus master logic for dual Microphone input, dual PCM Audio input (2-channel
•
•
•
•
•
stereo per input), PCM audio output (2-, 4- or 6-channel audio), Modem input, Modem output
and S/PDIF output.
20-bit sample resolution.
Multiple sample rates up to 48 kHz.
16 GPIOs.
Single modem line.
Configure up to three codecs with three AC_SDIN pins.
Table 5-99 shows a detailed list of features supported by the ICH4 AC ’97 digital controller.
Intel® 82801DB ICH4 Datasheet
227
Functional Description
.
Table 5-99. Features Supported by Intel® ICH4
Feature
Description
System Interface
• Isochronous low latency bus master memory interface
• Scatter/gather support for word-aligned buffers in memory.
(all mono or stereo 20-bit and 16-bit data types are supported, no 8-bit data types are
supported).
• Data buffer size in system memory from 3 to 65535 samples per input.
• Data buffer size in system memory from 0 to 65535 samples per output.
• Independent PCI audio and modem functions with configuration and IO spaces.
• AC ’97 codec registers are shadowed in system memory via driver.
• AC ’97 codec register accesses are serialized via semaphore bit in PCI IO space
(new accesses are not allowed while a prior access is still in progress).
Power
Management
• Power management via PCI Power Management
PCI Audio
Function
• Read/write access to audio codec registers 00h–3Ah and vendor registers 5Ah–7Eh.
• 20-bit stereo PCM output, up to 48 kHz (L,R, Center, Sub-woofer, L-rear and R-rear
channels on slots 3,4,6,7,8,9,10,11).
• 16-bit stereo PCM input, up to 48 kHz (L,R channels on slots 3,4).
• 16-bit mono mic in w/ or w/o mono mix, up to 48 kHz (L,R channel, slots 3,4) (mono
mix supports mono hardware AEC reference for speakerphone).
• 16-bit mono PCM input, up to 48 kHz from dedicated mic ADC (slot 6)
(supports speech recognition or stereo hardware AEC ref for speakerphone).
• During cold reset, AC_RST# is held low until after POST and software deassertion of
AC_RST# (supports passive PC_BEEP to speaker connection during POST).
PCI Modem
function
• Read/write access to modem codec registers 3Ch–58h and vendor registers 5Ah–
7Eh.
• 16-bit mono modem line1 output and input, up to 48 kHz (slot 5).
• Low latency GPIO[15:0] via hardwired update between slot 12 and PCI IO register.
• Programmable PCI interrupt on modem GPIO input changes via slot 12 GPIO_INT.
• SCI event generation on AC_SDIN[2:0] wake-up signals.
AC-link
• Supports AC ’97 2.3 AC-link interface.
• Variable sample rate output support via AC ’97 SLOTREQ protocol
(slots 3,4,5,6,7,8,9,10,11).
• Variable sample rate input support via monitoring of slot valid tag bits (slots 3,4,5,6)
• 3.3 V digital operation meets AC ’97 2.3 DC switching levels.
• AC-link IO driver capability meets AC ’97 2.3 triple codec specifications.
• Codec register status reads must be returned with data in the next AC-link frame, per
the AC ’97 2.3 specification.
• Triple codec addressing: All AC ’97 Audio codec register accesses are addressable to
codec ID 00 (primary), codec ID 01 (secondary), or codec ID 10 (tertiary).
• Modem codec addressing: All AC ’97 Modem codec register accesses are
addressable to codec ID 00 (primary) or codec ID 01 (secondary).
Multiple Codec
• Triple codec receive capability via AC_SDIN[2:0] pins
(AC_SDIN[2:0] frames are internally validated, synch’d, and OR’d depending on the
Steer Enable bit status in the SDM register).
• AC_SDIN mapping to DMA engine mapping capability allows for simultaneous input
from three different audio codecs.
NOTES:
1. Audio Codec IDs are remappable and not limited to 00,01,10.
2. Modem Codec IDs are remappable and limited to 00,01.
3. When using multiple codecs, the Modem Codec must be ID 01.
228
Intel® 82801DB ICH4 Datasheet
Functional Description
Note:
Throughout this document, references to D31:F5 indicate that the audio function exists in PCI
Device 31, Function 5. References to D31:F6 indicate that the modem function exists in PCI
Device 31, Function 6.
Note:
Throughout this document, references to tertiary, third, or triple codecs refer to the third codec in
the system connected to the AC_SDIN[2] pin. The AC ’97 2.3 specification refers to non-primary
codecs as multiple secondary codecs. To avoid confusion and excess verbiage this datasheet refers
to it as the third or tertiary codec.
Figure 5-20. Intel® ICH4 Based Audio Codec ’97 Specification, Revision 2.3
Audio In (Record)
Audio Out (6 Channel Playback)
PC
S/PDIF* Output
Modem
Mic.1
Mic.2
5.19.1
PCI Power Management
This Power Management section applies for all AC ’97 controller functions. After a power
management event is detected, the AC ’97 controller will wake the host system. The sections
below describe these events and the AC ’97 controller power states.
Device Power States
The AC ’97 controller supports D0 and D3 PCI Power Management states. Notes regarding the
Intel ICH4 AC ’97 controller implementation of the Device States:
1. The AC ’97 controller hardware does not inherently consume any more power when it is in the
D0 state than it does in D3 state. However, software can halt the DMA engine prior to entering
these low power states such that the maximum power consumption is reduced.
2. In the D0 state, all implemented AC ’97 controller features are enabled.
3. In D3 state, accesses to the AC ’97 controller memory-mapped or I/O range result in master
abort.
4. In D3 state, the AC ’97 controller interrupt must never assert for any reason. The internal
PME# signal is used to signal wake events, etc.
5. When the Device Power State field is written from D3HOT to D0, an internal reset is generated.
See Section 14.1 for general rules on the effects of this reset.
6. AC ’97 STS bit will be set only when the audio or modem resume events were detected and
their respective PME enable bits were set.
7. GPIO Status change interrupt no longer has a direct path to AC ’97 STS bit. This will cause a
wake up event only if the modem controller was in D3
8. Resume events on AC_SDIN[2:0] will cause resume interrupt status bits to be set only if their
respective controllers are not in D3.
9. Edge detect logic will prevent the interrupts from being asserted in case AC ’97 controller is
switched from D3 to D0 after a wake event.
10. Once the interrupt status bits are set, they will cause PIRQB# if their respective enable bits
were set. One of the audio or the modem drivers will handle the interrupt.
Intel® 82801DB ICH4 Datasheet
229
Functional Description
5.19.2
AC-Link Overview
The ICH4 supports the AC ’97 2.3 controller that communicates with companion codecs via a
digital serial link called the AC-link. All digital audio/modem streams and command/status
information is communicated over the AC-link.
The AC-link is a bi-directional, serial PCM digital stream. It handles multiple input and output data
streams, as well as control register accesses, employing a time division multiplexed (TDM)
scheme. The AC-link architecture provides for data transfer through individual frames transmitted
in a serial fashion. Each frame is divided into 12 outgoing and 12 incoming data streams, or slots.
The architecture of the ICH4 AC-link allows a maximum of three codecs to be connected.
Figure 5-21 shows a three codec topology of the AC-link for the ICH4.
Figure 5-21. AC ’97 2.3 Controller-Codec Connection
AC / MC / AMC
AC_RST#
AC_SDOUT
AC_SYNC
AC_BIT_CLK
Primary Codec
Intel® ICH4
AC_SDIN2
AC_SDIN1
AC_SDIN0
AC / MC / AMC
Secondary Codec
AC / MC / AMC
Tertiary Codec
230
Intel® 82801DB ICH4 Datasheet
Functional Description
The AC-link consists of a five signal interface between the controller and codec. Table 5-100
indicates the AC-link signal pins on the ICH4 and their associated power wells.
Table 5-100. AC ’97 Signals
Signal Name
Type
Power Well
Description
AC_RST#
Output
Resume
AC_SYNC
Output
Core
48 kHz fixed rate sample sync
AC_BIT_CLK
Input
Core
12.288 MHz Serial data clock
AC_SDOUT
Output
Core
Serial output data
AC_SDIN 0
Input
Resume
Serial input data
AC_SDIN 1
Input
Resume
Serial input data
AC_SDIN 2
Input
Resume
Serial input data
Master hardware reset
NOTE: Power well voltage levels are 3.3 V.
ICH4 core well outputs may be used as strapping options for the ICH4, sampled during system
reset. These signals may have weak pullups/pulldowns on them, however this will not interfere
with link operation. ICH4 inputs integrate weak pulldowns to prevent floating traces when a
secondary and/or tertiary codec is not attached. When the Shut Off bit in the control register is set,
all buffers will be turned off and the pins will be held in a steady state, based on these pullups/
pulldowns.
AC_BIT_CLK is fixed at 12.288 MHz and is sourced by the primary codec. It provides the
necessary clocking to support the twelve 20-bit time slots. AC-link serial data is transitioned on
each rising edge of AC_BIT_CLK. The receiver of AC-link data samples each serial bit on the
falling edge of AC_BIT_CLK.
If AC_BIT_CLK makes no transitions for four consecutive PCI clocks, the ICH4 assumes the
primary codec is not present or not working. It sets bit 28 of the Global Status Register (I/O offset
30h). All accesses to codec registers with this bit set will return data of FFh to prevent system
hangs.
Synchronization of all AC-link data transactions is signaled by the AC ’97 controller via the
AC_SYNC signal, as shown in Figure 5-22. The primary codec drives the serial bit clock onto the
AC-link, which the AC ’97 controller then qualifies with the AC_SYNC signal to construct data
frames. AC_SYNC, fixed at 48 kHz, is derived by dividing down AC_BIT_CLK. AC_SYNC
remains high for a total duration of 16 AC_BIT_CLKs at the beginning of each frame. The portion
of the frame where AC_SYNC is high is defined as the tag phase. The remainder of the frame
where AC_SYNC is low is defined as the data phase. Each data bit is sampled on the falling edge
of AC_BIT_CLK.
Figure 5-22. AC-Link Protocol
Tag Phase
Data Phase
20.8uS
(48 KHz)
SYNC
12.288 MHz
81.4 nS
BIT_CLK
Codec
Ready
SDIN
End of previous
Audio Frame
Intel® 82801DB ICH4 Datasheet
slot(1) slot(2)
slot(12) "0"
"0"
Time Slot "Valid"
Bits
("1" = time slot contains valid PCM
"0"
19
0
Slot 1
19
0
Slot 2
19
0
Slot 3
19
0
Slot 12
231
Functional Description
The ICH4 has three AC_SDIN pins allowing a single, dual, or triple codec configuration. When
multiple codecs are connected, the primary, secondary, and tertiary codecs can be connected to any
AC_SDIN line. The ICH4 does not distinguish between codecs on its AC_SDIN[2:0] pins;
however, the registers do distinguish between AC_SDIN[0], AC_SDIN[1], and AC_SDIN[2] for
wake events, etc. If using a Modem Codec it is recommended to connect it to AC_SDIN[1].
See your Platform Design Guide for a matrix of valid codec configurations. The ICH4 does not
support optional test modes as outlined in the AC ’97 specification.
5.19.2.1
AC-Link Output Frame (SDOUT)
A new output frame begins with a low-to-high transition of AC_SYNC. AC_SYNC is synchronous
to the rising edge of BIT_CLK. On the immediately following falling edge of AC_BIT_CLK, the
codec samples the assertion of AC_SYNC. This falling edge marks the time when both sides of
AC-link are aware of the start of a new frame. On the next rising edge of AC_BIT_CLK, the ICH4
transitions AC_SDOUT into the first bit position of slot 0, or the valid frame bit. Each new bit
position is presented to the AC-link on a rising edge of AC_BIT_CLK, and subsequently sampled
by the codec on the following falling edge of AC_BIT_CLK. This sequence ensures that data
transitions and subsequent sample points for both incoming and outgoing data streams are time
aligned.
The output frame data phase corresponds to the multiplexed bundles of all digital output data
targeting codec DAC inputs and control registers. Each output frame supports up to twelve
outgoing data time slots. The ICH4 generates 16 or 20 bits and stuffs remaining bits with zeros.
The output data stream is sent with the most significant bit first, and all invalid slots are stuffed
with zeros. When mono audio sample streams are output from the ICH4, software must ensure both
left and right sample stream time slots are filled with the same data.
5.19.2.2
Output Slot 0: Tag Phase
Slot 0 is considered the tag phase. The tag phase is a special 16-bit time slot wherein each bit
conveys a valid tag for its corresponding time slot within the current frame. A one in a given bit
position of slot 0 indicates that the corresponding time slot within the current frame has been
assigned to a data stream and contains valid data. If a slot is tagged invalid with a zero in the
corresponding bit position of slot 0, the ICH4 stuffs the corresponding slot with zeros during that
slot’s active time.
Within slot 0, the first bit is a valid frame bit (slot 0, bit 15) which flags the validity of the entire
frame. If the valid frame bit is set to one, this indicates that the current frame contains at least one
slot with valid data. When there is no transaction in progress, the ICH4 will deassert the frame
valid bit. Note that after a write to slot 12, that slot will always stay valid, and therefore the frame
valid bit will remain set.
The next 12 bit positions of slot 0 (bits [14:3]) indicate which of the corresponding twelve time
slots contain valid data. Bits [1:0] of slot 0 are used as codec ID bits to distinguish between
separate codecs on the link.
Using the valid bits in the tag phase allows data streams of differing sample rates to be transmitted
across the link at its fixed 48 kHz frame rate. The codec can control the output sample rate of the
ICH4 using the SLOTREQ bits as described in the AC ’97 specification.
232
Intel® 82801DB ICH4 Datasheet
Functional Description
5.19.2.3
Output Slot 1: Command Address Port
The command port is used to control features and monitor status of AC ’97 functions including, but
not limited to, mixer settings and power management.
The control interface architecture supports up to 64, 16-bit read/write registers, addressable on
even byte boundaries. Only the even registers (00h, 02h, etc.) are valid.
Output frame slot 1 communicates control register address, and write/read command information.
In the case of the multiple codec implementation, accesses to the codecs are differentiated by the
driver using address offsets 00h–7Fh for the primary codec, address offsets 80h–FEh for the
secondary codec, and address offsets 100h–17Fh for the tertiary codec. The differentiation on the
link, however, is done via the codec ID bits. See Section 5.19.2.23 for further details.
5.19.2.4
Output Slot 2: Command Data Port
The command data port is used to deliver 16-bit control register write data in the event that the
current command port operation is a write cycle as indicated in slot 1, bit 19. If the current
command port operation is a read then the entire slot time stuffed with zeros by the ICH4. Bits
[19:4] contain the write data. Bits [3:0] are reserved and are stuffed with zeros.
5.19.2.5
Output Slot 3: PCM Playback Left Channel
Output frame slot 3 is the composite digital audio left playback stream. Typically, this slot is
composed of standard PCM (.wav) output samples digitally mixed by the host processor. The ICH4
transmits sample streams of 16 bits or 20 bits and stuffs remaining bits with zeros.
Data in output slots 3 and 4 from the ICH4 should be duplicated by software if there is only a single
channel out.
5.19.2.6
Output Slot 4: PCM Playback Right Channel
Output frame slot 4 is the composite digital audio right playback stream. Typically, this slot is
composed of standard PCM (.wav) output samples digitally mixed by the host processor. The ICH4
transmits sample streams of 16 or 20 bits and stuffs remaining bits with zeros.
Data in output slots 3 and 4 from the ICH4 should be duplicated by software if there is only a single
channel out.
5.19.2.7
Output Slot 5: Modem Codec
Output frame slot 5 contains modem DAC data. The modem DAC output supports 16-bit
resolution. At boot time, if the modem codec is supported, the AC ’97 controller driver determines
the DAC resolution. During normal runtime operation the ICH4 stuffs trailing bit positions within
this time slot with zeros.
5.19.2.8
Output Slot 6: PCM Playback Center Front Channel
When set up for 6-channel mode, this slot is used for the front center channel. The format is the
same as Slots 3 and 4. If not set up for 6-channel mode, this channel will always be stuffed with
zeros by ICH4.
Intel® 82801DB ICH4 Datasheet
233
Functional Description
5.19.2.9
Output Slots 7-8: PCM Playback Left and Right Rear Channels
When set up for 4 or 6 channel modes, slots 7 and 8 are used for the rear Left and Right channels.
The format for these two channels are the same as Slots 3 and 4.
5.19.2.10
Output Slot 9: Playback Sub Woofer Channel
When set for 6-channel mode, this slot is used for the Sub Woofer. The format is the same as
Slots 3. If not set up for 6-channel mode, this channel will always be stuffed with zeros by ICH4.
5.19.2.11
Output Slots 10-11: Reserved
Output frame slots 10–11 are reserved and are always stuffed with zeros by the ICH4 AC ’97
controller.
5.19.2.12
Output Slot 12: I/O Control
The 16 bits of DAA and GPIO control (output) and status (input) have been directly assigned to
bits on slot 12 in order to minimize latency of access to changing conditions.
The value of the bits in this slot are the values written to the GPIO control register at offset 54h
and D4h (in the case of a secondary codec) in the modem codec I/O space. The following rules
govern the usage of slot 12.
1. Slot 12 is marked invalid by default on coming out of AC-link reset, and will remain invalid
until a register write to 54h/D4h.
2. A write to offset 54h/D4h in codec I/O space will cause the write data to be transmitted on
slot 12 in the next frame, with slot 12 marked valid, and the address/data information to also be
transmitted on slots 1 and 2.
3. After the first write to offset 54h/D4h, slot 12 remains valid for all following frames. The data
transmitted on slot 12 is the data last written to offset 54h/D4h. Any subsequent write to the
register will cause the new data to be sent out on the next frame.
4. Slot 12 will get invalidated after the following events: PCI reset, AC '97 cold reset, warm
reset, and, hence, a wake from S3, S4, or S5. Slot 12 will remain invalid until the next write to
offset 54h/D4h.
5.19.2.13
AC-Link Input Frame (SDIN)
There are three AC_SDIN lines on the ICH4 for use with up to three codecs. Each AC_SDIN pin
can have a codec attached. The input frame data streams correspond to the multiplexed bundles of
all digital input data targeting the AC ’97 controller. As in the case for the output frame, each AClink input frame consists of twelve time slots.
A new audio input frame begins with a low-to-high transition of AC_SYNC. AC_SYNC is
synchronous to the rising edge of AC_BIT_CLK. On the immediately following falling edge of
AC_BIT_CLK, the receiver samples the assertion of AC_SYNC. This falling edge marks the time
when both sides of AC-link are aware of the start of a new audio frame. On the next rising edge of
AC_BIT_CLK, the codec transitions AC_SDIN into the first bit position of slot 0 (codec ready
bit). Each new bit position is presented to AC-link on a rising edge of AC_BIT_CLK, and
subsequently sampled by the ICH4 on the following falling edge of AC_BIT_CLK. This sequence
ensures that data transitions and subsequent sample points for both incoming and outgoing data
streams are time aligned.
AC_SDIN data stream must follow the AC ’97 specification and be MSB justified with all nonvalid bit positions (for assigned and/or unassigned time slots) stuffed with zeros. AC_SDIN data is
sampled by the ICH4 on the falling edge of AC_BIT_CLK.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.19.2.14
Input Slot 0: Tag Phase
Input slot 0 consists of a codec ready bit (bit 15), and slot valid bits for each subsequent slot in the
frame (bits [14:3]).
The codec ready bit within slot 0 (bit 15) indicates whether the codec on the AC-link is ready for
register access (digital domain). If the codec ready bit in slot 0 is a zero, the codec is not ready for
register access. When the AC-link codec ready bit is a 1, it indicates that the AC-link and codec
control and status registers are in a fully operational state. The codec ready bits are visible through
the Global Status register of the ICH4. Software must further probe the Powerdown Control/Status
register in the codec to determine exactly which subsections, if any, are ready.
Bits [14:3] in slot 0 indicate which slots of the input stream to the ICH4 contain valid data, just as
in the output frame. The remaining bits in this slot are stuffed with zeros.
5.19.2.15
Input Slot 1: Status Address Port / Slot Request Bits
The status port is used to monitor status of codec functions including, but not limited to, mixer
settings and power management.
Slot 1 must echo the control register index, for historical reference, for the data to be returned in
slot 2, assuming that slots 1 and 2 had been tagged valid by the codec in slot 0.
For variable sample rate output, the codec examines its sample rate control registers, the state of its
FIFOs, and the incoming SDOUT tag bits at the beginning of each audio output frame to determine
which SLOTREQ bits to set active (low). SLOTREQ bits asserted during the current audio input
frame signal which output slots require data from the controller in the next audio output frame. For
fixed 48 kHz operation the SLOTREQ bits are always set active (low) and a sample is transferred
each frame.
For variable sample rate input, the tag bit for each input slot indicates whether valid data is present
or not.
Table 5-101. Input Slot 1 Bit Definitions
Bit
19
18:12
Description
Reserved (Set to zero)
Control Register Index (Stuffed with zeros if tagged invalid)
11
Slot 3 Request: PCM Left Channel(1)
10
Slot 4 Request: PCM Right Channel(1)
9
Slot 5 Request: Modem Line 1
8
Slot 6 Request: PCM Center Channel(1)
7
Slot 7 Request: PCM Left Surround(1)
6
Slot 8 Request: PCM Right Surround(1)
5
Slot 9 Request: PCM LFE Channel(1)
4:2
Slot Request 10–12: Not Implemented
1:0
Reserved (Stuffed with zeros)
NOTES:
1. Slot 3 Request and Slot 4 Request bits must be the same value (i.e., set or cleared in tandem). This is also
true for the Slot 7 and Slot 8 Request bits, as well as the Slot 6 and Slot 9 Request bits.
Intel® 82801DB ICH4 Datasheet
235
Functional Description
As shown in Table 5-101, slot 1 delivers codec control register read address and multiple sample
rate slot request flags for all output slots of the controller. When a slot request bit is set by the
codec, the controller will return data in that slot in the next output frame. Slot request bits for slots
3 and 4 are always set or cleared in tandem (i.e., both are set or cleared).
When set, the input slot 1 tag bit only pertains to Status Address Port data from a previous read.
SLOTREQ bits are always valid independent of the slot 1 tag bit.
5.19.2.16
Input Slot 2: Status Data Port
The status data port receives 16-bit control register read data.
• Bit [19:4]: Control Register Read Data
• Bit [3:0]: Reserved.
5.19.2.17
Input Slot 3: PCM Record Left Channel
Input slot 3 is the left channel input of the codec. The ICH4 supports 16-bit sample resolution.
Samples transmitted to the ICH4 must be in left/right channel order.
5.19.2.18
Input Slot 4: PCM Record Right Channel
Input slot 4 is the right channel input of the codec. The ICH4 supports 16-bit sample resolution.
Samples transmitted to the ICH4 must be in left/right channel order.
5.19.2.19
Input Slot 5: Modem Line
Input slot 5 contains MSB justified modem data. The ICH4 supports 16-bit sample resolution.
5.19.2.20
Input Slot 6: Optional Dedicated Microphone Record Data
Input slot 6 is a third PCM system input channel available for dedicated use by a microphone. This
input channel supplements a true stereo output which enables more precise echo cancellation
algorithm for speakerphone applications. The ICH4 supports 16-bit resolution for slot 6 input.
5.19.2.21
Input Slots 7–11: Reserved
Input frame slots 7–11 are reserved for future use and should be stuffed with zeros by the codec,
per the AC ’97 specification.
5.19.2.22
Input Slot 12: I/O Status
The status of the GPIOs configured as inputs are to be returned on this slot in every frame. The data
returned on the latest frame is accessible to software by reading the register at offset 54h/D4h in the
codec I/O space. Only the 16 MSBs are used to return GPI status. In order for GPI events to cause
an interrupt, both the 'sticky' and 'interrupt' bits must be set for that particular GPIO pin in regs 50h
and 52h. Therefore, the interrupt will be signalled until it has been cleared by the controller, which
can be much longer than one frame.
Reads from 54h/D4h will not be transmitted across the link in slot 1 and 2. The data from the most
recent slot 12 is returned on reads from offset 54h/D4h.
236
Intel® 82801DB ICH4 Datasheet
Functional Description
5.19.2.23
Register Access
In the ICH4 implementation of the AC-link, up to three codecs can be connected to the
AC_SDOUT pin. The following mechanism is used to address the primary, secondary, and tertiary
codecs individually.
The primary device uses bit 19 of slot 1 as the direction bit to specify read or write. Bits [18:12] of
slot 1 are used for the register index. For I/O writes to the primary codec, the valid bits [14:13] for
slots 1 and 2 must be set in slot 0, as shown in Table 5-102. Slot 1 is used to transmit the register
address, and slot 2 is used to transmit data. For I/O reads to the primary codec, only slot 1 should
be valid since only an address is transmitted. For I/O reads only slot 1 valid bit is set, while for I/O
writes both slots 1 and 2 valid bits are set.
The secondary and tertiary codec registers are accessed using slots 1 and 2 as described above,
however the slot valid bits for slots 1 and 2 are marked invalid in slot 0 and the codec ID bits [1:0]
(bit 0 and bit 1 of slot 0) is set to a non zero value. This allows the secondary or tertiary codec to
monitor the slot valid bits of slots 1and 2, and bits [1:0] of slot 0 to determine if the access is
directed to the secondary or tertiary codec. If the register access is targeted to the secondary or
tertiary codec, slot 1 and 2 will contain the address and data for the register access. Since slots 1
and 2 are marked invalid, the primary codec will ignore these accesses.
Table 5-102. Output Tag Slot 0
Bit
Primary Access
Example
Secondary Access
Example
Description
15
1
1
Frame Valid
14
1
0
Slot 1 Valid, Command Address bit (Primary codec only)
13
1
0
Slot 2 Valid, Command Data bit (Primary codec only)
12:3
X
X
Slot 3–12 Valid
2
0
0
Reserved
1:0
00
01
Codec ID (00 reserved for primary; 01 indicate secondary;
10 indicate tertiary)
When accessing the codec registers, only one I/O cycle can be pending across the AC-link at any
time. The ICH4 implements write posting on I/O writes across the AC-link (i.e., writes across the
link are indicated as complete before they are actually sent across the link). In order to prevent a
second I/O write from occurring before the first one is complete, software must monitor the CAS
bit in the Codec Access Semaphore register which indicates that a codec access is pending. Once
the CAS bit is cleared, then another codec access (read or write) can go through. The exception to
this being reads to offset 54h/D4h/154h (slot 12) which are returned immediately with the most
recently received slot 12 data. Writes to offset 54h, D4h, and 154h (primary, secondary and tertiary
codecs), get transmitted across the AC-link in slots 1 and 2 as a normal register access. Slot 12 is
also updated immediately to reflect the data being written.
The controller will not issue back to back reads. It must get a response to the first read before
issuing a second. In addition, codec reads and writes are only executed once across the link, and are
not repeated.
Intel® 82801DB ICH4 Datasheet
237
Functional Description
5.19.3
AC-Link Low Power Mode
The AC-link signals can be placed in a low-power mode. When the AC ’97 Powerdown Register
(26h), is programmed to the appropriate value, both AC_BIT_CLK and AC_SDIN will be brought
to, and held at a logic low voltage level.
Figure 5-23. AC-Link Powerdown Timing
AC_SYNC
AC_BIT_CLK
AC_SDOUT
slot 12
prev. frame
TAG
AC_SDIN
slot 12
prev. frame
TAG
Write to
Data
0x20
PR4
Note: AC_BIT_CLK not to scale
AC_BIT_CLK and AC_SDIN transition low immediately after a write to the Powerdown Register
(26h) with PR4 enabled. When the AC ’97 controller driver is at the point where it is ready to
program the AC-link into its low-power mode, slots 1 and 2 are assumed to be the only valid
stream in the audio output frame.
The AC ’97 controller also drives AC_SYNC, and AC_SDOUT low after programming AC ’97 to
this low power, halted mode
Once the codec has been instructed to halt AC_BIT_CLK, a special wake up protocol must be used
to bring the AC-link to the active mode since normal output and input frames cannot be
communicated in the absence of AC_BIT_CLK. Once in a low-power mode, the ICH4 provides
three methods for waking up the AC-link; external wake event, cold reset and warm reset.
Note:
238
Before entering any low-power mode where the link interface to the codec is expected to be
powered down while the rest of the system is awake, the software must set the “Shut Off” bit in the
control register.
Intel® 82801DB ICH4 Datasheet
Functional Description
5.19.3.1
External Wake Event
Codecs can signal the controller to wake the AC-link, and wake the system using AC_SDIN.
Figure 5-24. SDIN Wake Signaling
Power Down
Frame
Sleep State
New Audio
Frame
Wake Event
SYNC
BIT_CLK
SDOUT
slot 12
prev. frame
TAG
SDIN
slot 12
prev. frame
TAG
Write to
0x20
Data
PR4
TAG
Slot 1
Slot 2
TAG
Slot 1
Slot 2
The minimum AC_SDIN wake up pulse width is 1 us. The rising edge of AC_SDIN[0],
AC_SDIN[1] or AC_SDIN[2] causes the ICH4 to sequence through an AC-link warm reset and set
the AC ’97_STS bit in the GPE0_STS register to wake the system. The primary codec must wait to
sample AC_SYNC high and low before restarting BIT_CLK as diagrammed in Figure 5-24. The
codec that signaled the wake event must keep its AC_SDIN high until it has sampled AC_SYNC
having gone high, and then low.
The AC-link protocol provides for a cold reset and a warm reset. The type of reset used depends on
the system’s current power down state. Unless a cold or register reset (a write to the Reset register
in the codec) is performed, wherein the AC ‘97 codec registers are initialized to their default
values, registers are required to keep state during all power down modes.
Once powered down, activation of the AC-link via re-assertion of the AC_SYNC signal must not
occur for a minimum of 4 audio frame times following the frame in which the power down was
triggered. When AC-link powers up, it indicates readiness via the codec ready bit.
5.19.4
AC ’97 Cold Reset
A cold reset is achieved by asserting AC_RST# for 1 us. By driving AC_RST# low, BIT_CLK, and
SDOUT will be activated and all codec registers will be initialized to their default power on reset
values. AC_RST# is an asynchronous AC ’97 input to the codec.
5.19.5
AC ’97 Warm Reset
A warm reset will re-activate the AC-link without altering the current codec register values. A
warm reset is signaled by driving AC_SYNC high for a minimum of 1 µs in the absence of
BIT_CLK.
Within normal frames, AC_SYNC is a synchronous AC ’97 input to the codec. However, in the
absence of AC_BIT_CLK, AC_SYNC is treated as an asynchronous input to the codec used in the
generation of a warm reset.
The codec must not respond with the activation of AC_BIT_CLK until AC_SYNC has been
sampled low again by the codec. This will prevent the false detection of a new frame.
Note:
On receipt of wake up signalling from the codec, the digital controller will issue an interrupt if
enabled. Software will then have to issue a warm or cold reset to the codec by setting the
appropriate bit in the Global Control Register.
Intel® 82801DB ICH4 Datasheet
239
Functional Description
5.19.6
System Reset
Table 5-103 indicates the states of the link during various system reset and sleep conditions.
Table 5-103. AC-link State during PCIRST#
Power
Plane
I/O
During
PCIRST#/
After
PCIRST#/
S1
S3
S4/S5
AC_RST#
Resume3
Output
Low
Low
Cold Reset
bit (Hi)
Low
Low
AC_SDOUT
Core1
Output
Low
Running
Low
Low
Low
AC_SYNC
Core
Output
Low
Running
Low
Low
Low
Signal
2,4
2,4
AC_BIT_CLK
Core
Input
Driven by codec
Running
Low
Low
Low2,4
AC_SDIN[2:0]
Resume
Input
Driven by codec
Running
Low2,4
Low2,4
Low2,4
NOTES:
1. ICH4 core well outputs are used as strapping options for the ICH4, sampled during system reset. These
signals may have weak pullups/pulldowns on them. The ICH4 outputs will be driven to the appropriate level
prior to AC_RST# being deasserted, preventing a codec from entering test mode. Straps are tied to the core
well to prevent leakage during a suspend state.
2. The pull-down resistors on these signals are only enabled when the AC-Link Shut Off bit in the AC ’97 Global
Control Register is set to 1. All other times, the pull-down resistor is disabled.
3. AC_RST# will be held low during S3–S5. It cannot be programmed high during a suspend state.
4. AC_BIT_CLK and AC_SDIN[2:0] are driven low by the codecs during normal states. If the codec is powered
during suspend states it will hold these signals low. However, if the codec is not present, or not powered in
suspend, external pull-down resistors are required.
The transition of AC_RST# to the deasserted state will only occur under driver control. In the
S1sleep state, the state of the AC_RST# signal is controlled by the AC ’97 Cold Reset# bit (bit 1)
in the Global Control register. AC_RST# will be asserted (low) by the ICH4 under the following
conditions:
•
•
•
•
•
RSMRST# (system reset, including the a reset of the resume well and PCIRST#)
Mechanical power up (causes PCIRST#)
Write to CF9h hard reset (causes PCIRST#)
Transition to S3/S4/S5 sleep states (causes PCIRST#)
Write to AC ’97 Cold Reset# bit in the Global Control Register.
Hardware will never deassert AC_RST# (i.e., never deasserts the Cold Reset# bit) automatically.
Only software can deassert the Cold Reset# bit, and hence the AC_RST# signal. This bit, while it
resides in the core well, will remain cleared upon return from S3/S4/S5 sleep states. The AC_RST#
pin will remain actively driven from the resume well as indicated.
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Intel® 82801DB ICH4 Datasheet
Functional Description
5.19.7
Hardware Assist to Determine AC_SDIN Used Per Codec
Software first performs a read to one of the audio codecs. The read request goes out on
AC_SDOUT. Since under our micro-architecture only one read can be performed at a time on the
link, eventually the read data will come back in on one of the AC_SDIN[2:0] lines.
The codec will do this by indicating that status data is valid in its TAG, then echo the read address
in slot 1 followed by the read data in slot 2.
The new function of the ICH4 hardware is to notice which AC_SDIN line contains the read return
data, and to set new bits in the new register indicating which AC_SDIN line the register read data
returned on. If it returned on AC_SDIN0, bits [1:0] contain the value 00. If it returned on
AC_SDIN1, the bits contain the value 01, etc.
ICH4 hardware can set these bits every time register read data is returned from a function 5 read.
No special command is necessary to cause the bits to be set. The new driver/BIOS software will
read the bits from this register when it cares to, and can ignore it otherwise. When software is
attempting to establish the codec-to-AC_SDIN mapping, it will single feed the read request and not
pipeline to ensure it gets the right mapping, we cannot ensure the serialization of the access.
5.19.8
Software Mapping of AC_SDIN to DMA Engine
Once software has performed the register read to determine codec-to-AC_SDIN mapping, it will
then either set bits 5:4 or 7:6 in the SDATA_IN MAP register to map this codec to the DMA
engine. After it maps the audio codecs, it will set the “SE” (steer enable) bit, which now lets the
hardware know to no longer OR the AC_SDIN lines, and to use the mappings in the register to
steer the appropriate AC_SDIN line to the correct DMA engines.
Intel® 82801DB ICH4 Datasheet
241
Functional Description
This page is intentionally left blank
242
Intel® 82801DB ICH4 Datasheet
Register and Memory Mapping
Register and Memory Mapping
6
The ICH4 contains registers that are located in the processor’s I/O space and memory space and
sets of PCI configuration registers that are located in PCI configuration space. This chapter
describes the ICH4 I/O and memory maps at the register-set level. Register access is also
described. Register-level address maps and Individual register bit descriptions are provided in the
following chapters. The following notations and definitions are used in the register/instruction
description chapters.
RO
Read Only. In some cases, If a register is read only, writes to this register
location have no effect. However, in other cases, two separate registers
are located at the same location where a read accesses one of the registers
and a write accesses the other register. See the I/O and memory map
tables for details.
WO
Write Only. In some cases, If a register is write only, reads to this register
location have no effect. However, in other cases, two separate registers
are located at the same location where a read accesses one of the registers
and a write accesses the other register. See the I/O and memory map
tables for details.
R/W
Read/Write. A register with this attribute can be read and written.
R/WC
Read/Write Clear. A register bit with this attribute can be read and
written. However, a write of 1 clears (sets to 0) the corresponding bit and
a write of 0 has no effect.
R/WO
Read/Write-Once. A register bit with this attribute can be written only
once after power up. After the first write, the bit becomes read only.
Default
When ICH4 is reset, it sets its registers to predetermined default states.
The default state represents the minimum functionality feature set
required to successfully bring up the system. Hence, it does not represent
the optimal system configuration. It is the responsibility of the system
initialization software to determine configuration, operating parameters,
and optional system features that are applicable, and to program the
ICH4 registers accordingly.
Bold
Register bits that are highlighted in bold text indicate that the bit is
implemented in the ICH4. Register bits that are not implemented or are
hardwired will remain in plain text.
Intel® 82801DB ICH4 Datasheet
243
Register and Memory Mapping
6.1
PCI Devices and Functions
The ICH4 incorporates a variety of PCI functions as shown in Table 6-1. These functions are
divided into four logical devices (B0:D30, B0:D31, B0:D29 and B1:D8). D30 is the hub interfaceto-PCI bridge, D31 contains the PCI-to-LPC Bridge, IDE controller, SMBus controller and the
AC ’97 Audio and Modem controller functions and D29 contains the three USB UHCI controllers
and one USB EHCI controller. B1:D8 is the integrated LAN controller.
Note:
From a software perspective, the integrated LAN controller resides on the ICH4’s external PCI bus
(See Section 5.1.2). This is typically Bus 1, but may be assigned a different number depending
upon system configuration.
If for some reason, the particular system platform does not want to support any one of Device 31’s
Functions 1–6, Device 29’s functions, or Device 8, they can individually be disabled. The
integrated LAN controller will be disabled if no Platform LAN Connect component is detected
(See Section 5.2.1.3). When a function is disabled, it does not appear at all to the software. A
disabled function will not respond to any register reads or writes. This is intended to prevent
software from thinking that a function is present (and reporting it to the end-user).
Table 6-1. PCI Devices and Functions
Bus:Device:Function
Function Description
Bus 0:Device 30:Function 0
Hub Interface to PCI Bridge
Bus 0:Device 31:Function 0
PCI to LPC Bridge1
Bus 0:Device 31:Function 1
IDE Controller
Bus 0:Device 31:Function 3
SMBus Controller
Bus 0:Device 31:Function 5
AC ’97 Audio Controller
Bus 0:Device 31:Function 6
AC ’97 Modem Controller
Bus 0:Device 29:Function 0
USB UHCI Controller #1
Bus 0:Device 29:Function 1
USB UHCI Controller #2
Bus 0:Device 29:Function 2
USB UHCI Controller #3
Bus 0:Device 29:Function 7
USB 2.0 EHCI Controller
Bus n:Device 8:Function 0
LAN Controller
NOTES:
1. The PCI to LPC bridge contains registers that control LPC, power management, system management, GPIO,
processor interface, RTC, interrupts, timers, DMA.
244
Intel® 82801DB ICH4 Datasheet
Register and Memory Mapping
6.2
PCI Configuration Map
Each PCI function on the ICH4 has a set of PCI configuration registers. The register address map
tables for these register sets are included at the beginning of the chapter for the particular function.
Refer to Table A-1 for a complete list of all PCI Configuration Registers.
Configuration Space registers are accessed through configuration cycles on the PCI bus by the
Host bridge using configuration mechanism #1 detailed in the PCI Local Bus Specification,
Revision 2.2.
Some of the PCI registers contain reserved bits. Software must deal correctly with fields that are
reserved. On reads, software must use appropriate masks to extract the defined bits and not rely on
reserved bits being any particular value. On writes, software must ensure that the values of
reserved bit positions are preserved. That is, the values of reserved bit positions must first be read,
merged with the new values for other bit positions and then written back. Note the software does
not need to perform read, merge, write operation for the configuration address register.
In addition to reserved bits within a register, the configuration space contains reserved locations.
Software should not write to reserved PCI configuration locations in the device-specific region
(above address offset 3Fh).
6.3
I/O Map
The I/O map is divided into Fixed and Variable address ranges. Fixed ranges cannot be moved, but
in some cases can be disabled. Variable ranges can be moved and can also be disabled.
6.3.1
Fixed I/O Address Ranges
Table 6-2 shows the Fixed I/O decode ranges from the CPU perspective. Note that for each I/O
range, there may be separate behavior for reads and writes. The hub interface cycles that go to
target ranges that are marked as “Reserved” will not be decoded by the ICH4, and will be passed to
PCI. If a PCI master targets one of the fixed I/O target ranges, it will be positively decoded by the
ICH4 in Medium speed.
Refer to Table A-2 for a complete list of all fixed I/O registers.
Address ranges that are not listed or marked “Reserved” are NOT decoded by the ICH4 (unless
assigned to one of the variable ranges).
Intel® 82801DB ICH4 Datasheet
245
Register and Memory Mapping
Table 6-2. Fixed I/O Ranges Decoded by Intel® ICH4 (Sheet 1 of 2)
246
I/O Address
Read Target
Write Target
Internal Unit
00h–08h
DMA Controller
DMA Controller
DMA
09h–0Eh
RESERVED
DMA Controller
DMA
0Fh
DMA Controller
DMA Controller
DMA
10h–18h
DMA Controller
DMA Controller
DMA
19h–1Eh
RESERVED
DMA Controller
DMA
1Fh
DMA Controller
DMA Controller
DMA
20h–21h
Interrupt Controller
Interrupt Controller
Interrupt
24h–25h
Interrupt Controller
Interrupt Controller
Interrupt
28h–29h
Interrupt Controller
Interrupt Controller
Interrupt
2Ch–2Dh
Interrupt Controller
Interrupt Controller
Interrupt
2E–2F
LPC SIO
LPC SIO
Forwarded to LPC
30h–31h
Interrupt Controller
Interrupt Controller
Interrupt
34h–35h
Interrupt Controller
Interrupt Controller
Interrupt
38h–39h
Interrupt Controller
Interrupt Controller
Interrupt
3Ch–3Dh
Interrupt Controller
Interrupt Controller
Interrupt
40h–42h
Timer/Counter
Timer/Counter
PIT (8254)
43h
RESERVED
Timer/Counter
PIT
4E–4F
LPC SIO
LPC SIO
Forwarded to LPC
50h–52h
Timer/Counter
Timer/Counter
PIT
53h
RESERVED
Timer/Counter
PIT
60h
Microcontroller
Microcontroller
Forwarded to LPC
61h
NMI Controller
NMI Controller
CPU I/F
62h
Microcontroller
Microcontroller
Forwarded to LPC
63h
NMI Controller
NMI Controller
CPU I/F
64h
Microcontroller
Microcontroller
Forwarded to LPC
65h
NMI Controller
NMI Controller
CPU I/F
66h
Microcontroller
Microcontroller
Forwarded to LPC
67h
NMI Controller
NMI Controller
CPU I/F
70h
RESERVED
NMI and RTC Controller
RTC
71h
RTC Controller
RTC Controller
RTC
72h
RTC Controller
NMI and RTC Controller
RTC
73h
RTC Controller
RTC Controller
RTC
74h
RTC Controller
NMI and RTC Controller
RTC
75h
RTC Controller
RTC Controller
RTC
76h
RTC Controller
NMI and RTC Controller
RTC
77h
RTC Controller
RTC Controller
RTC
80h
DMA Controller
DMA Controller and LPC or PCI
DMA
Intel® 82801DB ICH4 Datasheet
Register and Memory Mapping
Table 6-2. Fixed I/O Ranges Decoded by Intel® ICH4 (Sheet 2 of 2)
I/O Address
Read Target
Write Target
Internal Unit
81h–83h
DMA Controller
DMA Controller
DMA
84h–86h
DMA Controller
DMA Controller and LPC or PCI
DMA
87h
DMA Controller
DMA Controller
DMA
88h
DMA Controller
DMA Controller and LPC or PCI
DMA
89h–8Bh
DMA Controller
DMA Controller
DMA
8Ch–8Eh
DMA Controller
DMA Controller and LPC or PCI
DMA
08Fh
DMA Controller
DMA Controller
DMA
90h–91h
DMA Controller
DMA Controller
DMA
92h
Reset Generator
Reset Generator
CPU I/F
93h–9Fh
DMA Controller
DMA Controller
DMA
A0h–A1h
Interrupt Controller
Interrupt Controller
Interrupt
A4h–A5h
Interrupt Controller
Interrupt Controller
Interrupt
A8h–A9h
Interrupt Controller
Interrupt Controller
Interrupt
ACh–ADh
Interrupt Controller
Interrupt Controller
Interrupt
B0h–B1h
Interrupt Controller
Interrupt Controller
Interrupt
B2h–B3h
Power Management
Power Management
Power Management
B4h–B5h
Interrupt Controller
Interrupt Controller
Interrupt
B8h–B9h
Interrupt Controller
Interrupt Controller
Interrupt
BCh–BDh
Interrupt Controller
Interrupt Controller
Interrupt
C0h–D1h
DMA Controller
DMA Controller
DMA
D2h–DDh
RESERVED
DMA Controller
DMA
DEh–DFh
DMA Controller
DMA Controller
DMA
F0h
See Note 3
FERR#/IGNNE# / Interrupt
Controller
CPU I/F
170h–177h
IDE Controller2
IDE Controller2
Forwarded to IDE
1F0h–1F7h
1
1
Forwarded to IDE
2
IDE Controller
2
IDE Controller
376h
IDE Controller
IDE Controller
Forwarded to IDE
3F6h
IDE Controller1
IDE Controller1
Forwarded IDE
4D0h–4D1h
Interrupt Controller
Interrupt Controller
Interrupt
CF9h
Reset Generator
Reset Generator
CPU I/F
NOTES:
1. Only if IDE Standard I/O space is enabled for Primary Channel and the IDE controller is in legacy mode.
Otherwise, the target is PCI.
2. Only if IDE Standard I/O space is enabled for Secondary Channel and the IDE controller is in legacy mode.
Otherwise, the target is PCI.
3. If POS_DEC_EN bit is enabled, reads from F0h will not be decoded by the ICH4. If POS_DEC_EN is not
enabled, reads from F0h will forward to LPC.
Intel® 82801DB ICH4 Datasheet
247
Register and Memory Mapping
6.3.2
Variable I/O Decode Ranges
Table 6-3 shows the Variable I/O Decode Ranges. They are set using Base Address Registers
(BARs) or other configuration bits in the various PCI configuration spaces. The PNP software (PCI
or ACPI) can use their configuration mechanisms to set and adjust these values.
When a cycle is detected on the hub interface, the ICH4 will positively decode the cycle. If the
response is on the behalf of an LPC device, ICH4 will forward the cycle to the LPC I/F.
Refer to Table A-3 for a complete list of all variable I/O registers.
Warning:
The Variable I/O Ranges should not be set to conflict with the Fixed I/O Ranges. Unpredictable
results if the configuration software allows conflicts to occur. The ICH4 does not perform any
checks for conflicts.
Table 6-3. Variable I/O Decode Ranges
Range Name
248
Mappable
Size (Bytes)
Target
ACPI
Anywhere in 64-KB I/O Space
64
Power Management
IDE Bus Master
Anywhere in 64-KB I/O Space
16
IDE Unit
USB UHCI Controller #1
Anywhere in 64-KB I/O Space
32
USB Unit 1
SMBus
Anywhere in 64-KB I/O Space
32
SMB Unit
AC ’97 Audio Mixer
Anywhere in 64-KB I/O Space
256
AC ’97 Unit
AC ’97 Bus Master
Anywhere in 64-KB I/O Space
64
AC ’97 Unit
AC ’97 Modem Mixer
Anywhere in 64-KB I/O Space
256
AC ’97 Unit
TCO
96 Bytes above ACPI Base
32
TCO Unit
GPIO
Anywhere in 64-KB I/O Space
64
GPIO Unit
Parallel Port
3 ranges in 64-KB I/O Space
8
LPC Peripheral
Serial Port 1
8 Ranges in 64-KB I/O Space
8
LPC Peripheral
Serial Port 2
8 Ranges in 64-KB I/O Space
8
LPC Peripheral
Floppy Disk Controller
2 Ranges in 64-KB I/O Space
8
LPC Peripheral
MIDI
4 Ranges in 64-KB I/O Space
2
LPC Peripheral
MSS
4 Ranges in 64-KB I/O Space
8
LPC Peripheral
SoundBlaster
2 Ranges in 64-KB I/O Space
32
LPC Peripheral
LAN
Anywhere in 64-KB I/O Space
64
LAN Unit
USB UHCI Controller #2
Anywhere in 64-KB I/O Space
32
USB Unit 2
USB UHCI Controller #3
Anywhere in 64-KB I/O Space
32
USB Unit 3
LPC Generic 1
Anywhere in 64-KB I/O Space
128
LPC Peripheral
LPC Generic 2
Anywhere in 64-KB I/O Space
16
LPC Peripheral
Monitors 4:7
Anywhere in 64-KB I/O Space
16
LPC Peripheral or Trap on PCI
Native IDE Primary
Command
Anywhere in 64-KB I/O Space
8
IDE Unit
Native IDE Primary Control
Anywhere in 64-KB I/O Space
4
IDE Unit
Native IDE Secondary
Command
Anywhere in 64-KB I/O Space
8
IDE Unit
Native IDE Secondary
Control
Anywhere in 64-KB I/O Space
4
IDE Unit
Intel® 82801DB ICH4 Datasheet
Register and Memory Mapping
6.4
Memory Map
Table 6-4 shows (from the processor perspective) the memory ranges that the ICH4 will decode.
Cycles that arrive from the hub interface that are not directed to any of the internal memory targets
that decode directly from hub interface will be driven out on PCI. The ICH4 may then claim the
cycle for it to be forwarded to LPC or claimed by the internal APIC. If subtractive decode is
enabled, the cycle can be forwarded to LPC.
PCI cycles generated by an external PCI master will be positively decoded unless it falls in the
PCI-PCI bridge forwarding range (those addresses are reserved for PCI peer-to-peer traffic). If the
cycle is not in the I/O APIC or LPC ranges, it will be forwarded up the hub interface to the Host
controller. PCI masters can not access the memory ranges for functions that decode directly from
Hub Interface.
Table 6-4. Memory Decode Ranges from Processor Perspective (Sheet 1 of 2)
Memory Range
Target
0000 0000–000D FFFFh
0010 0000h–TOM
(Top of Memory)
Main Memory
Dependency/Comments
TOM registers in Host controller
000E 0000–000F FFFFh
FWH
FEC0 0000–FEC0 0100h
I/O APIC inside
ICH4
FFC0 0000–FFC7 FFFFh
FF80 0000–FF87 FFFFh
FWH
Bit 0 in FWH Decode Enable Register
FFC8 0000–FFCF FFFFh
FF88 0000–FF8F FFFFh
FWH
Bit 1 in FWH Decode Enable Register
FFD0 0000–FFD7 FFFFh
FF90 0000–FF97 FFFFh
FWH
Bit 2 in FWH Decode Enable Register is set
FFD8 0000–FFDF FFFFh
FF98 0000–FF9F FFFFh
FWH
Bit 3 in FWH Decode Enable Register is set
FFE0 000–FFE7 FFFFh
FFA0 0000–FFA7 FFFFh
FWH
Bit 4 in FWH Decode Enable Register is set
FFE8 0000–FFEF FFFFh
FFA8 0000–FFAF FFFFh
FWH
Bit 5 in FWH Decode Enable Register is set
FFF0 0000–FFF7 FFFFh
FFB0 0000–FFB7 FFFFh
FWH
Bit 6 in FWH Decode Enable Register is set.
FFF8 0000–FFFF FFFFh
FFB8 0000–FFBF FFFFh
FWH
Always enabled.
The top two 64 KB blocks of this range can be swapped, as
described in Section 7.4.1.
FF70 0000–FF7F FFFFh
FF30 0000–FF3F FFFFh
FWH
Bit 3 in FWH Decode Enable 2 Register is set
FF60 0000–FF6F FFFFh
FF20 0000–FF2F FFFFh
FWH
Bit 2 in FWH Decode Enable 2 Register is set
FF50 0000–FF5F FFFFh
FF10 0000–FF1F FFFFh
FWH
Bit 1 in FWH Decode Enable 2 Register is set
FF40 0000–FF4F FFFFh
FF00 0000–FF0F FFFFh
FWH
Bit 0 in FWH Decode Enable 2 Register is set
4 KB anywhere in 4 GB
range
Integrated LAN
Controller
Intel® 82801DB ICH4 Datasheet
Bit 7 in FWH Decode Enable Register is set
Enable via BAR in Device 29:Function 0 (Integrated LAN
Controller)
249
Register and Memory Mapping
Table 6-4. Memory Decode Ranges from Processor Perspective (Sheet 2 of 2)
Memory Range
Target
1 KB anywhere in 4 GB
range
IDE Expansion2
1 KB anywhere in 4 GB
range
USB EHCI
Controller1,2
All other
PCI
Dependency/Comments
Enable via standard PCI mechanism and bits in IDE I/O
Configuration Register (Device 31, Function 1)
Enable via standard PCI mechanism (Device 29, Function
7)
None
NOTES:
1. These ranges are decoded directly from the hub interface. The memory cycles will not be seen on PCI.
2. Software must not attempt locks to memory mapped I/O ranges for USB EHCI and IDE Expansion. If
attempted, the lock is not honored, which means potential deadlock conditions may occur.
6.4.1
Boot-Block Update Scheme
The ICH4 supports a “top-block swap” mode that has the ICH4 swap the top block in the FWH (the
boot block) with another location. This allows for safe update of the Boot Block (even if a power
failure occurs). When the “TOP_SWAP” Enable bit is set, the ICH4 will invert A16 for cycles
targeting FWH BIOS space. When this bit is 0, the ICH4 will not invert A16. This bit is
automatically set to 0 by RTCRST#, but not by PCIRST#.
The scheme is based on the concept that the top block is reserved as the “boot” block, and the block
immediately below the top block is reserved for doing boot-block updates.
The algorithm is:
1. Software copies the top block to the block immediately below the top
2. Software checks that the copied block is correct. This could be done by performing a
checksum calculation.
3. Software sets the TOP_SWAP bit. This will invert A16 for cycles going to the FWH. CPU
access to FFFF_0000 through FFFF_FFFF will be directed to FFFE_0000 through
FFFE_FFFF in the FWH, and processor accesses to FFFE_0000 through FFFE_FFFF will be
directed to FFFF_0000 through FFFF_FFFF.
4. Software erases the top block
5. Software writes the new top block
6. Software checks the new top block
7. Software clears the TOP_SWAP bit
If a power failure occurs at any point after step 3, the system will be able to boot from the copy of
the boot block that is stored in the block below the top. This is because the TOP_SWAP bit is
backed in the RTC well.
250
Note:
The top-block swap mode may be forced by an external strapping option (See Section 2.20.1).
When top-block swap mode is forced in this manner, the TOP_SWAP bit cannot be cleared by
software. A re-boot with the strap removed will be required to exit a forced top-block swap mode.
Note:
Top-block swap mode only affects accesses to the FWH BIOS space, not feature space.
Note:
The top-block swap mode has no effect on accesses below FFFE_0000.
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7
LAN Controller Registers (B1:D8:F0)
The ICH4 integrated LAN controller appears to reside at PCI Device 8, Function 0 on the
secondary side of the ICH4’s virtual PCI-to-PCI Bridge (See Section 5.1.2). This is typically Bus 1,
but may be assigned a different number depending upon system configuration. The LAN controller
acts as both a master and a slave on the PCI bus. As a master, the LAN controller interacts with the
system main memory to access data for transmission or deposit received data. As a slave, some of
the LAN controller’s control structures are accessed by the host processor to read or write
information to the on-chip registers. The processor also provides the LAN controller with the
necessary commands and pointers that allow it to process receive and transmit data.
7.1
PCI Configuration Registers (B1:D8:F0)
Note:
Registers that are not shown should be treated as Reserved (See Section 6.2 for details).
.
Table 7-1. LAN Controller PCI Configuration Register Address Map
(LAN Controller—B1:D8:F0)
Offset
Mnemonic
00–01h
VID
Register Name
Default
Type
Vendor ID
8086h
RO
02–03h
DID
Device ID
103Ah
RO
04–05h
PCICMD
PCI Device Command Register
0000h
R/W, RO
06–07h
PCISTS
PCI Device Status Register
0290h
R/WC, RO
08h
REVID
See Note
RO
0Ah
SCC
Sub Class Code
00h
RO
0Bh
BCC
Base Class Code
02h
RO
PCI Master Latency Timer
00h
R/W
Header Type
00h
RO
CSR Memory-Mapped Base Address
0008h
R/W, RO
CSR I/O-Mapped Base Address
0001h
R/W, RO
Subsystem Vendor ID
0000h
RO
Subsystem ID
0000h
RO
0Dh
PMLT
0Eh
HEADTYP
10–13h
CSR_MEM_BASE
14–17h
CSR_IO_BASE
2C–2Dh
SVID
2E–2Fh
SID
34h
CAP_PTR
3Ch
Revision ID
Capabilities Pointer
DCh
RO
INT_LN
Interrupt Line
00h
R/W
3D
INT_PN
Interrupt Pin
01h
RO
3E
MIN_GNT
Minimum Grant
08h
RO
Maximum Latency
38h
RO
Capability ID
01h
RO
00h
RO
3F
MAX_LAT
DCh
CAP_ID
DDh
NXT_PTR
Next Item Pointer
DE–DFh
PM_CAP
Power Management Capabilities
E0–E1h
PMCSR
Power Management Control/Status
E3
PCIDATA
PCI Power Management Data
FE21h
RO
0000h
R/WC, R/W,
RO
00h
RO
NOTE: Refer to the ICH4 specification update for the value of the Revision ID Register.
Intel® 82801DB ICH4 Datasheet
251
LAN Controller Registers (B1:D8:F0)
7.1.1
VID—Vendor ID Register (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
00–01h
8086h
Bit
15:0
7.1.2
Attribute:
Size:
RO
16 bits
Description
Vendor Identification Value — RO. This is a 16-bit value assigned to Intel.
DID—Device ID Register (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
Bit
02–03h
103Ah
Attribute:
Size:
RO
16 bits
Description
Device Identification Value — RO. This is a 16-bit value assigned to the Intel® ICH4 integrated
LAN controller.
15:0
252
1. If the EEPROM is not present (or not properly programmed), reads to the Device ID return the
default value of 103Ah
2. If the EEPROM is present (and properly programmed) and if the value of Word 23h is not
0000f or FFFFh, the Device ID is loaded from the EEPROM, Word 23h after the hardware
reset. (See Section 7.1.14 for details)
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7.1.3
PCICMD—PCI Command Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
04–05h
0000h
Bit
15:10
9
Attribute:
Size:
R/W, RO
16 bits
Description
Reserved
Fast Back to Back Enable (FBE) — RO. Hardwired to 0. The integrated LAN controller will not run
fast back-to-back PCI cycles.
SERR# Enable (SERR_EN) — R/W.
8
0 = Disable.
1 = Enable. Allow SERR# to be asserted.
7
Wait Cycle Control (WCC) — RO. Hardwired to 0. Not implemented.
6
Parity Error Response (PER) — R/W
0 = The LAN controller will ignore PCI parity errors.
1 = The integrated LAN controller will take normal action when a PCI parity error is detected and
will enable generation of parity on the hub interface.
5
VGA Palette Snoop (VPS) — RO. Hardwired to 0. Not Implemented.
4
Memory Write and Invalidate Enable (MWIE) — R/W.
0 = Disable. The LAN controller will not use the Memory Write and Invalidate command.
1 = Enable.
3
Special Cycle Enable (SCE) — RO. Hardwired to 0. The LAN controller ignores special cycles.
2
Bus Master Enable (BME) — R/W.
0 = Disable.
1 = Enable. The Intel® ICH4’s integrated may function as a PCI bus master.
1
Memory Space Enable (MSE) — R/W.
0 = Disable.
1 = Enable. The ICH4’s integrated LAN controller will respond to the memory space accesses.
0
I/O Space Enable (IOSE) — R/W.
0 = Disable.
1 = Enable. The ICH4’s integrated LAN controller will respond to the I/O space accesses.
Intel® 82801DB ICH4 Datasheet
253
LAN Controller Registers (B1:D8:F0)
7.1.4
PCISTS—PCI Status Register (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
Attribute:
Size:
R/WC, RO
16 bits
Bit
Description
15
Detected Parity Error (DPE) — R/WC.
0 = This bit is cleared by writing a 1 to the bit location.
1 = The Intel® ICH4’s integrated LAN controller has detected a parity error on the PCI bus (will be
set even if Parity Error Response is disabled in the PCI Command register).
14
Signaled System Error (SSE) — R/WC.
0 = This bit is cleared by writing a 1 to the bit location.
1 = The ICH4’s integrated LAN controller has asserted SERR#. (SERR# can be routed to cause
NMI, SMI# or interrupt.
13
Master Abort Status (MAS) — R/WC.
0 = This bit is cleared by writing a 1 to the bit location.
1 = The ICH4’s integrated LAN controller (as a PCI master) has generated a master abort.
12
Received Target Abort (RTA) — R/WC.
0 = This bit is cleared by writing a 1 to the bit location.
1 = The ICH4’s integrated LAN controller (as a PCI master) has received a target abort.
11
Signaled Target Abort (STA) — RO. Hardwired to 0. The device will never signal Target Abort.
10:9
DEVSEL# Timing Status (DEV_STS) —RO.
01h = Medium timing.
8
Data Parity Error Detected (DPED) — R/WC.
0 = This bit is cleared by writing a 1 to the bit location.
1 = All of the following three conditions have been met:
1. The LAN controller is acting as bus master
2. The LAN controller has asserted PERR# (for reads) or detected PERR# asserted (for writes)
3. The Parity Error Response bit in the LAN controller’s PCI Command Register is set.
7
Fast Back to Back Capable (FB2BC) — RO. Hardwired to 1. The device can accept fast back-toback transactions.
6
User Definable Features (UDF) — RO. Hardwired to 0. Not implemented.
5
66 MHz Capable (66MHZ_CAP) — RO. Hardwired to 0. The device does not support 66 MHz PCI.
4
Capabilities List (CAP_LIST) — RO.
0 = The EEPROM indicates that the integrated LAN controller does not support PCI Power
Management.
1 = The EEPROM indicates that the integrated LAN controller supports PCI Power Management.
3:0
254
06–07h
0290h
Reserved
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7.1.5
REVID—Revision ID Register (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
08h
See Note
Attribute:
Size:
RO
8 bits
Bit
Description
7:0
Revision Identification Value — RO. This 8-bit value indicates the revision number for the
integrated LAN controller. The three least significant bits in this register may be overridden by the ID
and REV ID fields in the EEPROM.
NOTE: Refer to the ICH4 specification update for the value of the Revision ID Register.
7.1.6
SCC—Sub-Class Code Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
0Ah
00h
Bit
7:0
7.1.7
RO
8 bits
Description
Sub Class Code — RO. 8-bit value that specifies the sub-class of the device as an Ethernet
controller.
BCC—Base-Class Code Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
0Bh
02h
Bit
7:0
7.1.8
Attribute:
Size:
Attribute:
Size:
RO
8 bits
Description
Base Class Code — RO. 8-bit value that specifies the base class of the device as a network
controller.
CLS—Cache Line Size Register (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
Bit
0Ch
00h
Attribute:
Size:
R/W
8 bits
Description
7:5
Reserved
4:3
Cache Line Size (CLS) — R/W.
00 = Memory Write and Invalidate (MWI) command will not be used by the integrated LAN controller.
01 = MWI command will be used with Cache Line Size set to 8 DWords (only set if a value of 08h is
written to this register).
10 = MWI command will be used with Cache Line Size set to 16 DWords (only set if a value of 10h is
written to this register).
11 = Invalid. MWI command will not be used.
2:0
Reserved
Intel® 82801DB ICH4 Datasheet
255
LAN Controller Registers (B1:D8:F0)
7.1.9
PMLT—PCI Master Latency Timer Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
0Dh
00h
Bit
7.1.10
7:3
Master Latency Timer Count (MLTC) — R/W. Defines the number of PCI clock cycles that the
integrated LAN controller may own the bus while acting as bus master.
2:0
Reserved
HEADTYP—Header Type Register
(LAN Controller—B1:D8:F0)
0Eh
00h
Bit
7
6:0
RO
8 bits
Multi-Function Device — RO. Hardwired to 0 to indicate a single function device.
Header Type — RO. This 7-bit field identifies the header layout of the configuration space as an
Ethernet controller.
CSR_MEM_BASE CSR — Memory-Mapped Base Address
Register (LAN Controller—B1:D8:F0)
10–13h
0000 0008h
Attribute:
Size:
R/W, RO
32 bits
The ICH4’s integrated LAN controller requires one BAR for memory mapping. Software
determines which BAR (memory or I/O) is used to access the Lan controller’s CSR registers.
Bit
Description
31:12
Base Address — R/W. Upper 20 bits of the base address provides 4 KB of memory-Mapped space
for the LAN controller’s Control/Status Registers.
11:4
Reserved
3
Prefetchable — RO. Hardwired to 0 to indicate that this is not a pre-fetchable memory-Mapped
address range.
2:1
Type — RO. Hardwired to 00b to indicate the memory-Mapped address range may be located
anywhere in 32-bit address space.
0
256
Attribute:
Size:
Description
Offset Address:
Default Value:
Note:
R/W
8 bits
Description
Offset Address:
Default Value:
7.1.11
Attribute:
Size:
Memory Space Indicator — RO. Hardwired to 0 to indicate that this base address maps to memory
space.
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7.1.12
CSR_IO_BASE — CSR I/O-Mapped Base Address Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
Note:
14–17h
0000 0001h
Attribute:
Size:
The ICH4’s integrated LAN controller requires one BAR for memory mapping. Software
determines which BAR (memory or I/O) is used to access the Lan controller’s CSR registers.
Bit
Description
31:16
Reserved
15:6
Base Address — R/W. Provides 64 bytes of I/O-Mapped address space for the LAN controller’s
Control/Status Registers.
5:1
Reserved
I/O Space Indicator — RO. Hardwired to 1 to indicate that this base address maps to I/O space.
0
7.1.13
SVID — Subsystem Vendor ID (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
2C–2D
0000h
Attribute:
Size:
Bit
15:0
7.1.14
RO
16 bits
Description
Subsystem Vendor ID (SVID) — RO. (see Section 7.1.14 for details)
SID — Subsystem ID (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
2E–2Fh
0000h
Attribute:
Size:
Bit
15:0
Note:
R/W, RO
32 bits
RO
16 bits
Description
Subsystem ID (SID) — RO.
The ICH4’s integrated LAN controller provides support for configurable Subsystem ID and
Subsystem Vendor ID fields. After reset, the LAN controller automatically reads addresses Ah
through Ch, and 23h of the EEPROM. The LAN controller checks bits 15:13 in the EEPROM word
Ah, and functions according to Table 7-2.
Table 7-2. Configuration of Subsystem ID and Subsystem Vendor ID via EEPROM
Bits 15:14
Bit 13
Device ID
Vendor ID
Revision ID
Subsystem ID
Subsystem
Vendor ID
11b, 10b,
00b
X
103Ah
8086h
Note 1
0000h
0000h
01b
0b
Word 23h
8086h
Note 1
Word Bh
Word Ch
Word Ch
REVID + Word Ah, bits
10:8
Word Bh
Word Ch
01b
1b
Word 23h
NOTE:
1. Refer to the ICH4 specification update for the value of the Revision ID Register.
2. The Device ID is loaded from Word 23h only if the value of Word 23h is not 0000h or FFFFh
Intel® 82801DB ICH4 Datasheet
257
LAN Controller Registers (B1:D8:F0)
7.1.15
CAP_PTR — Capabilities Pointer
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
34h
DCh
Bit
7:0
7.1.16
Capabilities Pointer (CAP_PTR) — RO. Hardwired to DCh; indicates the offset within
configuration space for the location of the Power Management registers.
INT_LN — Interrupt Line Register
(LAN Controller—B1:D8:F0)
3Ch
00h
Bit
7:0
R/W
8 bits
Interrupt Line (INT_LN) — R/W. Identifies the system interrupt line to which the LAN controller’s
PCI interrupt request pin (as defined in the Interrupt Pin Register) is routed.
INT_PN — Interrupt Pin Register
(LAN Controller—B1:D8:F0)
3Dh
01h
Bit
7:0
Attribute:
Size:
RO
8 bits
Description
Interrupt Pin (INT_PN) — RO. Hardwired to 01h to indicate that the LAN controller’s interrupt
request is connected to PIRQA#. However, in the Intel® ICH4 implementation, when the LAN
controller interrupt is generated PIRQ[E]# will go active, not PIRQ[A]#. Note that if the PIRQ[E]#
signal is used as a GPIO, the external visibility will be lost (though PIRQ[E]# will still go active
internally).
MIN_GNT — Minimum Grant Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
258
Attribute:
Size:
Description
Offset Address:
Default Value:
7.1.18
RO
8 bits
Description
Offset Address:
Default Value:
7.1.17
Attribute:
Size:
3Eh
08h
Attribute:
Size:
RO
8 bits
Bit
Description
7:0
Minimum Grant (MIN_GNT) — RO. This field indicates the amount of time (in increments of 0.25 µs)
that the LAN controller needs to retain ownership of the PCI bus when it initiates a transaction.
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7.1.19
MAX_LAT — Maximum Latency Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
3Fh
38h
Bit
7:0
7.1.20
RO
8 bits
Description
Maximum Latency (MAX_LAT) — RO. This field defines how often (in increments of 0.25 µs) the
LAN controller needs to access the PCI bus.
CAP_ID — Capability ID Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
DCh
01h
Bit
7:0
7.1.21
Attribute:
Size:
Attribute:
Size:
RO
8 bits
Description
Capability ID (CAP_ID) — RO. Hardwired to 01h to indicate that the Intel® ICH4’s integrated LAN
controller supports PCI Power Management.
NXT_PTR — Next Item Pointer (LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
Bit
7:0
DDh
00h
Attribute:
Size:
RO
8 bits
Description
Next Item Pointer (NXT_PTR) — RO. Hardwired to 00b to indicate that power management is the
last item in the Capabilities list.
Intel® 82801DB ICH4 Datasheet
259
LAN Controller Registers (B1:D8:F0)
7.1.22
PM_CAP — Power Management Capabilities
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
DE–DFh
FE21h
Bit
RO
16 bits
Description
15:11
PME Support — RO. Hardwired to 11111b. This 5-bit field indicates the power states in which the
LAN controller may assert PME#. The LAN controller supports wake-up in all power states.
10
D2 Support — RO. Hardwired to 1 to indicate that the LAN controller supports the D2 power state.
9
D1 Support — RO. Hardwired to 1 to indicate that the LAN controller supports the D1 power state.
8:6
Auxiliary Current — RO. Hardwired to 000b to indicate that the LAN controller implements the Data
registers. The auxiliary power consumption is the same as the current consumption reported in the
D3 state in the Data register.
5
Device Specific Initialization (DSI) — RO. Hardwired to 1 to indicate that special initialization of this
function is required (beyond the standard PCI configuration header) before the generic class device
driver is able to use it. DSI is required for the LAN controller after D3-to-D0 reset.
4
Reserved
3
PME Clock — RO. Hardwired to 0 to indicate that the LAN controller does not require a clock to
generate a power management event.
2:0
7.1.23
Attribute:
Size:
Version — RO. Hardwired to 010b to indicate that the LAN controller complies with of the PCI
Power Management Specification, Revision 1.1.
PMCSR — Power Management Control/Status Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
E0–E1h
0000h
Bit
Attribute:
Size:
R/WC, R/W, RO
16 bits
Description
PME Status — R/WC.
15
14:13
Data Scale — RO. This field indicates the data register scaling factor. It equals 10b for registers
zero through eight and 00b for registers nine through fifteen, as selected by the “Data Select” field.
12:9
Data Select — R/W. This field is used to select which data is reported through the Data register and
Data Scale field.
8
PME Enable — R/W. This bit enables the Intel® ICH4’s integrated LAN controller to assert PME#.
0 = The device will not assert PME#.
1 = Enable PME# assertion when PME Status is set.
7:5
4
3:2
260
0 = Software clears this bit by writing a 1 to the bit location. This also deasserts the PME# signal
and clears the PME status bit in the Power Management Driver Register. When the PME#
signal is enabled, the PME# signal reflects the state of the PME status bit.
1 = Set upon occurrence of a wake-up event, independent of the state of the PME Enable bit.
Reserved
Dynamic Data — RO. Hardwired to 0 to indicate that the device does not support the ability to
monitor the power consumption dynamically.
Reserved
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
Bit
Description
Power State — R/W. This 2-bit field is used to determine the current power state of the integrated
LAN controller, and to put it into a new power state. The definition of the field values is as follows:
00 = D0
01 = D1
10 = D2
11 = D3
1:0
7.1.24
PCIDATA — PCI Power Management Data Register
(LAN Controller—B1:D8:F0)
Offset Address:
Default Value:
E3h
00h
Attribute:
Size:
Bit
7:0
Note:
RO
8 bits
Description
State dependent power consumption and heat dissipation data.
The data register is an 8-bit read only register that provides a mechanism for the ICH4’s integrated
LAN controller to report state dependent maximum power consumption and heat dissipation. The
value reported in this register depends on the value written to the Data Select field in the PMCSR
register. The power measurements defined in this register have a dynamic range of 0 W to 2.55 W
with 0.01 W resolution, scaled according to the Data Scale field in the PMCSR. The structure of
the Data Register is given in Table 7-3.
Table 7-3. Data Register Structure
Data Select
Data Scale
0
2
D0 Power Consumption
1
2
D1 Power Consumption
2
2
D2 Power Consumption
3
2
D3 Power Consumption
4
2
D0 Power Dissipated
5
2
D1 Power Dissipated
6
2
D2 Power Dissipated
7
2
D3 Power Dissipated
8
2
Common Function Power Dissipated
9–15
0
Reserved
Intel® 82801DB ICH4 Datasheet
Data Reported
261
LAN Controller Registers (B1:D8:F0)
7.2
LAN Control / Status Registers (CSR)
Table 7-4. Intel® ICH4 Integrated LAN Controller CSR Space
Offset
Default
Type
01h–00h
SCB Status Word
0000h
R/WC
03h–02h
SCB Command Word
0000h
R/W
07h–04h
SCB General Pointer
0000 0000h
R/W
0Bh–08h
PORT
0000 0000h
R/W-Special
0Dh–0Ch
Reserved
—
—
00h
R/W, RO, WO
—
—
0Eh
EEPROM Control Register
0Fh
Reserved
13h–10h
MDI Control Register
0000 0000h
R/W-Special
17h–14h
Receive DMA Byte Count
0000 0000h
RO
18h
Early Receive Interrupt
00h
R/W
1A–19h
Flow Control Register
0000h
R/W
1Bh
PMDR
00h
R/WC
1Ch
General Control
00
R/W
1Dh
General Status
N/A
RO
—
—
1Eh–3Ch
7.2.1
Register Name
Reserved
System Control Block Status Word Register
Offset Address:
Default Value:
00–01h
0000h
Attribute:
Size:
R/WC, RO
16 bits
The ICH4’s integrated LAN controller places the status of its Command and Receive units and
interrupt indications in this register for the processor to read.
262
Bit
Description
15
Command Unit (CU) Executed (CX)— R/WC.
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = Interrupt signaled because the CU has completed executing a command with its interrupt bit set.
14
Frame Received (FR) — R/WC.
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = Interrupt signaled because the Receive Unit (RU) has finished receiving a frame.
13
CU Not Active (CNA) — R/WC.
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = The Command Unit left the Active state or entered the Idle state. There are 2 distinct states of the
CU. When configured to generate CNA interrupt, the interrupt will be activated when the CU
leaves the Active state and enters either the Idle or the Suspended state. When configured to
generate CI interrupt, an interrupt will be generated only when the CU enters the Idle state.
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
Bit
Description
Receive Not Ready (RNR) — R/WC.
12
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = Interrupt signaled because the Receive Unit left the Ready state. This may be caused by an RU
Abort command, a no resources situation, or set suspend bit due to a filled Receive Frame
Descriptor.
11
Management Data Interrupt (MDI) — R/WC.
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = Set when a Management Data Interface read or write cycle has completed. The management
data interrupt is enabled through the interrupt enable bit (bit 29 in the Management Data
Interface Control register in the CSR).
10
Software Interrupt (SWI) — R/WC.
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = Set when software generates an interrupt.
9
Early Receive (ER) — R/WC.
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = Indicates the occurrence of an Early Receive Interrupt.
8
Flow Control Pause (FCP) — R/WC.
0 = Software acknowledges the interrupt and clears this bit by writing a 1 to the bit position.
1 = Indicates Flow Control Pause interrupt.
7:6
Command Unit Status (CUS) — RO.
00 = Idle
01 = Suspended
10 = LPQ (Low Priority Queue) active
11 = HPQ (High Priority Queue) active
5:2
Receive Unit Status (RUS) —RO.
0000 = Idle
1000 = Reserved
0001 = Suspended
1001 = Suspended with no more RBDs
0010 = No Resources
1010 = No resources due to no more RBDs
0011 = Reserved
1011 = Reserved
0100 = Ready
1100 = Ready with no RBDs present
0101 = Reserved
1101 = Reserved
0110 = Reserved
1110 = Reserved
0111 = Reserved
1111 = Reserved
1:0
Reserved
Intel® 82801DB ICH4 Datasheet
263
LAN Controller Registers (B1:D8:F0)
7.2.2
System Control Block Command Word Register
Offset Address:
Default Value:
02–03h
0000h
Attribute:
Size:
R/W
16 bits
The processor places commands for the Command and Receive units in this register. Interrupts are
also acknowledged in this register.
Bit
264
Description
15
CX Mask — R/W.
0 = Interrupt not masked.
1 = Disable the generation of a CX interrupt.
14
FR Mask — R/W.
0 = Interrupt not masked.
1 = Disable the generation of an FR interrupt.
13
CNA Mask — R/W.
0 = Interrupt not masked.
1 = Disable the generation of a CNA interrupt.
12
RNR Mask — R/W.
0 = Interrupt not masked.
1 = Disable the generation of an RNR interrupt.
11
ER Mask — R/W.
0 = Interrupt not masked.
1 = Disable the generation of an ER interrupt.
10
FCP Mask — R/W.
0 = Interrupt not masked.
1 = Disable the generation of an FCP interrupt.
9
Software Generated Interrupt (SI) — WO.
0 = No Effect.
1 = Setting this bit causes the LAN controller to generate an interrupt.
8
Interrupt Mask (IM) — R/W. This bit enables or disables the LAN controller’s assertion of the INTA#
signal. This bit has higher precedence that the Specific Interrupt Mask bits and the SI bit.
0 = Enable the assertion of INTA#.
1 = Disable the assertion of INTA#.
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
Bit
Description
7:4
Command Unit Command (CUC) — R/W. Valid values are listed below. All other values are
Reserved.
0000 = NOP: Does not affect the current state of the unit.
0001 = CU Start: Start execution of the first command on the CBL. A pointer to the first CB of the
CBL should be placed in the SCB General Pointer before issuing this command. The CU
Start command should only be issued when the CU is in the Idle or Suspended states
(never when the CU is in the active state), and all of the previously issued Command
Blocks have been processed and completed by the CU. Sometimes it is only possible to
determine that all Command Blocks are completed by checking that the Complete bit is set
in all previously issued Command Blocks.
0010 = CU Resume: Resume operation of the Command unit by executing the next command.
This command will be ignored if the CU is idle.
0011 = CU HPQ Start: Start execution of the first command on the high priority CBL. A pointer to
the first CB of the HPQ CBL should be placed in the SCB General POinter before issuing
this command.
0100 = Load Dump Counters Address: Tells the device where to write dump data when using the
Dump Statistical Counters or Dump and Reset Statistical Counters commands. This
command must be executed at least once before any usage of the Dump Statistical
Counters or Dump and Reset Statistical Counters commands. The address of the dump
area must be placed in the General Pointer register.
0101 = Dump Statistical Counters: Tells the device to dump its statistical counters to the area
designated by the Load Dump Counters Address command.
0110 = Load CU Base: The device’s internal CU Base Register is loaded with the value in the
CSB General Pointer.
0111 = Dump and Reset Statistical Counters: Tells the device to dump its statistical counters to
the area designated by the Load Dump Counters Address command, and then to clear
these counters.
1010 = CU Static Resume: Resume operation of the Command unit by executing the next
command. This command will be ignored if the CU is idle. This command should be used
only when the CU is in the Suspended state and has no pending CU Resume commands.
1011 = CU HPQ Resume: Resume execution of the first command on the HPQ CBL. this
command will be ignored if the HPQ was never started.
3
2:0
Reserved
Receive Unit Command (RUC) — R/W. Valid values are:
000 = NOP: Does not affect the current state of the unit.
001 = RU Start: Enables the receive unit. The pointer to the RFA must be placed in the SCB
General POinter before using this command. The device pre-fetches the first RFD and the
first RBD (if in flexible mode) in preparation to receive incoming frames that pass its address
filtering.
010 = RU Resume: Resume frame reception (only when in suspended state).
011 = RCV DMA Redirect: Resume the RCV DMA when configured to “Direct DMA Mode.” The
buffers are indicated by an RBD chain which is pointed to by an offset stored in the General
Pointer Register (this offset will be added to the RU Base).
100 = RU Abort: Abort RU receive operation immediately.
101 = Load Header Data Size (HDS): This value defines the size of the Header portion of the RFDs
or Receive buffers. The HDS value is defined by the lower 14 bits of the SCB General Pointer,
so bits 31:15 should always be set to zeros when using this command. Once a Load HDS
command is issued, the device expects only to find Header RFDs, or be used in “RCV Direct
DMA mode” until it is reset. Note that the value of HDS should be an even, non-zero number.
110 = Load RU Base: The device’s internal RU Base Register is loaded with the value in the SCB
General Pointer.
111 = RBD Resume: Resume frame reception into the RFA. This command should only be used
when the RU is already in the “No Resources due to no RBDs” state or the “Suspended with
no more RBDs” state.
Intel® 82801DB ICH4 Datasheet
265
LAN Controller Registers (B1:D8:F0)
7.2.3
System Control Block General Pointer Register
Offset Address:
Default Value:
04–07h
0000 0000h
Bit
15:0
7.2.4
Attribute:
Size:
R/W
32 bits
Description
SCB General Pointer — R/W. The SCB General Pointer register is programmed by software to
point to various data structures in main memory depending on the current SCB Command word.
PORT Register
Offset Address:
Default Value:
08–0Bh
0000 0000h
Attribute:
Size:
R/W (special)
32 bits
The PORT interface allows the processor to reset the ICH4’s internal LAN controller, or perform
an internal self test. The PORT DWORD may be written as a 32-bit entity, two 16-bit entities, or
four 8-bit entities. The LAN controller will only accept the command after the high byte (offset
0Bh) is written; therefore, the high byte must be written last.
266
Bit
Description
31:4
Pointer Field — R/W (special). A 16-byte aligned address must be written to this field when issuing
a Self-Test command to the PORT interface.The results of the Self Test will be written to the
address specified by this field.
3:0
PORT Function Selection — R/W (special). Valid values are listed below. All other values are
Reserved.
0000 = PORT Software Reset: Completely resets the LAN controller (all CSR and PCI registers).
This command should not be used when the device is active. If a PORT Software Reset is
desired, software should do a Selective Reset (described below), wait for the PORT
register to be cleared (completion of the Selective Reset), and then issue the PORT
Software Reset command. Software should wait approximately 10 µs after issuing this
command before attempting to access the LAN controller’s registers again.
0001 = Self Test: The Self-Test begins by issuing an internal Selective Reset followed by a
general internal self-test of the LAN controller. The results of the self-test are written to
memory at the address specified in the Pointer field of this register. The format of the selftest result is shown in Table 7-5. After completing the self-test and writing the results to
memory, the LAN controller will execute a full internal reset and will re-initialize to the
default configuration. Self-Test does not generate an interrupt of similar indicator to the
host processor upon completion.
0010 = Selective Reset: Sets the CU and RU to the Idle state, but otherwise maintains the current
configuration parameters (RU and CU Base, HDSSize, Error Counters, Configure
information and Individual/Multicast Addresses are preserved). Software should wait
approximately 10 µs after issuing this command before attempting to access the LAN
controller’s registers again.
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
Table 7-5. Self-Test Results Format
Bit
31:13
12
11:6
Description
Reserved
General Self-Test Result — R/W (special).
0 = Pass
1 = Fail
Reserved
5
Diagnose Result — R/W (special). This bit provides the result of an internal diagnostic test of the
Serial Subsystem.
0 = Pass
1 = Fail
4
Reserved
Register Result — R/W (special). This bit provides the result of a test of the internal Parallel
Subsystem registers.
3
2
1:0
7.2.5
0 = Pass
1 = Fail
ROM Content Result — R/W (special). This bit provides the result of a test of the internal
microcode ROM.
0 = Pass
1 = Fail
Reserved
EEPROM Control Register
Offset Address:
Default Value:
0Eh
00h
Attribute:
Size:
RO, R/W, WO
8 bits
The EEPROM Control Register is a 16-bit field that enables a read from and a write to the external
EEPROM.
Bit
7:4
Description
Reserved
3
EEPROM Serial Data Out (EEDO)— RO. Note that this bit represents "Data Out" from the
perspective of the EEPROM device. This bit contains the value read from the EEPROM when
performing read operations.
2
EEPROM Serial Data In (EEDI)— WO. Note that this bit represents "Data In" from the perspective
of the EEPROM device. The value of this bit is written to the EEPROM when performing write
operations.
EEPROM Chip Select (EECS)— R/W.
1
0
0 = Drives the Intel® ICH4’s EE_CS signal low, to disable the EEPROM. this bit must be set to 0 for
a minimum of 1 µs between consecutive instruction cycles.
1 = Drives the ICH4’s EE_CS signal high, to enable the EEPROM.
EEPROM Serial Clock (EESK)— R/W. Toggling this bit, clocks data into or out of the EEPROM.
Software must ensure that this bit is toggled at a rate that meets the EEPROM component’s
minimum clock frequency specification.
0 = Drives the ICH4’s EE_SHCLK signal low.
1 = Drives the ICH4’s EE_SHCLK signal high.
Intel® 82801DB ICH4 Datasheet
267
LAN Controller Registers (B1:D8:F0)
7.2.6
Management Data Interface (MDI) Control Register
Offset Address:
Default Value:
10–13h
0000 0000h
Attribute:
Size:
R/W (special)
32 bits
The Management Data Interface (MDI) Control register is a 32-bit field and is used to read and
write bits from the LAN Connect component. This register may be written as a 32-bit entity, two
16-bit entities, or four 8-bit entities. The LAN controller will only accept the command after the
high byte (offset 13h) is written, therefore the high byte must be written last.
Bit
31:30
29
Description
These bits are reserved and should be set to 00b.
Interrupt Enable — R/W.
0 = Disable.
1 = Enables the LAN controller to assert an interrupt to indicate the end of an MDI cycle.
Ready — R/W.
28
268
0 = Expected to be reset by software at the same time the command is written.
1 = Set by the LAN controller at the end of an MDI transaction.
27:26
Opcode — R/W. These bits define the opcode:
00 = Reserved
01 = MDI write
10 = MDI read
11 = Reserved
25:21
LAN Connect Address — R/W. This field of bits contains the LAN Connect address.
20:16
LAN Connect Register Address — R/W. This field of bits contains the LAN Connect Register
Address.
15:0
Data — R/W. In a write command, software places the data bits in this field, and the LAN controller
transfers the data to the external LAN Connect component. During a read command, the LAN
controller reads these bits serially from the LAN Connect, and software reads the data from this
location.
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7.2.7
Receive DMA Byte Count Register
Offset Address:
Default Value:
14–17h
0000 0000h
Bit
31:0
7.2.8
Attribute:
Size:
RO
32 bits
Description
Receive DMA Byte Count — RO. Keeps track of how many bytes of receive data have been
passed into host memory via DMA.
Early Receive Interrupt Register
Offset Address:
Default Value:
18h
00h
Attribute:
Size:
R/W
8 bits
The Early Receive Interrupt register allows the internal LAN controller to generate an early
interrupt depending on the length of the frame. The LAN controller will generate an interrupt at the
end of the frame regardless of whether or not Early Receive Interrupts are enabled.
Note:
It is recommended that software not utilize this register unless receive interrupt latency is a critical
performance issue in that particular software environment. Using this feature may reduce receive
interrupt latency, but will also result in the generation of more interrupts, that can degrade system
efficiency and performance in some environments.
Bit
Description
7:0
Early Receive Count — R/W. When some non-zero value x is programmed into this register, the
LAN controller will set the ER bit in the SCB Status Word Register and assert INTA# when the byte
count indicates that there are x quad-words remaining to be received in the current frame (based on
the Type/Length field of the received frame). No Early Receive interrupt will be generated if a value
of 00h (the default value) is programmed into this register.
Intel® 82801DB ICH4 Datasheet
269
LAN Controller Registers (B1:D8:F0)
7.2.9
Flow Control Register
Offset Address:
Default Value:
19–1Ah
h
Bit
15:13
Attribute:
Size:
RO, R/W (special)
16 bits
Description
Reserved
FC Paused Low — RO.
12
270
0 = Cleared when the FC timer reaches zero, or a Pause frame is received.
1 = Set when the LAN controller receives a Pause Low command with a value greater than zero.
11
FC Paused — RO.
0 = Cleared when the FC timer reaches zero.
1 = Set when the LAN controller receives a Pause command regardless of its cause (FIFO
reaching Flow Control Threshold, fetching a Receive Frame Descriptor with its Flow Control
Pause bit set, or software writing a 1 to the Xoff bit).
10
FC Full — RO.
0 = Cleared when the FC timer reaches zero.
1 = Set when the LAN controller sends a Pause command with a value greater than zero.
9
Xoff — R/W (special). This bit should only be used if the LAN controller is configured to operate with
IEEE frame-based flow control.
0 = This bit can only be cleared by writing a 1 to the Xon bit (bit 8 in this register).
1 = Writing a 1 to this bit forces the Xoff request to 1 and causes the LAN controller to behave as if
the FIFO extender is full. This bit will also be set to 1 when an Xoff request due to an “RFD
Xoff” bit.
8
Xon — WO. This bit should only be used if the LAN controller is configured to operate with IEEE
frame-based flow control.
0 = This bit always returns 0 on reads.
1 = Writing a 1 to this bit resets the Xoff request to the LAN controller, clearing bit 9 in this register.
7:3
Reserved
2:0
Flow Control Threshold — R/W. The LAN controller can generate a Flow Control Pause frame
when its Receive FIFO is almost full. The value programmed into this field determines the number of
bytes still available in the Receive FIFO when the Pause frame is generated.
Free Bytes
Bits 2:0
in Receive FIFO
Comment
000
0.50 KB
Fast system (recommended default)
001
1.00 KB
010
1.25 KB
011
1.50 KB
100
1.75 KB
101
2.00 KB
110
2.25 KB
111
2.50 KB
Slow system
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7.2.10
Power Management Driver (PMDR) Register
Offset Address:
Default Value:
1Bh
00h
Attribute:
Size:
R/WC
8 bits
The ICH4’s internal LAN controller provides an indication in the PMDR that a wake-up event has
occurred.
Bit
Description
Link Status Change Indication — R/WC.
7
0 = Software clears this bit by writing a 1 to the bit location
1 = The link status change bit is set following a change in link status.
Magic Packet — R/WC.
6
0 = Software clears this bit by writing a 1 to the bit location.
1 = This bit is set when a Magic Packet is received regardless of the Magic Packet wake-up disable
bit in the configuration command and the PME Enable bit in the Power Management Control/
Status Register.
Interesting Packet — R/WC.
5
4:1
0
0 = Software clears this bit by writing a 1 to the bit location.
1 = This bit is set when an “interesting” packet is received. Interesting packets are defined by the
LAN controller packet filters.
Reserved
PME Status — R/WC. This bit is a reflection of the PME Status bit in the Power Management
Control/Status Register (PMCSR).
0 = Software clears this bit by writing a 1 to the bit location. This also clears the PME Status bit in
the PMCSR and de-asserts the PME signal.
1 = Set upon a wake-up event, independent of the PME Enable bit.
Intel® 82801DB ICH4 Datasheet
271
LAN Controller Registers (B1:D8:F0)
7.2.11
General Control Register
Offset Address:
Default Value:
1Ch
00h
Bit
7:4
7.2.12
Attribute:
Size:
R/W
8 bits
Description
Reserved. These bits should be set to 0000b.
3
LAN Connect Software Reset — R/W.
0 = Cleared by software to begin normal LAN Connect operating mode. Software must not attempt
to access the LAN Connect interface for at least 1 ms after clearing this bit.
1 = Software can set this bit to force a reset condition on the LAN Connect interface.
2
Reserved. This bit should be set to 0.
1
Deep Power-Down on Link Down Enable — R/W.
0 = Disable
1 = The Intel® ICH4’s internal LAN controller may enter a deep power-down state (sub-3 mA) in the
D2 and D3 power states while the link is down. In this state, the LAN controller does not keep
link integrity. This state is not supported for point-to-point connection of two end stations.
0
Reserved
General Status Register
Offset Address:
Default Value:
1Dh
h
Bit
7:3
2
Attribute:
Size:
RO
8 bits
Description
Reserved
Duplex Mode — RO. This bit indicates the wire duplex mode.
0 = Half duplex
1 = Full duplex
Speed — RO. This bit indicates the wire speed.
1
0
272
0 = 10 Mbps
1 = 100 Mbps
Link Status Indication — RO. This bit indicates the status of the link.
0 = Invalid
1 = Valid
Intel® 82801DB ICH4 Datasheet
LAN Controller Registers (B1:D8:F0)
7.2.13
Statistical Counters
The ICH4’s integrated LAN controller provides information for network management statistics by
providing on-chip statistical counters that count a variety of events associated with both transmit
and receive. The counters are updated by the LAN controller when it completes the processing of a
frame (that is, when it has completed transmitting a frame on the link or when it has completed
receiving a frame). The Statistical Counters are reported to the software on demand by issuing the
Dump Statistical Counters command or Dump and Reset Statistical Counters command in the SCB
Command Unit Command (CUC) field.
Table 7-6. Statistical Counters (Sheet 1 of 2)
ID
Counter
Description
0
Transmit Good Frames
This counter contains the number of frames that were transmitted
properly on the link. It is updated only after the actual transmission
on the link is completed, not when the frame was read from memory
as is done for the Transmit Command Block status.
4
Transmit Maximum
Collisions (MAXCOL) Errors
This counter contains the number of frames that were not transmitted
because they encountered the configured maximum number of
collisions.
8
Transmit Late Collisions
(LATECOL) Errors
This counter contains the number of frames that were not transmitted
since they encountered a collision later than the configured slot time.
12
Transmit Underrun Errors
A transmit underrun occurs because the system bus cannot keep up
with the transmission. This counter contains the number of frames
that were either not transmitted or retransmitted due to a transmit
DMA underrun. If the LAN controller is configured to retransmit on
underrun, this counter may be updated multiple times for a single
frame.
16
Transmit Lost Carrier Sense
(CRS)
This counter contains the number of frames that were transmitted by
the LAN controller despite the fact that it detected the deassertion of
CRS during the transmission.
20
Transmit Deferred
This counter contains the number of frames that were deferred
before transmission due to activity on the link.
24
Transmit Single Collisions
This counter contains the number of transmitted frames that
encountered one collision.
28
Transmit Multiple Collisions
This counter contains the number of transmitted frames that
encountered more than one collision.
32
Transmit Total Collisions
This counter contains the total number of collisions that were
encountered while attempting to transmit. This count includes late
collisions and frames that encountered MAXCOL.
36
Receive Good Frames
This counter contains the number of frames that were received
properly from the link. It is updated only after the actual reception
from the link is completed and all the data bytes are stored in
memory.
Receive CRC Errors
This counter contains the number of aligned frames discarded
because of a CRC error. This counter is updated, if needed,
regardless of the Receive Unit state. The Receive CRC Errors
counter is mutually exclusive of the Receive Alignment Errors and
Receive Short Frame Errors counters.
Receive Alignment Errors
This counter contains the number of frames that are both misaligned
(for example, CRS deasserts on a non-octal boundary) and contain a
CRC error. The counter is updated, if needed, regardless of the
Receive Unit state. The Receive Alignment Errors counter is
mutually exclusive of the Receive CRC Errors and Receive Short
Frame Errors counters.
40
44
Intel® 82801DB ICH4 Datasheet
273
LAN Controller Registers (B1:D8:F0)
Table 7-6. Statistical Counters (Sheet 2 of 2)
ID
Counter
Description
Receive Resource Errors
This counter contains the number of good frames discarded due to
unavailability of resources. Frames intended for a host whose
Receive Unit is in the No Resources state fall into this category. If the
LAN controller is configured to Save Bad Frames and the status of
the received frame indicates that it is a bad frame, the Receive
Resource Errors counter is not updated.
52
Receive Overrun Errors
This counter contains the number of frames known to be lost
because the local system bus was not available. If the traffic problem
persists for more than one frame, the frames that follow the first are
also lost; however, because there is no lost frame indicator, they are
not counted.
56
Receive Collision Detect
(CDT)
This counter contains the number of frames that encountered
collisions during frame reception.
60
Receive Short Frame Errors
This counter contains the number of received frames that are shorter
than the minimum frame length. The Receive Short Frame Errors
counter is mutually exclusive to the Receive Alignment Errors and
Receive CRC Errors counters. A short frame will always increment
only the Receive Short Frame Errors counter.
64
This counter contains the number of Flow Control frames transmitted
Flow Control Transmit Pause by the LAN controller. This count includes both the Xoff frames
transmitted and Xon (PAUSE(0)) frames transmitted.
68
Flow Control Receive Pause
This counter contains the number of Flow Control frames received by
the LAN controller. This count includes both the Xoff frames received
and Xon (PAUSE(0)) frames received.
72
Flow Control Receive
Unsupported
This counter contains the number of MAC Control frames received
by the LAN controller that are not Flow Control Pause frames. These
frames are valid MAC control frames that have the predefined MAC
control Type value and a valid address but has an unsupported
opcode.
76
Receive TCO Frames
This counter contains the number of TCO packets received by the
LAN controller.
78
Transmit TCO Frames
This counter contains the number of TCO packets transmitted.
48
The Statistical Counters are initially set to zero by the ICH4’s integrated LAN controller after reset.
They cannot be preset to anything other than zero. The LAN controller increments the counters by
internally reading them, incrementing them and writing them back. This process is invisible to the
processor and PCI bus. In addition, the counters adhere to the following rules:
• The counters are wrap-around counters. After reaching FFFFFFFFh the counters wrap around
to 0.
• The LAN controller updates the required counters for each frame. It is possible for more than
one counter to be updated as multiple errors can occur in a single frame.
• The counters are 32 bits wide and their behavior is fully compatible with the IEEE 802.1
standard. The LAN controller supports all mandatory and recommend statistics functions
through the status of the receive header and directly through these Statistical Counters.
The processor can access the counters by issuing a Dump Statistical Counters SCB command. This
provides a “snapshot”, in main memory, of the internal LAN controller statistical counters. The
LAN controller supports 21 counters. The dump could consist of the either 16, 19, or all 21
counters, depending on the status of the Extended Statistics Counters and TCO Statistics
configuration bits in the Configuration command.
274
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
Hub Interface to PCI Bridge Registers
(D30:F0)
8
The hub interface to PCI Bridge resides in PCI Device 30, Function 0 on bus #0. This portion of the
ICH4 implements the buffering and control logic between PCI and the hub interface. The
arbitration for the PCI bus is handled by this PCI device. The PCI decoder in this device must
decode the ranges for the hub interface. All register contents will be lost when core well power is
removed.
8.1
PCI Configuration Registers (D30:F0)
Note:
Registers that are not shown should be treated as Reserved (see Section 6.2 for details).
.
Table 8-1. Hub Interface PCI Configuration Register Address Map (HUB-PCI—D30:F0) (Sheet 1
of 2)
Offset
Mnemonic
00–01h
VID
02–03h
Register Name
Default
Type
Vendor ID
8086h
RO
DID
Device ID
244Eh
RO
04–05h
CMD
PCI Device Command Register
0001h
R/W, RO
06–07h
PD_STS
08h
REVID
0Ah
SCC
0Bh
PCI Device Status Register
0080h
R/WC, RO
See Note
RO
Sub Class Code
04h
RO
BCC
Base Class Code
06h
RO
0Dh
PMLT
Primary Master Latency Timer
00h
RO
0Eh
HEADTYP
Header Type
01h
RO
18h
PBUS_NUM
Primary Bus Number
00h
RO
19h
SBUS_NUM
Secondary Bus Number
00h
R/W
1Ah
SUB_BUS_NUM
1Bh
SMLT
1Ch
1Dh
Revision ID
Subordinate Bus Number
00h
R/W
Secondary Master Latency Timer
00h
R/W
IOBASE
IO Base Register
F0h
R/W, RO
IOLIM
IO Limit Register
00h
R/W, RO
1E–1Fh
SECSTS
Secondary Status Register
0280h
R/WC, RO
20–21h
MEMBASE
Memory Base
FFF0h
R/W
22–23h
MEMLIM
Memory Limit
0000h
R/W
24–25h
PREF_MEM_BASE
Prefetchable Memory Base
0000h
RO
26–27h
PREF_MEM_MLT
Prefetchable Memory Limit
0000h
RO
30–31h
IOBASE_HI
I/O Base Upper 16 Bits
0000h
RO
32–33h
IOLIMIT_HI
I/O Limit Upper 16 Bits
0000h
RO
Intel® 82801DB ICH4 Datasheet
275
Hub Interface to PCI Bridge Registers (D30:F0)
Table 8-1. Hub Interface PCI Configuration Register Address Map (HUB-PCI—D30:F0) (Sheet 2
of 2)
Offset
Mnemonic
3Ch
INT_LINE
3E–3Fh
BRIDGE_CNT
40–43h
HI1_CMD
44–45h
DEVICE_HIDE
Register Name
Default
Type
Interrupt Line
00h
RO
Bridge Control
0000h
R/W, R/WC,
RO
00202802h
R/W, RO
00
R/W
Hub Interface 1 Command Control
Secondary PCI Device Hiding Register
®
50–51h
CNF
Intel ICH4 Configuration Register
1400h
R/W
70h
MTT
Multi-Transaction Timer
20h
R/W
82h
PCI_MAST_STS
PCI Master Status
00h
R/WC
90h
ERR_CMD
Error Command Register
00h
R/W
92h
ERR_STS
Error Status Register
00h
R/W
NOTE: Refer to the ICH4 specification update for the value of the Revision ID Register.
8.1.1
VID—Vendor ID Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
00–01h
8086h
Bit
15:0
8.1.2
RO
16 bits
Description
Vendor Identification Value—RO. This is a 16-bit value assigned to Intel. Intel VID = 8086h.
DID—Device ID Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
276
Attribute:
Size:
02–03h
244Eh
Attribute:
Size:
RO
16 bits
Bit
Description
15:0
Device Identification Value — RO. This is a 16-bit value assigned to the Intel® ICH4 hub interface
to PCI bridge (i.e., Device #2).
DID = 244Eh.
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.3
CMD—Command Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
Bit
15:10
04–05h
0001h
Attribute:
Size:
R/W, RO
16 bits
Description
Reserved
9
Fast Back to Back Enable (FBE) — RO. Hardwired to 0. The Intel® ICH4 does not support this
capability.
8
SERR# Enable (SERR_EN) — R/W.
0 = Disable.
1 = Enable the ICH4 to generate an NMI (or SMI# if NMI routed to SMI#) when the D30:F0 SSE bit
(offset 06h, bit 14) is set.
7
Wait Cycle Control (WCC) — RO. Hardwired to 0.
6
Parity Error Response (PER) — R/W.
0 = The ICH4 will ignore parity errors on the hub interface.
1 = The ICH4 is allowed to report parity errors detected on the hub interface.
5
VGA Palette Snoop (VPS) — RO. Hardwired to 0.
4
Memory Write and Invalidate Enable (MWIE) — RO. Hardwired to 0.
3
Special Cycle Enable (SCE) — RO. Hardwired to 0 by P2P Bridge spec.
Bus Master Enable (BME) — R/W.
0 = Disable
1 = Allows the Hub interface-to-PCI bridge to accept cycles from PCI to run on the hub interface.
2
NOTES:
1. This bit does not affect the CF8h and CFCh I/O accesses.
2. Cycles that generated from the ICH4’s Device 31 functionality are not blocked by clearing this
bit. (PC/PCI Cascade Mode cycles may be blocked)
1
Memory Space Enable (MSE) — R/W. The ICH4 provides this bit as read/writable for software
only. However, the ICH4 ignores the programming of this bit, and runs hub interface memory cycles
to PCI.
0
I/O Space Enable (IOSE) — R/W. The ICH4 provides this bit as read/writable for software only.
However, the ICH4 ignores the programming of this bit and runs hub interface I/O cycles to PCI that
are not intended for USB, IDE, or AC ’97.
Intel® 82801DB ICH4 Datasheet
277
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.4
PD_STS—Primary Device Status Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
06–07h
0080h
Attribute:
Size:
R/WC, RO
16 bits
For the writable bits in this register, writing a 1 will clear the bit. Writing a 0 to the bit will have no
effect.
Bit
Description
15
Detected Parity Error (DPE) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = Indicates that the Intel® ICH4 detected a parity error on the hub interface. This bit gets set even
if the Parity Error Response bit (offset 04, bit 6) is not set.
14
Signaled System Error (SSE) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = An address, or command parity error, or special cycles data parity error has been detected on
the PCI bus, and the Parity Error Response bit (D30:F0, Offset 04h, bit 6) is set. If this bit is set
because of parity error and the D30:F0 SERR_EN bit (Offset 04h, bit 8) is also set, the ICH4
will generate an NMI (or SMI# if NMI routed to SMI#).
13
Received Master Abort (RMA) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = ICH4 received a master abort from the hub interface device.
12
Received Target Abort (RTA) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = ICH4 received a target abort from the hub interface device. The TCO logic can cause an SMI#,
NMI, or interrupt based on this bit getting set.
11
Signaled Target Abort (STA) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = ICH4 signals a target abort condition on the hub interface.
10:9
8
Master Data Parity Error Detected (MDPD) — R/WC. Since this register applies to the hub
interface, the ICH4 must interpret this bit differently than it is in the PCI spec.
0 = Software clears this bit by writing a 1 to the bit location.
1 = ICH4 detects a parity error on the hub interface and the Parity Error Response bit in the
Command Register (offset 04h, bit 6) is set.
7
Fast Back to Back Capable (FB2BC) — RO. Hardwired to 1.
6
User Definable Features (UDF) — RO. Hardwired to 0.
5
66 MHz Capable (66MHZ_CAP) — RO. Hardwired to 0.
4:0
278
DEVSEL# Timing Status (DEV_STS) — RO.
00h = Fast timing. This register applies to the hub interface; therefore, this field does not matter.
Reserved
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.5
RID—Revision Identification Register (HUB-PCI—D30:F0)
Offset:
Default Value:
08h
See Bit Description
Bit
7:0
8.1.6
Revision Identification Value — RO. Refer to the Intel® ICH4 specification update for the value of
the Revision ID Register.e
SCC—Sub-Class Code Register (HUB-PCI—D30:F0)
0Ah
04h
Bit
7:0
Attribute:
Size:
RO
8 bits
Description
Sub Class Code — RO. 8-bit value that indicates the category of bridge for the Intel® ICH4 hub
interface to PCI bridge. The code is 04h indicating a PCI-to-PCI bridge.
BCC—Base-Class Code Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
8.1.8
RO
8 Bits
Description
Offset Address:
Default Value:
8.1.7
Attribute:
Size:
0Bh
06h
Attribute:
Size:
RO
8 bits
Bit
Description
7:0
Base Class Code — RO. 8-bit value that indicates the type of device for the Intel® ICH4 hub interface
to PCI bridge. The code is 06h indicating a bridge device.
PMLT—Primary Master Latency Timer Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
0Dh
00h
Attribute:
Size:
RO
8 bits
This register does not apply to hub interface.
Bit
Description
7:3
Master Latency Timer Count (MLTC). Not implemented.
2:0
Reserved
Intel® 82801DB ICH4 Datasheet
279
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.9
HEADTYP—Header Type Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
0Eh
01h
Bit
7
6:0
8.1.10
Multi-Function Device — RO. This bit is 0 to indicate a single function device.
Header Type — RO. 8-bit field identifies the header layout of the configuration space, which is a PCIto-PCI bridge in this case.
PBUS_NUM—Primary Bus Number Register
(HUB-PCI—D30:F0)
18h
00h
Bit
7:0
RO
8 bits
Primary Bus Number — RO. This field indicates the bus number of the hub interface and is
hardwired to 00h.
SBUS_NUM—Secondary Bus Number Register
(HUB-PCI—D30:F0)
19h
00h
Bit
7:0
Attribute:
Size:
R/W
8 bits
Description
Secondary Bus Number — R/W. This field indicates the bus number of PCI. Note: when this
number is equal to the primary bus number (i.e., bus #0), the Intel® ICH4 will run hub interface
configuration cycles to this bus number as Type 1 configuration cycles on PCI.
SUB_BUS_NUM—Subordinate Bus Number Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
280
Attribute:
Size:
Description
Offset Address:
Default Value:
8.1.12
RO
8 bits
Description
Offset Address:
Default Value:
8.1.11
Attribute:
Size:
1A
00h
Attribute:
Size:
R/W
8 bits
Bit
Description
7:0
Subordinate Bus Number — R/W. This field specifies the highest PCI bus number below the hub
interface to PCI bridge. If a Type 1 configuration cycle from the hub interface does not fall in the
Secondary-to-Subordinate Bus ranges of Device 30, the Intel® ICH4 will indicate a master abort
back to the hub interface.
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.13
SMLT—Secondary Master Latency Timer Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
1Bh
00h
Attribute:
Size:
R/W
8 bits
This Master Latency Timer (MLT) controls the amount of time that the ICH4 will continue to burst
data as a master on the PCI bus. When the ICH4 starts the cycle after being granted the bus, the
counter is loaded and starts counting down from the assertion of FRAME#. If the internal grant to
this device is removed, then the expiration of the MLT counter will result in the deassertion of
FRAME#. If the internal grant has not been removed, then the ICH4 can continue to own the bus.
8.1.14
Bit
Description
7:3
Master Latency Timer Count (MLTC) — R/W. 5-bit value that indicates the number of PCI clocks,
in 8-clock increments, that the Intel® ICH4 will remain as master of the bus.
2:0
Reserved
IOBASE—I/O Base Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
1Ch
F0h
Bit
8.1.15
Attribute:
Size:
R/W, RO
8 bits
Description
7:4
I/O Address Base Bits [15:12] — R/W. I/O Base bits corresponding to address lines 15:12 for 4KB alignment. Bits 11:0 are assumed to be padded to 000h.
3:0
I/O Addressing Capability — RO. This is hardwired to 0h, indicating that the hub interface to PCI
bridge does not support 32-bit I/O addressing. This means that the I/O base & limit upper address
registers must be read only.
IOLIM—I/O Limit Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
Bit
1Dh
00h
Attribute:
Size:
R/W, RO
8 bits
Description
7:4
I/O Address Limit Bits [15:12] — R/W. I/O Base bits corresponding to address lines 15:12 for
4-KB alignment. Bits 11:0 are assumed to be padded to FFFh.
3:0
I/O Addressing Capability — RO. This is hardwired to 0h, indicating that the hub interface-to-PCI
bridge does not support 32-bit I/O addressing. This means that the I/O Base and I/O Limit Upper
Address registers must be read only.
Intel® 82801DB ICH4 Datasheet
281
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.16
SECSTS—Secondary Status Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
1E–1Fh
0280h
Attribute:
Size:
R/WC
16 bits
For the writable bits in this register, writing a 1 will clear the bit. Writing a 0 to the bit will have no
effect.
Bit
Description
15
Detected Parity Error (DPE) — R/WC.
0 = This bit is cleared by software writing a 1.
1 = Intel® ICH4 detected a parity error on the PCI bus.
14
Received System Error (SSE) — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = SERR# assertion is received on PCI.
13
Received Master Abort (RMA) — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Hub interface to PCI cycle is master-aborted on PCI.
12
Received Target Abort (RTA) — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Hub interface to PCI cycle is target-aborted on PCI. For “completion required” cycles from the
hub interface, this event should also set the Signaled Target Abort in the Primary Status
Register in this device, and the ICH4 must send the “target abort” status back to the hub
interface.
11
Signaled Target Abort (STA) —RO. The ICH4 does not generate target aborts.
10:9
8
Master Data Parity Error Detected (MDPD) — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = The ICH4 sets this bit when all of the following three conditions are met:
• The Parity Error Response Enable bit in the Bridge Control Register (bit 0, offset 3Eh) is set
• USB, AC ’97 or IDE is a Master
• PERR# asserts during a write cycle OR a parity error is detected internally during a read
cycle
7
Fast Back to Back Capable (FB2BC) — RO. Hardwired to 1 to indicate that the PCI to hub interface
target logic is capable of receiving fast back-to-back cycles.
6
User Definable Features (UDF) — RO. Hardwired to 0.
5
4:0
282
DEVSEL# Timing Status (DEV_STS) — RO.
01h = Medium timing.
66 MHz Capable (66MHZ_CAP) — RO. Hardwired to 0.
Reserved
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.17
MEMBASE—Memory Base Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
20–21h
FFF0h
Attribute:
Size:
R/W
16 bits
This register defines the base of the hub interface to PCI non-prefetchable memory range. Since the
ICH4 will forward all hub interface memory accesses to PCI, the ICH4 will only use this
information for determining when not to accept cycles as a target.
This register must be initialized by the configuration software. For the purpose of address decode,
address bits A[19:0] are assumed to be 0. Thus, the bottom of the defined memory address range
will be aligned to a 1-MB boundary.
Bit
8.1.18
Description
15:4
Memory Address Base — R/W. Defines the base of the memory range for PCI. These 12 bits
correspond to address bits 31:20.
3:0
Reserved
MEMLIM—Memory Limit Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
22–23h
0000h
Attribute:
Size:
R/W
16 bits
This register defines the upper limit of the hub interface to PCI non-prefetchable memory range.
Since the ICH4 will forward all hub interface memory accesses to PCI, the ICH4 will only use this
information for determining when not to accept cycles as a target.
This register must be initialized by the config software. For the purpose of address decode, address
bits A[19:0] are assumed to be FFFFFh. Thus, the top of the defined memory address range will be
aligned to a 1-MB boundary.
Bit
8.1.19
Description
15:4
Memory Address Limit — R/W. Defines the top of the memory range for PCI. These 12 bits
correspond to address bits 31:20.
3:0
Reserved
PREF_MEM_BASE—Prefetchable Memory Base Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
24h–25h
0000FFF0h
Bit
Attribute:
Size:
R/W
16 bit
Description
15:4
Prefetchable Memory Address Base — R/W. Defines the base address of the prefetchable
memory address range for PCI. These 12 bits correspond to address bits 31:20.
3:0
Reserved. RO.
Intel® 82801DB ICH4 Datasheet
283
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.20
PREF_MEM_MLT—Prefetchable Memory Limit Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
8.1.21
26h–27h
00000000h
Description
15:4
Prefetchable Memory Address Limit — RW. Defines the limit address of the prefetchable memory
address range for PCI. These 12 bits correspond to address bits 31:20.
3:0
Reserved. RO
IOBASE_HI—I/O Base Upper 16 Bits Register
(HUB-PCI—D30:F0)
30–31h
0000h
Bit
15:0
RO
16 bits
I/O Address Base Upper 16 Bits [31:16] — RO. Not supported; hardwired to 0.
IOLIM_HI—I/O Limit Upper 16 Bits Register
(HUB-PCI—D30:F0)
32–33h
0000h
Bit
15:0
Attribute:
Size:
RO
16 bits
Description
I/O Address Limit Upper 16 Bits [31:16] — RO. Not supported; hardwired to 0.
INT_LINE—Interrupt Line Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
Bit
7:0
284
Attribute:
Size:
Description
Offset Address:
Default Value:
8.1.23
R/W
16 bit
Bit
Offset Address:
Default Value:
8.1.22
Attribute:
Size:
3Ch
00h
Attribute:
Size:
RO
8 bits
Description
Interrupt Line (INT_LN) — RO. Hardwired to 00h. The bridge does not generate interrupts, and
interrupts from downstream devices are routed around the bridge.
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.24
BRIDGE_CNT—Bridge Control Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
Bit
15:12
11
3E–3Fh
0000h
Attribute:
Size:
R/W, R/WC, RO
16 bits
Description
Reserved
Discard Timer SERR# Enable (DTSE) — R/W. Controls the generation of SERR# on the primary
interface in response to a timer discard on the secondary interface:
0 = Do not generate SERR# on a secondary timer discard
1 = Generate SERR# in response to a secondary timer discard.
NOTE: This bit replaces bit 1 of offset 90h, which held this function in Intel® ICH3.
10
Discard Timer Status (DTS) — R/WC.
0 = Not Expired. Software clears this bit by writing a 1 to the bit position.
1 = Secondary discard timer expired (there is no discard timer for the primary interface)
NOTE: This bit replaces bit 1 of offset 92h, which had this function in ICH3.
9
Secondary Discard Timer (SDT) — R/W. Sets the maximum number of PCI clock cycles that the
ICH4 waits for an initiator on PCI to repeat a delayed transaction request. The counter starts once the
delayed transaction completion is at the head of the queue. If the master has not repeated the
transaction at least once before the counter expires, the ICH4 discards the transaction from its queue.
0 = The PCI master timeout value is between 215 and 216 PCI clocks
1 = The PCI master timeout value is between 210 and 211 PCI clocks
8
Primary Discard Timer (PDT) — R/W. This bit is RW for software compatibility only.
7
Fast Back to Back Enable — RO. Hardwired to 0. The PCI logic will not generate fast back-to-back
cycles on the PCI bus.
6
Secondary Bus Reset — RO. Hardwired to 0. The ICH4 does not follow the P2P bridge reset scheme;
Software-controlled resets are implemented in the PCI-LPC device.
5
Master Abort Mode — R/W. This bit controls the behavior of the ICH4 when a master abort occurs
on a transaction that crosses the hub interface-PCI bridge in either direction. The default is 0.
0 = ICH4 behaves in the following manner:
• Hub Interface Completion-Required requests to PCI: when these master abort on PCI, the
ICH4 returns a master abort status. For reads, FFFFh is returned for each DWORD.
• Hub Interface Posted Writes to PCI: when these master abort on PCI, the ICH4 discards the
data.
• PCI Reads to Hub Interface: when these master abort on Hub Interface, the ICH4 returns the
data provided with the Hub Interface master abort packet to the PCI requestor.
• PCI writes to Hub Interface: the ICH4 has no idea when these “master-abort.”
1 = ICH4 treats the master abort as an error:
• Hub Interface Completion-Required requests to PCI: when these master abort on PCI, the
ICH4 returns a target abort status. For reads, FFFFh is returned for each DWORD.
• Hub Interface Posted Writes to PCI: when these master abort on PCI, the ICH4 discards the
data and sets the Primary Signaled SERR# bit (if the corresponding SERR_EN bit is set).
• PCI Reads to Hub Interface: when these master abort on Hub Interface, the ICH4 terminates
the cycle with a target abort and flushes the remainder of the prefetched data.
• PCI writes to Hub Interface: the ICH4 has no idea when these “master-abort.”
4
VGA 16-Bit Decode. This bit does not have any functionality relative to address decodes because
the ICH4 will forward the cycles to PCI, independent of the decode. Writes of 1 have no impact other
than to force the bit to 1. Writes of 0 have no impact other than to force the bit to 0. Reads to this bit
will return the previously written value (or 0 if no writes since reset).
Intel® 82801DB ICH4 Datasheet
285
Hub Interface to PCI Bridge Registers (D30:F0)
Bit
8.1.25
Description
3
VGA Enable — R/W.
0 = No VGA device on PCI.
1 = Indicates that the VGA device is on PCI. Therefore, the PCI to hub interface decoder will not
accept memory cycles in the range A0000h–BFFFFh. Note that the ICH4 will never take I/O
cycles in the VGA range from PCI.
2
ISA Enable — R/W. The ICH4 ignores this bit. However, this bit is read/write for software
compatibility. Since the ICH4 forwards all I/O cycles that are not in the USB, AC ’97, or IDE ranges to
PCI, this bit would have no effect.
1
SERR# Enable — R/W.
0 = Disable
1 = If this bit is set AND bit 8 in CMD register (D30:F0 Offset 04h) is also set, the ICH4 will set the
SSE bit in PD_STS register (D30:F0, offset 06h, bit 14) and also generate an NMI (or SMI# if
NMI routed to SMI) when the SERR# signal is asserted.
0
Parity Error Response Enable — R/W.
0 = Disable
1 = Enable the hub interface to PCI bridge for parity error detection and reporting on the PCI bus.
HI1_CMD—Hub Interface 1 Command Control Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
40–43h
00202802h
Bit
R/W, RO
32 bits
Description
31:24
Reserved
23:21
Hub ID — RO. This field identifies the Hub Interface ID number for the Intel® ICH4. The ICH4 will use
this field for sending request packets from the ICH4, and for routing completion packets back from
HI1.
20
Reserved
19:16
HI Timeslice — R/W. This field sets the HI arbiter time-slice value with 4 base-clock granularity. A
value of 0h means that the time-slice is immediately expired and that the ICH4 will allow the other
master’s request to be serviced after every message.
15:14
HI_Width — RO. This field is hardwired to 00b, indicating that the HI interface is 8 bits wide.
13
12:10
HI_Rate_Valid — RO. Hardwired to 1.
HI_Rate — RO. Encoded value representing the clock-to-transfer rate of the HI1 interface:
010 = 1:4
The value is loaded at reset by sampling the capability of the device connected to the HI1 port. The
value for this field is fixed for 4x mode only.
9:4
Reserved.
3:1
Max Data (MAXD) — RO. Hardwired to 001b. This field specifies the maximum amount of data that
the ICH4 is allowed to burst in one packet on the hub interface. The ICH4 will always do 64-byte
bursts.
0
286
Attribute:
Size:
Reserved
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.26
DEVICE_HIDE—Secondary PCI Device Hiding Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
Power Well:
44–45h
00h
00h
Attribute:
Size:
R/W
16 bits
This register allows software to “hide” PCI devices (0 through 5) in terms of configuration space.
Specifically, when PCI devices (0–5) are hidden, the configuration space is not accessible because
the PCI IDSEL pin does not assert. The ICH4 supports the hiding of 6 external devices (0 through
5), which matches the number of PCI request/grant pairs, and the ability to hide the integrated LAN
device by masking out the configuration space decode of LAN controller. Writing a 1 to this bit
will not restrict the configuration cycle to the PCI bus. This differs from bits 0 through 5 in which
the configuration cycle is restricted.
Hiding a PCI device can be useful for debugging, bug work-arounds, and system management
support. Devices should only be hidden during initialization before any configuration cycles are
run. This guarantees that the device is not in a semi-enable state.
Bit
15:9
8
7:6
Description
Reserved
HIDE_DEV8—R/W. Same as bit 0 of this register, except for device 8 (AD[24]), which is hardwired
to the integrated LAN device. This bit will not change the way the configuration cycle appears on
PCI bus
Reserved
5
HIDE_DEV5—R/W. Same as bit 0 of this register, except for device 5 (AD[21]).
4
HIDE_DEV4—R/W. Same as bit 0 of this register, except for device 4 (AD[20]).
3
HIDE_DEV3—R/W. Same as bit 0 of this register, except for device 3 (AD[19]).
2
HIDE_DEV2—R/W. Same as bit 0 of this register, except for device 2 (AD[18]).
1
HIDE_DEV1—R/W. Same as bit 0 of this register, except for device 1 (AD[17]).
HIDE_DEV0—R/W.
0
0 = PCI configuration cycles for this slot are not affected.
1 = Device 0 is hidden on the PCI bus. This is done by masking the IDSEL (keeping it low) for
configuration cycles to that device. Since the device will not see its IDSEL go active, it will not
respond to PCI configuration cycles and the processor will think the device is not present.
AD[16] is used as IDSEL for device 0.
Intel® 82801DB ICH4 Datasheet
287
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.27
CNF—ICH4 Configuration Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
50–51h
1400h
Bit
15:10
R/W
16 bits
Description
Reserved
9
High Priority PCI Enable (HP_PCI_EN) — R/W.
0 = All PCI REQ#/GNT pairs have the same arbitration priority.
1 = Enables a mode where the REQ[0]#/GNT[0]# signal pair has a higher arbitration priority.
8
Hole Enable (15 MB–16 MB) — R/W.
0 = Disable
1 = Enables the 15 MB to 16 MB hole in main memory.
7:2
8.1.28
Attribute:
Size:
Reserved
1
12-Clock Retry Enable — R/W. System BIOS must set this bit for PCI compliance.
0 = If this bit is not set, under the same circumstance, the bus will not be released since all other
masters see the lock in use.
1 = When a PCI Master is running a locked memory read or write cycle, while all other bus masters
are waiting to run locked cycles, this bit, when set allows the ICH4 to retry the cycle after 12
PCI clocks.
0
Reserved
MTT—Multi-Transaction Timer Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
70h
20h
Attribute:
Size:
R/W
8 bits
MTT is an 8-bit register that controls the amount of time that the ICH4’s arbiter allows a PCI
initiator to perform multiple back-to-back transactions on the PCI bus. The ICH4’s MTT
mechanism is used to guarantee a fair share of the Primary PCI bandwidth to an initiator that
performs multiple back-to-back transactions to fragmented memory ranges (and as a consequence
it can not use long burst transfers).
The number of clocks programmed in the MTT represents the guaranteed time slice (measured in
PCI clocks) allotted to the current agent, after which the arbiter will grant another agent that is
requesting the bus. The MTT value must be programmed with 8 clock granularity in the same
manner as MLT. For example, if the MTT is programmed to 18h, then the selected value
corresponds to the time period of 24 PCI clocks.The default value of MTT is 20h (32 PCI clocks).
Note:
Programming the MTT to a value of 00h disables this function, which could cause starvation
problems for some PCI master devices. Programming of the MTT to anything less than 16 clocks
will not allow the Grant-to-FRAME# latency to be 16 clocks. The MTT timer will timeout before
the Grant-to-FRAME# trigger causing a re-arbitration.
Bit
288
Description
7:3
Multi-Transaction Timer Count Value — R/W. This field specifies the amount of time that grant
will remain asserted to a master continuously asserting its request for multiple transfers. This field
specifies the count in an 8-clock (PCI clock) granularity.
2:0
Reserved
Intel® 82801DB ICH4 Datasheet
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.29
PCI_MAST_STS—PCI Master Status Register
(HUB-PCI—D30:F0)
Offset Address:
Default Value:
82h
00h
Bit
R/WC
8 bits
Description
7
Internal PCI Master Request Status (INT_MREQ_STS) — R/WC.
0 = Software clears this bit by writing a 1 to it.
1 = The Intel® ICH4’s internal DMA controller or LPC has requested use of the PCI bus.
6
Internal LAN Master Request Status (LAN_MREQ_STS) — R/WC.
0 = Software clears this bit by writing a 1 to it.
1 = The ICH4’s internal LAN controller has requested use of the PCI bus.
5:0
8.1.30
Attribute:
Size:
PCI Master Request Status (PCI_MREQ_STS) — R/WC. Allows software to see if a particular bus
master has requested use of the PCI bus. For example, bit 0 will be set if ICH4 has detected
REQ[0]# asserted and bit 5 will be set if ICH4 detected REQ[5]# asserted.
0 = Software clears these bits by writing a 1 to the bit position.
1 = The associated PCI master has requested use of the PCI bus.
ERR_CMD—Error Command Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
Lockable:
90h
00h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
This register configures the ICH4’s Device 30 responses to various system errors. The actual
assertion of the internal SERR# (routed to cause NMI# or SMI#) is enabled via the PCI Command
register.
Bit
7:3
2
1:0
Description
Reserved
SERR# Enable on Receiving Target Abort (SERR_RTA_EN) — R/W.
0 = Disable.
1 = Enable. When SERR_EN is set, the Intel® ICH4 will report SERR# when SERR_RTA is set.
Reserved
Intel® 82801DB ICH4 Datasheet
289
Hub Interface to PCI Bridge Registers (D30:F0)
8.1.31
ERR_STS—Error Status Register (HUB-PCI—D30:F0)
Offset Address:
Default Value:
Lockable:
92h
00h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
This register records the cause of system errors in Device 30. The actual assertion of SERR# is
enabled via the PCI Command register.
Bit
7:3
2
1:0
290
Description
Reserved
SERR# Due to Received Target Abort (SERR_RTA) — R/W.
0 = Software clears this bit by writing a 1 to it.
1 = The Intel® ICH4 sets this bit when the ICH4 receives a target abort. If SERR_EN, the ICH4 will
also generate an SERR# when SERR_RTA is set.
Reserved
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
LPC Interface Bridge Registers
(D31:F0)
9
The LPC Bridge function of the ICH4 resides in PCI Device 31:Function 0. This function contains
many other functional units, such as DMA and Interrupt controllers, Timers, Power Management,
System Management, GPIO, RTC, and LPC Configuration Registers.
Registers and functions associated with other functional units (USB UHCI, USB EHCI, IDE, etc.)
are described in their respective sections.
9.1
PCI Configuration Registers (D31:F0)
Note:
Registers that are not shown should be treated as Reserved (See Section 6.2 for details).
.
Table 9-1. LPC I/F PCI Configuration Register Address Map (LPC I/F—D31:F0) (Sheet 1 of 2)
Offset
Mnemonic
00–01h
VID
02–03h
DID
04–05h
06–07h
08h
RID
09h
PI
Register Name
Default
Type
Vendor ID
8086h
RO
Device ID
24C0h
RO
PCICMD
PCI Command
000Fh
R/W, RO
PCISTA
PCI Device Status
0280h
R/WC, RO
See Note
RO
Programming Interface
00h
RO
Revision ID
0Ah
SCC
Sub Class Code
01h
RO
0Bh
BCC
Base Class Code
06h
RO
0Eh
HEADT
Header Type
80h
RO
40–43h
PMBASE
00000001h
R/W, RO
ACPI Base Address
44h
ACPI_CNTL
ACPI Control
00h
R/W
4E–4Fh
BIOS_CNTL
BIOS Control
0000h
R/W
54h
TCO_CNTL
TCO Control
00h
R/W, RO
58–5Bh
GPIO_BASE
GPIO Base Address
00000001h
R/W
GPIO Control Register
5Ch
GPIO_CNTL
60–63h
PIRQ[n]_ROUT
64h
SIRQ_CNTL
68–6Bh
PIRQ[n]_ROUT
PIRQ[E–H] Routing Control
PIRQ[A–D] Routing Control
Serial IRQ Control
00h
R/W
80808080h
R/W
10h
R/W
80808080h
R/W
88h
D31_ERR_CFG
Device 31 Error Configuration
00h
R/W
8Ah
D31_ERR_STS
Device 31 Error Status
00h
R/WC
90–91h
PCI_DMA_C
0000h
R/W
Intel® 82801DB ICH4 Datasheet
PCI DMA Configuration Registers
291
LPC Interface Bridge Registers (D31:F0)
Table 9-1. LPC I/F PCI Configuration Register Address Map (LPC I/F—D31:F0) (Sheet 2 of 2)
Offset
Mnemonic
Register Name
Default
Type
Power Management Registers
(See Section 9.8.1)
A0–CFh
D0–D3h
GEN_CNTL
General Control
R/W
0Xh
R/W-Special,
RO
Depends on
Strap
R/W
D4h
GEN_STA
D5h
BACK_CNTL
Backed Up Control
D8h
RTC_CONF
Real Time Clock Configuration
00h
R/W
E0h
COM_DEC
LPC I/F COM Port Decode Ranges
00h
R/W
E1h
LPCFDD_DEC
LPC I/F FDD & LPT Decode Ranges
00h
R/W
E2h
SND_DEC
E3h
FWH_DEC_EN1
E4–E5h
GEN1_DEC
E6–E7h
LPC_EN
General Status
00000000h
LPC I/F Sound Decode Ranges
00h
R/W
FWH Decode Enable 1
FFh
R/W
0000h
R/W
00h
R/W
LPC I/F General 1 Decode Range
LPC I/F Enables
E8–EBh
FWH_SEL1
FWH Select 1
00112233h
R/W
EC–EDh
GEN2_DEC
LPC I/F General 2 Decode Range
0000h
R/W
EE–EFh
FWH_SEL2
FWH Select 2
5678h
R/W
F0h
FWH_DEC_EN2
FWH Decode Enable 2
0Fh
R/W
F2h
FUNC_DIS
Function Disable Register
00h
R/W
NOTE: Refer to the ICH4 Specification Update for the value of the Revision ID Register.
9.1.1
VID—Vendor ID Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
00–01h
8086h
No
Bit
15:0
9.1.2
RO
16 bit
Core
Description
Vendor Identification Value — RO. This is a 16-bit value assigned to Intel. Intel VID = 8086h
DID—Device ID Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
15:0
292
Attribute:
Size:
Power Well:
02–03h
24C0h
No
Attribute:
Size:
Power Well:
RO
16 bit
Core
Description
Device Identification Value — RO. This is a 16-bit value assigned to the ICH4 LPC Bridge.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.3
PCICMD—PCI COMMAND Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
15:10
04–05h
000Fh
No
Attribute:
Size:
Power Well:
R/W, RO
16 bit
Core
Description
Reserved
9
Fast Back to Back Enable (FBE) — RO. Hardwired to 0.
8
SERR# Enable (SERR_EN) — R/W.
0 = Disable.
1 = Enable. Allow SERR# to be generated.
7
Wait Cycle Control (WCC) — RO. Hardwired to 0.
6
Parity Error Response (PER) — R/W.
0 = No action is taken when detecting a parity error.
1 = The Intel® ICH will take normal action when a parity error is detected.
5
VGA Palette Snoop (VPS) — RO. Hardwired to 0
4
Postable Memory Write Enable (PMWE) — RO. Hardwired to 0
3
Special Cycle Enable (SCE) — Hardwired to 1.
2
Bus Master Enable (BME) — RO. Hardwired to 1 to indicate that bus mastering cannot be disabled
for function 0 (DMA/ISA Master)
1
Memory Space Enable (MSE) — RO. Hardwired to 1 to indicate that memory space cannot be
disabled for Function 0 (LPC I/F)
0
I/O Space Enable (IOSE) — RO. Hardwired to 1 to indicate that the I/O space cannot be disabled
for function 0 (LPC I/F)
Intel® 82801DB ICH4 Datasheet
293
LPC Interface Bridge Registers (D31:F0)
9.1.4
PCISTA—PCI Device Status (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
06–07h
0280h
No
Bit
Description
Detected Parity Error (DPE) — R/WC.
0 = This bit is cleared by software writing a 1 to the bit position.
1 = PERR# signal goes active. Set even if the PER bit is 0.
14
Signaled System Error (SSE) — R/WC.
0 = This bit is cleared by software writing a 1 to the bit position.
1 = Set by the Intel® ICH4 if the SERR_EN bit is set and the ICH4 generates an SERR# on function
0. The ERR_STS register can be read to determine the cause of the SERR#. The SERR# can be
routed to cause SMI#, NMI, or interrupt.
13
Master Abort Status (RMA) — R/WC.
0 = This bit is cleared by software writing a 1 to the bit position.
1 = ICH4 generated a master abort on PCI due to LPC I/F master or DMA cycles.
12
Received Target Abort (RTA) — R/WC.
0 = This bit is cleared by software writing a 1 to the bit position.
1 = ICH4 received a target abort during LPC I/F master or DMA cycles to PCI.
11
Signaled Target Abort (STA) — R/WC.
0 = This bit is cleared by software writing a 1 to the bit position.
1 = ICH4 generated a target abort condition on PCI cycles claimed by the ICH4 for ICH4 internal
registers or for going to LPC I/F.
DEVSEL# Timing Status (DEV_STS) — RO.
01 = Medium Timing.
8
Data Parity Error Detected (DPED) — R/WC.
0 = This bit is cleared by software writing a 1 to the bit position.
1 = Set when all three of the following conditions are true:
- The ICH4 is the initiator of the cycle,
- The ICH4 asserted PERR# (for reads) or observed PERR# (for writes), and
- The PER bit is set.
7
Fast Back to Back Capable (FB2BC) — RO. Hardwired to 1. Indicates ICH4 as a target can accept
fast back-to-back transactions.
6
User Definable Features (UDF) — RO. Hardwired to 0
5
4:0
66 MHz Capable (66MHZ_CAP) — RO. Hardwired to 0
Reserved
REVID—Revision ID Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
294
R/WC, RO
16 bit
Core
15
10:9
9.1.5
Attribute:
Size:
Power Well:
08h
See Bit Description
Attribute:
Size:
RO
8 bits
Bit
Description
7:0
Revision Identification Value — RO. Refer to the Intel® ICH4 specification update for the value of the
Revision ID Register.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.6
PI—Programming Interface (LPC I/F—D31:F0)
Offset Address:
Default Value:
09h
00h
Bit
7:0
9.1.7
Programming Interface Value — RO.
SCC—Sub-Class Code Register (LPC I/F—D31:F0)
0Ah
01h
Bit
7:0
Attribute:
Size:
RO
8 bits
Description
Sub Class Code — RO. This 8-bit value indicates the category of bridge for the LPC PCI bridge.
BCC—Base-Class Code Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
9.1.9
RO
8 bits
Description
Offset Address:
Default Value:
9.1.8
Attribute:
Size:
0Bh
06h
Attribute:
Size:
RO
8 bits
Bit
Description
7:0
Base Class Code — RO. This 8-bit value indicates the type of device for the LPC bridge. The code is
06h indicating a bridge device.
HEADTYP—Header Type Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Bit
7
6:0
0Eh
80h
Attribute:
Size:
RO
8 bits
Description
Multi-Function Device — RO. This bit is 1 to indicate a multi-function device.
Header Type — RO. 7-bit field identifies the header layout of the configuration space.
Intel® 82801DB ICH4 Datasheet
295
LPC Interface Bridge Registers (D31:F0)
9.1.10
PMBASE—ACPI Base Address (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
40–43h
00000001h
No
Attribute:
Size:
Usage:
Power Well:
R/W, RO
32 bit
ACPI, Legacy
Core
Sets base address for ACPI I/O registers, GPIO registers and TCO I/O registers. Can be mapped
anywhere in the 64K I/O space on 128-byte boundaries.
Bit
31:16
Reserved
15:7
Base Address — R/W. Provides 128 bytes of I/O space for ACPI, GPIO, and TCO logic. This is
placed on a 128-byte boundary.
6:1
Reserved
0
9.1.11
Description
Resource Indicator — RO. Tied to 1 to indicate I/O space.
ACPI_CNTL—ACPI Control (LPC I/F — D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
7:5
44h
00h
No
Attribute:
Size:
Usage:
Power Well:
R/W
8 bit
ACPI, Legacy
Core
Description
Reserved
4
ACPI Enable (ACPI_EN) — R/W.
0 = Disable.
1 = Decode of the I/O range pointed to by the ACPI Base register is enabled, and the ACPI power
management function is enabled. Note that the APM power management ranges (B2/B3h) are
always enabled and are not affected by this bit.
3
Reserved
2:0
SCI IRQ Select (SCI_IRQ_SEL) — R/W. This field specifies on which IRQ the SCI will internally
appear. If not using the APIC, the SCI must be routed to IRQ9-11, and that interrupt is not sharable
with the SERIRQ stream, but is shareable with other PCI interrupts. If using the APIC, the SCI can
also be mapped to IRQ20-23, and can be shared with other interrupts.
000 = IRQ9
001 = IRQ10
010 = IRQ11
011 = Reserved
100 = IRQ20 (Only available if APIC enabled)
101 = IRQ21 (Only available if APIC enabled)
110 = IRQ22 (Only available if APIC enabled)
111 = IRQ23 (Only available if APIC enabled)
NOTE: When the TCO interrupt is mapped to APIC interrupts 9, 10 or 11, the signal is in fact active
high. When the TCO interrupt is mapped to IRQ 20, 21, 22, or 23 the signal is active low and
can be shared with PCI interrupts that may be mapped to those same signals (IRQs).
296
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.12
BIOS_CNTL—BIOS Control Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
4E–4Fh
0000h
No
Bit
15:2
9.1.13
Attribute:
Size:
Power Well:
R/W
16 bit
Core
Description
Reserved
1
BIOS Lock Enable (BLE) — R/W.
0 = Setting the BIOSWE will not cause Sums. Once set, this bit can only be cleared by a
PCIRST#.
1 = Enables setting the BIOSWE bit to cause Sums.
0
BIOS Write Enable (BIOSWE) — R/W.
0 = Only read cycles result in FWH I/F cycles.
1 = Access to the BIOS space is enabled for both read and write cycles. When this bit is written
from a 0 to a 1 and BIOS lock Enable (BLE) is also set, an SMI# is generated. This ensures
that only SMI code can update BIOS.
TCO_CNTL — TCO Control (LPC I/F — D31:F0)
Offset Address:
Default Value:
Lockable:
Bits
7:4
3
2:0
54h
00h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Reserved
TCO Interrupt Enable (TCO_INT_EN) — R/W. This bit enables/disables the TCO interrupt.
0 = Disables TCO interrupt.
1 = Enables TCO Interrupt, as selected by the TCO_INT_SEL field.
TCO Interrupt Select (TCO_INT_SEL) — R/W. This field specifies on which IRQ the TCO will
internally appear. If not using the APIC, the TCO interrupt must be routed to IRQ9:11, and that
interrupt is not sharable with the SERIRQ stream, but is shareable with other PCI interrupts. If
using the APIC, the TCO interrupt can also be mapped to IRQ20:23, and can be shared with other
interrupt. Note that if the TCOSCI_EN bit is set (bit 6 of the GPEO_EN register), then the TCO
interrupt will be sent to the same interrupt as the SCI, and the TCO_INT_SEL bits will have no
meaning. When the TCO interrupt is mapped to APIC interrupts 9, 10 or 11, the signal is active
high. When the TCO interrupt is mapped to IRQ 20, 21, 22, or 23, the signal is active low and can
be shared with PCI interrupts that may be mapped to those same signals (IRQs).
000 = IRQ9
001 = IRQ10
010 = IRQ11
011 = Reserved
100 = IRQ20 (Only available if APIC enabled)
101 = IRQ21 (Only available if APIC enabled)
110 = IRQ22 (Only available if APIC enabled)
111 = IRQ23 (Only available if APIC enabled)
Intel® 82801DB ICH4 Datasheet
297
LPC Interface Bridge Registers (D31:F0)
9.1.14
GPIOBASE—GPIO Base Address (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
58h–5Bh
00000001h
No
Bit
31:16
Description
Reserved
Base Address — R/W. Provides the 64 bytes of I/O space for GPIO.
5:1
Reserved
Resource Indicator — RO. Hardwired to 1; indicates I/O space.
GPIO_CNTL—GPIO Control (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
5Ch
00h
No
Bit
7:5
4
3:0
9.1.16
R/W, RO
32 bit
Core
15:6
0
9.1.15
Attribute:
Size:
Power Well:
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Reserved
GPIO Enable (GPIO_EN) — R/W. This bit enables/disables decode of the I/O range pointed to by
the GPIO base register and enables/disables the GPIO function.
0 = Disable.
1 = Enable.
Reserved
PIRQ[n]_ROUT—PIRQ[A,B,C,D] Routing Control
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
PIRQA–60h, PIRQB–61h,
PIRQC–62h, PIRQD–63h
80h
No
Bit
Attribute:
R/W
Size:
Power Well:
8 bit
Core
Description
Interrupt Routing Enable (IRQEN) — R/W.
0 = The corresponding PIRQ is routed to one of the ISA-compatible interrupts specified in bits[3:0].
1 = The PIRQ is not routed to the 8259.
7
NOTE: BIOS must program this bit to 0 during POST for any of the PIRQs that are being used. The
value of this bit may subsequently be changed by the OS when setting up for I/O APIC
interrupt delivery mode.
298
6:4
Reserved
3:0
IRQ Routing — R/W. (ISA compatible)
0000 = Reserved
1000 = Reserved
0001 = Reserved
1001 = IRQ9
0010 = Reserved
1010 = IRQ10
0011 = IRQ3
1011 = IRQ11
0100 = IRQ4
1100 = IRQ12
0101 = IRQ5
1101 = Reserved
0110 = IRQ6
1110 = IRQ14
0111 = IRQ7
1111 = IRQ15
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.17
SERIRQ_CNTL—Serial IRQ Control (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
64h
10h
No
Bit
7
6
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Serial IRQ Enable (SIRQEN) — R/W.
0 = The buffer is input only and internally SERIRQ will be a 1.
1 = Serial IRQs will be recognized. The SERIRQ pin will be configured as SERIRQ.
Serial IRQ Mode Select (SIRQMD) — R/W.
0 = The serial IRQ machine will be in quiet mode.
1 = The serial IRQ machine will be in continuous mode.
NOTE: For systems using Quiet Mode, this bit should be set to 1 (Continuous Mode) for at least one
frame after coming out of reset before switching back to Quiet Mode. Failure to do so will
result in the Intel® ICH4 not recognizing SERIRQ interrupts.
9.1.18
5:2
Serial IRQ Frame Size (SIRQSZ) — R/W. Fixed field that indicates the size of the SERIRQ frame. In
the ICH4, this field needs to be programmed to 21 frames (0100). This is an offset from a base of 17
which is the smallest data frame size.
1:0
Start Frame Pulse Width (SFPW) — R/W. This is the number of PCI clocks that the SERIRQ pin will
be driven low by the serial IRQ machine to signal a start frame. In continuous mode, the ICH4 will
drive the start frame for the number of clocks specified. In quiet mode, the ICH4 will drive the start
frame for the number of clocks specified minus one, as the first clock was driven by the peripheral.
00 = 4 clocks
01 = 6 clocks
10 = 8 clocks
11 = Reserved
PIRQ[n]_ROUT—PIRQ[E,F,G,H] Routing Control
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
PIRQE–68h, PIRQF–69h,
PIRQG–6Ah, PIRQH–6Bh
80h
No
Bit
7
Attribute:
R/W
Size:
Power Well:
8 bit
Core
Description
Interrupt Routing Enable (IRQEN) — R/W.
0 = The corresponding PIRQ is routed to one of the ISA-compatible interrupts specified in bits[3:0].
1 = The PIRQ is not routed to the 8259.
NOTE: BIOS must program this bit to 0 during POST for any of the PIRQs that are being used. The
value of this bit may subsequently be changed by the OS when setting up for I/O APIC
interrupt delivery mode.
6:4
Reserved
3:0
IRQ Routing — R/W. (ISA compatible)
0000 = Reserved
1000 = Reserved
0001 = Reserved
1001 = IRQ9
0010 = Reserved
1010 = IRQ10
0011 = IRQ3
1011 = IRQ11
0100 = IRQ4
1100 = IRQ12
0101 = IRQ5
1101 = Reserved
0110 = IRQ6
1110 = IRQ14
0111 = IRQ7
1111 = IRQ15
Intel® 82801DB ICH4 Datasheet
299
LPC Interface Bridge Registers (D31:F0)
9.1.19
D31_ERR_CFG—Device 31 Error Configuration Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
.
88h
00h
No
R/W
8 bit
Core
This register configures the ICH4’s Device 31 responses to various system errors. The actual
assertion of SERR# is enabled via the PCI Command register
Bit
7:3
9.1.20
Attribute:
Size:
Power Well:
Description
Reserved
2
SERR# on Received Target Abort Enable (SERR_RTA_EN) — R/W.
0 = Disable. No SERR# assertion on Received Target Abort.
1 = The Intel® ICH4 will generate SERR# when SERR_RTA is set if SERR_EN is set.
1
SERR# on Delayed Transaction Timeout Enable (SERR_DTT_EN) — R/W.
0 = Disable. No SERR# assertion on Delayed Transaction Timeout.
1 = The ICH4 will generate SERR# when SERR_DTT bit is set if SERR_EN is set.
0
Reserved
D31_ERR_STS—Device 31 Error Status Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
8Ah
00h
No
Attribute:
Size:
Power Well:
R/WC
8 bit
Core
This register configures the ICH4’s Device 31 responses to various system errors. The actual
assertion of SERR# is enabled via the PCI Command register.
Bit
7:3
300
Description
Reserved
2
SERR# Due to Received Target Abort (SERR_RTA) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = The Intel® ICH4 sets this bit when it receives a target abort. If SERR_EN, the ICH4 will also
generate an SERR# when SERR_RTA is set.
1
SERR# Due to Delayed Transaction Timeout (SERR_DTT) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = When a PCI master does not return for the data within 1 ms of the cycle’s completion, the ICH4
clears the delayed transaction and sets this bit. If both SERR_DTT_EN and SERR_EN are set,
then ICH4 will also generate an SERR# when SERR_DTT is set.
0
Reserved
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.21
PCI_DMA_CFG—PCI DMA Configuration (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
90h–91h
0000h
No
Bit
Attribute:
Size:
Power Well:
Description
15:14
Channel 7 Select — R/W.
00 = Reserved
01 = PC/PCI DMA
10 = Reserved
11 = LPC I/F DMA
13:12
Channel 6 Select — R/W. Same bit decode as for Channel 7
11:10
R/W
16 bit
Core
Channel 5 Select — R/W. Same bit decode as for Channel 7
9:8
Reserved
7:6
Channel 3 Select — R/W. Same bit decode as for Channel 7
5:4
Channel 2 Select — R/W. Same bit decode as for Channel 7
3:2
Channel 1 Select — R/W. Same bit decode as for Channel 7
1:0
Channel 0 Select — R/W. Same bit decode as for Channel 7
Intel® 82801DB ICH4 Datasheet
301
LPC Interface Bridge Registers (D31:F0)
9.1.22
GEN_CNTL — General Control Register (LPC I/F — D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
31:26
Attribute:
Size:
Power Well:
R/W
32 bit
Core
Description
Reserved
25
REQ[5]#/GNT[5]# PC/PCI Protocol Select (PCPCIB_SEL) — R/W.
0 = REQ[5]#/GNT[5]# pins function as a standard PCI REQ/GNT signal pair.
1 = PCI REQ[5]#/GNT[5]# signal pair use the PC/PCI protocol as REQ[B]#/GNT[B]. The
corresponding bits in the GPIO_USE_SEL register must also be set to a 0. If the corresponding
bits in the GPIO_USE_SEL register are set to a 1, then the signals will be used as a GPI and
GPO.
24
Hide ISA Bridge (HIDE_ISA) — R/W.
0 = The Intel® ICH4 does not prevent AD22 from asserting during configuration cycles to the PCIto-ISA bridge.
1 = Software sets this bit to 1 to disable configuration cycle from being claimed by a PCI-to-ISA
bridge. This prevents the OS PCI PnP from getting confused by seeing two ISA bridges.
It is required for the ICH4 PCI address line AD22 to connect to the PCI-to-ISA bridge’s IDSEL
input. When this bit is set, the ICH4 will not assert AD22 during configuration cycles to the PCIto-ISA bridge.
23:22
Reserved
21
CPU Break Event Indication Enable (FERR#-MUX-EN) — R/W.
0 = Disable. The ICH4 does not examine the FERR# signal during C2. (Default)
1 = Enables the ICH4 to examine the FERR# signal during a C2 state as a break event. (See
Section 5.12.5 for details.)
20
Reserved
19:18
SCRATCHPAD. These bits are provided for possible future use.
17:14
Reserved
13
Coprocessor Error Enable (COPR_ERR_EN) — R/W.
0 = FERR# will not generate IRQ13 nor IGNNE#.
1 = When FERR# is low, ICH4 generates IRQ13 internally and holds it until an I/O write to port F0h.
It will also drive IGNNE# active.
12
Keyboard IRQ1 Latch Enable (IRQ1LEN) — R/W.
0 = IRQ1 bypasses the latch.
1 = The active edge of IRQ1 is latched and held until a port 60h read.
11
Mouse IRQ12 Latch Enable (IRQ12LEN) — R/W.
0 = IRQ12 bypasses the latch.
1 = The active edge of IRQ12 is latched and held until a port 60h read.
10:9
302
D0h–D3h
00000000h
No
Reserved
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
Bit
8
Description
APIC Enable (APIC_EN) — R/W.
0 = Disables internal I/O (x) APIC.
1 = Enables the internal I/O (x) APIC and its address decode.
The following behavioral rules apply for bits 8 and 7 in this register:
• Rule 1: If bit 8 is 0, the ICH4 does not decode any of the registers associated with the I/O APIC
or I/O (x) APIC. The state of bit 7 is “Don’t Care” in this case.
• Rule 2: If bit 8 is 1 and bit 7 is 0, the ICH4 decodes the memory space associated with the I/O
APIC, but not the extra registers associated I/O (x) APIC.
• Rule 3: If bit 8 is 1 and bit 7 is 1, the ICH4 decodes the memory space associated with both the
I/O APIC and the I/O (x) APIC. This also enables PCI masters to write directly to the register to
cause interrupts (PCI Message Interrupt).
NOTE: There is no separate way to disable PCI Message Interrupts if the I/O (x) APIC is enabled.
This is not considered necessary.
7
I/O (x) Extension Enable (XAPIC_EN) — R/W.
0 = The I/O (x) APIC extensions are not supported.
1 = Enables the extra features (beyond standard I/O APIC) associated with the I/O (x) APIC.
NOTE: This bit is only valid if the APIC_EN bit is also set to 1.
6
5:4
Alternate Access Mode Enable (ALTACC_EN) — R/W.
0 = Alt Access Mode Disabled (default). ALT access mode allows reads to otherwise unreadable
registers and writes otherwise unwritable registers.
1 = Alt Access Mode Enable.
Reserved
3
Reserved — RO. Reset 0.
2
DMA Collection Buffer Enable (DCB_EN) — R/W.
0 = DCB disabled.
1 = Enables DMA Collection Buffer (DCB) for LPC I/F and PC/PCI DMA.
1
Delayed Transaction Enable (DTE) — R/W.
0 = Delayed transactions disabled.
1 = ICH4 enables delayed transactions for internal register, FWH and LPC I/F accesses.
0
Positive Decode Enable (POS_DEC_EN) — R/W.
0 = The ICH4 will perform subtractive decode on the PCI bus and forward the cycles to LPC I/F if
not to an internal register or other known target on the LPC I/F. Accesses to internal registers
and to known LPC I/F devices will still be positively decoded.
1 = Enables ICH4 to only perform positive decode on the PCI bus.
Intel® 82801DB ICH4 Datasheet
303
LPC Interface Bridge Registers (D31:F0)
9.1.23
GEN_STA—General Status Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
D4h
0Xh
No
Bit
7:3
Attribute:
Size:
Power Well:
RO, R/W-Special
8 bit
Core
Description
Reserved
SAFE_MODE — RO.
2
9.1.24
0 = Intel® ICH4 sampled AC_SDOUT low on the rising edge of PWROK.
1 = ICH4 sampled AC_SDOUT high on the rising edge of PWROK. ICH4 will force
FREQ_STRAP[3:0] bits to all 1s (safe mode multiplier).
1
NO_REBOOT — R/W-Special.
0 = Normal TCO Timer reboot functionality (reboot after 2nd TCO timeout). This bit cannot be set to
0 by software if the strap is set to No Reboot.
1 = ICH4 will disable the TCO Timer system reboot feature. This bit is set either by hardware when
SPKR is sampled high on the rising edge of PWROK, or by software writing a 1 to the bit.
0
Reserved
BACK_CNTL—Backed Up Control Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
D5h
0Fh
Attribute:
R/W
Size:
Power Well:
8 bit
RTC
(upon RTCRST# assertion low)
2Fh
(if Safe Mode Strap is active)
Lockable:
No
Bit
Description
7
Reserved. Read only as 0.
6
Reserved. Read only as 0.
5
Top-Block Swap Mode (TOP_SWAP) — R/W.
0 = Intel® ICH4 will not invert A16. This bit is cleared by RTCRST# assertion, but not by any other
type of reset.
1 = ICH4 inverts A16 for cycles targeting FWH BIOS space (Does not affect accesses to FWH
feature space).
4
CPU BIST Enable (CPU_BIST_EN) — R/W.
0 = Disable.
1 = The INIT# signal will be driven active when CPURST# is active. INIT# will go inactive with the
same timings as the other CPU I/F signals (Hold Time after CPURST# inactive). Note that
CPURST# is generated by the memory controller hub, but the ICH4 has a hub interface special
cycle that allows the ICH4 to control the assertion/deassertion of CPURST#.
NOTE: This bit is in the Resume well and is reset by RSMRST#, but not by PCIRST# nor CF9h
writes.
3:0
304
CPU Frequency Strap (FREQ_STRAP[3:0]) — R/W. These bits determine the internal frequency
multiplier of the processor. These bits can be reset to 1111 based on an external pin strap or via the
RTCRST# input signal. Software must program this field based on the processor’s specified
frequency. Note that this field is only writable when the SAFE_MODE bit is cleared to 0, and
SAFE_MODE is only cleared by PWROK rising edge. These bits are in the RTC well.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.25
RTC_CONF—RTC Configuration Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
D8h
00h
Yes
Bit
7:5
R/W, R/W-Special
8 bit
Core
Description
Reserved
4
Upper 128-byte Lock (U128LOCK) — R/W-Special.
0 = Access to these bytes in the upper CMOS RAM range have not been locked.
1 = Locks reads and writes to bytes 38h–3Fh in the upper 128-byte bank of the RTC CMOS RAM.
Write cycles to this range will have no effect and read cycles will not return any particular
guaranteed value. This is a write once register that can only be reset by a hardware reset.
3
Lower 128-byte Lock (L128LOCK) — R/W-Special.
0 = Access to these bytes in the lower CMOS RAM range have not been locked.
1 = Locks reads and writes to bytes 38h–3Fh in the lower 128-byte bank of the RTC CMOS RAM.
Write cycles to this range will have no effect and read cycles will not return any particular
guaranteed value. This is a write once register that can only be reset by a hardware reset.
2
Upper 128-byte Enable (U128E) — R/W.
0 = Disable.
1 = Enables access to the upper 128-byte bank of RTC CMOS RAM.
1:0
9.1.26
Attribute:
Size:
Power Well:
Reserved
COM_DEC—LPC I/F Communication Port Decode Ranges
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
7
6:4
3
2:0
E0h
00h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Reserved
COMB Decode Range — R/W. This field determines which range to decode for the COMB Port.
000 = 3F8h–3FFh (COM1)
001 = F8h–2FFh (COM2)
010 = 220h–227h
011 = 228h–22Fh
100 = 238h–23Fh
101 = 2E8h–2EFh (COM4)
110 = 338h–33Fh
111 = 3E8h–3EFh (COM3)
Reserved
COMA Decode Range — R/W. This field determines which range to decode for the COMA Port.
000 = 3F8h–3FFh (COM1)
001 = 2F8h–2FFh (COM2)
010 = 220h–227h
011 = 228h–22Fh
100 = 238h–23Fh
101 = 2E8h–2EFh (COM4)
110 = 338h–33Fh
111 = 3E8h–3EFh (COM3)
Intel® 82801DB ICH4 Datasheet
305
LPC Interface Bridge Registers (D31:F0)
9.1.27
FDD/LPT_DEC—LPC I/F FDD & LPT Decode Ranges
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
E1h
00h
No
Bit
7:5
4
9.1.28
R/W
8 bit
Core
Description
Reserved
FDD Decode Range — R/W. Determines which range to decode for the FDD Port
0 = 3F0h–3F5h, 3F7h (Primary)
1 = 370h–2FFh (Secondary)
3:2
Reserved
1:0
LPT Decode Range — R/W. This field determines which range to decode for the LPTPort.
00 = 378h–37Fh and 778h–77Fh
01 = 278h–27Fh (port 279h is read only) and 678h–67Fh
10 = 3BCh–3BEh and 7BCh–7BEh
11 = Reserved
SND_DEC—LPC I/F Sound Decode Ranges
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
E2h
00h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
7:6
Reserved
5:4
MSS Decode Range — R/W. This field determines which range to decode for the Microsoft Sound
System (MSS)
00 = 530h–537h
01 = 604h–60Bh
10 = E80h–E87h
11 = F40h–F47h
3
MIDI Decode Range — R/W. This bit determines which range to decode for the Midi Port
0 = 330h–331h
1 = 300h–301h
2
Reserved
1:0
306
Attribute:
Size:
Power Well:
SB16 Decode Range — R/W. This field determines which range to decode for the Sound Blaster
16 (SB16) Port
00 = 220h–233h
01 = 240h–253h
10 = 260h–273h
11 = 280h–293h
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.29
FWH_DEC_EN1—FWH Decode Enable 1 Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
E3h
FFh
Attribute:
Size:
R/W
8 bits
This register determines which memory ranges will be decoded on the PCI bus and forwarded to
the FWH. The ICH4 will subtractively decode cycles on PCI unless POS_DEC_EN is set to 1.
Bit
Description
7
FWH_F8_EN — R/W. Enables decoding two 512 KB FWH memory ranges, and one 128KB
memory range.
0 = Disable
1 = Enable the following ranges for the FWH
FFF80000h–FFFFFFFFh
FFB80000h–FFBFFFFFh
000E0000h–000FFFFFh
6
FWH_F0_EN — R/W. Enables decoding two 512 KB FWH memory ranges.
0 = Disable.
1 = Enable the following ranges for the FWH:
FFF00000h–FFF7FFFFh
FFB00000h–FFB7FFFFh
5
FWH_E8_EN — R/W. Enables decoding two 512 KB FWH memory ranges.
0 = Disable.
1 = Enable the following ranges for the FWH:
FFE80000h–FFEFFFFh
FFA80000h–FFAFFFFFh
4
FWH_E0_EN — R/W. Enables decoding two 512 KB FWH memory ranges.
0 = Disable.
1 = Enable the following ranges for the FWH:
FFE00000h–FFE7FFFFh
FFA00000h–FFA7FFFFh
3
FWH_D8_EN — R/W. Enables decoding two 512 KB FWH memory ranges.
0 = Disable.
1 = Enable the following ranges for the FWH
FFD80000h–FFDFFFFFh
FF980000h–FF9FFFFFh
2
FWH_D0_EN — R/W. Enables decoding two 512KB FWH memory ranges.
0 = Disable.
1 = Enable the following ranges for the FWH
FFD00000h–FFD7FFFFh
FF900000h–FF97FFFFh
1
FWH_C8_EN — R/W. Enables decoding two 512KB FWH memory ranges.
0 = Disable.
1 = Enable the following ranges for the FWH
FFC80000h–FFCFFFFFh
FF880000h–FF8FFFFFh
0
FWH_C0_EN — R/W. Enables decoding two 512 KB FWH memory ranges.
0 = Disable.
1 = Enable the following ranges for the FWH
FFC00000h–FFC7FFFFh
FF800000h–FF87FFFFh
Intel® 82801DB ICH4 Datasheet
307
LPC Interface Bridge Registers (D31:F0)
9.1.30
GEN1_DEC—LPC I/F Generic Decode Range 1 Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
R/W
16 bit
Core
Description
15:7
Generic I/O Decode Range 1 Base Address (GEN1_BASE) — R/W. This address is aligned on a
128-byte boundary, and must have address lines 31:16 as 0.
NOTE: This generic decode is for I/O addresses only, not memory addresses. The size of this
range is 128 bytes.
6:1
Reserved
Generic Decode Range 1 Enable (GEN1_EN) — R/W.
0 = Disable.
1 = Enable the GEN1 I/O range to be forwarded to the LPC I/F
LPC_EN—LPC I/F Enables Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
15:14
308
Attribute:
Size:
Power Well:
Bit
0
9.1.31
E4h–E5h
00h
Yes
E6h–E7h
00h
Yes
Attribute:
Size:
Power Well:
R/W
16 bit
Core
Description
Reserved
13
CNF2_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the I/O locations 4Eh and 4Fh to the LPC interface. This range is used
for a microcontroller.
12
CNF1_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the I/O locations 2Eh and 2Fh to the LPC interface. This range is used
for Super I/O devices.
11
MC_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the I/O locations 62h and 66h to the LPC interface. This range is used
for a microcontroller.
10
KBC_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the I/O locations 60h and 64h to the LPC interface. This range is used
for a microcontroller.
9
GAMEH_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the I/O locations 208h to 20Fh to the LPC interface. This range is
used for a gameport.
8
GAMEL_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the I/O locations 200h to 207h to the LPC interface. This range is
used for a gameport.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
Bit
Description
7
ADLIB_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the I/O locations 388h–38Bh to the LPC interface.
6
MSS_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the MSS range to the LPC interface. This range is selected in the
LPC_Sound Decode Range Register.
5
MIDI_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the MIDI range to the LPC interface. This range is selected in the
LPC_Sound Decode Range Register.
4
SB16_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the SB16 range to the LPC interface. This range is selected in the
LPC_Sound Decode Range Register.
3
FDD_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the FDD range to the LPC interface. This range is selected in the
LPC_FDD/LPT Decode Range Register.
2
LPT_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the LPTrange to the LPC interface. This range is selected in the
LPC_FDD/LPT Decode Range Register.
1
COMB_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the COMB range to the LPC interface. This range is selected in the
LPC_COM Decode Range Register.
0
COMA_LPC_EN — R/W.
0 = Disable.
1 = Enables the decoding of the COMA range to the LPC interface. This range is selected in the
LPC_COM Decode Range Register.
Intel® 82801DB ICH4 Datasheet
309
LPC Interface Bridge Registers (D31:F0)
9.1.32
FWH_SEL1—FWH Select 1 Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Bit
310
E8h
00112233h
Attribute:
Size:
R/W, RO
32 bits
Description
31:28
FWH_F8_IDSEL — RO. IDSEL for two 512 KB FWH memory ranges and one 128 KB memory
range. This field is fixed at 0000. The IDSEL programmed in this field addresses the following
memory ranges:
FFF8 0000h–FFFF FFFFh
FFB8 0000h–FFBF FFFFh
000E 0000h–000F FFFFh
27:24
FWH_F0_IDSEL — R/W. IDSEL for two 512 KB FWH memory ranges. The IDSEL programmed in
this field addresses the following memory ranges:
FFF0 0000h–FFF7 FFFFh
FFB0 0000h–FFB7 FFFFh
23:20
FWH_E8_IDSEL — R/W. IDSEL for two 512 KB FWH memory ranges. The IDSEL programmed in
this field addresses the following memory ranges:
FFE8 0000h–FFEF FFFFh
FFA8 0000h–FFAF FFFFh
19:16
FWH_E0_IDSEL — R/W. IDSEL for two 512 KB FWH memory ranges. The IDSEL programmed in
this field addresses the following memory ranges:
FFE0 0000h–FFE7 FFFFh
FFA0 0000h–FFA7 FFFFh
15:12
FWH_D8_IDSEL — R/W. IDSEL for two 512 KB FWH memory ranges. The IDSEL programmed in
this field addresses the following memory ranges:
FFD8 0000h–FFDF FFFFh
FF98 0000h–FF9F FFFFh
11:8
FWH_D0_IDSEL — R/W. IDSEL for two 512 KB FWH memory ranges. The IDSEL programmed in
this field addresses the following memory ranges:
FFD0 0000h–FFD7 FFFFh
FF90 0000h–FF97 FFFFh
7:4
FWH_C8_IDSEL — R/W. IDSEL for two 512 KB FWH memory ranges. The IDSEL programmed in
this field addresses the following memory ranges:
FFC8 0000h–FFCF FFFFh
FF88 0000h–FF8F FFFFh
3:0
FWH_C0_IDSEL — R/W. IDSEL for two 512 KB FWH memory ranges. The IDSEL programmed in
this field addresses the following memory ranges:
FFC0 0000h–FFC7 FFFFh
FF80 0000h–FF87 FFFFh
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.33
GEN2_DEC—LPC I/F Generic Decode Range 2 Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Attribute:
Size:
Power Well:
R/W
16 bit
Core
Bit
Description
15:4
Generic I/O Decode Range 2 Base Address (GEN2_BASE) — R/W. This address is aligned on a
64-byte boundary, and must have address lines 31:16 as 0.
Note that this generic decode is for I/O addresses only, not memory addresses. The size of this
range is 16 bytes.
3:1
Reserved. Read as 0
0
9.1.34
ECh–EDh
00h
Yes
Generic I/O Decode Range 2 Enable (GEN2_EN) — R/W.
0 = Disable.
1 = Accesses to the GEN2 I/O range will be forwarded to the LPC I/F
FWH_SEL2—FWH Select 2 Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
EEh–EFh
4567h
Attribute:
Size:
R/W
32 bits
Bit
Description
15:12
FWH_70_IDSEL — R/W. IDSEL for two 1M FWH memory ranges. The IDSEL programmed in this
field addresses the following memory ranges:
FF70 0000h–FF7F FFFFh
FF30 0000h–FF3F FFFFh
11:8
FWH_60_IDSEL — R/W. IDSEL for two 1M FWH memory ranges. The IDSEL programmed in this
field addresses the following memory ranges:
FF60 0000h–FF6F FFFFh
FF20 0000h–FF2F FFFFh
7:4
FWH_50_IDSEL — R/W. IDSEL for two 1M FWH memory ranges. The IDSEL programmed in this
field addresses the following memory ranges:
FF50 0000h–FF5F FFFFh
FF10 0000h–FF1F FFFFh
3:0
FWH_40_IDSEL — R/W. IDSEL for two 1M FWH memory ranges. The IDSEL programmed in this
field addresses the following memory ranges:
FF40 0000h–FF4F FFFFh
FF00 0000h–FF0F FFFFh
Intel® 82801DB ICH4 Datasheet
311
LPC Interface Bridge Registers (D31:F0)
9.1.35
FWH_DEC_EN2—FWH Decode Enable 2 Register
(LPC I/F—D31:F0)
Offset Address:
Default Value:
F0h
0Fh
Attribute:
Size:
R/W
8 bits
This register determines which memory ranges will be decoded on the PCI bus and forwarded to
the FWH. The ICH4 will subtractively decode cycles on PCI unless POS_DEC_EN is set to 1.
Bit
7:4
Description
Reserved
FWH_70_EN — R/W. Enables decoding two 1M FWH memory ranges.
3
0 = Disable.
1 = Enable the following ranges for the FWH
FF70 0000h–FF7F FFFFh
FF30 0000h–FF3F FFFFh
FWH_60_EN — R/W. Enables decoding two 1M FWH memory ranges.
2
0 = Disable.
1 = Enable the following ranges for the FWH
FF60 0000h–FF6F FFFFh
FF20 0000h–FF2F FFFFh
FWH_50_EN — R/W. Enables decoding two 1M FWH memory ranges.
1
0 = Disable.
1 = Enable the following ranges for the FWH
FF50 0000h–FF5F FFFFh
FF10 0000h–FF1F FFFFh
FWH_40_EN — R/W. Enables decoding two 1M FWH memory ranges.
0
312
0 = Disable.
1 = Enable the following ranges for the FWH
FF40 0000h–FF4F FFFFh
FF00 0000h–FF0F FFFFh
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.1.36
FUNC_DIS—Function Disable Register (LPC I/F—D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
F2h
00h
No
Attribute:
Size:
Power Well:
R/W
16 bits
Core
Description
15
D29_F7_Disable — R/W. Software sets this bit to disable the USB EHCI controller function. BIOS
must not enable I/O or memory address space decode, interrupt generation, or any other
functionality of functions that are to be disabled.
0 = Enable. USB EHCI controller is enabled
1 = Disable. USB EHCI controller is disabled
14
LPC Bridge Disable (D31F0D) — R/W.
0 = Enable.
1 = Disable LPC bridge. When disabled, the following spaces will no longer be decoded by the LPC
bridge:
– Device 31, Function 0 Configuration space
– Memory cycles below 16 MB (100000h)
– I/O cycles below 64 KB (100h)
– The Internal I/OxAPIC at FEC0_0000 to FECF_FFFF
Memory cycles in the LPC BIOS range below 4GB will still be decoded when this bit is set, but
the aliases at the top of 1 MB (the E and F segment) no longer will be decoded.
13:11
Reserved
10
D29_F2_Disable — R/W. Software sets this bit to disable the USB UHCI controller #3 function.
BIOS must not enable I/O or memory address space decode, interrupt generation, or any other
functionality of functions that are to be disabled.
0 = Enable. USB UHCI controller #3 is enabled
1 = Disable. USB UHCI controller #3 is disabled
9
D29_F1_Disable — R/W. Software sets this bit to disable the USB UHCI controller #2 function.
BIOS must not enable I/O or memory address space decode, interrupt generation, or any other
functionality of functions that are to be disabled.
0 = Enable. USB UHCI controller #2 is enabled
1 = Disable. USB UHCI controller #2 is disabled
8
D29_F0_Disable — R/W. Software sets this bit to disable the USB UHCI controller #1
function.BIOS must not enable I/O or memory address space decode, interrupt generation, or any
other functionality of functions that are to be disabled.
0 = Enable. USB UHCI controller #1 is enabled
1 = Disable. USB UHCI controller #1 is disabled
7
Reserved
6
D31_F6_Disable — R/W. Software sets this bit to disable the AC ’97 modem controller function.
BIOS must not enable I/O or memory address space decode, interrupt generation, or any other
functionality of functions that are to be disabled.
0 = Enable. AC ’97 Modem is enabled
1 = Disable. AC ’97 Modem is disabled
5
D31_F5_Disable — R/W. Software sets this bit to disable the AC ’97 audio controller function. BIOS
must not enable I/O or memory address space decode, interrupt generation, or any other
functionality of functions that are to be disabled.
0 = Enable. AC ’97 audio controller is enabled
1 = Disable. AC ’97 audio controller is disabled
4
Reserved
Intel® 82801DB ICH4 Datasheet
313
LPC Interface Bridge Registers (D31:F0)
Bit
Description
3
D31_F3_Disable — R/W. Software sets this bit to disable the SMBus Host controller function. BIOS
must not enable I/O or memory address space decode, interrupt generation, or any other
functionality of functions that are to be disabled.
0 = Enable. SMBus controller is enabled
1 = Disable. SMBus controller is disabled
2
Reserved
1
D31_F1_Disable — R/W. Software sets this bit to disable the IDE controller function. BIOS must not
enable I/O or memory address space decode, interrupt generation, or any other functionality of
functions that are to be disabled.
0 = Enable. IDE controller is enabled
1 = Disable. IDE controller is disabled
0
SMB_FOR_BIOS — R/W. This bit is used in conjunction with bit 3 in this register.
0 = No effect.
1 = Allows the SMBus I/O space to be accessible by software when bit 3 in this register is set. The
PCI configuration space is hidden in this case. Note that if bit 3 is set alone, the decode of both
SMBus PCI configuration and I/O space will be disabled.
NOTES:
1. Software must always disable all functionality within the function before disabling the configuration space.
2. Configuration writes to internal ICH4 USB EHCI (D29:F7) and AC ‘97 (D31:F5, F6) devices when disabled
are illegal and may cause undefined results.
314
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.2
DMA I/O Registers
Table 9-2. DMA Registers
Port
Alias
00h
01h
02h
03h
04h
05h
06h
07h
10h
11h
12h
13h
14h
15h
16h
17h
08h
18h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
80h
81h
82h
83h
84h–86h
87h
88h
89h
8Ah
8Bh
8Ch–8Eh
8Fh
C0h
C2h
C4h
C6h
C8h
CAh
CCh
CEh
1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
90h
91h
—
93h
94h–96h
97h
98h
99h
9Ah
9Bh
9Ch–9Eh
9Fh
C1h
C3h
C5h
C7h
C9h
CBh
CDh
CFh
D0h
D1h
D4h
D6h
D8h
DAh
DCh
DEh
D5h
D7h
D9h
DBh
DDh
DFh
Intel® 82801DB ICH4 Datasheet
Register Name
Channel 0 DMA Base & Current Address Register
Channel 0 DMA Base & Current Count Register
Channel 1 DMA Base & Current Address Register
Channel 1 DMA Base & Current Count Register
Channel 2 DMA Base & Current Address Register
Channel 2 DMA Base & Current Count Register
Channel 3 DMA Base & Current Address Register
Channel 3 DMA Base & Current Count Register
Channel 0–3 DMA Command Register
Channel 0–3 DMA Status Register
Channel 0–3 DMA Write Single Mask Register
Channel 0–3 DMA Channel Mode Register
Channel 0–3 DMA Clear Byte Pointer Register
Channel 0–3 DMA Master Clear Register
Channel 0–3 DMA Clear Mask Register
Channel 0–3 DMA Write All Mask Register
Reserved Page Register
Channel 2 DMA Memory Low Page Register
Channel 3 DMA Memory Low Page Register
Channel 1 DMA Memory Low Page Register
Reserved Page Registers
Channel 0 DMA Memory Low Page Register
Reserved Page Register
Channel 6 DMA Memory Low Page Register
Channel 7 DMA Memory Low Page Register
Channel 5 DMA Memory Low Page Register
Reserved Page Registers
Refresh Low Page Register
Channel 4 DMA Base & Current Address Register
Channel 4 DMA Base & Current Count Register
Channel 5 DMA Base & Current Address Register
Channel 5 DMA Base & Current Count Register
Channel 6 DMA Base & Current Address Register
Channel 6 DMA Base & Current Count Register
Channel 7 DMA Base & Current Address Register
Channel 7 DMA Base & Current Count Register
Channel 4–7 DMA Command Register
Channel 4–7 DMA Status Register
Channel 4–7 DMA Write Single Mask Register
Channel 4–7 DMA Channel Mode Register
Channel 4–7 DMA Clear Byte Pointer Register
Channel 4–7 DMA Master Clear Register
Channel 4–7 DMA Clear Mask Register
Channel 4–7 DMA Write All Mask Register
Default
Type
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
000001XXb
000000XXb
Undefined
Undefined
Undefined
0Fh
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
Undefined
000001XXb
000000XXb
Undefined
Undefined
Undefined
0Fh
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
WO
RO
WO
WO
WO
WO
WO
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
WO
RO
WO
WO
WO
WO
WO
R/W
315
LPC Interface Bridge Registers (D31:F0)
9.2.1
DMABASE_CA—DMA Base and Current Address Registers
I/O Address:
Default Value:
Lockable:
9.2.2
Attribute:
Size:
R/W
16 bit (per channel),
but accessed in two 8-bit
quantities
Power Well:
Core
Bit
Description
15:0
Base and Current Address — R/W. This register determines the address for the transfers to be
performed. The address specified points to two separate registers. On writes, the value is stored in
the Base Address register and copied to the Current Address register. On reads, the value is returned
from the Current Address register.
The address increments/decrements in the Current Address register after each transfer, depending
on the mode of the transfer. If the channel is in auto-initialize mode, the Current Address register will
be reloaded from the Base Address register after a terminal count is generated.
For transfers to/from a 16-bit slave (channel’s 5–7), the address is shifted left one bit location. Bit 15
will be shifted into Bit 16.
The register is accessed in 8-bit quantities. The byte is pointed to by the current byte pointer flip/flop.
Before accessing an address register, the byte pointer flip/flop should be cleared to ensure that the
low byte is accessed first
DMABASE_CC—DMA Base and Current Count Registers
I/O Address:
Default Value:
Lockable:
316
Ch. #0 = 00h; Ch. #1 = 02h
Ch. #2 = 04h; Ch. #3 = 06h
Ch. #5 = C4h Ch. #6 = C8h
Ch. #7 = CCh;
Undef
No
Ch. #0: = 01h; Ch. #1 = 03h
Ch. #2: = 05h; Ch. #3 = 07h
Ch. #5 = C6h; Ch. #6 = CAh
Ch. #7 = CEh;
Undefined
No
Attribute:
Size:
R/W
16 bit (per channel),
but accessed in two 8-bit
quantities
Power Well:
Core
Bit
Description
15:0
Base and Current Count — R/W. This register determines the number of transfers to be performed.
The address specified points to two separate registers. On writes, the value is stored in the Base
Count register and copied to the Current Count register. On reads, the value is returned from the
Current Count register.
The actual number of transfers is one more than the number programmed in the Base Count Register
(i.e., programming a count of 4h results in 5 transfers). The count is decrements in the Current Count
register after each transfer. When the value in the register rolls from zero to FFFFh, a terminal count
is generated. If the channel is in auto-initialize mode, the Current Count register will be reloaded from
the Base Count register after a terminal count is generated.
For transfers to/from an 8-bit slave (channels 0–3), the count register indicates the number of bytes to
be transferred. For transfers to/from a 16-bit slave (channels 57), the count register indicates the
number of words to be transferred.
The register is accessed in 8-bit quantities. The byte is pointed to by the current byte pointer flip/flop.
Before accessing a count register, the byte pointer flip/flop should be cleared to ensure that the low
byte is accessed first.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.2.3
DMAMEM_LP—DMA Memory Low Page Registers
I/O Address:
Default Value:
Lockable:
9.2.4
Ch. #0 = 87h; Ch. #1 = 83h
Ch. #2 = 81h; Ch. #3 = 82h
Ch. #5 = 8Bh; Ch. #6 = 89h
Ch. #7 = 8Ah;
Undefined
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Bit
Description
7:0
DMA Low Page (ISA Address bits [23:16]) — R/W. This register works in conjunction with the DMA
controller's Current Address Register to define the complete 24-bit address for the DMA channel.
This register remains static throughout the DMA transfer. Bit 16 of this register is ignored when in 16bit I/O count by words mode as it is replaced by the bit 15 shifted out from the current address
register.
DMACMD—DMA Command Register
I/O Address:
Default Value:
Lockable:
Ch. #0–3 = 08h;
Ch. #4–7 = D0h
Undefined
No
Bit
7:5
Attribute:
Size:
Power Well:
WO
8 bit
Core
Description
Reserved. Must be 0.
4
DMA Group Arbitration Priority — WO. Each channel group is individually assigned either fixed or
rotating arbitration priority. At part reset, each group is initialized in fixed priority.
0 = Fixed priority to the channel group
1 = Rotating priority to the group.
3
Reserved. Must be 0
2
DMA Channel Group Enable — WO. Both channel groups are enabled following part reset.
0 = Enable the DMA channel group.
1 = Disable. Disabling channel group 4–7 also disables channel group 0–3, which is cascaded
through channel 4.
1:0
Reserved. Must be 0.
Intel® 82801DB ICH4 Datasheet
317
LPC Interface Bridge Registers (D31:F0)
9.2.5
DMASTA—DMA Status Register
I/O Address:
Default Value:
Lockable:
9.2.6
Ch. #0–3 = 08h;
Ch. #4–7 = D0h
Undefined
No
Attribute:
Size:
Power Well:
RO
8 bit
Core
Bit
Description
7:4
Channel Request Status — RO. When a valid DMA request is pending for a channel, the
corresponding bit is set to 1. When a DMA request is not pending for a particular channel, the
corresponding bit is set to 0. The source of the DREQ may be hardware or a software request. Note
that channel 4 is the cascade channel, so the request status of channel 4 is a logical OR of the
request status for channels 0 through 3.
4 = Channel 0
5 = Channel 1 (5)
6 = Channel 2 (6)
7 = Channel 3 (7)
3:0
Channel Terminal Count Status — RO. When a channel reaches terminal count (TC), its status bit
is set to 1. If TC has not been reached, the status bit is set to 0. Channel 4 is programmed for
cascade, so the TC bit response for channel 4 is irrelevant:
0 = Channel 0
1 = Channel 1 (5)
2 = Channel 2 (6)
3 = Channel 3 (7)
DMA_WRSMSK—DMA Write Single Mask Register
I/O Address:
Default Value:
Lockable:
Ch. #0–3 = 0Ah;
Ch. #4–7 = D4h
0000 01xx
No
Bit
7:3
2
1:0
Attribute:
Size:
Power Well:
WO
8 bit
Core
Description
Reserved. Must be 0.
Channel Mask Select — WO.
0 = Enable DREQ for the selected channel. The channel is selected through bits [1:0]. Therefore,
only one channel can be masked / unmasked at a time.
1 = Disable DREQ for the selected channel.
DMA Channel Select — WO. These bits select the DMA Channel Mode Register to program.
00 = Channel 0 (4)
01 = Channel 1 (5)
10 = Channel 2 (6)
11 = Channel 3 (7)
318
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.2.7
DMACH_MODE—DMA Channel Mode Register
I/O Address:
Default Value:
Lockable:
9.2.8
Ch. #0–3 = 0Bh;
Ch. #4–7 = D6h
0000 00xx
No
Attribute:
Size:
Power Well:
WO
8 bit
Core
Bit
Description
7:6
DMA Transfer Mode — WO. Each DMA channel can be programmed in one of four different modes:
00 = Demand mode
01 = Single mode
10 = Reserved
11 = Cascade mode
5
Address Increment/Decrement Select — WO. This bit controls address increment/decrement
during DMA transfers.
0 = Address increment. (default after part reset or Master Clear)
1 = Address decrement.
4
Autoinitialize Enable — WO.
0 = Autoinitialize feature is disabled and DMA transfers terminate on a terminal count. A part reset or
Master Clear disables autoinitialization.
1 = DMA restores the Base Address and Count registers to the current registers following a terminal
count (TC).
3:2
DMA Transfer Type — WO. These bits represent the direction of the DMA transfer. When the
channel is programmed for cascade mode, (bits[7:6] = 11) the transfer type is irrelevant.
00 = Verify: No I/O or memory strobes generated
01 = Write: Data transferred from the I/O devices to memory
10 = Read: Data transferred from memory to the I/O device
11 = Illegal
1:0
DMA Channel Select — WO. These bits select the DMA Channel Mode Register that will be written
by bits [7:2].
00 = Channel 0 (4)
01 = Channel 1 (5)
10 = Channel 2 (6)
11 = Channel 3 (7)
DMA Clear Byte Pointer Register
I/O Address:
Default Value:
Lockable:
Ch. #0–3 = 0Ch;
Ch. #4–7 = D8h
xxxx xxxx
No
Attribute:
Size:
Power Well:
WO
8 bit
Core
Bit
Description
7:0
Clear Byte Pointer — WO. No specific pattern. Command enabled with a write to the I/O port
address. Writing to this register initializes the byte pointer flip/flop to a known state. It clears the
internal latch used to address the upper or lower byte of the 16-bit Address and Word Count
Registers. The latch is also cleared by part reset and by the Master Clear command. This command
precedes the first access to a 16-bit DMA controller register. The first access to a 16-bit register will
then access the significant byte, and the second access automatically accesses the most significant
byte.
Intel® 82801DB ICH4 Datasheet
319
LPC Interface Bridge Registers (D31:F0)
9.2.9
DMA Master Clear Register
I/O Address:
Default Value:
Ch. #0–3 = 0Dh;
Ch. #4–7 = DAh
xxxx xxxx
Bit
7:0
9.2.10
WO
8 bit
Description
Master Clear — WO. No specific pattern. Enabled with a write to the port. This has the same effect
as the hardware Reset. The Command, Status, Request, and Byte Pointer flip/flop registers are
cleared and the Mask Register is set.
DMA_CLMSK—DMA Clear Mask Register
I/O Address:
Default Value:
Lockable:
Ch. #0–3 = 0Eh;
Ch. #4–7 = DCh
xxxx xxxx
No
Bit
7:0
9.2.11
Attribute:
Size:
Attribute:
Size:
Power Well:
WO
8 bit
Core
Description
Clear Mask Register — WO. No specific pattern. Command enabled with a write to the port.
DMA_WRMSK—DMA Write All Mask Register
I/O Address:
Default Value:
Lockable:
Ch. #0–3 = 0Fh;
Ch. #4–7 = DEh
0000 1111
No
Bit
7:4
3:0
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Reserved. Must be 0.
Channel Mask Bits — R/W. This register permits all four channels to be simultaneously enabled/
disabled instead of enabling/disabling each channel individually, as is the case with the Mask
Register - Write Single Mask Bit. In addition, this register has a read path to allow the status of the
channel mask bits to be read. A channel's mask bit is automatically set to 1 when the Current Byte/
Word Count Register reaches terminal count (unless the channel is in auto-initialization mode).
Setting the bit(s) to a 1 disables the corresponding DREQ(s). Setting the bit(s) to a 0 enables the
corresponding DREQ(s). Bits [3:0] are set to 1 upon part reset or Master Clear. When read, bits [3:0]
indicate the DMA channel [3:0] ([7:4]) mask status.
Bit 0 = Channel 0 (4)
1 = Masked, 0 = Not Masked
Bit 1 = Channel 1 (5)
1 = Masked, 0 = Not Masked
Bit 2 = Channel 2 (6)
1 = Masked, 0 = Not Masked
Bit 3 = Channel 3 (7)
1 = Masked, 0 = Not Masked
NOTE: Disabling channel 4 also disables channels 0–3 due to the cascade of channel’s 0–3 through
channel 4.
320
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.3
Timer I/O Registers
Port
Aliases
40h
50h
41h
51h
42h
52h
43h
53h
Register Name/Function
Counter 0 Interval Time Status Byte Format
Counter 0 Counter Access Port Register
Counter 1 Interval Time Status Byte Format
Counter 1 Counter Access Port Register
Counter 2 Interval Time Status Byte Format
Counter 2 Counter Access Port Register
Timer Control Word Register
Timer Control Word Register Read Back
Counter Latch Command
9.3.1
Default Value
Type
0XXXXXXXb
RO
Undefined
R/W
0XXXXXXXb
RO
Undefined
R/W
0XXXXXXXb
RO
Undefined
R/W
Undefined
WO
XXXXXXX0b
WO
X0h
WO
TCW—Timer Control Word Register
I/O Address:
Attribute:
43h
WO
Default Value:
Size:
All bits undefined
8 bits
This register is programmed prior to any counter being accessed to specify counter modes.
Following part reset, the control words for each register are undefined and each counter output is 0.
Each timer must be programmed to bring it into a known state.
Bit
Description
7:6
Counter Select — WO. The Counter Selection bits select the counter the control word acts upon as
shown below. The Read Back Command is selected when bits[7:6] are both 1.
00 = Counter 0 select
01 = Counter 1 select
10 = Counter 2 select
11 = Read Back Command
5:4
Read/Write Select — WO. These bits are the read/write control bits. The actual counter
programming is done through the counter port (40h for counter 0, 41h for counter 1, and 42h for
counter 2).
00 = Counter Latch Command
01 = Read/Write Least Significant Byte (LSB)
10 = Read/Write Most Significant Byte (MSB)
11 = Read/Write LSB then MSB
3:1
Counter Mode Selection — WO. These bits select one of six possible modes of operation for the
selected counter.
000 = Mode 0Out signal on end of count (=0)
001 = Mode 1Hardware retriggerable one-shot
x10 = Mode 2Rate generator (divide by n counter)
x11 = Mode 3Square wave output
100 = Mode 4Software triggered strobe
101 = Mode 5Hardware triggered strobe
0
Binary/BCD Countdown Select — WO.
0 = Binary countdown is used. The largest possible binary count is 216
1 = Binary coded decimal (BCD) count is used. The largest possible BCD count is 104
There are two special commands that can be issued to the counters through this register, the Read
Back Command and the Counter Latch Command. When these commands are chosen, several bits
within this register are redefined. These register formats are described below.
Intel® 82801DB ICH4 Datasheet
321
LPC Interface Bridge Registers (D31:F0)
9.3.1.1
RDBK_CMD—Read Back Command
The Read Back Command is used to determine the count value, programmed mode, and current
states of the OUT pin and Null count flag of the selected counter or counters. Status and/or count
may be latched in any or all of the counters by selecting the counter during the register write. The
count and status remain latched until read, and further latch commands are ignored until the count
is read. Both count and status of the selected counters may be latched simultaneously by setting
both bit 5 and bit 4 to 0. If both are latched, the first read operation from that counter returns the
latched status. The next one or two reads, depending on whether the counter is programmed for one
or two byte counts, returns the latched count. Subsequent reads return an unlatched count.
Bit
7:6
Description
Read Back Command. Must be 11 to select the Read Back Command
Latch Count of Selected Counters.
5
0 = Current count value of the selected counters will be latched
1 = Current count will not be latched
Latch Status of Selected Counters.
4
3
2
1
0
9.3.1.2
0 = Status of the selected counters will be latched
1 = Status will not be latched
Counter 2 Select.
1 = Counter 2 count and/or status will be latched
Counter 1 Select.
1 = Counter 1 count and/or status will be latched
Counter 0 Select.
1 = Counter 0 count and/or status will be latched.
Reserved. Must be 0.
LTCH_CMD—Counter Latch Command
The Counter Latch Command latches the current count value. This command is used to insure that
the count read from the counter is accurate. The count value is then read from each counter's count
register through the Counter Ports Access Ports Register (40h for counter 0, 41h for counter 1, and
42h for counter 2). The count must be read according to the programmed format, i.e. if the counter
is programmed for two byte counts, two bytes must be read. The two bytes do not have to be read
one right after the other (read, write, or programming operations for other counters may be inserted
between the reads). If a counter is latched once and then latched again before the count is read, the
second Counter Latch Command is ignored.
Bit
7:6
Description
Counter Selection. These bits select the counter for latching. If 11 is written, then the write is
interpreted as a read back command.
00 = Counter 0
01 = Counter 1
10 = Counter 2
Counter Latch Command.
322
5:4
00 = Selects the Counter Latch Command.
Others = Reserved
3:0
Reserved. Must be 0.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.3.2
SBYTE_FMT—Interval Timer Status Byte Format Register
I/O Address:
Default Value:
Counter 0 = 40h,
Counter 1 = 41h,
Counter 2 = 42h
Bits[6:0] undefined, Bit 7=0
Attribute:
Size:
RO
8 bits per counter
Each counter's status byte can be read following a Read Back Command. If latch status is chosen
(bit 4=0, Read Back Command) as a read back option for a given counter, the next read from the
counter's Counter Access Ports Register (40h for counter 0, 41h for counter 1, and 42h for counter
2) returns the status byte. The status byte returns the following:
Bit
7
Counter OUT Pin State — RO.
0 = OUT pin of the counter is also a 0.
1 = OUT pin of the counter is also a 1.
6
Count Register Status — RO. This bit indicates when the last count written to the Count Register
(CR) has been loaded into the counting element (CE). The exact time this happens depends on the
counter mode, but until the count is loaded into the counting element (CE), the count value will be
incorrect.
0 = Count has been transferred from CR to CE and is available for reading.
1 = Null Count. Count has not been transferred from CR to CE and is not yet available for reading.
5:4
Read/Write Selection Status — RO. These reflect the read/write selection made through bits[5:4] of
the control register. The binary codes returned during the status read match the codes used to
program the counter read/write selection.
00 = Counter Latch Command
01 = Read/Write Least Significant Byte (LSB)
10 = Read/Write Most Significant Byte (MSB)
11 = Read/Write LSB then MSB
3:1
Mode Selection Status — RO. These bits return the counter mode programming. The binary code
returned matches the code used to program the counter mode, as listed under the bit function above.
000 = Mode 0Out signal on end of count (=0)
001 = Mode 1Hardware retriggerable one-shot
x10 = Mode 2Rate generator (divide by n counter)
x11 = Mode 3Square wave output
100 = Mode 4Software triggered strobe
101 = Mode 5Hardware triggered strobe
0
9.3.3
Description
Countdown Type Status — RO. This bit reflects the current countdown type.
0 = Binary countdown
1 = Binary Coded Decimal (BCD) countdown.
Counter Access Ports Register
I/O Address:
Default Value:
Counter 0–40h,
Counter 1–41h,
Counter 2–42h
All bits undefined
Attribute:
R/W
Size:
8 bit
Bit
Description
7:0
Counter Port — R/W. Each counter port address is used to program the 16-bit Count Register. The
order of programming, either LSB only, MSB only, or LSB then MSB, is defined with the Interval
Counter Control Register at port 43h. The counter port is also used to read the current count from the
Count Register, and return the status of the counter programming following a Read Back Command.
Intel® 82801DB ICH4 Datasheet
323
LPC Interface Bridge Registers (D31:F0)
9.4
8259 Interrupt Controller (PIC) Registers
The interrupt controller registers are located at 20h and 21h for the master controller (IRQ0–7), and
at A0h and A1h for the slave controller (IRQ8–13). These registers have multiple functions,
depending upon the data written to them. Below is a description of the different register
possibilities for each address. Table 9-3 provides the register I/O map for the interrupt controller.
Table 9-3. Interrupt Controller I/O Address Map (PIC Registers)
Port
Aliases
20h
24h, 28h,
2Ch, 30h,
34h, 38h, 3Ch
21h
A0h
A1h
324
25h, 29h,
2Dh, 31h,
35h, 39h, 3Dh
A4h, A8h,
ACh, B0h,
B4h, B8h, BCh
A5h, A9h,
ADh, B1h,
B5h, B9h, BDh
Register Name/Function
Default Value
Type
Master PIC ICW1 Init. Cmd Word 1 Register
Undefined
WO
Master PIC OCW2 Op Ctrl Word 2 Register
001XXXXXb
WO
Master PIC OCW3 Op Ctrl Word 3 Register
X01XXX10b
R/W
Master PIC ICW2 Init. Cmd Word 2 Register
Undefined
WO
Master PIC ICW3 Init. Cmd Word 3 Register
Undefined
WO
Master PIC ICW4 Init. Cmd Word 4 Register
01h
WO
Master PIC OCW1 Op Ctrl Word 1 Register
00h
R/W
Slave PIC ICW1 Init. Cmd Word 1 Register
Undefined
WO
Slave PIC OCW2 Op Ctrl Word 2 Register
001XXXXXb
WO
Slave PIC OCW3 Op Ctrl Word 3 Register
X01XXX10b
R/W
Slave PIC ICW2 Init. Cmd Word 2 Register
Undefined
WO
Slave PIC ICW3 Init. Cmd Word 3 Register
Undefined
WO
Slave PIC ICW4 Init. Cmd Word 4 Register
01h
WO
Slave PIC OCW1 Op Ctrl Word 1 Register
00h
R/W
4D0h
—
Master PIC Edge/Level Triggered Register
00h
R/W
4D1h
—
Slave PIC Edge/Level Triggered Register
00h
R/W
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.4.1
ICW1—Initialization Command Word 1 Register
Offset Address:
Default Value:
Master Controller–020h
Slave Controller–0A0h
All bits undefined
Attribute:
Size:
WO
8 bit /controller
A write to Initialization Command Word 1 starts the interrupt controller initialization sequence,
during which the following occurs:
1. The Interrupt Mask register is cleared.
2. IRQ7 input is assigned priority 7.
3. The slave mode address is set to 7.
4. Special mask mode is cleared and Status Read is set to IRR.
Once this write occurs, the controller expects writes to ICW2, ICW3, and ICW4 to complete the
initialization sequence.
Bit
7:5
Description
ICW/OCW Select — WO. These bits are MCS-85 specific, and not needed.
000 = Should be programmed to 000
4
ICW/OCW Select — WO.
1 = This bit must be a 1 to select ICW1 and enable the ICW2, ICW3, and ICW4 sequence.
3
Edge/Level Bank Select (LTIM) — WO. Disabled. Replaced by the edge/level triggered control
registers (ELCR).
2
ADI — WO.
0 = Ignored for the Intel® ICH4. Should be programmed to 0.
1
Single or Cascade (SNGL) — WO.
0 = Must be programmed to a 0 to indicate two controllers operating in cascade mode.
0
ICW4 Write Required (IC4) — WO.
1 = This bit must be programmed to a 1 to indicate that ICW4 needs to be programmed.
Intel® 82801DB ICH4 Datasheet
325
LPC Interface Bridge Registers (D31:F0)
9.4.2
ICW2—Initialization Command Word 2 Register
Offset Address:
Default Value:
Master Controller–021h
Slave Controller–0A1h
All bits undefined
Attribute:
Size:
WO
8 bit /controller
ICW2 is used to initialize the interrupt controller with the five most significant bits of the interrupt
vector address. The value programmed for bits[7:3] is used by the CPU to define the base address
in the interrupt vector table for the interrupt routines associated with each IRQ on the controller.
Typical ISA ICW2 values are 08h for the master controller and 70h for the slave controller.
Bit
9.4.3
Description
7:3
Interrupt Vector Base Address — WO. Bits [7:3] define the base address in the interrupt vector
table for the interrupt routines associated with each interrupt request level input.
2:0
Interrupt Request Level — WO. When writing ICW2, these bits should all be 0. During an
interrupt acknowledge cycle, these bits are programmed by the interrupt controller with the
interrupt to be serviced. This is combined with bits [7:3] to form the interrupt vector driven onto the
data bus during the second INTA# cycle. The code is a three bit binary code:
Code
Master Interrupt Slave Interrupt
000
IRQ0
IRQ8
001
IRQ1
IRQ9
010
IRQ2
IRQ10
011
IRQ3
IRQ11
100
IRQ4
IRQ12
101
IRQ5
IRQ13
110
IRQ6
IRQ14
111
IRQ7
IRQ15
ICW3—Master Controller Initialization Command Word 3
Register
Offset Address:
Default Value:
Bit
7:3
2
1:0
326
21h
All bits undefined
Attribute:
Size:
WO
8 bits
Description
0 = These bits must be programmed to zero.
Cascaded Interrupt Controller IRQ Connection — WO. This bit indicates that the slave controller is
cascaded on IRQ2. When IRQ8#–IRQ15 is asserted, it goes through the slave controller’s priority
resolver. The slave controller’s INTR output onto IRQ2. IRQ2 then goes through the master
controller’s priority solver. If it wins, the INTR signal is asserted to the CPU, and the returning interrupt
acknowledge returns the interrupt vector for the slave controller.
1 = This bit must always be programmed to a 1.
0 = These bits must be programmed to zero.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.4.4
ICW3—Slave Controller Initialization Command Word 3
Register
Offset Address:
Default Value:
A1h
All bits undefined
Bit
9.4.5
WO
8 bits
Description
7:3
0 = These bits must be programmed to zero.
2:0
Slave Identification Code — WO. These bits are compared against the slave identification code
broadcast by the master controller from the trailing edge of the first internal INTA# pulse to the trailing
edge of the second internal INTA# pulse. These bits must be programmed to 02h to match the code
broadcast by the master controller. When 02h is broadcast by the master controller during the INTA#
sequence, the slave controller assumes responsibility for broadcasting the interrupt vector.
ICW4—Initialization Command Word 4 Register
Offset Address:
Master Controller–021h
Slave Controller–0A1h
Bit
7:5
9.4.6
Attribute:
Size:
Attribute:
Size:
WO
8 bits
Description
0 = These bits must be programmed to zero.
4
Special Fully Nested Mode (SFNM) — WO.
0 = Should normally be disabled by writing a 0 to this bit.
1 = Special fully nested mode is programmed.
3
Buffered Mode (BUF) — WO.
0 = Must be programmed to 0 for the Intel® ICH4. This is non-buffered mode.
2
Master/Slave in Buffered Mode — WO. Not used.
0 = Should always be programmed to 0.
1
Automatic End of Interrupt (AEOI) — WO.
0 = This bit should normally be programmed to 0. This is the normal end of interrupt.
1 = Automatic End of Interrupt (AEOI) mode is programmed.
0
Microprocessor Mode — WO.
1 = Must be programmed to 1 to indicate that the controller is operating in an Intel Architecturebased system.
OCW1—Operational Control Word 1 (Interrupt Mask)
Register
Offset Address:
Default Value:
Master Controller–021h
Slave Controller–0A1h
00h
Attribute:
Size:
R/W
8 bits
Bit
Description
7:0
Interrupt Request Mask — R/W. When a 1 is written to any bit in this register, the corresponding
IRQ line is masked. When a 0 is written to any bit in this register, the corresponding IRQ mask bit is
cleared, and interrupt requests will again be accepted by the controller. Masking IRQ2 on the master
controller will also mask the interrupt requests from the slave controller.
Intel® 82801DB ICH4 Datasheet
327
LPC Interface Bridge Registers (D31:F0)
9.4.7
OCW2—Operational Control Word 2 Register
Offset Address:
Default Value:
Master Controller–020h
Attribute:
Slave Controller–0A0h
Size:
Bit[4:0]=undefined, Bit[7:5]=001
WO
8 bits
Following a part reset or ICW initialization, the controller enters the fully nested mode of
operation. Non-specific EOI without rotation is the default. Both rotation mode and specific EOI
mode are disabled following initialization.
9.4.8
Bit
Description
7:5
Rotate and EOI Codes (R, SL, EOI) — WO. These three bits control the Rotate and End of Interrupt
modes and combinations of the two.
000 = Rotate in Auto EOI Mode (Clear)
001 = Non-specific EOI command
010 = No Operation
011 = Specific EOI Command
100 = Rotate in Auto EOI Mode (Set)
101 = Rotate on Non-Specific EOI Command
110 = *Set Priority Command
111 = *Rotate on Specific EOI Command
*L0–L2 Are Used
4:3
OCW2 Select — WO. When selecting OCW2, bits 4:3 = 00
2:0
Interrupt Level Select (L2, L1, L0) — WO. L2, L1, and L0 determine the interrupt level acted upon
when the SL bit is active. A simple binary code, outlined below, selects the channel for the command
to act upon. When the SL bit is inactive, these bits do not have a defined function; programming L2,
L1 and L0 to 0 is sufficient in this case.
Bits
Interrupt Level
Bits
Interrupt Level
000
IRQ0/8
100
IRQ4/12
001
IRQ1/9
101
IRQ5/13
010
IRQ2/10
110
IRQ6/14
011
IRQ3/11
111
IRQ7/15
OCW3—Operational Control Word 3 Register
Offset Address:
Default Value:
Master Controller–020h
Attribute:
Slave Controller–0A0h
Size:
Bit[6,0]=0, Bit[7,4:2]=undefined,
Bit[5,1]=1
Bit
328
WO
8 bits
Description
7
Reserved. Must be 0.
6
Special Mask Mode (SMM) — WO.
1 = The Special Mask Mode can be used by an interrupt service routine to dynamically alter the
system priority structure while the routine is executing, through selective enabling/disabling of
the other channel's mask bits. Bit 5, the ESMM bit, must be set for this bit to have any meaning.
5
Enable Special Mask Mode (ESMM) — WO.
0 = Disable. The SMM bit becomes a “don't care”.
1 = Enable the SMM bit to set or reset the Special Mask Mode.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
Bit
4:3
9.4.9
Description
OCW3 Select — WO. When selecting OCW3, bits 4:3 = 01
2
Poll Mode Command — WO.
0 = Disable. Poll Command is not issued.
1 = Enable. The next I/O read to the interrupt controller is treated as an interrupt acknowledge cycle.
An encoded byte is driven onto the data bus, representing the highest priority level requesting
service.
1:0
Register Read Command — WO. These bits provide control for reading the In-Service Register
(ISR) and the Interrupt Request Register (IRR). When bit 1=0, bit 0 will not affect the register read
selection. When bit 1=1, bit 0 selects the register status returned following an OCW3 read. If bit 0=0,
the IRR will be read. If bit 0=1, the ISR will be read. Following ICW initialization, the default OCW3
port address read will be “read IRR”. To retain the current selection (read ISR or read IRR), always
write a 0 to bit 1 when programming this register. The selected register can be read repeatedly
without reprogramming OCW3. To select a new status register, OCW3 must be reprogrammed prior
to attempting the read.
00 = No Action
01 = No Action
10 = Read IRQ Register
11 = Read IS Register
ELCR1—Master Controller Edge/Level Triggered Register
Offset Address:
Default Value:
4D0h
00h
Attribute:
Size:
R/W
8 bits
In edge mode, (bit[x] = 0), the interrupt is recognized by a low to high transition. In level mode
(bit[x] = 1), the interrupt is recognized by a high level. The cascade channel, IRQ2, the heart beat
timer (IRQ0), and the keyboard controller (IRQ1), cannot be put into level mode.
Bit
Description
7
IRQ7 ECL — R/W.
0 = Edge.
1 = Level.
6
IRQ6 ECL — R/W.
0 = Edge.
1 = Level.
5
IRQ5 ECL — R/W.
0 = Edge.
1 = Level.
4
IRQ4 ECL — R/W.
0 = Edge.
1 = Level.
3
IRQ3 ECL — R/W.
0 = Edge.
1 = Level.
2:0
Reserved. Must be 0.
Intel® 82801DB ICH4 Datasheet
329
LPC Interface Bridge Registers (D31:F0)
9.4.10
ELCR2—Slave Controller Edge/Level Triggered Register
Offset Address:
Default Value:
4D1h
00h
Attribute:
Size:
R/W
8 bits
In edge mode, (bit[x] = 0), the interrupt is recognized by a low to high transition. In level mode
(bit[x] = 1), the interrupt is recognized by a high level. The real time clock, IRQ8#, and the floating
point error interrupt, IRQ13, cannot be programmed for level mode.
Bit
330
Description
7
IRQ15 ECL — R/W.
0 = Edge.
1 = Level.
6
IRQ14 ECL — R/W.
0 = Edge.
1 = Level.
5
Reserved. Must be 0.
4
IRQ12 ECL — R/W.
0 = Edge.
1 = Level.
3
IRQ11 ECL — R/W.
0 = Edge.
1 = Level.
2
IRQ10 ECL — R/W.
0 = Edge.
1 = Level.
1
IRQ9 ECL — R/W.
0 = Edge.
1 = Level.
0
Reserved. Must be 0.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.5
Advanced Interrupt Controller (APIC)
9.5.1
APIC Register Map
The APIC is accessed via an indirect addressing scheme. Two registers are visible by software for
manipulation of most of the APIC registers. These registers are mapped into memory space. The
registers are shown in Table 9-4.
Table 9-4. APIC Direct Registers
Address
Register Name
Size
Type
FEC0_0000h
Index Register
8 bits
R/W
FEC0_0010h
Data Register
32 bits
R/W
FECO_0020h
IRQ Pin Assertion Register
8 bits
WO
FECO_0040h
EOI Register
8 bits
WO
Table 9-5 lists the registers which can be accessed within the APIC via the Index Register. When
accessing these registers, accesses must be done a DWORD at a time. For example, software
should never access byte 2 from the Data register before accessing bytes 0 and 1. The hardware
will not attempt to recover from a bad programming model in this case.
Table 9-5. APIC Indirect Registers
Index
Register Name
Size
Type
00h
ID
32 bits
R/W
01h
Version
32 bits
RO
02h
Arbitration ID
32 bits
RO
03h
Boot Configuration
32 bits
R/W
03–0Fh
Reserved
10–11h
Redirection Table 0
64 bits
R/W, RO
12–13h
Redirection Table 1
64 bits
R/W, RO
...
...
64 bits
R/W, RO
...
...
3E–3Fh
Redirection Table 23
40–FFh
Reserved
Intel® 82801DB ICH4 Datasheet
RO
RO
331
LPC Interface Bridge Registers (D31:F0)
9.5.2
IND—Index Register
Memory Address
Default Value:
FEC0_0000h
00h
Attribute:
Size:
R/W
8 bits
The Index Register will select which APIC indirect register to be manipulated by software. The
selector values for the indirect registers are listed in Table 9-5. Software will program this register
to select the desired APIC internal register
.
Bit
7:0
9.5.3
Description
APIC Index — R/W. This is an 8-bit pointer into the I/O APIC register table.
DAT—Data Register
Memory Address
Default Value:
FEC0_0010h
00000000h
Attribute:
Size:
R/W
32 bits
This is a 32-bit register specifying the data to be read or written to the register pointed to by the
Index register. This register can only be accessed in DWORD quantities.
Bit
7:0
9.5.4
Description
APIC Data — R/W. This is a 32-bit register for the data to be read or written to the APIC indirect
register pointed to by the Index register.
IRQPA—IRQ Pin Assertion Register
Memory Address
Default Value:
FEC0_0020h
N/A
Attribute:
Size:
WO
32 bits
The IRQ Pin Assertion Register is present to provide a mechanism to scale the number of interrupt
inputs into the I/O APIC without increasing the number of dedicated input pins. When a device that
supports this interrupt assertion protocol requires interrupt service, that device will issue a write to
this register. Bits 4:0 written to this register contain the IRQ number for this interrupt. The only
valid values are 0–23. Bits 31:5 are ignored. To provide for future expansion, peripherals should
always write a value of 0 for Bits 31:5.
See Section 5.8.4 for more details on how PCI devices will use this field.
Note:
332
Writes to this register are only allowed by the processor and by masters on the ICH4’s PCI bus.
Writes by devices on PCI buses above the ICH4 (e.g., a PCI segment on a P64H) are not supported.
Bit
Description
31:5
Reserved. To provide for future expansion, the CPU should always write a value of 0 to Bits 31:5.
4:0
IRQ Number — WO. Bits 4:0 written to this register contain the IRQ number for this interrupt. The
only valid values are 0–23.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.5.5
EOIR—EOI Register
Memory Address
Default Value:
FEC0_0040h
N/A
Attribute:
Size:
WO
32 bits
The EOI register is present to provide a mechanism to maintain the level triggered semantics for
level-triggered interrupts issued on the parallel bus.
When a write is issued to this register, the I/O APIC will check the lower 8 bits written to this
register, and compare it with the vector field for each entry in the I/O Redirection Table. When a
match is found, the Remote_IRR bit for that I/O Redirection Entry will be cleared.
9.5.6
Note:
This is similar to what already occurs when the APIC sees the EIO message on the serial bus. Note
that if multiple I/O Redirection entries, for any reason, assign the same vector for more than one
interrupt input, each of those entries will have the Remote_IRR bit reset to 0. The interrupt which
was prematurely reset will not be lost because if its input remained active when the Remote_IRR
bit is cleared, the interrupt will be reissued and serviced at a later time. Note: Only bits 7:0 are
actually used. Bits 31:8 are ignored by the ICH4.
Note:
To provide for future expansion, the CPU should always write a value of 0 to Bits 31:8.
Bit
Description
31:8
Reserved. To provide for future expansion, the processor should always write a value of 0 to Bits
31:8.
7:0
Redirection Entry Clear — WO. When a write is issued to this register, the I/O APIC will check
this field, and compare it with the vector field for each entry in the I/O Redirection Table. When a
match is found, the Remote_IRR bit for that I/O Redirection Entry will be cleared.
ID—Identification Register
Index Offset:
Default Value:
00h
00000000h
Attribute:
Size:
R/W
32 bits
The APIC ID serves as a physical name of the APIC. The APIC bus arbitration ID for the APIC is
derived from its I/O APIC ID. This register is reset to zero on power up reset
Bit
Description
31:28
Reserved
27:24
APIC ID — R/W. Software must program this value before using the APIC.
23:16
Reserved
15
14:0
Scratchpad bit.
Reserved
Intel® 82801DB ICH4 Datasheet
333
LPC Interface Bridge Registers (D31:F0)
9.5.7
VER—Version Register
Index Offset:
Default Value:
01h
00170002h
Attribute:
Size:
RO
32 bits
Each I/O APIC contains a hardwired Version Register that identifies different implementation of
APIC and their versions. The maximum redirection entry information also is in this register, to let
software know how many interrupt are supported by this APIC.
Bit
31:24
Reserved
23:16
Maximum Redirection Entries — RO. This is the entry number (0 being the lowest entry) of the
highest entry in the redirection table. It is equal to the number of interrupt input pins minus one and
is in the range 0 through 239. In the Intel® ICH4 this field is hardwired to 17h to indicate 24
interrupts.
15
9.5.8
Description
PRQ — RO. This bit is set to 1 to indicate that this version of the I/O APIC implements the IRQ
Assertion register and allows PCI devices to write to it to cause interrupts.
14:8
Reserved
7:0
Version — RO. This is a version number that identifies the implementation version.
ARBID—Arbitration ID Register
Index Offset:
Default Value:
02h
00000000h
Attribute:
Size:
RO
32 bits
This register contains the bus arbitration priority for the APIC. If APIC Clock is running, this
register is loaded whenever the APIC ID register is loaded. A rotating priority scheme is used for
APIC bus arbitration. The winner of the arbitration becomes the lowest priority agent and assumes
an arbitration ID of 0.
a
Bit
31:28
9.5.9
Description
Reserved
27:24
I/O APIC Identification — RO. This 4-bit field contains the I/O APIC Arbitration ID.
23:0
Reserved
BOOT_CONFIG—Boot Configuration Register
Index Offset:
Default Value:
03h
00000000h
Attribute:
Size:
R/W
32 bits
This register is used to control the interrupt delivery mechanism for the APIC.
a
Bit
31:1
0
334
Description
Reserved
Delivery Type (DT) — R/W.
0 = Interrupt delivery mechanism is via the APIC serial bus (default).
1 = Interrupt delivery mechanism is a Processor System Bus message.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.5.10
Redirection Table
Index Offset:
Default Value:
10h–11h (vector 0) through
3E–3Fh (vector 23)
Bit 16=1, Bits[15:12]=0.
All other bits undefined
Attribute:
R/W, RO
Size:
64 bits each, (accessed as
two 32 bit quantities)
The Redirection Table has a dedicated entry for each interrupt input pin. The information in the
Redirection Table is used to translate the interrupt manifestation on the corresponding interrupt pin
into an APIC message.
The APIC will respond to an edge triggered interrupt as long as the interrupt is held until after the
acknowledge cycle has begun. Once the interrupt is detected, a delivery status bit internally to the
I/O APIC is set. The state machine will step ahead and wait for an acknowledgment from the APIC
bus unit that the interrupt message was sent over the APIC bus. Only then will the I/O APIC be
able to recognize a new edge on that interrupt pin. That new edge will only result in a new
invocation of the handler if its acceptance by the destination APIC causes the Interrupt Request
Register bit to go from 0 to 1. (In other words, if the interrupt was not already pending at the
destination.)
Bit
Description
63:56
Destination — R/W.
If bit 11 of this entry is 0 [Physical], then bits [59:56] specifies an APIC ID. In this case, bits 63:59
should be programmed by software to 0.
If bit 11 of this entry is 1 [Logical], then bits [63:56] specify the logical destination address of a set
of processors.
55:48
Extended Destination ID (EDID). These bits are only sent to a local APIC when in Processor
System Bus mode. They become bits [11:4] of the address.
47:17
Reserved
Mask — R/W.
16
0 = Not masked: An edge or level on this interrupt pin results in the delivery of the interrupt to the
destination.
1 = Masked: Interrupts are not delivered nor held pending. Setting this bit after the interrupt is
accepted by a local APIC has no effect on that interrupt. This behavior is identical to the
device withdrawing the interrupt before it is posted to the processor. It is software's
responsibility to deal with the case where the mask bit is set after the interrupt message has
been accepted by a local APIC unit but before the interrupt is dispensed to the processor.
Trigger Mode — R/W. This field indicates the type of signal on the interrupt pin that triggers an
interrupt.
15
14
0 = Edge triggered.
1 = Level triggered.
Remote IRR — R/W. This bit is used for level-triggered interrupts; its meaning is undefined for
edge-triggered interrupts.
0 = Reset when an EOI message is received from a local APIC.
1 = Set when Local APIC/s accept the level interrupt sent by the I/O APIC.
13
Interrupt Input Pin Polarity — R/W. This bit specifies the polarity of each interrupt signal
connected to the interrupt pins.
0 = Active high.
1 = Active low.
Intel® 82801DB ICH4 Datasheet
335
LPC Interface Bridge Registers (D31:F0)
Bit
Description
12
Delivery Status — RO. This field contains the current status of the delivery of this interrupt.
Writes to this bit have no effect.
0 = Idle. No activity for this interrupt.
1 = Pending. Interrupt has been injected, but delivery is held up due to the APIC bus being busy
or the inability of the receiving APIC unit to accept the interrupt at this time.
11
Destination Mode — R/W. This field determines the interpretation of the Destination field.
0 = Physical. Destination APIC ID is identified by bits [59:56].
1 = Logical. Destinations are identified by matching bit [63:56] with the Logical Destination in the
Destination Format Register and Logical Destination Register in each Local APIC.
10:8
Delivery Mode — R/W. This field specifies how the APICs listed in the destination field should act
upon reception of this signal. Certain Delivery Modes will only operate as intended when used in
conjunction with a specific trigger mode. These encodings are listed in the note below:
7:0
Vector — R/W. This field contains the interrupt vector for this interrupt. Values range between 10h
and FEh.
NOTE: Delivery Mode Encoding (Bits 10:8):
000 = Fixed. Deliver the signal on the INTR signal of all processor cores listed in the destination.
Trigger Mode can be edge or level.
001 = Lowest Priority. Deliver the signal on the INTR signal of the processor core that is executing at
the lowest priority among all the processors listed in the specified destination. Trigger Mode can
be edge or level.
010 = SMI (System Management Interrupt). Requires the interrupt to be programmed as edge
triggered. The vector information is ignored but must be programmed to all zeroes for future
compatibility. Not supported
011 = Reserved
100 = NMI. Deliver the signal on the NMI signal of all processor cores listed in the destination. Vector
information is ignored. NMI is treated as an edge triggered interrupt even if it is programmed as
level triggered. For proper operation this redirection table entry must be programmed to edge
triggered. The NMI delivery mode does not set the RIRR bit. Once the interrupt is detected, it will
be sent over the APIC bus. If the redirection table is incorrectly set to level, the loop count will
continue counting through the redirection table addresses. Once the count for the NMI pin is
reached again, the interrupt will be sent over the APIC bus again. Not supported
101 = INIT. Deliver the signal to all processor cores listed in the destination by asserting the INIT signal.
All addressed local APICs will assume their INIT state. INIT is always treated as an edge
triggered interrupt even if programmed as level triggered. For proper operation this redirection
table entry must be programmed to edge triggered. The INIT delivery mode does not set the
RIRR bit. Once the interrupt is detected, it will be sent over the APIC bus. If the redirection table
is incorrectly set to level, the loop count will continue counting through the redirection table
addresses. Once the count for the INIT pin is reached again, the interrupt will be sent over the
APIC bus again. Not supported
110 = Reserved
111 = ExtINT. Deliver the signal to the INTR signal of all processor cores listed in the destination as an
interrupt that originated in an externally connected 8259A compatible interrupt controller. The
INTA cycle that corresponds to this ExtINT delivery will be routed to the external controller that is
expected to supply the vector. Requires the interrupt to be programmed as edge triggered.
336
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.6
Real Time Clock Registers
9.6.1
I/O Register Address Map
The RTC internal registers and RAM are organized as two banks of 128 bytes each, called the
standard and extended banks. The first 14 bytes of the standard bank contain the RTC time and date
information along with four registers, A–D, that are used for configuration of the RTC. The
extended bank contains a full 128 bytes of battery backed SRAM, and will be accessible even when
the RTC module is disabled (via the RTC configuration register). Registers A–D do not physically
exist in the RAM.
All data movement between the host processor and the real-time clock is done through registers
mapped to the standard I/O space. The register map appears in Table 9-6.
Table 9-6. RTC I/O Registers
I/O Locations
If U128E bit = 0
Function
70h and 74h
Also alias to 72h and 76h
Real-Time Clock (Standard RAM) Index Register
71h and 75h
Also alias to 73h and 77h
Real-Time Clock (Standard RAM) Target Register
72h and 76h
Extended RAM Index Register (if enabled)
73h and 77h
Extended RAM Target Register (if enabled)
NOTES:
1. I/O locations 70h and 71h are the standard ISA location for the real-time clock. The map for this bank is
shown in Table 9-7. Locations 72h and 73h are for accessing the extended RAM. The extended RAM bank is
also accessed using an indexed scheme. I/O address 72h is used as the address pointer and I/O address
73h is used as the data register. Index addresses above 127h are not valid. If the extended RAM is not
needed, it may be disabled.
2. Software must preserve the value of bit 7 at I/O addresses 70h and 74h. When writing to these addresses,
software must first read the value, and then write the same value for bit 7 during the sequential address write.
3. Accesses to 70h, 72h, 74h, and 76h do affect the NMI mask (bit 7 of 70h).
Intel® 82801DB ICH4 Datasheet
337
LPC Interface Bridge Registers (D31:F0)
9.6.2
Indexed Registers
The RTC contains two sets of indexed registers that are accessed using the two separate Index and
Target registers (70/71h or 72/73h), as shown in Table 9-7.
Table 9-7. RTC (Standard) RAM Bank
Index
00h
Seconds
01h
Seconds Alarm.
02h
Minutes
03h
Minutes Alarm
04h
Hours
05h
Hours Alarm
06h
Day of Week
07h
Day of Month
08h
Month
09h
Year
0Ah
Register A
0Bh
Register B
0Ch
Register C
0Dh
Register D
0Eh–7Fh
338
Name
114 Bytes of User RAM
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.6.2.1
RTC_REGA—Register A
RTC Index:
Default Value:
Lockable:
0A
Undefined
No
Attribute:
Size:
Power Well:
R/W
8 bit
RTC
This register is used for general configuration of the RTC functions. None of the bits are affected
by RSMRST# or any other ICH4 reset signal.
Bit
Description
7
Update In Progress (UIP) — R/W. This bit may be monitored as a status flag.
0 = The update cycle will not start for at least 492 µs. The time, calendar, and alarm information in
RAM is always available when the UIP bit is 0.
1 = The update is soon to occur or is in progress.
6:4
Division Chain Select (DV[2:0]) — R/W. These three bits control the divider chain for the oscillator,
and are not affected by RSMRST# or any other reset signal. DV[2] corresponds to bit 6.
010 = Normal Operation
11X = Divider Reset
101 = Bypass 15 stages (test mode only)
100 = Bypass 10 stages (test mode only)
011 = Bypass 5 stages (test mode only)
001 = Invalid
000 = Invalid
3:0
Rate Select (RS[3:0]) — R/W. Selects one of 13 taps of the 15 stage divider chain. The selected tap
can generate a periodic interrupt if the PIE bit is set in Register B. Otherwise this tap will set the PF
flag of Register C. If the periodic interrupt is not to be used, these bits should all be set to zero. RS3
corresponds to bit 3.
0000 = Interrupt never toggles
0001 = 3.90625 ms
0010 = 7.8125 ms
0011 = 122.070 µs
0100 = 244.141 µs
0101 = 488.281 µs
0110 = 976.5625 µs
0111 = 1.953125 ms
1000 = 3.90625 ms
1001 = 7.8125 ms
1010 = 15.625 ms
1011 = 31.25 ms
1100 = 62.5 ms
1101 = 125 ms
1110 = 250 ms
1111= 500 ms
Intel® 82801DB ICH4 Datasheet
339
LPC Interface Bridge Registers (D31:F0)
9.6.2.2
RTC_REGB—Register B (General Configuration)
RTC Index:
Default Value:
Lockable:
Bit
7
0Bh
U0U00UUU (U: Undefined)
No
Attribute:
Size:
Power Well:
R/W
8 bit
RTC
Description
Update Cycle Inhibit (SET) — R/W. Enables/Inhibits the update cycles. This bit is not affected by
RSMRST# nor any other reset signal.
0 = Update cycle occurs normally once each second.
1 = A current update cycle will abort and subsequent update cycles will not occur until SET is
returned to zero. When set is one, the BIOS may initialize time and calendar bytes safely.
NOTE: This bit should be set then cleared by BIOS early in BIOS POST, after each powerup directly
after coin-cell batter insertion.
6
Periodic Interrupt Enable (PIE) — R/W. This bit is cleared by RSMRST#, but not on any other reset.
0 = Disable.
1 = Allows an interrupt to occur with a time base set with the RS bits of register A.
Alarm Interrupt Enable (AIE) — R/W. This bit is cleared by RSMRST#, but not on any other reset.
5
340
0 = Disable.
1 = Allows an interrupt to occur when the AF is set by an alarm match from the update cycle. An
alarm can occur once a second, one an hour, once a day, or one a month.
4
Update-Ended Interrupt Enable (UIE) — R/W. This bit is cleared by RSMRST#, but not on any other
reset.
0 = Disable.
1 = Allows an interrupt to occur when the update cycle ends.
3
Square Wave Enable (SQWE) — R/W. This bit serves no function in the Intel® ICH4. It is left in this
register bank to provide compatibility with the Motorola 146818B. The ICH4 has no SQW pin. This bit
is cleared by RSMRST#, but not on any other reset.
2
Data Mode (DM) — R/W. Specifies either binary or BCD data representation. This bit is not affected
by RSMRST# nor any other reset signal.
0 = BCD
1 = Binary
1
Hour Format (HOURFORM) — R/W. Indicates the hour byte format. This bit is not affected by
RSMRST# nor any other reset signal.
0 = Twelve-hour mode. In twelve-hour mode, the seventh bit represents AM as zero and PM as one.
1 = Twenty-four hour mode.
0
Daylight Savings Enable (DSE) — R/W. Triggers two special hour updates per year. The days for
the hour adjustment are those specified in United States federal law as of 1987, which is different
than previous years. This bit is not affected by RSMRST# nor any other reset signal.
0 = Daylight Savings Time updates do not occur.
1 = a) Update on the first Sunday in April, where time increments from 1:59:59 AM to 3:00:00 AM.
b) Update on the last Sunday in October when the time first reaches 1:59:59 AM, it is changed to
1:00:00 AM. The time must increment normally for at least two update cycles (seconds) previous
to these conditions for the time change to occur properly.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.6.2.3
RTC_REGC—Register C (Flag Register)
RTC Index:
Default Value:
Lockable:
0Ch
00U00000 (U: Undefined)
No
Attribute:
Size:
Power Well:
RO
8 bit
RTC
Writes to Register C have no effect.
Bit
Description
7
Interrupt Request Flag (IRQF) — RO. IRQF = (PF * PIE) + (AF * AIE) + (UF *UFE). This also causes
the CH_IRQ_B signal to be asserted. This bit is cleared upon RSMRST# or a read of Register C.
6
Periodic Interrupt Flag (PF) — RO. This bit is cleared upon RSMRST# or a read of Register C.
0 = If no taps are specified via the RS bits in Register A, this flag will not be set.
1 = Periodic interrupt Flag will be 1 whenever the tap specified by the RS bits of register A is 1.
5
Alarm Flag (AF) — RO.
0 = This bit is cleared upon RTCRST# or a read of Register C.
1 = Alarm Flag will be set after all Alarm values match the current time.
Update-ended Flag (UF) — RO.
4
3:0
9.6.2.4
0 = The bit is cleared upon RSMRST# or a read of Register C.
1 = Set immediately following an update cycle for each second.
Reserved. Will always report 0.
RTC_REGD—Register D (Flag Register)
RTC Index:
Default Value:
Lockable:
0Dh
10UUUUUU (U: Undefined)
No
Attribute:
Size:
Power Well:
R/W
8 bit
RTC
Bit
Description
7
Valid RAM and Time Bit (VRT) — R/W.
0 = This bit should always be written as a 0 for write cycle; however, it will return a 1 for read cycles.
1 = This bit is hardwired to 1 in the RTC power well.
6
Reserved. This bit always returns a 0 and should be set to 0 for write cycles.
5:0
Date Alarm — R/W. These bits store the date of month alarm value. If set to 000000b, then a don’t
care state is assumed. The host must configure the date alarm for these bits to do anything, yet they
can be written at any time. If the date alarm is not enabled, these bits will return zeros to mimic the
functionality of the Motorola 146818B. These bits are not affected by RESET.
Intel® 82801DB ICH4 Datasheet
341
LPC Interface Bridge Registers (D31:F0)
9.7
Processor Interface Registers
9.7.1
NMI_SC—NMI Status and Control Register
I/O Address:
Default Value:
Lockable:
342
61h
00h
No
Attribute:
Size:
Power Well:
R/W, RO
8 bit
Core
Bit
Description
7
SERR# NMI Source Status (SERR#_NMI_STS) — RO.
1 = PCI agent detected a system error and pulses the PCI SERR# line. This interrupt source is
enabled by setting bit 2 to 0. To reset the interrupt, set bit 2 to 1 and then set it to 0. When writing
to port 61h, this bit must be 0.
6
IOCHK# NMI Source Status (IOCHK_NMI_STS) — RO.
1 = An ISA agent (via SERIRQ) asserted IOCHK# on the ISA bus. This interrupt source is enabled
by setting bit 3 to 0. To reset the interrupt, set bit 3 to 0 and then set it to 1. When writing to port
61h, this bit must be a 0.
5
Timer Counter 2 OUT Status (TMR2_OUT_STS) — RO. This bit reflects the current state of the
8254 counter 2 output. Counter 2 must be programmed following any PCI reset for this bit to have a
determinate value. When writing to port 61h, this bit must be a 0.
4
Refresh Cycle Toggle (REF_TOGGLE) — RO. This signal toggles from either 0 to 1 or 1 to 0 at a
rate that is equivalent to when refresh cycles would occur. When writing to port 61h, this bit must be a
0.
3
IOCHK# NMI Enable (IOCHK_NMI_EN) — R/W.
0 = Enabled.
1 = Disabled and cleared.
2
PCI SERR# Enable (PCI_SERR_EN) — R/W.
0 = SERR# NMIs are enabled.
1 = SERR# NMIs are disabled and cleared.
1
Speaker Data Enable (SPKR_DAT_EN) — R/W.
0 = SPKR output is a 0.
1 = SPKR output is equivalent to the Counter 2 OUT signal value.
0
Timer Counter 2 Enable (TIM_CNT2_EN) — R/W.
0 = Disable
1 = Enable
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.7.2
NMI_EN—NMI Enable (and Real Time Clock Index) Register
I/O Address:
Default Value:
Lockable:
Note:
70h
80h
No
7
6:0
Description
NMI Enable (NMI_EN) — R/W.
0 = Enable NMI sources.
1 = Disable All NMI sources.
Real Time Clock Index Address (RTC_INDX) — R/W. This data goes to the RTC to select which
register or CMOS RAM address is being accessed.
PORT92—Fast A20 and Init Register
I/O Address:
Default Value:
Lockable:
92h
00h
No
Bit
7:2
9.7.4
R/W-Special
8 bit
Core
The RTC Index field is write-only for normal operation. This field can only be read in Alt-Access
Mode. Note, however, that this register is aliased to Port 74h (documented in Table 17-2), and all
bits are readable at that address.
Bits
9.7.3
Attribute:
Size:
Power Well:
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Reserved
1
Alternate A20 Gate (ALT_A20_GATE) — R/W. This bit is Or’d with the A20GATE input signal to
generate A20M# to the processor.
0 = A20M# signal can potentially go active.
1 = This bit is set when INIT# goes active.
0
INIT_NOW — R/W. When this bit transitions from a 0 to a 1, the Intel® ICH4 will force INIT# active
for 16 PCI clocks.
COPROC_ERR—Coprocessor Error Register
I/O Address:
Default Value:
Lockable:
F0h
00h
No
Attribute:
Size:
Power Well:
WO
8 bits
Core
Bits
Description
7:0
COPROC_ERR — WO. Any value written to this register will cause IGNNE# to go active, if FERR#
had generated an internal IRQ13. For FERR# to generate an internal IRQ13, the
COPROC_ERR_EN bit (Device 31:Function 0, Offset D0, Bit 13) must be 1.
Intel® 82801DB ICH4 Datasheet
343
LPC Interface Bridge Registers (D31:F0)
9.7.5
RST_CNT—Reset Control Register
I/O Address:
Default Value:
Lockable:
Bit
7:4
344
CF9h
00h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Reserved
3
Full Reset (FULL_RST) — R/W. This bit is used to determine the states of SLP_S3#, SLP_S4# and
SLP_S5# after a CF9 hard reset (SYS_RST =1 and RST_CPU is set to 1), after PWROK going low
(with RSMRST# high), or after two TCO timeouts.
0 = Intel® ICH4 will keep SLP_S3#, SLP_S4# and SLP_S5# high.
1 = ICH4 will drive SLP_S3#, SLP_S4# and SLP_S5# low for 3–5 seconds.
2
Reset CPU (RST_CPU) — R/W. When this bit transitions from a 0 to a 1, it initiates a hard or soft
reset, as determined by the SYS_RST bit (bit 1 of this register).
1
System Reset (SYS_RST) — R/W. This bit is used to determine a hard or soft reset to the
processor.
0 = When RST_CPU bit goes from 0 to 1, the ICH4 performs a soft reset by activating INIT# for
16 PCI clocks.
1 = When RST_CPU bit goes from 0 to 1, the ICH4 performs a hard reset by activating PCIRST#
for 1 millisecond. It also resets the resume well bits (except for those noted throughout the
EDS). The SLP_S3#, SLP_S4#, and SLP_S5# signals will not go active.
0
Reserved
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8
Power Management Registers (D31:F0)
The power management registers are distributed within the PCI Device 31: Function 0 space, as
well as a separate I/O range. Each register is described below. Unless otherwise indicate, bits are in
the main (core) power well.
Bits not explicitly defined in each register are assumed to be reserved. When writing to a reserved
bit, the value should always be 0. Software should not attempt to use the value read from a reserved
bit, as it may not be consistently 1 or 0.
9.8.1
Power Management PCI Configuration Registers (D31:F0)
Table 9-8 shows a small part of the configuration space for PCI Device 31: Function 0. It includes
only those registers dedicated for power management. Some of the registers are only used for
Legacy Power management schemes.
Table 9-8. PCI Configuration Map (PM—D31:F0)
Offset
Mnemonic
40h–43h
PM_BASE
44h
ACPI_CNTL
Register Name
ACPI Base Address (See
Section 9.1.10)
ACPI Control (See Section 9.1.11)
Default
Type
00000001h
R/W
00h
R/W
0000h
R/W, RO,
R/WO, R/WC
A0h
GEN_PMCON_1
General Power Management
Configuration 1
A2h
GEN_PMCON_2
General Power Management
Configuration 2
0000h
R/WC, R/W
A4h
GEN_PMCON_3
General Power Management
Configuration 3
00h
R/W, R/WC
A8h
STPCLK_DEL
Stop Clock Delay Register
0Dh
R/W
B8–BBh
GPI_ROUT
00000000h
R/W
C0
TRP_FWD_EN
C4–CAhh
MON[n]_TRP_RNG
CCh
MON_TRP_MSK
Intel® 82801DB ICH4 Datasheet
GPI Route Control
I/O Monitor Trap Forwarding Enable
I/O Monitor[4:7] Trap Range
0000h
R/W
I/O Monitor Trap Range Mask
0000h
R/W
345
LPC Interface Bridge Registers (D31:F0)
9.8.1.1
GEN_PMCON_1—General PM Configuration 1 Register (PM—D31:F0)
Offset Address:
Default Value:
Lockable:
A0h
00h
No
Bit
Attribute:
Size:
Usage:
Power Well:
R/W, RO, R/WO, R/WC
16 bit
ACPI, Legacy
Core
Description
15:11
Reserved
10
Reserved
PWRBTN_LVL — RO. This read-only bit indicates the current state of the PWRBTN# signal.
346
9
0 = Low.
1 = High.
8:7
Reserved
6
64_EN. Software sets this bit to indicate that the processor is an IA_64 processor, not an IA_32
processor.This may be used in various state machines where there are behavioral differences.
5
CPU SLP# Enable (CPUSLP_EN) — R/W.
0 = Disable.
1 = Enables the CPUSLP# signal to go active in the S1 states. This reduces the CPU power.
Note that CPUSLP# will go active on entry to S3, S4 and S5 even if this bit is not set.
4
SMI_LOCK — R/W-Once. When this bit is set, writes to the GLB_SMI_EN bit will have no effect.
Once the SMI_LOCK bit is set, writes of 0 to SMI_LOCK bit will have no effect (i.e., once set, this
bit can only be cleared by PCIRST#).
3:2
Reserved
1:0
Periodic SMI# Rate Select (PER_SMI_SEL) — R/W. Set by software to control the rate the
periodic SMI# is generated.
00 = 1 minute
01 = 32 seconds
10 = 16 seconds
11 = 8 seconds
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.1.2
GEN_PMCON_2—General PM Configuration 2 Register (PM—D31:F0)
Offset Address:
Default Value:
Lockable:
A2h
00h
No
Bit
7
6:5
Attribute:
Size:
Usage:
Power Well:
R/WC, R/W
8 bit
ACPI, Legacy
Resume
Description
Reserved
CPU PLL Lock Time (CPLT) — R/W. This field indicates the amount of time that the processor
needs to lock its PLLs. This is used where timing t208 applies (see Chapter 17).
00 = Minimum lock time of 30.7 µs (Default)
01 = min 61.4 µs,
10 = min 122.8 µs, and
11 = min 245.6 µs.
4
System Reset Status (SRS)— R/WC. Intel® ICH4 sets this bit when the SYS_RESET# button is
pressed. BIOS is expected to read this bit and clear it if it is set. This bit is also reset by RSMRST#
and CF9h resets.
3
CPU Thermal Trip Status (CTS)— R/WC. This bit is set when PCIRST# is inactive and
CPUTHRMTRIP# goes active while the system is in an S0 or S1 state. This bit is also reset by
RSMRST# and CF9h resets. It is not reset by the shutdown and reboot associated with the
CPUTHRMTRIP# event.
2
Reserved
1
CPU Power Failure (CPUPWR_FLR) — R/WC.
0 = Software clears this bit by writing a 0 to the bit position.
1 = Indicates that the VRMPWRGD signalfrom the processor’s VRM went low.
PWROK Failure (PWROK_FLR) — R/WC.
0
0 = Software clears this bit by writing a 1 to the bit position, or when the system goes into a G3
state.
1 = This bit will be set any time PWROK goes low, when the system was in S0, or S1 state. The bit
will be cleared only by software by writing a 1 to this bit or when the system goes to a G3 state.
NOTES:
1. Traditional designs have a reset button logically AND’d with the PWROK signal from the power
supply and the CPU’s voltage regulator module. If this is done with the ICH4, the PWROK_FLR
bit will be set. The ICH4 treats this internally as if the RSMRST# signal had gone active.
However, it is not treated as a full power failure. If PWROK goes inactive and then active (but
RSMRST# stays high), then the ICH4 will reboot (regardless of the state of the AFTERG3 bit). If
the RSMRST# signal also goes low before PWROK goes high, then this is a full power failure,
and the reboot policy is controlled by the AFTERG3 bit.
2. In the case of true PWROK failure, PWROK will go low first before the VRMPWRGD.
NOTE: VRMPWROK is sampled using the RTC clock. Therefore, low times that are less than one RTC clock
period may not be detected by the ICH4.
Intel® 82801DB ICH4 Datasheet
347
LPC Interface Bridge Registers (D31:F0)
9.8.1.3
GEN_PMCON_3—General PM Configuration 3 Register (PM—D31:F0)
Offset Address:
Default Value:
Lockable:
A4h
00h
No
Bit
Attribute:
Size:
Usage:
Power Well:
R/W, R/WC
8 bit
ACPI, Legacy
RTC
Description
SWSMI_RATE_SEL — R/W. This 2-bit value indicates when the SWSMI timer will time out. Valid
values are:
7:6
00 = 1.5 ms ± 0.5 ms
01 = 16 ms ± 4 ms
10 = 32 ms ± 4 ms
11 = 64 ms ± 4 ms
5:3
2
1
Reserved
RTC Power Status (RTC_PWR_STS) — R/W. This bit is set when RTCRST# is low. The bit is not
cleared by any type of reset. When the system boots, BIOS can detect that the FREQ_STRAP
register contents are 1111 (the default when RTCRST# has been low). If this bit is also set, then
BIOS knows the RTC battery had been removed. In that case, BIOS should take steps to reprogram
the FREQ_STRAP register with the correct value, and then reboot the system.
Power Failure (PWR_FLR) — R/WC. This bit is in the RTC well, and is not cleared by any type of
reset except RTCRST#.
0 = Indicates that the trickle current has not failed since the last time the bit was cleared. Software
clears this bit by writing a 1 to the bit position.
1 = Indicates that the trickle current (from the main battery or trickle supply) was removed or failed.
NOTE: Clearing CMOS in an Intel® ICH4-based platform can be done by using a jumper on
RTCRST# or GPI, or using SAFEMODE strap. Implementations should not attempt to clear
CMOS by using a jumper to pull VccRTC low.
0
AFTERG3_EN — R/W. Determines what state to go to when power is re-applied after a power
failure (G3 state). This bit is in the RTC well and is not cleared by any type of reset except writes to
CF9h or RTCRST#.
0 = System will return to S0 state (boot) after power is re-applied.
1 = System will return to the S5 state (except if it was in S4, in which case it will return to S4). In the
S5 state, the only enabled wake event is the Power Button or any enabled wake event that was
preserved through the power failure.
NOTE: RSMRST# is sampled using the RTC clock. Therefore, low times that are less than one RTC clock
period may not be detected by the ICH4.
348
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.1.4
STPCLK_DEL—Stop Clock Delay Register (PM—D31:F0)
Offset Address:
Default Value:
Power Well:
A8h
0Dh
Core
Bit
7:6
Attribute:
Size:
Usage:
R/W
8 bit
ACPI, Legacy
Description
Reserved
STPCLK_DEL — R/W. This field selects the AC timing value for t190 (CPUSLP# inactive to
STPCLK# inactive). The default value of 0Dh yields a default of approximately 50.045
microseconds. The maximum value of 3Fh will result in a time of 245 microseconds.
5:0
NOTE: Software must program the value to a range that can be tolerated by the associated
processor and chipset. The Intel® ICH4 requires that software does not program a value of
00h or 01h; a minimum programming of 02h yields the minimum possible delay of 3.87 µs.
9.8.1.5
GPI_ROUT—GPI Routing Control Register (PM—D31:F0)
Offset Address:
Default Value:
Lockable:
Bit
B8h–BBh
0000h
No
Attribute:
Size:
Power Well:
R/W
32-bit
Resume
Description
31:30
GPI15 Route — R/W. See bits 1:0 for description.
5:4
GPI2 Route — R/W. See bits 1:0 for description.
3:2
GPI1 Route — R/W. See bits 1:0 for description.
1:0
GPI0 Route — R/W. GPIO[15:0] can be routed to cause an SMI or SCI when the GPI[n]_STS bit is
set. If the GPIO is not set to an input, this field has no effect.
If the system is in an S1–S5 state and if the GPE0_EN bit is also set, then the GPI can cause a
Wake event, even if the GPI is NOT routed to cause an SMI# or SCI.
00 = No effect.
01 = SMI# (if corresponding ALT_GP_SMI_EN bit is also set)
10 = SCI (if corresponding GPE0_EN bit is also set)
11 = Reserved
Same pattern for GPI14 through GPI3
NOTE: GPIOs that are not implemented will not have the corresponding bits implemented in this register.
Intel® 82801DB ICH4 Datasheet
349
LPC Interface Bridge Registers (D31:F0)
9.8.1.6
TRP_FWD_EN—IO Monitor Trap Forwarding Enable Register
(PM—D31:F0)
Offset Address:
Default Value:
Lockable:
Power Well:
C0h
00h
No
Core
Attribute:
Size:
Usage:
R/W (Special)
8 bits
Legacy Only
The ICH4 uses this register to enable the monitors to forward cycles to LPC, independent of the
POS_DEC_EN bit and the bits that enable the monitor to generate an SMI#. The only criteria is
that the address passes the decoding logic as determined by the MON[n]_TRP_RNG and
MON_TRP_MSK register settings.
Bit
7
MON7_FWD_EN — R/W.
0 = Disable. Cycles trapped by I/O Monitor 7 will not be forwarded to LPC.
1 = Enable. Cycles trapped by I/O Monitor 7 will be forwarded to LPC.
6
MON6_FWD_EN — R/W.
0 = Disable. Cycles trapped by I/O Monitor 6 will not be forwarded to LPC.
1 = Enable. Cycles trapped by I/O Monitor 6 will be forwarded to LPC.
5
MON5_FWD_EN — R/W.
0 = Disable. Cycles trapped by I/O Monitor 5 will not be forwarded to LPC.
1 = Enable. Cycles trapped by I/O Monitor 5 will be forwarded to LPC.
4
MON4_FWD_EN — R/W.
0 = Disable. Cycles trapped by I/O Monitor 4 will not be forwarded to LPC.
1 = Enable. Cycles trapped by I/O Monitor 4 will be forwarded to LPC.
3:0
350
Description
Reserved
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.1.7
MON[n]_TRP_RNG—I/O Monitor [4:7] Trap Range Register for
Devices 4–7 (PM—D31:F0)
Offset Address:
Default Value:
Lockable:
Power Well:
C4h, C6h, C8h, CAh
00h
No
Core
Attribute:
Size:
Usage:
R/W
16 bits
Legacy Only
These registers set the ranges that Device Monitors 4–7 should trap. Offset 4Ch corresponds to
Monitor 4. Offset C6h corresponds to Monitor 5, etc.
If the trap is enabled in the MON_SMI register and the address is in the trap range (and passes the
mask set in the MON_TRP_MSK register) the ICH4 will generate an SMI#. This SMI# occurs if
the address is positively decoded by another device on PCI or by the ICH4 (because it would be
forwarded to LPC or some other ICH4 internal registers). The trap ranges should not point to
registers in the ICH4’s internal IDE, USB, AC ’97 or LAN I/O space. If the cycle is to be claimed
by the ICH4 and targets one of the permitted ICH4 internal registers (interrupt controller, RTC,
etc.), the cycle will complete to the intended target and an SMI# will be generated (this is the same
functionality as the ICH component). If the cycle is to be claimed by the ICH4 and the intended
target is on LPC, an SMI# will be generated but the cycle will only be forwarded to the intended
target if forwarding to LPC is enabled via the TRP_FWD_EN register settings.
9.8.1.8
Bit
Description
15:0
MON[n]_TRAP_BASE — R/W. Base I/O locations that MON[n] traps (where n = 4, 5, 6 or 7). The
range can be mapped anywhere in the processor I/O space (0–64 KB).
Any access to the range will generate an SMI# if enabled by the associated DEV[n]_TRAP_EN bit in
the MON_SMI register (PMBASE +40h).
MON_TRP_MSK—I/O Monitor Trap Range Mask Register for Devices
4–7 (PM—D31:F0)
Offset Address:
Default Value:
Lockable:
Power Well:
Bit
CCh
00h
No
Core
Attribute:
Size:
Usage:
R/W
16 bits
Legacy Only
Description
15:12
MON7_MASK — R/W. Selects low 4-bit mask for the I/O locations that MON7 will trap. Similar to
MON4_MASK.
11:8
MON6_MASK — R/W. Selects low 4-bit mask for the I/O locations that MON6 will trap. Similar to
MON4_MASK.
7:4
MON5_MASK — R/W. Selects low 4-bit mask for the I/O locations that MON5 will trap. Similar to
MON4_MASK.
3:0
MON4_MASK — R/W. Selects low 4-bit mask for the I/O locations that MON7 will trap. When a
mask bit is set to a 1, the corresponding bit in the base I/O selection will not be decoded.
For example, if MON4_TRAP_BASE = 1230h, and MON4_MSK = 0011b, the Intel® ICH4 will
decode 1230h, 1231h, 1232h, and 1233h for Monitor 4.
Intel® 82801DB ICH4 Datasheet
351
LPC Interface Bridge Registers (D31:F0)
9.8.2
APM I/O Decode
Table 9-9 shows the I/O registers associated with APM support. This register space is enabled in
the PCI Device 31: Function 0 space (APMDEC_EN), and cannot be moved (fixed I/O location).
Table 9-9. APM Register Map
9.8.2.1
Address
Mnemonic
B2h
APM_CNT
B3h
APM_STS
B2h
00h
No
Core
Bit
7:0
Type
Advanced Power Management Control Port
00h
R/W
Advanced Power Management Status Port
00h
R/W
Attribute:
Size:
Usage:
R/W
8 bit
Legacy Only
Description
Used to pass an APM command between the OS and the SMI handler. Writes to this port not only
store data in the APMC register, but also generates an SMI# when the APMC_EN bit is set.
APM_STS—Advanced Power Management Status Port Register
I/O Address:
Default Value:
Lockable:
Power Well:
352
Default
APM_CNT—Advanced Power Management Control Port Register
I/O Address:
Default Value:
Lockable:
Power Well:
9.8.2.2
Register Name
B3h
00h
No
Core
Attribute:
Size:
Usage:
R/W
8 bit
Legacy Only
Bit
Description
7:0
Used to pass data between the OS and the SMI handler. Basically, this is a scratchpad register and
is not affected by any other register or function (other than a PCI reset).
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.3
Power Management I/O Registers
Table 9-10 shows the registers associated with ACPI and Legacy power management support.
These registers are enabled in the PCI Device 31: Function 0 space (PM_IO_EN), and can be
moved to any I/O location (128-byte aligned). The registers are defined to be compliant with the
ACPI 1.0 specification, and use the same bit names.
Note:
All reserved bits and registers will always return 0 when read, and will have no effect when written.
Table 9-10. ACPI and Legacy I/O Register Map
PMBASE
+ Offset
Register Name
ACPI Pointer
Default
Attributes
00–01h
Power Management 1 Status
PM1a_EVT_BLK
0000h
R/WC
02–03h
Power Management 1 Enable
PM1a_EVT_BLK+2
0000h
R/W
04–07h
Power Management 1 Control
PM1a_CNT_BLK
00000000h
R/W, WO
08–0Bh
Power Management 1 Timer
PMTMR_BLK
00000000h
RO
P_BLK
00000000h
R/W, RO
P_BLK+4
00h
RO
GPE0_BLK
00000000h
R/W, R/WC
GPE0_BLK+4
00000000h
R/W
0Ch
10h–13h
14h
Reserved
Processor Control
Level 2 Register
15h–16h
Reserved
17–1Fh
Reserved
20h
Reserved
28–2Bh
General Purpose Event 0 Status
2C–2Fh
General Purpose Event 0 Enables
30–33h
SMI# Control and Enable
00000000h
R/W, WO,
R/W-Special
34–37h
SMI Status Register
00000000h
R/WC, RO
38–39h
Alternate GPI SMI Enable
0000h
R/W
3A–3Bh
Alternate GPI SMI Status
0000h
R/WC
3C–3Fh
Reserved
0000h
RO
40h
Monitor SMI Status
0000h
R/W, R/WC
42h
Reserved
44h
Device Trap Status
0000h
R/W
48h
Trap Enable register
0000h
R/W
4Ch–4Dh
Bus Address Tracker
Last Cycle
RO
4Eh
Bus Cycle Tracker
Last Cycle
RO
50h
Reserved
51h–5Fh
Reserved
60h–7Fh
Reserved for TCO Registers
Intel® 82801DB ICH4 Datasheet
353
LPC Interface Bridge Registers (D31:F0)
9.8.3.1
PM1_STS—Power Management 1 Status Register
I/O Address:
Default Value:
Lockable:
Power Well:
PMBASE + 00h
(ACPI PM1a_EVT_BLK)
0000h
No
Bits 0–7: Core,
Bits 8–10, 12–15: Resume,
Bit 11: RTC
Attribute:
Size:
Usage:
R/WC
16 bit
ACPI or Legacy
If bit 10 or 8 in this register is set, and the corresponding _EN bit is set in the PM1_EN register,
then the ICH4 will generate a Wake Event. Once back in an S0 state (or if already in an S0 state
when the event occurs), the ICH4 will also generate an SCI if the SCI_EN bit is set, or an SMI# if
the SCI_EN bit is not set.
Note:
Bit 5 does not cause an SMI# or a wake event. Bit 0 does not cause a wake event but can cause an
SMI# or SCI.
Bit
Description
15
Wake Status (WAK_STS) — R/WC. This bit is not affected by hard resets caused by a CF9 write,
but is reset by RSMRST#.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when the system is in one of the sleep states (via the SLP_EN bit) and an
enabled wake event occurs. Upon setting this bit, the Intel® ICH4 will transition the system to
the ON state.
If the AFTERG3_EN bit is not set and a power failure occurs without the SLP_EN bit set, the
system will return to an S0 state when power returns and the WAK_STS bit will not be set.
If the AFTERG3_EN bit is set and a power failure occurs without the SLP_EN bit having been set,
the system will go into an S5 state when power returns, and a subsequent wake event will cause
the WAK_STS bit to be set. Note that any subsequent wake event would have to be caused by
either a Power Button press, or an enabled wake event that was preserved through the power
failure (enable bit in the RTC well).
14:12
354
Reserved
11
Power Button Override Status (PRBTNOR_STS) — R/WC. This bit is set any time a Power
Button Override occurs (i.e., the power button is pressed for at least 4 consecutive seconds), or
due to the corresponding bit in the SMBus slave message. The power button override causes an
unconditional transition to the S5 state, as well as sets the AFTERG# bit. The BIOS or SCI
handler clears this bit by writing a 1 to it. This bit is not affected by hard resets via CF9h writes,
and is not reset by RSMRST#. Thus, this bit is preserved through power failures.
10
RTC Status (RTC_STS) — R/WC. This bit is not affected by hard resets caused by a CF9 write,
but is reset by RSMRST#.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when the RTC generates an alarm (assertion of the IRQ8# signal).
Additionally if the RTC_EN bit is set, the setting of the RTC_STS bit will generate a wake
event.
9
Reserved
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
Bit
Description
Power Button Status (PWRBTN__STS) — R/WC. This bit is not affected by hard resets caused
by a CF9 write.
0 = If the PWRBTN# signal is held low for more than 4 seconds, the hardware clears the
PWRBTN_STS bit, sets the PWRBTNOR_STS bit, and the system transitions to the S5 state
with only PWRBTN# enabled as a wake event.
8
This bit can be cleared by software by writing a one to the bit position.
1 = This bit is set by hardware when the PWRBTN# signal is asserted Low, independent of any
other enable bit.
In the S0 state, while PWRBTN_EN and PWRBTN_STS are both set, an SCI (or SMI# if
SCI_EN is not set) will be generated.
In any sleeping state S1–S5, while PWRBTN_EN and PWRBTN_STS are both set, a wake
event is generated.
7:6
5
Reserved
Global Status (GBL _STS) — R/WC.
0 = The SCI handler should then clear this bit by writing a 1 to the bit location.
1 = Set when an SCI is generated due to BIOS wanting the attention of the SCI handler. BIOS
has a corresponding bit, BIOS_RLS, which will cause an SCI and set this bit.
4
Reserved
3:1
Reserved
0
Timer Overflow Status (TMROF_STS) — R/WC.
0 = The SCI or SMI# handler clears this bit by writing a 1 to the bit location.
1 = This bit gets set any time bit 22 of the 24-bit timer goes high (bits are numbered from 0 to 23).
This will occur every 2.3435 seconds. When the TMROF_EN bit is set, then the setting of the
TMROF_STS bit will additionally generate an SCI or SMI# (depending on the SCI_EN).
Intel® 82801DB ICH4 Datasheet
355
LPC Interface Bridge Registers (D31:F0)
9.8.3.2
PM1_EN—Power Management 1 Enable Register
I/O Address:
Default Value:
Lockable:
Power Well:
Bit
15:11
Attribute:
Size:
Usage:
R/W
16 bit
ACPI or Legacy
Description
Reserved
10
RTC Event Enable (RTC_EN) — R/W. This bit is in the RTC well to allow an RTC event to wake
after a power failure. This bit is not cleared by any reset other than RTCRST# or a Power Button
Override event.
0 = No SCI (or SMI#) or wake event is generated then RTC_STS goes active.
1 = An SCI (or SMI#) or wake event will occur when this bit is set and the RTC_STS bit goes
active.
9
Reserved.
8
Power Button Enable (PWRBTN_EN) — R/W. This bit is used to enable the setting of the
PWRBTN_STS bit to generate a power management event (SMI#, SCI). PWRBTN_EN has no
effect on the PWRBTN_STS bit being set by the assertion of the power button. The Power Button is
always enabled as a Wake event.
0 = Disable.
1 = Enable.
7:6
5
4:1
0
356
PMBASE + 02h
(ACPI PM1a_EVT_BLK + 2)
0000h
No
Bits 0–7: Core,
Bits 8–9, 11–15: Resume
Bit 10: RTC
Reserved.
Global Enable (GBL_EN) — R/W. When both the GBL_EN and the GBL_STS are set, an SCI is
raised.
0 = Disable.
1 = Enable SCI on GBL_STS going active.
Reserved.
Timer Overflow Interrupt Enable (TMROF_EN) — R/W. Works in conjunction with the SCI_EN bit
as described below:
TMROF_EN
SCI_EN
Effect when TMROF_STS is set
0
x
No SMI# or SCI
1
0
SMI#
1
1
SCI
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.3.3
PM1_CNT—Power Management 1 Control Register
I/O Address:
Default Value:
Lockable:
Power Well:
PMBASE + 04h
(ACPI PM1a_CNT_BLK)
0000h
No
Bits 0–7: Core,
Bits 8–12: RTC
Bits 13–15: Resume
Bit
15:14
13
12:10
Attribute:
Size:
Usage:
R/W, WO
32-bit
ACPI or Legacy
Description
Reserved.
Sleep Enable (SLP_EN) — WO.
Setting this bit causes the system to sequence into the Sleep state defined by the SLP_TYP field.
Sleep Type (SLP_TYP) — R/W. This 3-bit field defines the type of Sleep the system should enter
when the SLP_EN bit is set to 1.
000 = N: Typically maps to S0 state.
001 = It asserts STPCLK#. Puts CPU in Stop-Grant state. Optional to assert CPUSLP# to put
processor in sleep state: Typically maps to S1 state.
010 = Reserved
011 = Reserved
100 = Reserved
101 = Suspend-To-RAM. Assert SLP_S1# and SLP_S3#: Typically maps to S3 state.
110 = Suspend-To-Disk. Assert SLP_S1#, SLP_S3#, and SLP_S4#: Typically maps to S4 state.
111 = Soft Off. Assert SLP_S1#, SLP_S3#, SLP_S4#, and SLP_S5#: Typically maps to S5 state.
NOTE: These bits are only reset by RTCRST#.
9:3
Reserved.
2
Global Release (GBL_RLS) — WO.
0 = This bit always reads as 0.
1 = ACPI software writes a 1 to this bit to raise an event to the BIOS. BIOS software has a
corresponding enable and status bits to control its ability to receive ACPI events.
1
Reserved
0
SCI Enable (SCI_EN) — R/W. Selects the SCI interrupt or the SMI# interrupt for various events
including the bits in the PM1_STS register (bit 10, 8, 0), and bits in GPE0_STS.
0 = These events will generate an SMI#.
1 = These events will generate an SCI.
Intel® 82801DB ICH4 Datasheet
357
LPC Interface Bridge Registers (D31:F0)
9.8.3.4
PM1_TMR—Power Management 1 Timer Register
I/O Address:
PMBASE + 08h
(ACPI PMTMR_BLK)
Default Value:
Lockable:
Power Well:
xx000000h
No
Core
Bit
9.8.3.5
Attribute:
Size:
Usage:
RO
32-bit
ACPI
Description
31:24
Reserved
23:0
Timer Value (TMR_VAL) — RO. Returns the running count of the PM timer. This counter runs off a
3.579545 MHz clock (14.31818 MHz divided by 4). It is reset to zero during a PCI reset, and then
continues counting as long as the system is in the S0 state.
Anytime bit 22 of the timer goes HIGH to LOW (bits referenced from 0 to 23), the TMROF_STS bit is
set. The high-to-low transition will occur every 2.3435 seconds. If the TMROF_EN bit is set, an SCI
interrupt is also generated.
PROC_CNT—Processor Control Register
I/O Address:
Default Value:
Lockable:
Power Well:
PMBASE + 10h
(ACPI P_BLK)
00000000h
No (bits 7:5 are write once)
Core
Bit
31:18
Attribute:
Size:
Usage:
R/W, RO
32 bit
ACPI or Legacy
Description
Reserved
Throttle Status (THTL_STS) — RO.
17
16:9
8
358
0 = No clock throttling is occurring (maximum processor performance).
1 = Indicates that the clock state machine is in some type of low power state (where the processor
is not running at its maximum performance): thermal throttling or hardware throttling.
Reserved
Force Thermal Throttling (FORCE_THTL) — R/W. Software can set this bit to force the thermal
throttling function. This has the same effect as the THRM# signal being active for 2 seconds.
0 = No forced throttling.
1 = Throttling at the duty cycle specified in THRM_DTY starts immediately (no 2 second delay), and
no SMI# is generated.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
Bit
Description
7:5
THRM_DTY — R/W. This write-once 3-bit field determines the duty cycle of the throttling when the
thermal override condition occurs. The duty cycle indicates the approximate percentage of time the
STPCLK# signal is asserted while in the throttle mode. The STPCLK# throttle period is 1024
PCICLKs. Note that the throttling only occurs if the system is in the C0 state. If in the C2 state, no
throttling occurs.
There is no enable bit for thermal throttling, because it should not be disabled. Once the
THRM_DTY field is written, any subsequent writes will have no effect until PCIRST# goes active.
THRM_DTY
Throttle Mode
PCI Clocks
000
50% (Default)
512
001
87.5%
896
010
75.0%
768
011
62.5%
640
100
50%
512
101
37.5%
384
110
25%
256
111
12.5%
128
4
THTL_EN — R/W. When set and the system is in a C0 state, it enables a processor-controlled
STPCLK# throttling. The duty cycle is selected in the THTL_DTY field.
0 = Disable
1 = Enable
3:1
THTL_DTY — R/W. This 3-bit field determines the duty cycle of the throttling when the THTL_EN bit
is set. The duty cycle indicates the approximate percentage of time the STPCLK# signal is asserted
(low) while in the throttle mode. The STPCLK# throttle period is 1024 PCICLKs.
THTL_DTY
Throttle Mode
PCI Clocks
000
50% (Default)
512
001
87.5%
896
010
75.0%
768
011
62.5%
640
100
50%
512
101
37.5%
384
110
25%
256
111
12.5%
128
0
9.8.3.6
Reserved
LV2 — Level 2 Register
I/O Address:
Default Value:
Lockable:
Power Well:
PMBASE + 14h
(ACPI P_BLK+4)
00h
No
Core
Attribute:
Size:
Usage:
RO
8 bit
ACPI or Legacy
Bit
Description
7:0
Reads to this register return all zeros, writes to this register have no effect. Reads to this register
generate a “enter a level 2 power state” (C2) to the clock control logic. This will cause the STPCLK#
signal to go active, and stay active until a break event occurs. Throttling (due either to THTL_EN or
THRM# override) will be ignored.
Intel® 82801DB ICH4 Datasheet
359
LPC Interface Bridge Registers (D31:F0)
9.8.3.7
GPE0_STS—General Purpose Event 0 Status Register
I/O Address:
Default Value:
Lockable:
Power Well:
Note:
PMBASE + 28h
(ACPI GPE0_BLK)
00000000h
No
Resume
Attribute:
Size:
Usage:
R/WC, R/W
32 bit
ACPI
This register is symmetrical to the General Purpose Event 0 Enable Register. If the corresponding
_EN bit is set, then when the _STS bit gets set, the ICH4 generates a Wake Event. Once back in an
S0 state (or if already in an S0 state when the event occurs), the ICH4 also generates an SCI if the
SCI_EN bit is set, or an SMI# if the SCI_EN bit is not set. There is no SCI/SMI# or wake event on
THRMOR_STS since there is no corresponding _EN bit. None of these bits are reset by CF9h
write. All are reset by RSMRST#.
Bit
Description
GPIn_STS — R/WC. These bits are set any time the corresponding GPIO is set up as an input
and the corresponding GPIO signal is high (or low if the corresponding GP_INV bit is set). If the
corresponding enable bit is set in the GPE0_EN register, then when the GPI[n]_STS bit is set:
31:16
15:14
Reserved
13
PME_B0_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position. (default)
1 = This bit will be set to 1 by the Intel® ICH4 when any internal device on bus 0 asserts the
equivalent of the PME# signal. Additionally, if the PME_B0_EN bit is set, and the system is in
an S0 state, then the setting of the PME_B0_STS bit will generate an SCI (or SMI# if
SCI_EN is not set). If the PME_B0_STS bit is set, and the system is in an S1–S4 state (or S5
state due to SLP_TYP and SLP_EN), then the setting of the PME_B0_STS bit will generate
a wake event, and an SCI (or SMI# if SCI_EN is not set) will be generated. If the system is in
an S5 state due to power button override, then the PME_B0_STS bit will not cause a wake
event or SCI.
12
USB3_STS — R/W
0 = Disable.
1 = Set by hardware and can be reset by writing a one to this bit position or a resume-well reset.
This bit is set when USB UHCI controller #3 needs to cause a wake. Additionally if the
USB3_EN bit is set, the setting of the USB3_STS bit will generate a wake event.
11
PME_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when the PME# signal goes active. Additionally, if the PME_EN bit is set,
and the system is in an S0 state, then the setting of the PME_STS bit will generate an SCI or
SMI# (if SCI_EN is not set). If the PME_EN bit is set, and the system is in an S1–S4 state (or
S5 state due to setting SLP_TYP and SLP_EN), then the setting of the PME_STS bit will
generate a wake event, and an SCI will be generated. If the system is in an S5 state due to
power button override or a power failure, then PME_STS will not cause a wake event or SCI.
10:9
8
360
• If the system is in an S1–S5 state, the event will also wake the system.
• If the system is in an S0 state (or upon waking back to an S0 state), a SCI will be caused
depending on the GPI_ROUT bits for the corresponding GPI.
Reserved
RI_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when the RI# input signal goes active.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
Bit
Description
7
SMBus Wake Status (SMB_WAK_STS) — R/WC. The SMBus controller can independently
cause an SMI# or SCI, so this bit does not need to do so (unlike the other bits in this register).
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware to indicate that the wake event was caused by the ICH4’s SMBus logic.This
bit will be set by the WAKE/SMI# command type, even if the system is already awake. The
SMI handler should then clear this bit.
NOTES:
1. This bit is set by the SMBus slave command 01h (Wake/SMI#) even when the system is in the
S0 state. Therefore, to avoid an instant wake on subsequent transitions to sleep states,
software must clear this bit after each reception of the Wake/SMI# command or just prior to
entering the sleep state.
2. If SMB_WAK_STS is set due to SMBus slave receiving a message, it will be cleared by
internal logic when a THRMTRIP# event happens or a Power Button Override event.
However, THRMTRIP# or Power Button Override event will not clear SMB_WAK_STS if it is
set due to SMBALERT# signal going active.
3. The SMBALERT_STS bit (D31:F3:I/O Offset 00h:Bit 5) should be cleared by software before
this bit is cleared.
6
TCOSCI_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when the TCO logic causes an SCI.
5
AC97_STS — R/WC. This bit will be set to 1 by when the codecs are attempting to wake the
system and the PME events for the codecs are armed for wakeup. A PME is armed by
programming the appropriate PMEE bit in the Power Management Control and Status register at
bit 8 of offset 54h in each AC ’97 function.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when the codecs are attempting to wake the system. The AC97_STS bit
gets set only from the following two cases:
• The PMEE bit for the function is set, and o The AC-link bit clock has been shut and the
routed AC_SDIN line is high (for audio, if routing is disabled, no wake events are
allowed.
• For modem, if audio routing is disabled, then the wake event is an OR of all AC_SDIN
lines. If routing is enabled, then the wake event for modem is the remaining non-routed
AC_SDIN line), or o GPI Status Change Interrupt bit (NABMBAR + 30h, bit 0) is 1.
This bit is not affected by a hard reset caused by a CF9h write.
4
USB2_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when USB UHCI controller 2 needs to cause a wake. Wake event will be
generated if the corresponding USB2_EN bit is set.
3
USB1_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware when USB UHCI controller 1 needs to cause a wake. Wake event will be
generated if the corresponding USB1_EN bit is set.
2
Reserved
1
Thermal Interrupt Override Status (THRMOR_STS) — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = This bit is set by hardware anytime a thermal over-ride condition occurs and starts throttling
the processor’s clock at the THRM_DTY ratio. This will not cause an SMI#, SCI, or wake
event.
0
Thermal Interrupt Status (THRM_STS) — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by hardware anytime the THRM# signal is driven active as defined by the THRM_POL
bit. Additionally, if the THRM_EN bit is set, then the setting of the THRM_STS bit will also
generate a power management event (SCI or SMI#).
Intel® 82801DB ICH4 Datasheet
361
LPC Interface Bridge Registers (D31:F0)
9.8.3.8
GPE0_EN—General Purpose Event 0 Enables Register
I/O Address:
Default Value:
Lockable:
Power Well:
Note:
PMBASE + 2Ch
(ACPI GPE0_BLK + 2)
00000000h
No
Bits 0–7, 12, 16–31 Resume,
Bits 8–11, 13–15 RTC
Attribute:
Size:
Usage:
R/W
32-bit
ACPI
This register is symmetrical to the General Purpose Event 0 Status Register. All the bits in this
register should be cleared to 0 based on a Power Button Override. The resume well bits are all
cleared by RSMRST#. The RTC sell bits are cleared by RTCRST#.
Bit
Description
31:16
GPIn_EN — R/W. These bits enable the corresponding GPI[n]_STS bits being set to cause a
SCI, and/or wake event. These bits are cleared by RSMRST#.
15:14
Reserved
13
PME_B0_EN — R/W. Enables the setting of the PME_B0_STS bit to generate a wake event and/
or an SCI or SMI#. PME_B0_STS can be a wake event from the S1–S4 states, or from S5 (if
entered via SLP_TYP and SLP_EN) or power failure, but not Power Button Override. This bit
defaults to 0. It is only cleared by Software or RTCRST#. It is not cleared by CF9h writes.
12
USB3_EN — R/W.
0 = Disable.
1 = Enable the setting of the USB3_STS bit to generate a wake event. The USB3_STS bit is set
anytime USB UHCI controller #3 signals a wake event. Break events are handled via the
USB interrupt.
PME_EN — R/W.
11
362
0 = Disable.
1 = Enables the setting of the PME_STS to generate a wake event and/or an SCI. PME# can be
a wake event from the S1–S4 state or from S5 (if entered via SLP_EN, but not power button
override).
10
Reserved
9
Reserved
8
RI_EN — R/W. The value of this bit will be maintained through a G3 state and is not affected by a
hard reset caused by a CF9h write.
0 = Disable.
1 = Enables the setting of the RI_STS to generate a wake event.
7
Reserved
6
TCOSCI_EN — R/W.
0 = Disable.
1 = Enables the setting of the TCOSCI_STS to generate an SCI.
5
AC97_EN — R/W.
0 = Disable.
1 = Enables the setting of the AC97_STS to generate a wake event.
4
USB2_EN — R/W.
0 = Disable.
1 = Enable the setting of the USB2_STS bit to generate a wake event. The USB2_STS bit is set
anytime USB UHCI controller #2 signals a wake event. Break events are handled via the
USB interrupt.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.3.9
Bit
Description
3
USB1_EN — R/W.
0 = Disable.
1 = Enable the setting of the USB1_STS bit to generate a wake event. The USB1_STS bit is set
anytime USB UHCI controller #1 signals a wake event. Break events are handled via the
USB interrupt.
2
THRM#_POL — R/W. This bit controls the polarity of the THRM# pin needed to set the
THRM_STS bit.
0 = Low value on the THRM# signal will set the THRM_STS bit.
1 = HIGH value on the THRM# signal will set the THRM_STS bit.
1
Reserved
0
THRM_EN — R/W.
0 = Disable.
1 = Active assertion of the THRM# signal (as defined by the THRM_POL bit) will set the
THRM_STS bit and generate a power management event (SCI or SMI).
SMI_EN—SMI Control and Enable Register
I/O Address:
Default Value:
Lockable:
Power Well:
Bit
31:19
PMBASE + 30h
0000h
No
Core
Attribute:
Size:
Usage:
Description
Reserved
18
INTEL_USB2_EN — R/W.
0 = Disable.
1 = Enables Intel-Specific USB EHCI SMI logic to cause SMI#.
17
LEGACY_USB2_EN — R/W.
0 = Disable.
1 = Enables legacy USB EHCI logic to cause SMI#.
16:15
R/W, WO, R/W-Special
32 bit
ACPI or Legacy
Reserved
14
PERIODIC_EN — R/W.
0 = Disable.
1 = Enables the Intel® ICH4 to generate an SMI# when the PERIODIC_STS bit is set in the
SMI_STS register.
13
TCO_EN — R/W.
0 = Disables TCO logic generating an SMI#. Note that if the NMI2SMI_EN bit is set, SMIs that are
caused by re-routed NMIs will not be gated by the TCO_EN bit. Even if the TCO_EN bit is 0,
NMIs will still be routed to cause SMIs.
1 = Enables the TCO logic to generate SMI#.
12
Reserved
11
Microcontroller SMI Enable (MCSMI_EN) — R/W.
0 = Disable.
1 = Enables ICH4 to trap accesses to the microcontroller range (62h or 66h) and generate an
SMI#. Note that “trapped’ cycles will be claimed by the ICH4 on PCI, but not forwarded to LPC.
10:8
Reserved
Intel® 82801DB ICH4 Datasheet
363
LPC Interface Bridge Registers (D31:F0)
Bit
Description
7
BIOS Release (BIOS_RLS) — WO.
0 = This bit will always return 0 on reads. Writes of 0 to this bit have no effect.
1 = Enables the generation of an SCI interrupt for ACPI software when a one is written to this bit
position by BIOS software.
6
Software SMI# Timer Enable (SWSMI_TMR_EN) — R/W.
0 = Disable. Clearing the SWSMI_TMR_EN bit before the timer expires will reset the timer and the
SMI# will not be generated.
1 = Starts Software SMI# Timer. When the SWSMI timer expires (the timeout period depends upon
the SWSMI_RATE_SEL bit setting), SWSMI_TMR_STS is set and an SMI# is generated.
SWSMI_TMR_EN stays set until cleared by software.
5
APMC_EN — R/W.
0 = Disable. Writes to the APM_CNT register will not cause an SMI#.
1 = Enables writes to the APM_CNT register to cause an SMI#.
4
SLP_SMI_EN — R/W.
0 = Disables the generation of SMI# on SLP_EN. Note that this bit must be 0 before the software
attempts to transition the system into a sleep state by writing a 1 to the SLP_EN bit.
1 = A write of 1 to the SLP_EN bit (bit 13 in PM1_CNT register) will generate an SMI#, and the
system will not transition to the sleep state based on that write to the SLP_EN bit.
3
LEGACY_USB_EN — R/W.
0 = Disable.
1 = Enables legacy USB circuit to cause SMI#.
2
BIOS_EN — R/W.
0 = Disable.
1 = Enables the generation of SMI# when ACPI software writes a 1 to the GBL_RLS bit.
1
End of SMI (EOS) — R/W-Special. This bit controls the arbitration of the SMI signal to the
processor. This bit must be set for the ICH4 to assert SMI# low to the processor.
0 = Once the ICH4 asserts SMI# low, the EOS bit is automatically cleared.
1 = When this bit is set, SMI# signal will be deasserted for 4 PCI clocks before its assertion. In the
SMI handler, the CPU should clear all pending SMIs (by servicing them and then clearing their
respective status bits), set the EOS bit, and exit SMM. This will allow the SMI arbiter to reassert SMI upon detection of an SMI event and the setting of a SMI status bit.
NOTE: ICH4 is able to generate 1st SMI after reset even though EOS bit is not set. Subsequent
SMI require EOS bit is set.
0
364
GBL_SMI_EN — R/W.
0 = No SMI# will be generated by ICH4. This bit is reset by a PCI reset event.
1 = Enables the generation of SMI# in the system upon any enabled SMI event.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.3.10
SMI_STS—SMI Status Register
I/O Address:
Default Value:
Lockable:
Power Well:
Note:
PMBASE + 34h
0000h
No
Core
Attribute:
Size:
Usage:
R/WC, RO
32-bit
ACPI or Legacy
If the corresponding _EN bit is set when the _STS bit is set, the ICH4 will cause an SMI# (except
bits 8:10 and 12, which don’t need enable bits since they are logic ORs of other registers that have
enable bits). The ICH4 uses the same GPE0_EN register (I/O address: PMBase+2Ch) to enable/
disable both SMI and ACPI SCI general purpose input events. ACPI OS assumes that it owns the
entire GPE0_EN register per ACPI spec. Problems arise when some of the general-purpose inputs
are enabled as SMI by BIOS, and some of the general purpose inputs are enabled for SCI. In this
case ACPI OS turns off the enabled bit for any GPIx input signals that are not indicated as SCI
general-purpose events at boot, and exit from sleeping states. BIOS should define a dummy control
method which prevents the ACPI OS from clearing the SMI GPE0_EN bits.
Bit
31:19
Description
Reserved
18
INTEL_USB2_STS — RO. This non-sticky read-only bit is a logical OR of each of the SMI status bits
in the Intel-Specific USB EHCI SMI Status Register ANDed with the corresponding enable bits. This
bit will not be active if the enable bits are not set. Writes to this bit have no effect.
17
LEGACY_USB2_STS — RO. This non-sticky read-only bit is a logical OR of each of the SMI status
bits in the USB EHCI Legacy Support Register ANDed with the corresponding enable bits. This bit will
not be active if the enable bits are not set. Writes to this bit will have no effect.
16
SMBus SMI Status (SMBUS_SMI_STS) — R/WC.
0 = This bit is cleared by writing a 1 to its bit position. This bit is set from the 64 KHz clock domain
used by the SMBus. Software must wait at least 15.63 us after the initial assertion of this bit
before clearing it.
1 = Indicates that the SMI# was caused by:
• The SMBus Slave receiving a message, or
• The SMBALERT# signal goes active and the SMB_SMI_EN bit is set and the
SMBALERT_DIS bit is cleared, or
• The SMBus Slave receiving a Host Notify message and the HOST_NOTIFY_INTREN and
the SMB_SMI_EN bits are set, or
• The Intel® ICH4 detecting the SMLINK_SLAVE_SMI command while in the S0 state.
15
SERIRQ_SMI_STS — RO.
0 = SMI# was not caused by SERIRQ decoder. This is not a sticky bit.
1 = SMI# was caused by the SERIRQ decoder.
PERIODIC_STS — R/WC.
14
13
• This bit is cleared by writing a 1 to its bit position.
1 = This bit will be set at the rate determined by the PER_SMI_SEL bits. If the PERIODIC_EN bit is
also set, the ICH4 will generate an SMI#.
TCO_STS — RO.
0 = SMI# not caused by TCO logic.
1 = SMI# was caused by the TCO logic. Note that this is not a wake event.
Intel® 82801DB ICH4 Datasheet
365
LPC Interface Bridge Registers (D31:F0)
Bit
Description
12
Device Monitor Status (DEVMON_STS) — RO.
0 = SMI# not caused by Device Monitor.
1 = Set under any of the following conditions:
• Any of the DEV[7:4]_TRAP_STS bits are set and the corresponding DEV[7:4]_TRAP_EN
bits are also set.
• Any of the DEVTRAP_STS bits are set and the corresponding DEVTRAP_EN bits are also
set.
11
Microcontroller SMI# Status (MCSMI_STS) — R/WC.
0 = Indicates that there has been no access to the power management microcontroller range (62h or
66h). This bit is cleared by software writing a 1 to the bit position.
1 = Set if there has been an access to the power management microcontroller range (62h or 66h). If
this bit is set and the MCSMI_EN bit is also set, the ICH4 will generate an SMI#.
10
GPE0_STS — RO. This bit is a logical OR of the bits in the ALT_GP_SMI_STS register that are also
set up to cause an SMI# (as indicated by the GPI_ROUT registers) and have the corresponding bit
set in the ALT_GP_SMI_EN register. Bits that are not routed to cause an SMI# will have no effect on
this bit.
0 = SMI# was not generated by a GPI assertion.
1 = SMI# was generated by a GPI assertion.
9
GPE0_STS — RO. This bit is a logical OR of the bits in the GPE0_STS register that also have the
corresponding bit set in the GPE0_EN register.
0 = SMI# was not generated by a GPE0 event.
1 = SMI# was generated by a GPE0 event.
8
PM1_STS_REG — RO. This is an ORs of the bits in the ACPI PM1 Status Register (offset
PMBASE+00h) that can cause an SMI#.
0 = SMI# was not generated by a PM1_STS event.
1 = SMI# was generated by a PM1_STS event.
7
Reserved
6
SWSMI_TMR_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = Set by the hardware when the Software SMI# Timer expires.
APM_STS — R/WC.
5
4
SLP_SMI_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = Indicates an SMI# was caused by a write of 1 to SLP_EN bit when SLP_SMI_EN bit is also set.
3
LEGACY_USB_STS — RO. This bit is a logical OR of each of the SMI status bits in the USB Legacy
Keyboard/Mouse Control Registers ANDed with the corresponding enable bits. This bit will not be
active if the enable bits are not set.
0 = SMI# was not generated by USB Legacy event.
1 = SMI# was generated by USB Legacy event.
2
BIOS_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = SMI# was generated due to ACPI software requesting attention (writing a 1 to the GBL_RLS bit
with the BIOS_EN bit set).
1:0
366
0 = Software clears this bit by writing a 1 to the bit location.
1 = SMI# was generated by a write access to the APM control register with the APMC_EN bit set.
Reserved
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.8.3.11
ALT_GP_SMI_EN—Alternate GPI SMI Enable Register
I/O Address:
Default Value:
Lockable:
Power Well:
PMBASE +38h
0000h
No
Resume
Bit
15:0
9.8.3.12
R/W
16 bit
ACPI or Legacy
Description
Alternate GPI SMI Enable — R/W. These bits are used to enable the corresponding GPIO to cause
an SMI#. For these bits to have any effect, the following must be true.
• The corresponding bit in the ALT_GP_SMI_EN register is set.
• The corresponding GPI must be routed in the GPI_ROUT register to cause an SMI.
• The corresponding GPIO must be implemented.
ALT_GP_SMI_STS—Alternate GPI SMI Status Register
I/O Address:
Default Value:
Lockable:
Power Well:
PMBASE +3Ah
0000h
No
Resume
Bit
15:0
9.8.3.13
Attribute:
Size:
Usage:
Attribute:
Size:
Usage:
R/WC
16 bit
ACPI or Legacy
Description
Alternate GPI SMI Status — R/WC. These bits report the status of the corresponding GPIs.
1 = active, 0 = inactive. These bits are sticky. If the following conditions are true, an SMI# will be
generated and the GPE0_STS bit set:
• The corresponding bit in the ALT_GPI_SMI_EN register is set
• The corresponding GPI must be routed in the GPI_ROUT register to cause an SMI.
• The corresponding GPIO must be implemented.
All bits are in the resume well. Default for these bits is dependent on the state of the GPI pins.
MON_SMI—Device Monitor SMI Status and Enable Register
I/O Address:
Default Value:
Lockable:
Power Well:
Bit
PMBASE +40h
0000h
No
Core
Attribute:
Size:
Usage:
R/W, R/WC
16 bit
Legacy Only
Description
15:12
DEV[7:4]_TRAP_STS — R/WC. Bit 12 corresponds to Monitor 4, bit 13 corresponds to Monitor 5
etc.
0 = SMI# was not caused by the associated device monitor.
1 = SMI# was caused by an access to the corresponding device monitor’s I/O range.
11:8
DEV[7:4]_TRAP_EN — R/W. Bit 8 corresponds to Monitor 4, bit 9 corresponds to Monitor 5 etc.
0 = Disable.
1 = Enables SMI# due to an access to the corresponding device monitor’s I/O range.
7:0
Reserved
Intel® 82801DB ICH4 Datasheet
367
LPC Interface Bridge Registers (D31:F0)
9.8.3.14
DEVACT_STS — Device Activity Status Register
I/O Address:
Default Value:
Lockable:
Power Well:
PMBASE +44h
0000h
No
Core
Attribute:
Size:
Usage:
R/WC
16 bit
Legacy Only
This register is used in conjunction with the Periodic SMI# timer to detect any system activity for
legacy power management.
Bit
15:14
Description
Reserved
13
ADLIB_ACT_STS — R/WC. Ad-Lib.
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
12
KBC_ACT_STS — R/WC. KBC (60/64h).
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
11
MIDI_ACT_STS — R/WC. MIDI.
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
10
AUDIO_ACT_STS — R/WC. Audio (Sound Blaster “OR’d” with MSS).
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
9
PIRQDH_ACT_STS — R/WC. PIRQ[D or H].
0 = The corresponding PCI interrupts have not been active.
1 = At least one of the corresponding PCI interrupts has been active. Clear this bit by writing a 1 to
the bit location.
8
PIRQCG_ACT_STS — R/WC. PIRQ[C or G].
0 = The corresponding PCI interrupts have not been active.
1 = At least one of the corresponding PCI interrupts has been active. Clear this bit by writing a 1 to
the bit location.
7
PIRQBF_ACT_STS — R/WC. PIRQ[B or F].
0 = The corresponding PCI interrupts have not been active.
1 = At least one of the corresponding PCI interrupts has been active. Clear this bit by writing a 1 to
the bit location.
6
PIRQAE_ACT_STS — R/WC. PIRQ[A or E].
0 = The corresponding PCI interrupts have not been active.
1 = At least one of the corresponding PCI interrupts has been active. Clear this bit by writing a 1 to
the bit location.
LEG_ACT_STS — R/WC. Parallel Port, Serial Port 1, Serial Port 2, Floppy Disk controller.
368
5
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
4
Reserved
3
IDES1_ACT_STS — R/WC. IDE Secondary Drive 1.
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
Bit
9.8.3.15
Description
2
IDES0_ACT_STS — R/WC. IDE Secondary Drive 0.
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
1
IDEP1_ACT_STS — R/WC. IDE Primary Drive 1.
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
0
IDEP0_ACT_STS — R/WC. IDE Primary Drive 0.
0 = Indicates that there has been no access to this device’s I/O range.
1 = This device’s I/O range has been accessed. Clear this bit by writing a 1 to the bit location.
DEVTRAP_EN— Device Trap Enable Register
I/O Address:
Default Value
Lockable:
Power Well:
PMBASE +48h
0000h
No
Core
Attribute:
Size:
Usage:
R/W
16 bit
Legacy Only
This register enables the individual trap ranges to generate an SMI# when the corresponding status
bit in the DEVACT_STS register is set. When a range is enabled, I/O cycles associated with that
range will not be forwarded to LPC or IDE.
Bit
15:14
13
Description
Reserved
ADLIB_TRP_EN — R/W. Ad-Lib.
0 = Disable.
1 = Enable.
KBC_TRP_EN — R/W. KBC (60/64h).
12
0 = Disable.
1 = Enable.
11
MIDI_TRP_EN — R/W. MIDI.
0 = Disable.
1 = Enable.
10
AUDIO_TRP_EN — R/W. Audio (Sound Blaster “OR’d” with MSS).
0 = Disable.
1 = Enable.
9:6
Reserved
5
LEG_IO_TRP_EN — R/W. Parallel Port, Serial Port 1, Serial Port 2, Floppy Disk controller.
0 = Disable.
1 = Enable.
4
Reserved
3
IDES1_TRP_EN — R/W. IDE Secondary Drive 1.
0 = Disable.
1 = Enable.
Intel® 82801DB ICH4 Datasheet
369
LPC Interface Bridge Registers (D31:F0)
Bit
9.8.3.16
Description
2
IDES0_TRP_EN — R/W. IDE Secondary Drive 0.
0 = Disable.
1 = Enable.
1
IDEP1_TRP_EN — R/W. IDE Primary Drive 1.
0 = Disable.
1 = Enable.
0
IDEP0_TRP_EN — R/W. IDE Primary Drive 0.
0 = Disable.
1 = Enable.
BUS_ADDR_TRACK— Bus Address Tracker
I/O Address:
Lockable:
Power Well:
PMBASE +4Ch
No
Core
Attribute:
Size:
Usage:
RO
16 bit
Legacy Only
This register could be used by the SMI# handler to assist in determining what was the last cycle
from the processor. BUS_ADDR_TRACK may not contain “expected” last I/O cycle data if
Asynchronous SMIs and Synchronous SMIs are occurring simultaneously. This register only
reports “expected” last I/O cycle data if Asynchronous SMIs are disabled.
9.8.3.17
Bit
Description
15:0
Corresponds to the low 16 bits of the last I/O cycle, as would be defined by the PCI AD[15:0] signals
on the PCI bus (even though it may not be a real PCI cycle). The value is latched based on SMI#
active. This functionality is useful for figuring out which I/O was last being accessed.
BUS_CYC_TRACK— Bus Cycle Tracker
I/O Address:
Lockable:
Power Well:
PMBASE +4Eh
No
Core
Attribute:
Size:
Usage:
RO
8 bit
Legacy Only
This register could be used by the SMM handler to assist in determining what was the last cycle
from the CPU. BUS_CYC_TRACK may not contain “expected” last I/O cycle data if
Asynchronous SMIs and Synchronous SMIs are occurring simultaneously. This register only
reports “expected” last I/O cycle data if Asynchronous SMIs are disabled.
Bit
370
Description
7:4
Corresponds to the byte enables, as would be defined by the PCI C/BE# signals on the PCI bus
(even though it may not be a real PCI cycle). The value is latched based on SMI# going active.
3:0
Corresponds to the cycle type, as would be defined by the PCI C/BE# signals on the PCI bus (even
though it may not be a real PCI cycle). The value is latched based on SMI# going active.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.9
System Management TCO Registers (D31:F0)
The TCO logic is accessed via registers mapped to the PCI configuration space
(Device 31:Function 0) and the system I/O space. For TCO PCI Configuration registers, see LPC
Device 31:Function 0 PCI Configuration registers.
The TCO I/O registers reside in a 32-byte range pointed to by a TCOBASE value, which is,
ACPIBASE + 60h in the PCI configuration space. Table 9-11 shows the mapping of the registers
within that 32-byte range. Each register is described in the following sections.
Table 9-11. TCO I/O Register Map
9.9.1
Offset
Mnemonic
Register Name
Type
00h
TCO_RLD
TCO Timer Reload and Current Value
R/W
01h
TCO_TMR
TCO Timer Initial Value
R/W
02h
TCO_DAT_IN
TCO Data In
R/W
03h
TCO_DAT_OUT
04h–05h
TCO1_STS
TCO Data Out
TCO Status
R/W, RO
R/W
06h–07h
TCO2_STS
TCO Status
R/W
08h–09h
TCO1_CNT
TCO Control
R/W, R/WC,
R/W-Special
0Ah–0Bh
TCO2_CNT
TCO Control
R/W
0Ch–0Dh
TCO_MESSAGE1
TCO_MESSAGE2
Used by BIOS to indicate POST/Boot progress
R/W
0Eh
TCO_WDSTATUS
Watchdog Status Register
R/W
0Fh
—
Reserved
RO
10h
SW_IRQ_GEN
Software IRQ Generation Register
R/W
11h–1Fh
—
Reserved
RO
TCO1_RLD—TCO Timer Reload and Current Value Register
I/O Address:
Default Value:
Lockable:
TCOBASE +00h
0000h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Bit
Description
7:0
Reading this register will return the current count of the TCO timer. Writing any value to this register
will reload the timer to prevent the timeout. Bits 7:6 will always be 0.
Intel® 82801DB ICH4 Datasheet
371
LPC Interface Bridge Registers (D31:F0)
9.9.2
TCO1_TMR—TCO Timer Initial Value Register
I/O Address:
Default Value:
Lockable:
TCOBASE +01h
0004h
No
Bit
9.9.3
7:6
Reserved
5:0
Value that is loaded into the timer each time the TCO_RLD register is written. Values of 0h–3h will
be ignored and should not be attempted. The timer is clocked at approximately 0.6 seconds, and
this allows timeouts ranging from 2.4 seconds to 38 seconds.
TCO1_DAT_IN—TCO Data In Register
TCOBASE +02h
0000h
No
Bit
7:0
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Description
Data Register for passing commands from the OS to the SMI handler. Writes to this register will
cause an SMI and set the OS_TCO_SMI bit in the TCO_STS register.
TCO1_DAT_OUT—TCO Data Out Register
I/O Address:
Default Value:
Lockable:
372
R/W
8 bit
Core
Description
I/O Address:
Default Value:
Lockable:
9.9.4
Attribute:
Size:
Power Well:
TCOBASE +03h
0000h
No
Attribute:
Size:
Power Well:
R/W
8 bit
Core
Bit
Description
7:0
Data Register for passing commands from the SMI handler to the OS. Writes to this register will set
the TCO_INT_STS bit in the TCO_STS register. It will also cause an interrupt, as selected by the
TCO_INT_SEL bits.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.9.5
TCO1_STS—TCO1 Status Register
I/O Address:
Default Value:
Lockable:
Bit
15:13
12
TCOBASE +04h
0000h
No
Attribute:
Size:
Power Well:
R/WC, RO
16 bit
Core
(Except bit 7, in RTC)
Description
Reserved
HUBSERR_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Intel® ICH4 received an SERR# message via the hub interface. The software must read the
memory controller hub (or its equivalent) to determine the reason for the SERR#.
NOTE: If this bit is set AND the SERR_EN bit in CMD register (D30:F0, Offset 04h, bit 8) is also
set, the ICH4 will set the SSE bit in SECSTS register (D30:F0, offset 1Eh, bit 14) AND will
also generate a NMI (or SMI# if NMI routed to SMI#).
11
HUBNMI_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = ICH4 received an NMI message via the hub interface. The software must read the memory
controller hub (or its equivalent) to determine the reason for the NMI.
10
HUBSMI_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = ICH4 received an SMI message via the hub interface. The software must read the memory
controller hub (or its equivalent) to determine the reason for the SMI#.
9
HUBSCI_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = ICH4 received an SCI message via the hub interface. The software must read the memory
controller hub (or its equivalent) to determine the reason for the SCI.
8
BIOSWR_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = ICH4 sets this bit and generates and SMI# to indicate an illegal attempt to write to the BIOS.
This occurs when either:
• The BIOSWP bit is changed from 0 to 1 and the BLD bit is also set, or
• Any write is attempted to the BIOS and the BIOSWP bit is also set.
NOTE: On write cycles attempted to the 4-MB lower alias to the BIOS space, the BIOSWR_STS
will not be set.
7
6:4
NEWCENTURY_STS — R/WC. This bit is in the RTC well.
0 = Cleared by writing a 1 to the bit position or by RTCRST# going active.
1 = This bit is set when the Year byte (RTC I/O space, index offset 09h) rolls over from 99 to 00.
Setting this bit will cause an SMI# (but not a wake event).
Note that the NEWCENTURY_STS bit is not valid when the RTC battery is first installed (or when
RTC power has not been maintained). Software can determine if RTC power has not been
maintained by checking the RTC_PWR_STS bit, or by other means (e.g., a checksum on RTC
RAM). If RTC power is determined to have not been maintained, BIOS should set the time to a
legal value and then clear the NEWCENTURY_STS bit.
The NEWCENTURY_STS bit may take up to 3 RTC clocks for the bit to be cleared after a 1 is
written to the bit to clear it. After writing a 1 to this bit, software should not exit the SMI handler until
verifying that the bit has actually been cleared. This will ensure that the SMI is not re-entered.
Reserved
Intel® 82801DB ICH4 Datasheet
373
LPC Interface Bridge Registers (D31:F0)
Bit
9.9.6
Description
3
TIMEOUT — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Set by ICH4 to indicate that the SMI was caused by the TCO timer reaching 0.
2
TCO_INT_STS — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = SMI handler caused the interrupt by writing to the TCO_DAT_OUT register.
1
SW_TCO_SMI — R/WC.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Software caused an SMI# by writing to the TCO_DAT_IN register.
0
NMI2SMI_STS — RO.
0 = Cleared by clearing the associated NMI status bit.
1 = Set by the ICH4 when an SMI# occurs because an event occurred that would otherwise have
caused an NMI (because NMI2SMI_EN is set).
TCO2_STS—TCO2 Status Register
I/O Address:
Default Value:
Lockable:
TCOBASE +06h
0000h
No
Bit
15:5
Attribute:
Size:
Power Well:
R/WC
16 bit
Resume
(Except Bit 0, in RTC)
Description
Reserved
4
SMLink Slave SMI Status (SMLINK_SLV_SMI_STS) — R/WC. This allow the software to go directly
into pre-determined sleep state. This avoids race conditions.
0 = The bit is reset by RSMRST#, but not due to the PCI Reset associated with exit from S3–S5
states. Software clears the bit by writing a 1 to this bit position.
1 = Intel® ICH4 sets this bit to 1 when it receives the SMI message on the SMLink's Slave Interface.
3
Reserved
BOOT_STS — R/WC.
2
0 = Cleared by ICH4 based on RSMRST# or by software writing a 1 to this bit. Note that software
should first clear the SECOND_TO_STS bit before writing a 1 to clear the BOOT_STS bit.
1 = Set to 1 when the SECOND_TO_STS bit goes from 0 to 1 and the processor has not fetched the
first instruction.
If rebooting due to a second TCO timer timeout, and if the BOOT_STS bit is set, the ICH4 will reboot
using the ‘safe’ multiplier (1111). This allows the system to recover from a CPU frequency multiplier
that is too high, and allows the BIOS to check the BOOT_STS bit at boot. If the bit is set and the
frequency multiplier is 1111, then the BIOS knows that the processor has been programmed to an
illegal multiplier.
SECOND_TO_STS — R/WC.
0 = This bit is cleared by writing a 1 to the bit position or by a RSMRST#.
1
1 = The ICH4 sets this bit to a 1 to indicate that the TCO timer timed out a second time (probably due
to system lock). If this bit is set and the NO_REBOOT configuration bit is 0, then the ICH4 will
reboot the system after the second timeout. The reboot is done by asserting PCIRST#.
NOTE: BIOS should always clear this bit before executing SMBus reads and writes.
0
374
Intruder Detect (INTRD_DET) — R/WC.
0 = This bit is only cleared by writing a 1 to the bit position, or by RTCRST# assertion.
1 = Set by ICH4 to indicate that an intrusion was detected. This bit is set even if the system is in G3
state.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.9.7
TCO1_CNT—TCO1 Control Register
I/O Address:
Default Value:
Lockable:
Bit
15:12
11
10
TCOBASE +08h
0000h
No
Attribute:
Size:
Power Well:
R/W, R/WC, R/W-Special
16 bit
Core
Description
Reserved
TCO Timer Halt (TCO_TMR_HLT) — R/W.
0 = The TCO Timer is enabled to count.
1 = The TCO Timer will halt. It will not count, and thus cannot reach a value that will cause an SMI#
or set the SECOND_TO_STS bit. When set, this bit will prevent rebooting and prevent Alert On
LAN event messages from being transmitted on the SMLINK (but not Alert On LAN* heartbeat
messages).
SEND_NOW — R/W-Special.
0 = The Intel® ICH4 will clear this bit when it has completed sending the message. Software must
not set this bit to 1 again until the ICH4 has set it back to 0.
1 = Writing a 1 to this bit will cause the ICH to send an Alert On LAN Event message over the
SMLINK interface, with the Software Event bit set.
NOTE: Setting the SEND_NOW bit causes the ICH4 integrated LAN controller to reset, which can
have unpredictable side-effects. Unless software protects against these side effects,
software should not attempt to set this bit.
9
NMI2SMI_EN — R/W.
0 = Normal NMI functionality.
1 = Forces all NMIs to instead cause SMIs. The functionality of this bit is dependent upon the
settings of the NMI_EN bit and the GBL_SMI_EN bit as detailed in the following table:
NMI_EN
GBL_SMI_EN
Description
0
0
No SMI# at all because GBL_SMI_EN = 0
0
1
SMI# will be caused due to NMI events
1
0
No SMI# at all because GBL_SMI_EN = 0
1
1
No SMI# due to NMI because NMI_EN = 1
8
NMI_NOW — R/WC.
0 = This bit is cleared by writing a 1 to the bit position. The NMI handler is expected to clear this bit.
Another NMI will not be generated until the bit is cleared.
1 = Writing a 1 to this bit causes an NMI. This allows the BIOS or SMI handler to force an entry to
the NMI handler.
7:0
Reserved
Intel® 82801DB ICH4 Datasheet
375
LPC Interface Bridge Registers (D31:F0)
9.9.8
TCO2_CNT—TCO2 Control Register
I/O Address:
Default Value:
Lockable:
Bit
15:4
3
2:1
0
9.9.9
Attribute:
Size:
Power Well:
R/W
16 bit
Resume
Description
Reserved
GPIO11_ALERT_DISABLE — R/W. At reset (via RSMRST# asserted) this bit is set and GPIO[11]
alerts are disabled.
0 = Enable.
1 = Disable GPIO11/SMBALERT# as an alert source for the heartbeats and the SMBus slave.
INTRD_SEL — R/W. Selects the action to take if the INTRUDER# signal goes active.
00 = No interrupt or SMI#
01 = Interrupt (as selected by TCO_INT_SEL).
10 = SMI
11 = Reserved
Reserved
TCO_MESSAGE1 and TCO_MESSAGE2 Registers
I/O Address:
Default Value:
Lockable:
Bit
7:0
376
TCOBASE +0Ah
0008h
No
TCOBASE +0Ch (Message 1) Attribute:
TCOBASE +0Dh (Message 2)
00h
Size:
No
Power Well:
R/W
8 bit
Resume
Description
TCO_MESSAGE[n] — R/W.The value written into this register will be sent out via the SMLINK
interface in the MESSAGE field of the Alert On LAN message. BIOS can write to this register to
indicate its boot progress which can be monitored externally.
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.9.10
TCO_WDSTATUS—TCO2 Control Register
Offset Address:
Default Value:
Power Well:
TCOBASE + 0Eh
00h
Resume
Bit
7:0
9.9.11
Attribute:
Size:
R/W
8 bits
Description
Watchdog Status (WDSTATUS) — R/W. The value written to this register will be sent in the Alert
On LAN message on the SMLINK interface. It can be used by the BIOS or system management
software to indicate more details on the boot progress. This register will be reset to the default of
00h based on RSMRST# (but not PCI reset).
SW_IRQ_GEN—Software IRQ Generation Register
Offset Address:
Default Value:
Power Well:
Bit
7:2
TCOBASE + 10h
11h
Core
Attribute:
Size:
R/W
8 bits
Description
Reserved
1
IRQ12_CAUSE — R/W. The state of this bit is logically ANDed with the IRQ12 signal as received
by the Intel® ICH4’s SERIRQ logic. This bit must be a 1 (default) if the ICH4 is expected to receive
IRQ12 assertions from a SERIRQ device.
0
IRQ1_CAUSE — R/W. The state of this bit is logically ANDed with the IRQ1 signal as received by
the ICH4’s SERIRQ logic. This bit must be a 1 (default) if the ICH4 is expected to receive IRQ1
assertions from a SERIRQ device.
Intel® 82801DB ICH4 Datasheet
377
LPC Interface Bridge Registers (D31:F0)
9.10
General Purpose I/O Registers (D31:F0)
The control for the general purpose I/O signals is handled through a separate 64-byte I/O space.
The base offset for this space is selected by the GPIO_BAR register. Table 9-12 shows the GPIO
Register I/O address map.
Table 9-12. Registers to Control GPIO
Offset
Mnemonic
Register Name
Default
Access
GPIO Use Select
1A003180h
R/W
GPIO Input/Output Select
0000 FFFFh
R/W
00h
RO
1F1F 0000h
R/W
00h
RO
GPIO TTL Select
06630000h
RO
GPIO Blink Enable
General Registers
00–03h
GPIO_USE_SEL
04–07h
GP_IO_SEL
08–0Bh
—
0C–0Fh
GP_LVL
10–13h
—
Reserved
GPIO Level for Input or Output
Reserved
Output Control Registers
14–17h
GPO_TTL
18–1Bh
GPO_BLINK
1C–1Fh
—
00000000h
R/W
Reserved
0
RO
Reserved
00000000h
RO
Input Control Registers
20–2Bh
—
2C–2Fh
30–33h
9.10.1
GPI_INV
GPIO Signal Invert
00000000h
R/W
00000000h
R/W
GPIO Input/Output Select 2
00000000h
R/W
GPIO Level for Input or Output 2
00000FFFh
R/W
GPIO_USE_SEL2 GPIO Use Select
34–37h
GP_IO_SEL2
38–3Bh
GP_LVL2
GPIO_USE_SEL—GPIO Use Select Register
Offset Address:
Default Value:
Lockable:
Bit
GPIOBASE + 00h
1A003180h
Yes
Attribute:
Size:
Power Well:
R/W
32-bit
Resume
Description
GPIO_USE_SEL — R/W. Each bit in this register enables the corresponding GPIO (if it exists) to be
used as a GPIO, rather than for the native function.
0 = Signal used as native function.
1 = Signal used as a GPIO.
21,11,
5:0
378
NOTES:
1. Bits 31:29, 26, 15:14, and 10:9 are not implemented because there is no corresponding GPIO.
Bits 28:27, 25:22, 20:18, 13:12, and 8:6 are not implemented because the corresponding GPIOs
are not multiplexed. Bits 16:17 are not implemented because the GPIO selection is controlled by
bits 0:1. The REQ/GNT# pairs are enabled/disabled together. For example, if bit 0 is set to 1,
then the REQ/GNT[A]# pair will function as GPIO[0] and GPIO[16].
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.10.2
GP_IO_SEL—GPIO Input/Output Select Register
Offset Address:
Default Value:
Lockable:
GPIOBASE +04h
0000FFFFh
No
Bit
31:29, 26
9.10.3
Attribute:
Size:
Power Well:
R/W
32-bit
Resume
Description
Reserved
28:27
25:24
GPIO[n]_SEL — R/W.
0 = Output. The corresponding GPIO signal is an output.
1 = Input. The corresponding GPIO signal is an input.
23:16
Always 0. The GPIOs are fixed as outputs.
15:0
Always 1. These GPIOs are fixed as inputs.
GP_LVL—GPIO Level for Input or Output Register
Offset Address:
Default Value:
Lockable:
GPIOBASE +0Ch
1B3F 0000h
No
Bit
31:29, 26
Attribute:
Size:
Power Well:
R/W, RO
32-bit
See bit descriptions
Description
Reserved
28:27,
25:24
GP_LVL[n] — R/W. If GPIO[n] is programmed to be an output (via the corresponding bit in the
GP_IO_SEL register) then the bit can be updated by software to drive a high or low value on the
output pin. If GPIO[n] is programmed as an input, then software can read the bit to determine the
level on the corresponding input pin. These bits correspond to GPIO that are in the Resume well,
and will be reset to their default values by RSMRST# and also by a write to the CF9h register.
0 = Low
1 = High
23:16
GP_LVL[n] — R/W. These bits can be updated by software to drive a high or low value on the
output pin. These bits correspond to GPIO that are in the core well, and will be reset to their
default values by PCIRST#.
0 = Low
1 = High
15:0
Reserved. GPI[13:11], and [8:0] the active status of a GPI is read from the corresponding bit in
GPE0_STS register.
Intel® 82801DB ICH4 Datasheet
379
LPC Interface Bridge Registers (D31:F0)
9.10.4
GPO_BLINK—GPO Blink Enable Register
Offset Address:
Default Value:
Lockable:
GPIOBASE +18h
0004 0000h
No
Bit
31:29, 26,
24:20, 17:0
Attribute:
Size:
Power Well:
R/W
32-bit
See bit description
Description
Reserved
28:27, 25
GP_BLINK[n] — R/W. The setting of these bits will have no effect if the corresponding GPIO
is programmed as an input. These bits correspond to GPIO that are in the Resume well, and
will be reset to their default values by RSMRST# or a write to the CF9h register.
0 = The corresponding GPIO will function normally.
1 = If the corresponding GPIO is programmed as an output, the output signal will blink at a
rate of approximately once per second. The high and low times have approximately 0.5
seconds each. The GP_LVL bit is not altered when this bit is set.
19:18
GP_BLINK[n] — R/W. The setting of these bits will have no effect if the corresponding GPIO
is programmed as an input. These bits correspond to GPIO that are in the Core well, and will
be reset to their default values by PCIRST#.
0 = The corresponding GPIO will function normally.
1 = If the corresponding GPIO is programmed as an output, the output signal will blink at a
rate of approximately once per second. The high and low times are approximately 0.5
seconds each. The GP_LVL bit is not altered when this bit is set.
NOTE: GPIO[18] will blink by default immediately after reset. This signal could be connected to an LED to
indicate a failed boot (by programming BIOS to clear GP_BLINK[18] after successful POST).
380
Intel® 82801DB ICH4 Datasheet
LPC Interface Bridge Registers (D31:F0)
9.10.5
GPI_INV—GPIO Signal Invert Register
Offset Address:
Default Value:
Lockable:
GPIOBASE +2Ch
00000000h
No
Bit
31:14,
10:9
9.10.6
Attribute:
Size:
Power Well:
R/W
32-bit
See bit description
Description
Reserved
13:11, 8
GP_INV[n] — R/W. These bits are used to allow both active-low and active-high inputs to cause
SMI# or SCI. Note that in the S0 or S1 state, the input signal must be active for at least 2 PCI
clocks to ensure detection by the Intel® ICH4. In the S3, S4 or S5 states the input signal must be
active for at least 2 RTC clocks to ensure detection. The setting of these bits will have no effect if
the corresponding GPIO is programmed as an output. These bits correspond to GPIO that are in
the Resume well, and will be reset to their default values by RSMRST# or a write to the CF9h
register.
0 = The corresponding GPI_STS bit will be set when the ICH4 detects the state of the input pin
to be high.
1 = The corresponding GPI_STS bit will be set when the ICH4 detects the state of the input pin
to be low.
7:0
GP_INV[n] — R/W. These bits are used to allow both active-low and active-high inputs to cause
SMI# or SCI. Note that in the S0 or S1 state, the input signal must be active for at least 2 PCI
clocks to ensure detection by the ICH4. The setting of these bits will have no effect if the
corresponding GPIO is programmed as an output. These bits correspond to GPIO that are in the
Core well, and will be reset to their default values by PCIRST#.
0 = The corresponding GPI_STS bit will be set when the ICH4 detects the state of the input pin
to be high.
1 = The corresponding GPI_STS bit will be set when the ICH4 detects the state of the input pin
to be low.
GPIO_USE_SEL2—GPIO Use Select 2 Register
Offset Address:
Default Value:
Lockable:
Bit
GPIOBASE +30h
00000FFFh
No
Attribute:
Size:
Power Well:
R/W
32-bit
Core
Description
GPIO_USE_SEL2[43:32]— R/W. Each bit in this register enables the corresponding GPIO (if it
exists) to be used as a GPIO, rather than for the native function.
0 = Signal used as native function.
1 = Signal used as a GPIO.
31:0
NOTES:
1. The following bits are not implemented because there is no corresponding GPIO: 31:12
2. If GPIO[n] does not exist, then the bit in this register will always read as 0 and writes will have
no effect.
After a full reset (RSMRST#) all multiplexed signals in the resume and core wells are configured
as their native function rather than as a GPIO. After just a PCIRST#, the GPIO in the core well are
configured as their native function.
Intel® 82801DB ICH4 Datasheet
381
LPC Interface Bridge Registers (D31:F0)
9.10.7
GP_IO_SEL2—GPIO Input/Output Select 2 Register
Offset Address:
Default Value:
Lockable:
GPIOBASE +34h
00000000h
No
Bit
31:12
11:0
9.10.8
R/W
32-bit
Core
Description
Always 0. No corresponding GPIO.
GP_IO_SEL2[43:32] — R/W. When set to a 1, the corresponding GPIO signal (if enabled in the
GPIO_USE_SEL2 register) is programmed as an input. When set to 0, the GPIO signal is
programmed as an output.
GP_LVL2—GPIO Level for Input or Output 2 Register
Offset Address:
Default Value:
Lockable:
GPIOBASE +38h
00000FFFh
No
Bit
31:12
11:0
382
Attribute:
Size:
Power Well:
Attribute:
Size:
Power Well:
R/W
32-bit
See below
Description
Reserved. Read-only 0
GP_LVL2[43:32] — R/W. If GPIO[n] is programmed to be an output (via the corresponding bit
in the GP_IO_SEL2 register), then the corresponding GP_LVL2[n] bit can be updated by
software to drive a high or low value on the output pin. 1 = high, 0 = low. If GPIO[n] is
programmed as an input, then the corresponding GP_LVL2 bit reflects the state of the input
signal (1 = high, 0 = low). Writes will have no effect.
Since these bits correspond to GPIO that are in the core well, these bits will be reset by
PCIRST#.
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
10
IDE Controller Registers (D31:F1)
10.1
PCI Configuration Registers (IDE—D31:F1)
Note:
Registers that are not shown should be treated as Reserved (See Section 6.2 for details).
All of the IDE registers are in the core well. None can be locked.
Table 10-1. PCI Configuration Register Address Map (IDE—D31:F1)
Offset
Mnemonic
00–01h
VID
Register Name
Default
Type
Vendor ID
8086h
RO
24CBh
RO
00h
R/W, RO
0280h
R/WC, RO
See Note 2
RO
02–03h
DID
Device ID
04–05h
CMD
Command Register
06–07h
STS
Device Status
08h
RID
Revision ID
09h
PI
Programming Interface
8Ah
RO
0Ah
SCC
Sub Class Code
01h
RO
0Bh
BCC
Base Class Code
01h
RO
0Dh
MLT
Master Latency Timer (Note 1)
00
RO
0Eh
HTYPE
00h
RO
10–13h
PCMD_BAR
Primary Command Block Base Address
00000001h
R/W
14–17h
PCNL_BAR
Primary Control Block Base Address
00000001h
R/W
18–1Bh
SCMD_BAR
Secondary Command Block Base
Address
00000001h
R/W
1C–1Fh
SCNL_BAR
Secondary Control Block Base Address
00000001h
R/W
Base Address Register
20–23h
BAR
24–27h
EXBAR
2C–2Dh
SVID
2E–2Fh
SID
Header Type
00000001h
R/W
Expansion BAR
00h
R/W
Subsystem Vendor ID
00
R/WO
Subsystem ID
00
R/WO
3C
INTR_LN
Interrupt Line
00
R/W
3D
INTR_PN
Interrupt Pin
01
R/W
40–41h
IDE_TIMP
Primary IDE Timing
0000h
R/W
42–43h
ID_TIMS
Secondary IDE Timing
0000h
R/W
44h
SIDETIM
Slave IDE Timing
00h
R/W
48h
SDMAC
Synchronous DMA Control Register
00h
R/W
Synchronous DMA Timing Register
0000h
R/W
00h
R/W
4A–4Bh
SDMATIM
54h
IDE_CONFIG
IDE I/O Configuration Register
NOTES:
1. The ICH4 IDE controller is not arbitrated as a PCI device, therefore it does not need a master latency timer.
2. Refer to the ICH4 Specification Update for the value of the Revision ID Register.
Intel® 82801DB ICH4 Datasheet
383
IDE Controller Registers (D31:F1)
10.1.1
VID—Vendor ID Register (LPC I/F—D31:F1)
Offset Address:
Default Value:
Lockable:
00–01h
8086h
No
Bit
15:0
10.1.2
RO
16 bit
Core
Description
Vendor Identification Value — RO. This is a 16-bit value assigned to Intel. Intel VID = 8086h
DID—Device ID Register (LPC I/F—D31:F1)
Offset Address:
Default Value:
Lockable:
02–03h
24CBh
No
Bit
15:0
10.1.3
Attribute:
Size:
Power Well:
Attribute:
Size:
Power Well:
RO
16 bit
Core
Description
Device Identification Value — RO. This is a 16-bit value assigned to the ICH4 IDE controller.
CMD — Command Register (IDE—D31:F1)
Address Offset:
Default Value:
04h–05h
00h
Bit
15:10
Attribute:
Size:
R/W, RO
16 bits
Description
Reserved
9
Fast Back to Back Enable (FBE) — RO. Reserved as 0.
8
SERR# Enable (SERR_EN) — RO. Reserved as 0.
7
Wait Cycle Control (WCC) — RO. Reserved as 0.
6
Parity Error Response (PER) — RO. Reserved as 0.
5
VGA Palette Snoop (VPS) — RO. Reserved as 0.
4
Postable Memory Write Enable (PMWE) — RO. Reserved as 0.
3
Special Cycle Enable (SCE) — RO. Reserved as 0.
2
Bus Master Enable (BME) — R/W. Controls the ICH4’s ability to act as a PCI master for IDE Bus
Master transfers.
0 = Disable
1 = Enable
1
Memory Space Enable (MSE) — R/W.
0 = Disables access.
1 = Enables access to the IDE Expansion memory range. The EXBAR register (Offset 24h) must
be programmed before this bit is set.
NOTE: BIOS should set this bit to a 1.
384
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
Bit
Description
I/O Space Enable (IOSE) — R/W. This bit controls access to the I/O space registers.
0 = Disables access to the Legacy or Native IDE ports (both Primary and Secondary) as well as
the Bus Master IO registers.
1 = Enable. Note that the Base Address register for the Bus Master registers should be
programmed before this bit is set.
0
10.1.4
NOTES:
1. Separate bits are provided (IDE Decode Enable, in the IDE Timing register) to independently
disable the Primary or Secondary I/O spaces.
2. When this bit is 0 and the IDE controller is in Native Mode, the Interrupt Pin Register (see
Section 10.1.19) will be masked (the interrupt will not be asserted). If an interrupt occurs while
the masking is in place and the interrupt is still active when the masking ends, the interrupt will
be allowed to be asserted.
STS — Device Status Register (IDE—D31:F1)
Address Offset:
Default Value:
06–07h
0280h
Bit
Attribute:
Size:
R/WC, RO
16 bits
Description
15
Detected Parity Error (DPE) — RO. Reserved as 0.
14
Signaled System Error (SSE) — RO. Reserved as 0.
13
Received Master Abort (RMA) — R/WC.
0 = Cleared by writing a 1 to it.
1 = Bus Master IDE interface function, as a master, generated a master-abort.
12
Reserved as 0 — RO.
11
Signaled Target Abort (STA) — R/WC.
0 = Cleared by writing a 1 to it.
1 = ICH4 IDE interface function is targeted with a transaction that the ICH4 terminates with a target
abort.
DEVSEL# Timing Status (DEV_STS) — RO.
10:9
8
Data Parity Error Detected (DPED)— RO. Reserved as 0.
7
Fast Back to Back Capable (FB2BC)— RO. Reserved as 1.
6
User Definable Features (UDF)— RO. Reserved as 0.
5
66 MHz Capable (66MHZ_CAP)— RO. Reserved as 0.
4:0
10.1.5
01 = Hardwired; however, the ICH4 does not have a real DEVSEL# signal associated with the IDE
unit, so these bits have no effect.
Reserved
REVID—Revision ID Register (IDE—D31:F1)
Offset Address:
Default Value:
Bit
7:0
08h
See Bit Description
Attribute:
Size:
RO
8 bits
Description
Revision Identification Value — RO. Refer to the ICH4 Specification Update for the value of the
Revision ID Register.
Intel® 82801DB ICH4 Datasheet
385
IDE Controller Registers (D31:F1)
10.1.6
PI — Programming Interface Register (IDE—D31:F1)
Address Offset:
Default Value:
09h
8Ah
Bit
7
6:4
10.1.7
This read-only bit is a 1 to indicate that the ICH4 supports bus master operation
Reserved. Will always return 0.
3
SOP_MODE_CAP — RO. This read-only bit is a 1 to indicate that the secondary controller supports
both legacy and native modes.
2
SOP_MODE_SEL — R/W. This read/write bit determines the mode that the secondary IDE channel
is operating in.
0 = Legacy-PCI mode (default)
1 = Native-PCI mode
1
POP_MODE_CAP — RO. This read-only bit is a 1 to indicate that the primary controller supports
both legacy and native modes.
0
POP_MODE_SEL — R/W. This read/write bit determines the mode that the primary IDE channel is
operating in.
0 = Legacy-PCI mode (default)
1 = Native-PCI mode
SCC — Sub Class Code Register (IDE—D31:F1)
0Ah
01h
Bit
7:0
Attribute:
Size:
RO
8 bits
Description
Sub Class Code — RO.
01h = IDE device, in the context of a mass storage device.
BCC — Base Class Code Register (IDE—D31:F1)
Address Offset:
Default Value:
0Bh
01h
Bit
7:0
386
R/W
8 bits
Description
Address Offset:
Default Value:
10.1.8
Attribute:
Size:
Attribute:
Size:
RO
8 bits
Description
Base Class Code — RO.
01 = Mass storage device
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
10.1.9
MLT — Master Latency Timer Register (IDE—D31:F1)
Address Offset:
Default Value:
0Dh
00h
Bit
7:0
10.1.10
Attribute:
Size:
RO
8 bits
Description
Master Latency Timer Count (MLTC) — RO. Hardwired to 00h. The IDE controller is implemented
internally, and is not arbitrated as a PCI device, so it does not need a Master Latency Timer.
PCMD_BAR—Primary Command Block Base Address
Register (IDE—D31:F1)
Address Offset:
Default Value:
10h–13h
00000001h
Attribute:
Size:
R/W
32 bits
.
Bit
Description
31:16
Reserved
15:3
Base Address — R/W. Base address of the I/O space (8 consecutive I/O locations).
2:1
Reserved
0
Resource Type Indicator (RTE) — RO. his bit is set to one, indicating a request for I/O space.
NOTE: This 8-byte I/O space is used in native mode for the Primary controller’s Command Block.
10.1.11
PCNL_BAR—Primary Control Block Base Address Register
(IDE—D31:F1)
Address Offset:
Default Value:
14h–17h
00000001h
Attribute:
Size:
R/W
32 bits
.
Bit
31:16
15:2
Description
Reserved
Base Address — R/W. Base address of the I/O space (4 consecutive I/O locations).
1
Reserved
0
Resource Type Indicator (RTE) — RO. This bit is set to one, indicating a request for I/O space.
NOTE: This 4-byte I/O space is used in native mode for the Primary controller’s Command Block.
Intel® 82801DB ICH4 Datasheet
387
IDE Controller Registers (D31:F1)
10.1.12
SCMD_BAR—Secondary Command Block Base Address
Register (IDE D31:F1)
Address Offset:
Default Value:
18h–1Bh
00000001h
Bit
Attribute:
Size:
R/W
32 bits
Description
31:16
Reserved
15:3
Base Address — R/W. Base address of the I/O space (8 consecutive I/O locations).
2:1
Reserved
0
Resource Type Indicator (RTE) — RO. This bit is set to one, indicating a request for I/O space.
NOTE: This 4-byte I/O space is used in native mode for the Secondary controller’s Command Block.
10.1.13
SCNL_BAR—Secondary Control Block Base Address
Register (IDE D31:F1)
Address Offset:
Default Value:
1Ch–1Fh
00000001h
Bit
Attribute:
Size:
R/W
32 bits
Description
31:16
Reserved
15:2
Base Address — R/W. Base address of the I/O space (4 consecutive I/O locations).
1
Reserved
0
Resource Type Indicator (RTE) — RO. This bit is set to one, indicating a request for I/O space.
NOTE: This 4-byte I/O space is used in native mode for the Secondary controller’s Command Block.
10.1.14
BM_BASE — Bus Master Base Address Register
(IDE—D31:F1)
Address Offset:
Default Value:
20h–23h
00000001h
Attribute:
Size:
R/W
32 bits
The Bus Master IDE interface function uses Base Address register 5 to request a 16-byte I/O space
to provide a software interface to the Bus Master functions. Only 12 bytes are actually used
(6 bytes for primary, 6 bytes for secondary). Only bits [15:4] are used to decode the address.
Bit
31:16
Reserved
15:4
Base Address — R/W. Base address of the I/O space (16 consecutive I/O locations).
3:1
Reserved
0
388
Description
Resource Type Indicator (RTE) — RO. Hardwired to 1, indicating a request for I/O space.
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
10.1.15
EXBAR — Expansion Base Address Register (IDE—D31:F1)
Address Offset:
Default Value:
Note:
24h–27h
00h
31:0
Description
Intel Reserved for Future Functionality.
IDE_SVID — Subsystem Vendor ID Register (IDE—D31:F1)
Address Offset:
Default Value:
Lockable:
10.1.17
R/W
32 bits
This is a memory mapped BAR that requires 1 KB of DWord-aligned memory that is Intel reserved
for future functionality. BIOS needs to program the base address for a 1-KB memory space.
Bit
10.1.16
Attribute:
Size:
2Ch–2Dh
00h
No
Attribute:
R/WO
Size:
16 bits
Power Well: Core
Bit
Description
15:0
Subsystem Vendor ID (SVID) — R/Write-Once. The SVID register, in combination with the
Subsystem ID (SID) register, enables the operating system (OS) to distinguish subsystems from
each other. Software (BIOS) sets the value in this register. After that, the value can be read, but
subsequent writes to this register have no effect. The value written to this register will also be
readable via the corresponding SVID registers for the USB UHCI #1, USB UHCI #2, USB UHCI #3,
and SMBus functions.
IDE_SID — Subsystem ID Register (IDE—D31:F1)
Address Offset:
Default Value:
Lockable:
2Eh–2Fh
00h
No
Attribute:
R/WO
Size:
16 bits
Power Well: Core
Bit
Description
15:0
Subsystem ID (SID) — R/Write-Once. The SID register, in combination with the SVID register,
enables the operating system (OS) to distinguish subsystems from each other. Software (BIOS)
sets the value in this register. After that, the value can be read, but subsequent writes to this register
have no effect. The value written to this register will also be readable via the corresponding SID
registers for the USB UHCI #1, USB UHCI #2, USB UHCI #3, and SMBus functions.
Intel® 82801DB ICH4 Datasheet
389
IDE Controller Registers (D31:F1)
10.1.18
INTR_LN—Interrupt Line Register (IDE—D31:F1)
Address Offset:
Default Value:
3Ch
00h
Bit
7:0
10.1.19
R/W
8 bits
Description
Interrupt Line (INT_LN) — R/W. It is to communicate to software the interrupt line that the
interrupt pin is connected to.
INTR_PN—Interrupt Pin Register (IDE—D31:F1)
Address Offset:
Default Value:
3Dh
01h
Bit
10.1.20
Attribute:
Size:
Attribute:
Size:
RO
8 bits
Description
7:3
Reserved
2:0
Interrupt Pin (INT_PN) — RO. The value of 01h indicates to “software” that the ICH4 will drive
INTA#. Note that this is only used in native mode. Also note that the routing to the internal interrupt
controller does not necessarily relate to the value in this register. The IDE interrupt is in fact routed
to PIRQ[C]# (IRQ18 in APIC mode).
IDE_TIM — IDE Timing Register (IDE—D31:F1)
Address Offset:
Default Value:
Primary:
40–41h
Secondary: 42–43h
0000h
Attribute:
R/W
Size:
16 bits
This register controls the timings driven on the IDE cable for PIO and 8237 style DMA transfers. It
also controls operation of the buffer for PIO transfers.
Bit
Description
15
IDE Decode Enable (IDE) — R/W. Individually enable/disable the Primary or Secondary decode.
The IDE I/O Space Enable bit in the Command register must be set for this bit to have any effect.
Additionally, separate configuration bits are provided (in the IDE I/O Configuration register) to
individually disable the primary or secondary IDE interface signals, even if the IDE Decode Enable
bit is set.
0 = Disable.
1 = Enables the ICH4 to decode the associated Command Blocks (1F0–1F7h for primary,
170–177h for secondary) and Control Block (3F6h for primary and 376h for secondary).
This bit effects the IDE decode ranges for both legacy and native-Mode decoding. It also effects the
corresponding primary or secondary memory decode range for IDE Expansion.
14
Drive 1 Timing Register Enable (SITRE) — R/W.
0 = Use bits 13:12, 9:8 for both drive 0 and drive 1.
1 = Use bits 13:12, 9:8 for drive 0, and use the Slave IDE Timing register for drive 1.
13:12
390
IORDY Sample Point (ISP) — R/W. The setting of these bits determine the number of PCI clocks
between IDE IOR#/IOW# assertion and the first IORDY sample point.
00 = 5 clocks
01 = 4 clocks
10 = 3 clocks
11 = Reserved
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
Bit
11:10
9:8
Description
Reserved
Recovery Time (RCT) — R/W. The setting of these bits determines the minimum number of PCI
clocks between the last IORDY sample point and the IOR#/IOW# strobe of the next cycle.
00 = 4 clocks
01 = 3 clocks
10 = 2 clocks
11 = 1 clock
7
Drive 1 DMA Timing Enable (DTE1) — R/W.
0 = Disable.
1 = Enable the fast timing mode for DMA transfers only for this drive. PIO transfers to the IDE data
port will run in compatible timing.
6
Drive 1 Prefetch/Posting Enable (PPE1) — R/W.
0 = Disable.
1 = Enable Prefetch and posting to the IDE data port for this drive.
5
Drive 1 IORDY Sample Point Enable (IE1) — R/W.
0 = Disable IORDY sampling for this drive.
1 = Enable IORDY sampling for this drive.
4
Drive 1 Fast Timing Bank (TIME1) — R/W.
0 = Accesses to the data port will use compatible timings for this drive.
1 = When this bit =1 and bit 14 = 0, accesses to the data port will use bits 13:12 for the IORDY
sample point, and bits 9:8 for the recovery time. When this bit = 1 and bit 14 = 1, accesses to
the data port will use the IORDY sample point and recover time specified in the slave IDE
timing register.
3
Drive 0 DMA Timing Enable (DTE0) — R/W.
0 = Disable
1 = Enable fast timing mode for DMA transfers only for this drive. PIO transfers to the IDE data
port will run in compatible timing.
2
Drive 0 Prefetch/Posting Enable (PPE0) — R/W.
0 = Disable prefetch and posting to the IDE data port for this drive.
1 = Enable prefetch and posting to the IDE data port for this drive.
1
Drive 0 IORDY Sample Point Enable (IE0) — R/W.
0 = Disable IORDY sampling is disabled for this drive.
1 = Enable IORDY sampling for this drive.
0
Drive 0 Fast Timing Bank (TIME0) — R/W.
0 = Accesses to the data port will use compatible timings for this drive.
1 = Accesses to the data port will use bits 13:12 for the IORDY sample point, and bits 9:8 for the
recovery time.
Intel® 82801DB ICH4 Datasheet
391
IDE Controller Registers (D31:F1)
10.1.21
SLV_IDETIM—Slave (Drive 1) IDE Timing Register
(IDE—D31:F1)
Address Offset:
Default Value:
392
44h
00h
Attribute:
Size:
R/W
8 bits
Bit
Description
7:6
Secondary Drive 1 IORDY Sample Point (SISP1) — R/W. This field determines the number of PCI
clocks between IDE IOR#/IOW# assertion and the first IORDY sample point, if the access is to drive
1 data port and bit 14 of the IDE timing register for secondary is set.
00 = 5 clocks
01 = 4 clocks
10 = 3 clocks
11 = Reserved
5:4
Secondary Drive 1 Recovery Time (SRCT1) — R/W. This field determines the minimum number of
PCI clocks between the last IORDY sample point and the IOR#/IOW# strobe of the next cycle, if the
access is to drive 1 data port and bit 14 of the IDE Timing (IDE_TIM) register for secondary is set.
00 = 4 clocks
01 = 3 clocks
10 = 2 clocks
11 = 1 clocks
3:2
Primary Drive 1 IORDY Sample Point (PISP1) — R/W. This field determines the number of PCI
clocks between IOR#/IOW# assertion and the first IORDY sample point, if the access is to drive 1
data port and bit 14 of the IDE timing register for primary is set.
00 = 5 clocks
01 = 4 clocks
10 = 3 clocks
11 = Reserved
1:0
Primary Drive 1 Recovery Time (PRCT1) — R/W. This field determines the minimum number of PCI
clocks between the last IORDY sample point and the IOR#/IOW# strobe of the next cycle, if the
access is to drive 1 data port and bit 14 of the IDE timing register for primary is set.
00 = 4 clocks
01 = 3 clocks
10 = 2 clocks
11 = 1 clocks
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
10.1.22
SDMA_CNT—Synchronous DMA Control Register
(IDE—D31:F1)
Address Offset:
Default Value:
Bit
7:4
48h
00h
Attribute:
Size:
R/W
8 bits
Description
Reserved
3
Secondary Drive 1 Synchronous DMA Mode Enable (SSDE1) — R/W.
0 = Disable (default)
1 = Enable Synchronous DMA mode for secondary channel drive 1.
2
Secondary Drive 0 Synchronous DMA Mode Enable (SSDE0) — R/W.
0 = Disable (default)
1 = Enable Synchronous DMA mode for secondary drive 0.
1
Primary Drive 1 Synchronous DMA Mode Enable (PSDE1) — R/W.
0 = Disable (default)
1 = Enable Synchronous DMA mode for primary channel drive 1.
0
Primary Drive 0 Synchronous DMA Mode Enable (PSDE0) — R/W.
0 = Disable (default)
1 = Enable Synchronous DMA mode for primary channel drive 0.
Intel® 82801DB ICH4 Datasheet
393
IDE Controller Registers (D31:F1)
10.1.23
SDMA_TIM—Synchronous DMA Timing Register
(IDE—D31:F1)
Address Offset:
Default Value:
Note:
Attribute:
Size:
R/W
16 bits
For FAST_SCB1=1 (133 MHz clk) in bits [13:12, 9:8, 5:4, 1:0], refer to Section 5.15.6 for details.
Bit
394
4A–4Bh
0000h
Description
15:14
Reserved
13:12
Secondary Drive 1 Cycle Time (SCT1) — R/W. For Ultra ATA mode. The setting of these bits
determines the minimum write strobe cycle time (CT). The DMARDY#-to-STOP (RP) time is also
determined by the setting of these bits.
SCB1 = 0 (33 MHz clk)
SCB1 = 1 (66 MHz clk)
FAST_SCB1 = 1 (133 MHz clk)
00 = CT 4 clocks, RP 6 clocks 00 = Reserved
00 = Reserved
01 = CT 3 clocks, RP 5 clocks 01 = CT 3 clocks, RP 8 clocks 01 = CT 3 clks, RP 16 clks
10 = CT 2 clocks, RP 4 clocks 10 = CT 2 clocks, RP 8 clocks 10 = Reserved
11 = Reserved
11 = Reserved
11 = Reserved
11:10
Reserved
9:8
Secondary Drive 0 Cycle Time (SCT0) — R/W. For Ultra ATA mode. The setting of these bits
determines the minimum write strobe cycle time (CT). The DMARDY#-to-STOP (RP) time is also
determined by the setting of these bits.
SCB1 = 0 (33 MHz clk)
SCB1 = 1 (66 MHz clk)
FAST_SCB1 = 1 (133 MHz clk)
00 = CT 4 clocks, RP 6 clocks 00 = Reserved
00 = Reserved
01 = CT 3 clocks, RP 5 clocks 01 = CT 3 clocks, RP 8 clocks 01 = CT 3 clks, RP 16 clks
10 = CT 2 clocks, RP 4 clocks 10 = CT 2 clocks, RP 8 clocks 10 = Reserved
11 = Reserved
11 = Reserved
11 = Reserved
7:6
Reserved
5:4
Primary Drive 1 Cycle Time (PCT1) — R/W. For Ultra ATA mode, the setting of these bits
determines the minimum write strobe cycle time (CT). The DMARDY#-to-STOP (RP) time is also
determined by the setting of these bits.
PCB1 = 0 (33 MHz clk)
PCB1 = 1 (66 MHz clk)
FAST_PCB1 = 1 (133 MHz clk)
00 = CT 4 clocks, RP 6 clocks 00 = Reserved
00 = Reserved
01 = CT 3 clocks, RP 5 clocks 01 = CT 3 clocks, RP 8 clocks 01 = CT 3 clks, RP 16 clks
10 = CT 2 clocks, RP 4 clocks 10 = CT 2 clocks, RP 8 clocks 10 = Reserved
11 = Reserved
11 = Reserved
11 = Reserved
3:2
Reserved
1:0
Primary Drive 0 Cycle Time (PCT0) — R/W. For Ultra ATA mode, the setting of these bits
determines the minimum write strobe cycle time (CT). The DMARDY#-to-STOP (RP) time is also
determined by the setting of these bits.
PCB1 = 0 (33 MHz clk)
PCB1 = 1 (66 MHz clk)
FAST_PCB1 = 1 (133 MHz clk)
00 = CT 4 clocks, RP 6 clocks 00 = Reserved
00 = Reserved
01 = CT 3 clocks, RP 5 clocks 01 = CT 3 clocks, RP 8 clocks 01 = CT 3 clks, RP 16 clks
10 = CT 2 clocks, RP 4 clocks 10 = CT 2 clocks, RP 8 clocks 10 = Reserved
11 = Reserved
11 = Reserved
11 = Reserved
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
10.1.24
IDE_CONFIG—IDE I/O Configuration Register
(IDE—D31:F1)
Address Offset:
Default Value:
Bit
54h
00h
Attribute:
Size:
R/W
32 bits
Description
31:20
Reserved
19:18
SEC_SIG_MODE — R/W. These bits are used to control the mode of the Secondary IDE signal
pins. If the SRS bit (bit 7, offset D5h of D31:F0) is 1, the reset states of bits 19:18 will be 01 (tristate) instead of 00 (normal).
00 = Normal (Enabled)
01 = Tri-state (Disabled)
10 = Drive low (Disabled)
11 = Reserved
17:16
PRIM_SIG_MODE — R/W. These bits are used to control the mode of the Primary IDE signal pins.
If the PRS bit (bit 6, offset D5h of D31:F0) is 1, then the reset states of bits 17:16 will be 01
(tri-state) instead of 00 (normal).
00 = Normal (Enabled)
01 = Tri-state (Disabled)
10 = Drive low (Disabled)
11 = Reserved
15
Fast Secondary Drive 1 Base Clock (FAST_SCB1) — R/W. This bit is used in conjunction with
the SCT1 bits to enable/disable Ultra ATA/100 timings for the Secondary Slave drive.
0 = Disable Ultra ATA/100 timing for the Secondary Slave drive.
1 = Enable Ultra ATA/100 timing for the Secondary Slave drive (overrides bit 3 in this register).
14
Fast Secondary Drive 0 Base Clock (FAST_SCB0) — R/W. This bit is used in conjunction with
the SCT0 bits to enable/disable Ultra ATA/100 timings for the Secondary Master drive.
0 = Disable Ultra ATA/100 timing for the Secondary Master drive.
1 = Enable Ultra ATA/100 timing for the Secondary Master drive (overrides bit 2 in this register).
13
Fast Primary Drive 1 Base Clock (FAST_PCB1) — R/W. This bit is used in conjunction with the
PCT1 bits to enable/disable Ultra ATA/100 timings for the Primary Slave drive.
0 = Disable Ultra ATA/100 timing for the Primary Slave drive.
1 = Enable Ultra ATA/100 timing for the Primary Slave drive (overrides bit 1 in this register).
12
Fast Primary Drive 0 Base Clock (FAST_PCB0) — R/W. This bit is used in conjunction with the
PCT0 bits to enable/disable Ultra ATA/100 timings for the Primary Master drive.
0 = Disable Ultra ATA/100 timing for the Primary Master drive.
1 = Enable Ultra ATA/100 timing for the Primary Master drive (overrides bit 0 in this register).
11
Reserved
10
WR_PingPong_EN — R/W.
0 = Disabled. The buffer behaves similar to PIIX4.
1 = Enables the write buffer to be used in a split (ping/pong) manner.
9: 8
Reserved
7
Secondary Slave Channel Cable Reporting — R/W. BIOS should program this bit to tell the IDE
driver which cable is plugged into the channel.
0 = 40 conductor cable is present.
1 = 80 conductor cable is present.
6
Secondary Master Channel Cable Reporting — R/W. Same description as bit 7
Intel® 82801DB ICH4 Datasheet
395
IDE Controller Registers (D31:F1)
Bit
10.2
Description
5
Primary Slave Channel Cable Reporting — R/W. Same description as bit 7
4
Primary Master Channel Cable Reporting — R/W. Same description as bit 7
3
Secondary Drive 1 Base Clock (SCB1) — R/W.
0 = 33 MHz base clock for Ultra ATA timings.
1 = 66 MHz base clock for Ultra ATA timings.
2
Secondary Drive 0 Base Clock (SCBO) — R/W.
0 = 33 MHz base clock for Ultra ATA timings.
1 = 66 MHz base clock for Ultra ATA timings.
1
Primary Drive 1 Base Clock (PCB1) — R/W.
0 = 33 MHz base clock for Ultra ATA timings.
1 = 66 MHz base clock for Ultra ATA timings.
0
Primary Drive 0 Base Clock (PCB0) — R/W.
0 = 33 MHz base clock for Ultra ATA timings.
1 = 66 MHz base clock for Ultra ATA timings.
Bus Master IDE I/O Registers (D31:F1)
The bus master IDE function uses 16 bytes of I/O space, allocated via the BMIBA register, located
in Device 31:Function 1 Configuration space, offset 20h. All bus master IDE I/O space registers
can be accessed as byte, word, or DWord quantities. Reading reserved bits returns an
indeterminate, inconsistent value, and writes to reserved bits have no affect (but should not be
attempted). The description of the I/O registers is shown below in Table 10-2.
Table 10-2. Bus Master IDE I/O Registers
Offset
Mnemonic
00
BMICP
01
02
BMISP
03
Default
Type
Bus Master IDE Command Primary
00h
R/W
Reserved
00h
RO
Bus Master IDE Status Primary
00h
R/WC, R/W,
RO
Reserved
00h
RO
xxxxxxxxh
R/W
R/W
04–07
BMIDP
Bus Master IDE Descriptor Table Pointer Primary
08
BMICS
Bus Master IDE Command Secondary
00h
Reserved
00h
RO
Bus Master IDE Status Secondary
00h
R/WC, R/W,
RO
Reserved
00h
RO
xxxxxxxxh
R/W
09
0A
BMISS
0B
0C–0F
396
Register Name
BMIDS
Bus Master IDE Descriptor Table Pointer Secondary
Intel® 82801DB ICH4 Datasheet
IDE Controller Registers (D31:F1)
10.2.1
BMIC[P,S]—Bus Master IDE Command Register
Address Offset:
Default Value:
Primary: 00h
Secondary: 08h
00h
Bit
7:4
3
2:1
0
Attribute:
R/W
Size:
8 bits
Description
Reserved. Returns 0.
Read / Write Control (RWC) — R/W. This bit sets the direction of the bus master transfer: This bit
must NOT be changed when the bus master function is active.
0 = Memory reads
1 = Memory writes
Reserved. Returns 0.
Start/Stop Bus Master (START) — R/W.
0 = All state information is lost when this bit is cleared. Master mode operation cannot be stopped
and then resumed. If this bit is reset while bus master operation is still active (i.e., the Bus Master
IDE Active bit of the Bus Master IDE Status register for that IDE channel is set) and the drive has
not yet finished its data transfer (the Interrupt bit in the Bus Master IDE Status register for that
IDE channel is not set), the bus master command is said to be aborted and data transferred from
the drive may be discarded instead of being written to system memory.
1 = Enables bus master operation of the controller. Bus master operation begins when this bit is
detected changing from 0-to-1. The controller will transfer data between the IDE device and
memory only when this bit is set. Master operation can be halted by writing a 0 to this bit.
NOTE: This bit is intended to be cleared by software after the data transfer is completed, as
indicated by either the Bus Master IDE Active bit being cleared or the Interrupt bit of the Bus
Master IDE Status register for that IDE channel being set, or both. Hardware does not clear
this bit automatically.
Intel® 82801DB ICH4 Datasheet
397
IDE Controller Registers (D31:F1)
10.2.2
BMIS[P,S]—Bus Master IDE Status Register
Address Offset:
Default Value:
Primary: 02h
Secondary: 0Ah
00h
Bit
Size:
8 bits
Description
Reserved. Returns 0.
6
Drive 1 DMA Capable — R/W.
0 = Not Capable.
1 = Capable. Set by device dependent code (BIOS or device driver) to indicate that drive 1 for this
channel is capable of DMA transfers, and that the controller has been initialized for optimum
performance. The ICH4 does not use this bit. It is intended for systems that do not attach BMIDE
to the PCI bus.
5
Drive 0 DMA Capable — R/W.
0 = Not Capable
1 = Capable. Set by device dependent code (BIOS or device driver) to indicate that drive 0 for this
channel is capable of DMA transfers, and that the controller has been initialized for optimum
performance. The ICH4 does not use this bit. It is intended for systems that do not attach BMIDE
to the PCI bus.
Reserved. Returns 0s.
2
Interrupt — R/WC. Software can use this bit to determine if an IDE device has asserted its interrupt
line (IRQ 14 for the Primary channel, and IRQ 15 for Secondary).
0 = This bit is cleared by software writing a 1 to the bit position. If this bit is cleared while the interrupt
is still active, this bit will remain clear until another assertion edge is detected on the interrupt line.
1 = Set by the rising edge of the IDE interrupt line, regardless of whether or not the interrupt is
masked in the 8259 or the internal I/O APIC. When this bit is read as a 1, all data transferred from
the drive is visible in system memory.
1
Error — R/WC.
0 = This bit is cleared by software writing a 1 to the bit position.
1 = This bit is set when the controller encounters a target abort or master abort when transferring
data on PCI.
0
Bus Master IDE Active (ACT) — RO.
0 = This bit is cleared by the ICH4 when the last transfer for a region is performed, where EOT for
that region is set in the region descriptor. It is also cleared by the ICH4 when the Start bit is
cleared in the Command register. When this bit is read as a 0, all data transferred from the drive
during the previous bus master command is visible in system memory, unless the bus master
command was aborted.
1 = Set by the ICH4 when the Start bit is written to the Command register.
BMID[P,S]—Bus Master IDE Descriptor Table Pointer
Register
Address Offset:
Default Value:
Bit
398
R/WC, R/W, RO
7
4:3
10.2.3
Attribute:
Primary: 04h
Secondary: 0Ch
All bits undefined
Attribute:
R/W
Size:
32 bits
Description
31:2
Address of Descriptor Table (ADDR) — R/W. Corresponds to A[31:2]. The Descriptor Table must
be DWord-aligned. The Descriptor Table must not cross a 64-KB boundary in memory.
1:0
Reserved
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11
USB UHCI Controllers Registers
11.1
PCI Configuration Registers (D29:F0/F1/F2)
Note:
Address locations not shown in Table 11-1 should be treated as Reserved (see Section 6.2 for
details).
Table 11-1. PCI Configuration Register Address Map (USB—D29:F0/F1/F2)
Offset
Mnemonic
Register Name
Function 0
Default
Function 1
Default
Function 2
Default
Type
00–01h
VID
Vendor ID
8086h
8086h
8086h
RO
02–03h
DID
Device ID
24C2h
24C4h
24C7h
RO
04–05h
CMD
Command Register
0000h
0000h
0000h
R/W, RO
06–07h
STA
Device Status
0280h
0280h
0280h
R/WC, RO
08h
RID
09h
PI
0Ah
See Note
See Note
See Note
RO
Programming Interface
Revision ID
00h
00h
00h
RO
SCC
Sub Class Code
03h
03h
03h
RO
0Bh
BCC
Base Class Code
0Ch
0Ch
0Ch
RO
0Eh
HTYPE
80h
00h
00h
RO
20–23h
Base
Header Type
Base Address Register
00000001h
00000001h
00000001h
R/W, RO
2C–2Dh
SVID
Subsystem Vendor ID
00
00
00
RO
2E–2Fh
SID
Subsystem ID
00
00
00
RO
3Ch
INTR_LN
Interrupt Line
00h
00h
00h
R/W
3Dh
INTR_PN
Interrupt Pin
01h
02h
03h
RO
60h
SB_RELNUM
USB Release Number
10h
10
10
RO
C0–C1h
USB_LEGKEY
USB Legacy
Keyboard/Mouse
Control
2000h
2000h
2000h
R/W,
R/WC, RO
C4h
USB_RES
00h
00h
00h
R/W
USB Resume Enable
NOTE: Refer to the ICH4 Specification Update for the value of the Revision ID Register.
11.1.1
VID—Vendor Identification Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
Bit
15:0
00–01h
8086h
Attribute:
Size:
RO
16 bits
Description
Vendor Identification Value — RO. This is a 16-bit value assigned to Intel
Intel® 82801DB ICH4 Datasheet
399
USB UHCI Controllers Registers
11.1.2
DID—Device Identification Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
02–03h
Function 0: 24C2h
Function 1: 24C4h
Function 2: 24C7h
Bit
15:0
11.1.3
RO
16 bits
Description
Device Identification Value — RO. This is a 16-bit value assigned to the ICH4 USB Host
controllers.
CMD—Command Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
Bit
15:10
400
Attribute:
Size:
04–05h
0000h
Attribute:
Size:
R/W, RO
16 bits
Description
Reserved
9
Fast Back to Back Enable (FBE) — RO. Reserved as 0.
8
SERR# Enable (SERR_EN) — RO. Reserved as 0.
7
Wait Cycle Control (WCC) — RO. Reserved as 0.
6
Parity Error Response (PER) — RO. Reserved as 0.
5
VGA Palette Snoop (VSP) — RO. Reserved as 0.
4
Postable Memory Write Enable (PMWE) — RO. Reserved as 0.
3
Special Cycle Enable (SCE) — RO. Reserved as 0.
2
Bus Master Enable (BME) — RW. When set, the ICH4 can act as a master on the PCI bus for USB
transfers.
1
Memory Space Enable (MSE) — RO. Reserved as 0.
0
I/O Space Enable (IOSE) — RW. This bit controls access to the I/O space registers.
0 = Disable
1 = Enable accesses to the USB I/O registers. The Base Address register for USB should be
programmed before this bit is set.
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11.1.4
STA—Device Status Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
06–07h
0280h
Bit
15:14
Attribute:
Size:
R/WC, RO
16 bits
Description
Reserved as 00b. Read Only.
Received Master Abort (RMA) — R/WC.
13
0 = Software clears this bit by writing a 1 to the bit location.
1 = USB, as a master, generated a master-abort.
12
Reserved. Always read as 0.
11
Signaled Target Abort (STA) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = USB function is targeted with a transaction that the ICH4 terminates with a target abort.
10:9
8
Data Parity Error Detected (DPED) — RO. Reserved as 0.
7
Fast Back to Back Capable (FB2BC) — RO. Reserved as 1.
6
User Definable Features (UDF) — RO. Reserved as 0.
5
66 MHz Capable (66MHZ_CAP) — RO. Reserved as 0.
4:0
11.1.5
DEVSEL# Timing Status (DEV_STS) — RO: This 2-bit field defines the timing for DEVSEL#
assertion. These read only bits indicate the ICH4's DEVSEL# timing when performing a positive
decode. ICH4 generates DEVSEL# with medium timing for USB.
Reserved
RID—Revision Identification Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
08h
See Bit Description
Bit
7:0
11.1.6
Attribute:
Size:
RO
8 bits
Description
Revision Identification Value — RO. Refer to the ICH4 specification update for the value of the
Revision ID Register.
PI—Programming Interface (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
Bit
7:0
09h
00h
Attribute:
Size:
RO
8 bits
Description
Programming Interface — RO.
00h = No specific register level programming interface defined.
Intel® 82801DB ICH4 Datasheet
401
USB UHCI Controllers Registers
11.1.7
SCC—Sub Class Code Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
0Ah
03h
Bit
7:0
11.1.8
RO
8 bits
Description
Sub Class Code — RO.
03h = Universal Serial Bus Host controller.
BCC—Base Class Code Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
0Bh
0Ch
Bit
7:0
11.1.9
Attribute:
Size:
Attribute:
Size:
RO
8 bits
Description
Base Class Code — RO.
0Ch = Serial Bus controller.
HTYPE—Header Type Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
0Eh
FN 0: 80h
FN 1: 00h
FN 2: 00h
Attribute:
Size:
RO
8 bits
For functions 1 and 2, this register is hard-wired to 00h. For function 0, bit 7 is determined by the
values in bits 15, 10, and 9 of the function disable register (D31:F0:F2h).
Bit
7
6:0
402
Description
Multi-Function Bit — RO. When set to 1, this bit indicates to software that this is a multi-function
device. A 0 indicates a single-function device. Since the upper functions in this device can be
individually hidden, this bit must be based on the function-disable bits in Device 31, Function 0,
Offset F2h as follows:
D29:F7_Disable
D29:F2_Disable
D29:F1_Disable
Multi-Function Bit
(bit 15)
(bit 10)
(bit 9)
0
X
X
1
X
0
X
1
X
X
0
1
1
1
1
0
Header Type — RO. Hardwired to 00h, which indicates the standard PCI configuration layout.
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11.1.10
BASE—Base Address Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
20–23h
00000001h
Bit
Description
Reserved
15:5
Base Address — R/W. Bits [15:5] correspond to I/O address signals AD [15:5], respectively. This
gives 32 bytes of relocatable I/O space.
4:1
Reserved
Resource Type Indicator (RTE) — RO. This bit is hardwired to 1 indicating that the base address
field in this register maps to I/O space
SVID — Subsystem Vendor ID (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
Lockable:
11.1.12
R/W, RO
32 bits
31:16
0
11.1.11
Attribute:
Size:
2Ch–2Dh
00h
No
Attribute:
Size:
Power Well:
RO
16 bits
Core
Bit
Description
15:0
Subsystem Vendor ID (SVID) — RO. The SVID register, in combination with the Subsystem ID
(SID) register, enables the operating system (OS) to distinguish subsystems from each other. The
value returned by reads to this register is the same as what was written by BIOS into the IDE_SVID
register.
SID — Subsystem ID (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
Lockable:
2Eh–2Fh
00h
No
Attribute:
Size:
Power Well:
RO
16 bits
Core
Bit
Description
15:0
Subsystem ID (SID) — R/Write-Once. The SID register, in combination with the SVID register,
enables the operating system (OS) to distinguish subsystems from each other. The value returned
by reads to this register is the same as what was written by BIOS into the IDE_SID register.
Intel® 82801DB ICH4 Datasheet
403
USB UHCI Controllers Registers
11.1.13
INTR_LN—Interrupt Line Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
11.1.14
3Ch
00h
Description
7:0
Interrupt Line (INT_LN) — R/W. This data is not used by the ICH4. It is to communicate to software
the interrupt line that the interrupt pin is connected to.
INTR_PN—Interrupt Pin Register (USB—D29:F0/F1/F2)
3Dh
Function 0: 01h
Function 1: 02h
Function 2: 03h
Bit
Attribute:
Size:
RO
8 bits
Description
7:3
Reserved
2:0
Interrupt Pin (INT_PN) — RO. The values of 01h, 02h, and 03h in function 0, 1, and 2, respectively,
indicate to software that the corresponding ICH4 UHCI USB controllers drive the INTA#, INTB#, and
INTC# PCI signals.
Note that this does not determine the mapping to the ICH4 PIRQ inputs. Function 0 will drive PIRQA.
Function 1 will drive PIRQD. Function 2 will drive PIRQC. Function 1 does not use the corresponding
mapping in order to spread the interrupts with AC97, which has historically been mapped to PIRQB.
USB_RELNUM—USB Release Number Register
(USB—D29:F0/F1/F2)
Address Offset:
Default Value:
Bit
7:0
404
R/W
8 bits
Bit
Address Offset:
Default Value:
11.1.15
Attribute:
Size:
60h
10h
Attribute:
Size:
RO
8 bits
Description
USB Release Number — RO.
10h = Indicates that the USB controller is compliant with the USB specification, Release 1.0.
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11.1.16
USB_LEGKEY—USB Legacy Keyboard/Mouse Control
Register (USB—D29:F0/F1/F2)
Address Offset:
Default Value:
C0–C1h
2000h
Attribute:
Size:
R/W, R/WC, RO
16 bits
This register is implemented separately in each of the USB UHCI functions. However, the enable
and status bits for the trapping logic are OR’d and shared, respectively, since their functionality is
not specific to any one host controller.
Bit
Description
15
SMI Caused by End of Pass-through (SMIBYENDPS) — R/WC. Indicates if the event occurred.
Note that even if the corresponding enable bit is not set in bit 7, then this bit will still be active. It is up
to the SMM code to use the enable bit to determine the exact cause of the SMI#.
0 = Software clears this bit by writing a 1 to the bit location in any of the controllers.
1 = Event Occurred
14
Reserved
13
PCI Interrupt Enable (USBPIRQEN) — R/W. Used to prevent the USB controller from generating an
interrupt due to transactions on its ports. Note, when disabled, that it will probably be configured to
generate an SMI using bit 4 of this register. Default to 1 for compatibility with older USB software.
0 = Disable
1 = Enable
12
SMI Caused by USB Interrupt (SMIBYUSB) — RO. Indicates if an interrupt event occurred from this
controller. The interrupt from the controller is taken before the enable in bit 13 has any effect to create
this read-only bit. Note that even if the corresponding enable bit is not set in the Bit 4, then this bit may
still be active. It is up to the SMM code to use the enable bit to determine the exact cause of the SMI#.
0 = Software should clear the interrupts via the USB controllers. Writing a 1 to this bit will have no
effect.
1 = Event Occurred.
11
SMI Caused by Port 64 Write (TRAPBY64W) — R/WC. Indicates if the event occurred. Note that
even if the corresponding enable bit is not set in the bit 3, then this bit will still be active. It is up to the
SMM code to use the enable bit to determine the exact cause of the SMI#. Note that the A20Gate
Pass-Through Logic allows specific port 64h writes to complete without setting this bit.
0 = Software clears this bit by writing a 1 to the bit location in any of the controllers.
1 = Event Occurred.
10
SMI Caused by Port 64 Read (TRAPBY64R) — R/WC. Indicates if the event occurred. Note that
even if the corresponding enable bit is not set in the bit 2, then this bit will still be active. It is up to the
SMM code to use the enable bit to determine the exact cause of the SMI#.
0 = Software clears this bit by writing a 1 to the bit location in any of the controllers.
1 = Event Occurred.
9
SMI Caused by Port 60 Write (TRAPBY60W) — R/WC. Indicates if the event occurred. Note that
even if the corresponding enable bit is not set in the bit 1, then this bit will still be active. It is up to the
SMM code to use the enable bit to determine the exact cause of the SMI#. Note that the A20Gate
Pass-Through Logic allows specific port 64h writes to complete without setting this bit.
0 = Software clears this bit by writing a 1 to the bit location in any of the controllers.
1 = Event Occurred.
8
SMI Caused by Port 60 Read (TRAPBY60R) — R/WC. Indicates if the event occurred. Note that
even if the corresponding enable bit is not set in the bit 0, then this bit will still be active. It is up to the
SMM code to use the enable bit to determine the exact cause of the SMI#.
0 = Software clears this bit by writing a 1 to the bit location in any of the controllers.
1 = Event Occurred.
Intel® 82801DB ICH4 Datasheet
405
USB UHCI Controllers Registers
11.1.17
Bit
Description
7
SMI at End of Pass-through Enable (SMIATENDPS) — R/W. May need to cause SMI at the end of
a pass-through. Can occur if an SMI is generated in the middle of a pass through, and needs to be
serviced later.
0 = Disable
1 = Enable
6
Pass Through State (PSTATE) — RO.
0 = If software needs to reset this bit, it should set bit 5 in all of the host controllers to 0.
1 = Indicates that the state machine is in the middle of an A20GATE pass-through sequence.
5
A20Gate Pass-Through Enable (A20PASSEN) — R/W.
0 = Disable.
1 = Allows A20GATE sequence Pass-Through function. A specific cycle sequence involving writes to
port 60h and 64h does not result in the setting of the SMI status bits.
4
SMI on USB IRQ Enable (USBSMIEN) — R/W.
0 = Disable
1 = USB interrupt will cause an SMI event.
3
SMI on Port 64 Writes Enable (64WEN) — R/W.
0 = Disable
1 = A 1 in bit 11 will cause an SMI event.
2
SMI on Port 64 Reads Enable (64REN) — R/W.
0 = Disable
1 = A 1 in bit 10 will cause an SMI event.
1
SMI on Port 60 Writes Enable (60WEN) — R/W.
0 = Disable
1 = A 1 in bit 9 will cause an SMI event.
0
SMI on Port 60 Reads Enable (60REN) — R/W.
0 = Disable
1 = A 1 in bit 8 will cause an SMI event.
USB_RES—USB Resume Enable Register
(USB—D29:F0/F1/F2)
Address Offset:
Default Value:
Bit
7:2
C4h
00h
Attribute:
Size:
R/W
8 bits
Description
Reserved
PORT1EN — R/W. Enable port 1 of the USB controller to respond to wakeup events.
1
0
406
0 = The USB controller will not look at this port for a wakeup event.
1 = The USB controller will monitor this port for remote wakeup and connect/disconnect events.
PORT0EN — R/W. Enable port 0 of the USB controller to respond to wakeup events.
0 = The USB controller will not look at this port for a wakeup event.
1 = The USB controller will monitor this port for remote wakeup and connect/disconnect events.
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11.2
USB I/O Registers
Some of the read/write register bits which deal with changing the state of the USB hub ports
function such that on read back they reflect the current state of the port, and not necessarily the
state of the last write to the register. This allows the software to poll the state of the port and wait
until it is in the proper state before proceeding. A Host controller reset, Global reset, or Port reset
will immediately terminate a transfer on the affected ports and disable the port. This affects the
USBCMD register, bit [4] and the PORTSC registers, bits [12, 6, 2]. See individual bit descriptions
for more detail.
Table 11-2. USB I/O Registers
Offset
Mnemonic
00–01h
USBCMD
USB Command
0000h
R/W
02–03h
USBSTS
USB Status
0020h
R/WC
04–05h
USBINTR
USB Interrupt Enable
0000h
R/W
06–07h
FRNUM
USB Frame Number
0000h
R/W (1)
08–0Bh
FRBASEADD
0Ch
SOFMOD
0D–0Fh
Register
USB Frame List Base Address
USB Start of Frame Modify
Reserved
Default
Type
Undefined
R/W
40h
R/W
0
RO
10–11h
PORTSC0
Port 0 Status/Control
0080h
R/WC, R/W,
RO (1)
12–13h
PORTSC1
Port 1 Status/Control
0080h
R/WC, R/W,
RO (1)
0
RO
14–17h
Reserved
NOTES:
1. These registers are Word writable only. Byte writes to these registers have unpredictable effects.
Intel® 82801DB ICH4 Datasheet
407
USB UHCI Controllers Registers
11.2.1
USBCMD—USB Command Register
I/O Offset:
Default Value:
Base + (00–01h)
0000h
Attribute:
Size:
R/W
16 bits
The Command Register indicates the command to be executed by the serial bus host controller.
Writing to the register causes a command to be executed. The table following the bit description
provides additional information on the operation of the Run/Stop and Debug bits.
Bit
15:7
Description
Reserved
Loop Back Test Mode — R/W.
8
0 = Disable loop back test mode.
1 = ICH4 is in loop back test mode. When both ports are connected together, a write to one port will
be seen on the other port and the data will be stored in I/O offset 18h.
7
Max Packet (MAXP) — R/W. This bit selects the maximum packet size that can be used for full
speed bandwidth reclamation at the end of a frame. This value is used by the Host controller to
determine whether it should initiate another transaction based on the time remaining in the SOF
counter. Use of reclamation packets larger than the programmed size will cause a Babble error if
executed during the critical window at frame end. The Babble error results in the offending endpoint
being stalled. Software is responsible for ensuring that any packet which could be executed under
bandwidth reclamation be within this size limit.
0 = 32 bytes
1 = 64 bytes
6
Configure Flag (CF) — R/W. This bit has no effect on the hardware. It is provided only as a
semaphore service for software.
0 = Indicates that software has not completed host controller configuration.
1 = HCD software sets this bit as the last action in its process of configuring the Host controller.
5
Software Debug (SWDBG) — R/W. The SWDBG bit must only be manipulated when the controller
is in the stopped state. This can be determined by checking the HCHalted bit in the USBSTS
register.
0 = Normal Mode.
1 = Debug mode. In SW Debug mode, the Host controller clears the Run/Stop bit after the
completion of each USB transaction. The next transaction is executed when software sets the
Run/Stop bit back to 1.
4
Force Global Resume (FGR) — R/W.
0 = Software resets this bit to 0 after 20 ms has elapsed to stop sending the Global Resume signal.
At that time all USB devices should be ready for bus activity. The 1-to-0 transition causes the
port to send a low speed EOP signal. This bit will remain a 1 until the EOP has completed.
1 = Host controller sends the Global Resume signal on the USB, and sets this bit to 1 when a
resume event (connect, disconnect, or K-state) is detected while in global suspend mode.
3
Enter Global Suspend Mode (EGSM) — R/W.
0 = Software resets this bit to 0 to come out of Global Suspend mode. Software writes this bit to 0 at
the same time that Force Global Resume (bit 4) is written to 0 or after writing bit 4 to 0.
1 = Host controller enters the Global Suspend mode. No USB transactions occur during this time.
The Host controller is able to receive resume signals from USB and interrupt the system.
Software must ensure that the Run/Stop bit (bit 0) is cleared prior to setting this bit.
408
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
Bit
Description
2
Global Reset (GRESET) — R/W.
0 = This bit is reset by the software after a minimum of 10 ms has elapsed as specified in Chapter 7
of the USB Specification.
1 = Global Reset. The Host controller sends the global reset signal on the USB and then resets all
its logic, including the internal hub registers. The hub registers are reset to their power on state.
Chip Hardware Reset has the same effect as Global Reset (bit 2), except that the Host
controller does not send the Global Reset on USB.
1
Host Controller Reset (HCRESET) — R/W. The effects of HCRESET on Hub registers are slightly
different from Chip Hardware Reset and Global USB Reset. The HCRESET affects bits [8,3:0] of the
Port Status and Control Register (PORTSC) of each port. HCRESET resets the state machines of
the Host controller including the Connect/Disconnect state machine (one for each port). When the
Connect/Disconnect state machine is reset, the output that signals connect/disconnect are negated
to 0, effectively signaling a disconnect, even if a device is attached to the port. This virtual
disconnect causes the port to be disabled. This disconnect and disabling of the port causes bit 1
(connect status change) and bit 3 (port enable/disable change) of the PORTSC to get set. The
disconnect also causes bit 8 of PORTSC to reset. About 64 bit times after HCRESET goes to 0, the
connect and low-speed detect will take place, and bits 0 and 8 of the PORTSC will change
accordingly.
0 = Reset by the Host controller when the reset process is complete.
1 = Reset. When this bit is set, the Host controller module resets its internal timers, counters, state
machines, etc. to their initial value. Any transaction currently in progress on USB is immediately
terminated.
Run/Stop (RS) — R/W. When set to 1, the ICH4 proceeds with execution of the schedule. The ICH4
continues execution as long as this bit is set. When this bit is cleared, the ICH4 completes the
current transaction on the USB and then halts. The HC Halted bit in the status register indicates
when the Host controller has finished the transaction and has entered the stopped state. The Host
controller clears this bit when the following fatal errors occur: consistency check failure, PCI Bus
errors.
0 = Stop
1 = Run
0
NOTE: This bit should only be cleared if there are no active Transaction Descriptors in the
executable schedule or software will reset the host controller prior to setting this bit again.
Table 11-3. Run/Stop, Debug Bit Interaction SWDBG (Bit 5), Run/Stop (Bit 0) Operation
SWDBG
(Bit 5)
Run/Stop
(Bit 0)
Description
0
0
If executing a command, the Host controller completes the command and then
stops. The 1.0 ms frame counter is reset and command list execution resumes
from start of frame using the frame list pointer selected by the current value in
the FRNUM register. (While Run/Stop=0, the FRNUM register can be
reprogrammed).
0
1
Execution of the command list resumes from Start Of Frame using the frame list
pointer selected by the current value in the FRNUM register. The Host controller
remains running until the Run/Stop bit is cleared (by software or hardware).
0
If executing a command, the Host controller completes the command and then
stops and the 1.0 ms frame counter is frozen at its current value. All status are
preserved. The Host controller begins execution of the command list from where
it left off when the Run/Stop bit is set.
1
Execution of the command list resumes from where the previous execution
stopped. The Run/Stop bit is set to 0 by the Host controller when a TD is being
fetched. This causes the Host controller to stop again after the execution of the
TD (single step). When the Host controller has completed execution, the HC
Halted bit in the Status Register is set.
1
1
Intel® 82801DB ICH4 Datasheet
409
USB UHCI Controllers Registers
When the USB Host controller is in software debug mode (USBCMD Register bit 5=1), the singlestepping software debug operation is as follows:
To enter software debug mode:
1. HCD puts Host controller in Stop state by setting the Run/Stop bit to 0.
2. HCD puts Host controller in debug mode by setting the SWDBG bit to 1.
3. HCD sets up the correct command list and Start Of Frame value for starting point in the Frame
List Single Step Loop.
4. HCD sets Run/Stop bit to 1.
5. Host controller executes next active TD, sets Run/Stop bit to 0, and stops.
6. HCD reads the USBCMD register to check if the single step execution is completed
(HCHalted=1).
7. HCD checks results of TD execution. Go to step 4 to execute next TD or step 8 to end software
debug mode.
8. HCD ends Software Debug mode by setting SWDBG bit to 0.
9. HCD sets up normal command list and Frame List table.
10. HCD sets Run/Stop bit to 1 to resume normal schedule execution.
In software debug mode, when the Run/Stop bit is set, the Host controller starts. When a valid TD
is found, the Run/Stop bit is reset. When the TD is finished, the HCHalted bit in the USBSTS
register (bit 5) is set.
The software debug mode skips over inactive TDs and only halts after an active TD has been
executed. When the last active TD in a frame has been executed, the Host controller waits until the
next SOF is sent and then fetches the first TD of the next frame before halting.
This HCHalted bit can also be used outside of software debug mode to indicate when the Host
controller has detected the Run/Stop bit and has completed the current transaction. Outside of the
software debug mode, setting the Run/Stop bit to 0 always resets the SOF counter so that when the
Run/Stop bit is set the Host controller starts over again from the frame list location pointed to by
the Frame List Index (see FRNUM Register description) rather than continuing where it stopped.
410
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11.2.2
USBSTS—USB Status Register
I/O Offset:
Default Value:
Base + (02–03h)
0020h
Attribute:
Size:
R/WC
16 bits
This register indicates pending interrupts and various states of the Host controller. The status
resulting from a transaction on the serial bus is not indicated in this register. Software sets a bit to 0
in this register by writing a 1 to it.
Bit
15:6
Description
Reserved
5
HCHalted — R/WC.
0 = Software resets this bit to 0 by writing a 1 to the bit position.
1 = The Host controller has stopped executing as a result of the Run/Stop bit being set to 0, either
by software or by the Host controller hardware (debug mode or an internal error). Default.
4
Host Controller Process Error — R/WC.
0 = Software resets this bit to 0 by writing a 1 to the bit position.
1 = The Host controller has detected a fatal error. This indicates that the Host controller suffered a
consistency check failure while processing a Transfer Descriptor. An example of a consistency
check failure would be finding an illegal PID field while processing the packet header portion
of the TD. When this error occurs, the Host controller clears the Run/Stop bit in the Command
register to prevent further schedule execution. A hardware interrupt is generated to the
system.
3
Host System Error — R/WC.
0 = Software resets this bit to 0 by writing a 1 to the bit position.
1 = A serious error occurred during a host system access involving the Host controller module. In
a PCI system, conditions that set this bit to 1 include PCI Parity error, PCI Master Abort, and
PCI Target Abort. When this error occurs, the Host controller clears the Run/Stop bit in the
Command register to prevent further execution of the scheduled TDs. A hardware interrupt is
generated to the system.
2
Resume Detect (RSM_DET) — R/WC.
0 = Software resets this bit to 0 by writing a 1 to the bit position.
1 = The Host controller received a “RESUME” signal from a USB device. This is only valid if the
Host controller is in a global suspend state (bit 3 of Command register = 1).
1
USB Error Interrupt — R/WC.
0 = Software resets this bit to 0 by writing a 1 to the bit position.
1 = Completion of a USB transaction resulted in an error condition (e.g., error counter underflow).
If the TD on which the error interrupt occurred also had its IOC bit set, both this bit and Bit 0
are set.
0
USB Interrupt (USBINT) — R/WC.
0 = Software resets this bit to 0 by writing a 1 to the bit position.
1 = The Host controller sets this bit when the cause of an interrupt is a completion of a USB
transaction whose Transfer Descriptor had its IOC bit set. Also set when a short packet is
detected (actual length field in TD is less than maximum length field in TD), and short packet
detection is enabled in that TD.
Intel® 82801DB ICH4 Datasheet
411
USB UHCI Controllers Registers
11.2.3
USBINTR—Interrupt Enable Register
I/O Offset:
Default Value:
Base + (04–05h)
0000h
Attribute:
Size:
R/W
16 bits
This register enables and disables reporting of the corresponding interrupt to the software. When a
bit is set and the corresponding interrupt is active, an interrupt is generated to the host. Fatal errors
(Host Controller Processor Error-bit 4, USBSTS Register) cannot be disabled by the host
controller. Interrupt sources that are disabled in this register still appear in the Status Register to
allow the software to poll for events.
Bit
15:4
11.2.4
Description
Reserved
3
Short Packet Interrupt Enable — R/W.
0 = Disabled.
1 = Enabled.
2
Interrupt On Complete (IOC) Enable — R/W.
0 = Disabled.
1 = Enabled.
1
Resume Interrupt Enable — R/W.
0 = Disabled.
1 = Enabled.
0
Timeout/CRC Interrupt Enable — R/W.
0 = Disabled.
1 = Enabled.
FRNUM—Frame Number Register
I/O Offset:
Default Value:
Base + (06–07h)
0000h
Attribute:
Size:
R/W (Writes must be Word Writes)
16 bits
Bits [10:0] of this register contain the current frame number which is included in the frame SOF
packet. This register reflects the count value of the internal frame number counter. Bits [9:0] are
used to select a particular entry in the Frame List during scheduled execution. This register is
updated at the end of each frame time.
This register must be written as a word. Byte writes are not supported. This register cannot be
written unless the Host controller is in the STOPPED state as indicated by the HCHalted bit
(USBSTS register). A write to this register while the Run/Stop bit is set (USBCMD register) is
ignored.
Bit
412
Description
15:11
Reserved
10:0
Frame List Current Index/Frame Number — R/W. Provides the frame number in the SOF Frame.
The value in this register increments at the end of each time frame (approximately every 1 ms). In
addition, bits [9:0] are used for the Frame List current index and correspond to memory address
signals [11:2].
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11.2.5
FRBASEADD—Frame List Base Address
I/O Offset:
Default Value:
Base + (08–0Bh)
Undefined
Attribute:
Size:
R/W
32 bits
This 32-bit register contains the beginning address of the Frame List in the system memory. HCD
loads this register prior to starting the schedule execution by the Host controller. When written,
only the upper 20 bits are used. The lower 12 bits are written as 0s (4-KB alignment). The contents
of this register are combined with the frame number counter to enable the Host controller to step
through the Frame List in sequence. The two least significant bits are always 00. This requires
DWord alignment for all list entries. This configuration supports 1024 Frame List entries.
Bit
31:12
11:0
Description
Base Address — R/W. These bits correspond to memory address signals [31:12], respectively.
Reserved
Intel® 82801DB ICH4 Datasheet
413
USB UHCI Controllers Registers
11.2.6
SOFMOD—Start of Frame Modify Register
I/O Offset:
Default Value:
Base + (0Ch)
40h
Attribute:
Size:
R/W
8 bits
This 1-byte register is used to modify the value used in the generation of SOF timing on the USB.
Only the 7 least significant bits are used. When a new value is written into these 7 bits, the SOF
timing of the next frame will be adjusted. This feature can be used to adjust out any offset from the
clock source that generates the clock that drives the SOF counter. This register can also be used to
maintain real time synchronization with the rest of the system so that all devices have the same
sense of real time. Using this register, the frame length can be adjusted across the full range
required by the USB specification. Its initial programmed value is system dependent based on the
accuracy of hardware USB clock and is initialized by system BIOS. It may be reprogrammed by
USB system software at any time. Its value will take effect from the beginning of the next frame.
This register is reset upon a Host Controller Reset or Global Reset. Software must maintain a copy
of its value for reprogramming if necessary.
Bit
7
6:0
414
Description
Reserved
SOF Timing Value — R/W. Guidelines for the modification of frame time are contained in Chapter 7
of the USB Specification. The SOF cycle time (number of SOF counter clock periods to generate a
SOF frame length) is equal to 11936 + value in this field. The default value is decimal 64 which gives
a SOF cycle time of 12000. For a 12 MHz SOF counter clock input, this produces a 1 ms Frame
period. The following table indicates what SOF Timing Value to program into this field for a certain
frame period.
Frame Length
(# 12 MHz Clocks)
SOF Reg. Value
(decimal)
(decimal)
11936
0
11937
1
.
.
.
.
11999
63
12000
64
12001
65
.
.
.
.
12062
126
12063
127
Intel® 82801DB ICH4 Datasheet
USB UHCI Controllers Registers
11.2.7
PORTSC[0,1]—Port Status and Control Register
I/O Offset:
Default Value:
Note:
Port 0/2/4: Base + (10–11h)Attribute:
Port 1/3/5: Base + (12–13h)
0080h
Size:
R/WC, RO, R/W (Word writes only)
16 bits
For Function 0, this register applies to ICH4 USB ports 0 and 1; for Function 1, this register applies
to ICH4 USB ports 2 and 3; for Function 2, this register applies to ICH4 USB ports 4 and 5.
After a Power-up reset, Global reset, or Host controller reset, the initial conditions of a port are: no
device connected, port disabled, and the bus line status is 00 (single-ended zero).
Bit
15:13
12
Description
Reserved — RO.
Suspend — R/W. This bit should not be written to a 1 if global suspend is active (bit 3=1 in the
USBCMD register). Bit 2 and bit 12 of this register define the hub states as follows:
Bits [12,2]
Hub State
X0
Disable
01
Enable
11
Suspend
When in suspend state, downstream propagation of data is blocked on this port, except for singleended 0 resets (global reset and port reset). The blocking occurs at the end of the current
transaction, if a transaction was in progress when this bit was written to 1. In the suspend state, the
port is sensitive to resume detection. Note that the bit status does not change until the port is
suspended and that there may be a delay in suspending a port if there is a transaction currently in
progress on the USB.
0 = Port not in suspend state.
1 = Port in suspend state.
NOTE: Normally, if a transaction is in progress when this bit is set, the port will be suspended
when the current transaction completes. However, in the case of a specific error condition
(out transaction with babble), the ICH4 may issue a start-of-frame, and then suspend the
port.
11
Over-current Indicator — R/WC. Set by hardware.
0 = Software clears this bit by writing a 1 to the bit position.
1 = Overcurrent pin has gone from inactive to active on this port.
10
Over-current Active — RO. This bit is set and cleared by hardware.
0 = Indicates that the overcurrent pin is inactive (high).
1 = Indicates that the overcurrent pin is active (low).
9
Port Reset — RO.
0 = Port is not in Reset.
1 = Port is in Reset. When set, the port is disabled and sends the USB Reset signaling.
8
Low Speed Device Attached (LS) — RO. Writes have no effect.
0 = Full speed device is attached.
1 = Low speed device is attached to this port.
7
Reserved — RO. Always read as 1.
Intel® 82801DB ICH4 Datasheet
415
USB UHCI Controllers Registers
416
Bit
Description
6
Resume Detect (RSM_DET) — R/W. Software sets this bit to a 1 to drive resume signaling. The
Host controller sets this bit to a 1 if a J-to-K transition is detected for at least 32 microseconds while
the port is in the Suspend state. The ICH4 will then reflect the K-state back onto the bus as long as
the bit remains a 1, and the port is still in the suspend state (bit 12,2 are 11). Writing a 0 (from 1)
causes the port to send a low speed EOP. This bit will remain a 1 until the EOP has completed.
0 = No resume (K-state) detected/driven on port.
1 = Resume detected/driven on port.
5:4
Line Status — RO. These bits reflect the D+ (bit 4) and D- (bit 5) signals line’s logical levels. These
bits are used for fault detect and recovery as well as for USB diagnostics. This field is updated at
EOF2 time (See Chapter 11 of the USB Specification).
3
Port Enable/Disable Change — R/WC. For the root hub, this bit gets set only when a port is
disabled due to disconnect on that port or due to the appropriate conditions existing at the EOF2
point (See Chapter 11 of the USB Specification).
0 = No change. Software clears this bit by writing a 1 to the bit location.
1 = Port enabled/disabled status has changed.
2
Port Enabled/Disabled (PORT_EN) — R/W. Ports can be enabled by host software only. Ports can
be disabled by either a fault condition (disconnect event or other fault condition) or by host software.
Note that the bit status does not change until the port state actually changes and that there may be
a delay in disabling or enabling a port if there is a transaction currently in progress on the USB.
0 = Disable
1 = Enable..
1
Connect Status Change — R/WC. Indicates that a change has occurred in the port’s Current
Connect Status (see bit 0). The hub device sets this bit for any changes to the port device connect
status, even if system software has not cleared a connect status change. If, for example, the
insertion status changes twice before system software has cleared the changed condition, hub
hardware will be setting” an already-set bit (i.e., the bit will remain set). However, the hub transfers
the change bit only once when the Host controller requests a data transfer to the Status Change
endpoint. System software is responsible for determining state change history in such a case.
0 = No change. Software clears this bit by writing a 1 to the bit location.
1 = Change in Current Connect Status.
0
Current Connect Status — RO. This value reflects the current state of the port, and may not
correspond directly to the event that caused the Connect Status Change bit (Bit 1) to be set.
0 = No device is present.
1 = Device is present on port.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12
EHCI Controller Registers (D29:F7)
12.1
USB EHCI Configuration Registers (D29:F7)
Note:
Register address locations not shown in Table 12-1 should be treated as Reserved (see Section 6.2
for details).
Table 12-1. USB EHCI PCI Configuration Register Address Map (D29:F7) (Sheet 1 of 2)
Offset
Mnemonic
Register Name
Default
Value
Type
00–01h
VID
Vendor ID
8086h
RO
02–03h
DID
Device ID
24CDh
RO
04–05h
PCICMD
Command Register
0000h
R/W, RO
06–07h
PCISTS
Device Status
0290h
R/WC, RO
08h
REVID
09h
PI
0Ah
0Bh
See Note
RO
Programming Interface
20h
RO
SCC
Sub Class Code
03h
RO
BCC
Base Class Code
0Ch
RO
0Dh
MLT
10–13h
MEM_BASE
2C–2Dh
SVID
2E–2Fh
SID
Revision ID
Master Latency Timer
00h
RO
00000000h
R/W, RO
Subsystem Vendor ID
XXXXh
R/W-Special
Subsystem ID
XXXXh
R/W-Special
Memory Base Address Register
34h
CAP_PTR
Capabilities Pointer
50h
3Ch
INT_LN
Interrupt Line
00h
R/W
3Dh
INT_PN
Interrupt Pin
04h
RO
50h
PWR_CAPID
Power Management Capability ID
01h
RO
51h
NXT_PRT1
Next Item Pointer #1
58h
R/W-Special
52–53h
PWR_CAP
Power Management Capabilities
C9C2h
R/W-Special
54–55h
PWR_CNTL_STS
Power Management Control/Status
0000h
R/W, R/WC
58h
DEBUG_CAPID
0Ah
RO
Debug Port Capability ID
59h
NXT_PRT2
5A–5Bh
DEBUG_BASE
Debug Port Base Offset
60h
USB_RELNUM
61h
FL_ADJ
62–63h
PWAKE_CAP
66–67h
68–6Bh
Next Item Pointer #2
00h
RO
2080h
RO
USB Release Number
20h
RO
Frame Length Adjustment
20h
R/W
Power Wake Capabilities
007Fh
R/W
0
RO
00000001h
R/W, RO
Reserved
LEG_EXT_CAP
Intel® 82801DB ICH4 Datasheet
USB EHCI Legacy Support Extended
Capability
417
EHCI Controller Registers (D29:F7)
Table 12-1. USB EHCI PCI Configuration Register Address Map (D29:F7) (Sheet 2 of 2)
Offset
Mnemonic
6C–6Fh
LEG_EXT_CS
70–73h
SPECIAL_SMI
74–7F
Default
Value
Type
USB EHCI Legacy Support Control/Status
00000000h
R/W, R/WC,
RO
Intel Specific USB EHCI SMI
00000000h
R/WC, R/W
Register Name
Reserved
80h
ACCESS_CNTL
DC–DFh
USB_REF_V
0
RO
00h
R/W
00000000h
R/W
Access Control
USB HS Reference Voltage Register
NOTE: Refer to the ICH4 Specification Update for the value of the Revision ID Register.
12.1.1
VID—Vendor ID Register (USB EHCI—D29:F7)
Offset Address:
Default Value:
00–01h
8086h
Bit
15:0
12.1.2
RO
16 bits
Description
Vendor Identification Value — RO. This is a 16-bit value assigned to Intel.
DID—Device ID Register (USB EHCI—D29:F7)
Offset Address:
Default Value:
Bit
15:0
418
Attribute:
Size:
02–03h
24CDh
Attribute:
Size:
RO
16 bits
Description
Device Identification Value — RO. This is a 16-bit value assigned to the ICH4 USB EHCI
controller.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.1.3
PCICMD—PCI Command Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
Bit
15:10
04–05h
0000h
Attribute:
Size:
R/W, RO
16 bits
Description
Reserved
9
Fast Back to Back Enable (FBE) — RO. Reserved as 0.
8
SERR# Enable (SERR_EN) — R/W.
0 = Disables EHC’s capability to generate an SERR#.
1 = The Enhanced Host Controller (EHC) is capable of generating (internally) SERR# when it
receive a completion status other than “successful” for one of its DMA-initiated memory reads
on the hub interface (and subsequently on its internal interface).
7
Wait Cycle Control (WCC) — RO. Reserved as 0.
6
Parity Error Response (PER) — RO. Reserved as 0.
5
VGA Palette Snoop (VPS) — RO. Reserved as 0.
4
Postable Memory Write Enable (PMWE) — RO. Reserved as 0.
3
Special Cycle Enable (SCE) — RO. Reserved as 0.
2
Bus Master Enable (BME) — R/W.
0 = Disables this functionality.
1 = Enables the ICH4 can act as a master on the PCI bus for USB transfers.
1
Memory Space Enable (MSE) — R/W. This bit controls access to the USB EHCI Memory Space
registers.
0 = Disables this functionality.
1 = Enables accesses to the USB EHCI registers. The Base Address register for USB EHCI should
be programmed before this bit is set.
0
I/O Space Enable (IOSE) — RO. Reserved as 0.
Intel® 82801DB ICH4 Datasheet
419
EHCI Controller Registers (D29:F7)
12.1.4
PCISTS—PCI Device Status Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
06–07h
0290h
Bit
Description
Detected Parity Error (DPE) — RO. Reserved as 0.
14
Signaled System Error (SSE) — R/WC.
0 = Software clears this bit by writing a 1 to this bit location.
1 = ICH4 signaled SERR# (internally). The SER_EN bit (bit 8 of the Command Register) must be 1
for this bit to be set.
13
Received Master Abort (RMA) — R/WC.
0 = Software clears this bit by writing a 1 to this bit location.
1 = USB EHCI, as a master, received a master abort status on a memory access. This is treated as
a Host Error and halts the DMA engines. This event can optionally generate an SERR# by
setting the SERR# Enable bit.
12
Received Target Abort (RTA) — R/WC.
0 = Software clears this bit by writing a 1 to this bit location.
1 = USB EHCI, as a master, received a target abort status on a memory access. This is treated as
a Host Error and halts the DMA engines. This event can optionally generate an SERR# by
setting the SERR# Enable bit.
11
Signaled Target Abort (STA) — RO. Hardwired to 0. This bit is used to indicate when the USB EHCI
function responds to a cycle with a target abort. There is no reason for this to happen; thus, this bit is
hardwired to 0.
DEVSEL# Timing Status (DEV_STS) — RO. This 2-bit field defines the timing for DEVSEL#
assertion.
8
Master Data Parity Error Detected (DPED) — R/WC.
0 = Software clears this bit by writing a 1 to this bit location.
1 = ICH4 detected a data parity error on a USB EHCI read completion packet on the internal
interface to the USB EHCI host controller (due to an equivalent data parity error on hub
interface), and bit 6 of the Command register is set to 1.
7
Fast Back to Back Capable (FB2BC) — RO. Reserved as 1.
6
User Definable Features (UDF) — RO. Reserved as 0.
5
66 MHz Capable (66MHZ_CAP) — RO. Reserved as 0.
4
Capabilities List (CAP_LIST) — RO. This bit is hardwired to 1 indicating the presence of a valid
capabilities pointer at offset 34h.
3:0
Reserved.
REVID—Revision ID Register (USB EHCI—D29:F7)
Offset Address:
Default Value:
Bit
7:0
420
R/WC, RO
16 bits
15
10:9
12.1.5
Attribute:
Size:
08h
See Bit Description
Attribute:
Size:
RO
8 bits
Description
Revision Identification Value — RO. Refer to the ICH4 Specification Update for the value of the
Revision ID Register.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.1.6
PI—Programming Interface Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
09h
20h
Bit
7:0
12.1.7
Programming Interface — RO. A value of 20h indicates that this USB High-speed Host controller
conforms to the EHCI Specification.
SCC—Sub Class Code Register (USB EHCI—D29:F7)
0Ah
03h
Bit
7:0
Attribute:
Size:
RO
8 bits
Description
Sub Class Code — RO. A value of 03h indicates that this is a Universal Serial Bus Host controller.
BCC—Base Class Code Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
0Bh
0Ch
Bit
7:0
12.1.9
RO
8 bits
Description
Address Offset:
Default Value:
12.1.8
Attribute:
Size:
Attribute:
Size:
RO
8 bits
Description
Base Class Code — RO. A value of 0Ch indicates that this is a Serial Bus controller.
MLT— PCI Master Latency Timer Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
0Dh
00h
Attribute:
Size:
RO
8 bits
Bit
Description
7:0
Master Latency Timer Count (MLTC) — RO. Hardwired to 00h. Because the USB EHCI controller is
internally implemented with arbitration via hub interface (and not PCI), it does not need a master
latency timer.
Intel® 82801DB ICH4 Datasheet
421
EHCI Controller Registers (D29:F7)
12.1.10
MEM_BASE—Memory Base Address Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
10–13h
00000000h
Bit
31:10
9:4
3
2:1
0
12.1.11
Attribute:
Size:
R/W, RO
32 bits
Description
Base Address — R/W. Bits [31:10] correspond to memory address signals [31:10], respectively.
This provides 1 KB of locatable memory space aligned to 1 KB boundaries.
Reserved
Prefetchable — RO. Hardwired to 0; indicates that this range should not be prefetched.
Type — RO. Hardwired to 00b; indicates that this range can be mapped anywhere within 32-bit
address space.
Resource Type Indicator (RTE) — RO. Hardwired to 0; indicates that the base address field in this
register maps to memory space.
SVID—USB EHCI Subsystem Vendor ID Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
Reset:
2C–2Dh
XXXXh
None
Attribute:
Size:
R/W-Special
16 bits
Bit
Description
15:0
Subsystem Vendor ID (SVID) — R/W-Special. This register, in combination with the USB EHCI
Subsystem ID register, enables the operating system to distinguish each subsystem from the others.
NOTE: Writes to this register are enabled when the WRT_RDONLY bit (offset 80h, bit 0) is set to 1.
12.1.12
SID—USB EHCI Subsystem ID Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
Reset:
Bit
15:0
2E–2Fh
XXXXh
None
Attribute:
Size:
R/W-Special
16 bits
Description
Subsystem ID (SID) — R/W-Special. BIOS sets the value in this register to identify the Subsystem
ID. This register, in combination with the Subsystem Vendor ID register, enables the operating
system to distinguish each subsystem from other(s).
NOTE: Writes to this register are enabled when the WRT_RDONLY bit (offset 80h, bit 0) is set to 1.
422
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.1.13
CAP_PTR—Capabilities Pointer Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
34h
50h
Bit
7: 0
12.1.14
RO
8 bits
Description
Capabilities Pointer (CAP_PTR) — RO. This register points to the starting offset of the USB EHCI
capabilities ranges.
INT_LN—Interrupt Line Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
3Ch
00h
Bit
7:0
12.1.15
Attribute:
Size:
Attribute:
Size:
R/W
8 bits
Description
Interrupt Line (INT_LN) — R/W. This data is not used by the ICH4. It is used as a scratchpad
register to communicate to software the interrupt line that the interrupt pin is connected to.
INT_PN—Interrupt Pin Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
3Dh
04h
Bit
7:0
Attribute:
Size:
RO
8 bits
Description
Interrupt Pin (INT_PN) — RO. The value of 04h indicates that the USB EHCI function within the
ICH4’s multi-function USB device will drive the fourth interrupt pin from the device (INTD# in PCI
terms). The value of 04h in function 7 is required because the PCI specification does not recognize
more than 4 interrupts and older APM-based OSs require that each function within a multi-function
device has a different Interrupt Pin Register value.
NOTE: Internally the USB EHCI controller uses PIRQ[H]#.
12.1.16
PWR_CAPID—PCI Power Management Capability ID
Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
Bit
7:0
50h
01h
Attribute:
Size:
RO
8 bits
Description
Power Management Capability ID — RO. A value of 01h indicates that this is a PCI Power
Management capabilities field.
Intel® 82801DB ICH4 Datasheet
423
EHCI Controller Registers (D29:F7)
12.1.17
NXT_PTR1—Next Item Pointer #1 Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
12.1.18
51h
58h
Attribute:
Size:
R/W-Special
8 bits
Bit
Description
7:0
Next Item Pointer #1 Value — R/W-Special. This register defaults to 58h, which indicates that the
next capability registers begin at configuration offset 58h. This register is writable when the
WRT_RDONLY bit is set. This allows BIOS to effectively hide the Debug Port capability registers, if
necessary. This register should only be written during system initialization before the plug-and-play
software has enabled any master-initiated traffic. Only values of 58h (Debug Port visible) and 00h
(Debug Port invisible) are expected to be programmed in this register.
PWR_CAP—Power Management Capabilities Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
52–53h
C9C2h
Attribute:
Size:
R/W-Special
16 bits
Bit
Description
15:11
PME Support — R/W-Special. This 5-bit field indicates the power states in which the function may
assert PME#. The ICH4 EHC does not support the D1 or D2 states. For all other states, the ICH4
EHC is capable of generating PME#. Software should never need to modify this field.
D2 Support — R/W-Special.
10
0 = D2 State is not supported
1 = D2 State is supported
D1 Support — R/W-Special.
9
0 = D1 State is not supported
1 = D1 State is supported
8:6
Auxiliary Current — R/W-Special. The ICH4 EHC reports 375 mA maximum Suspend well current
required when in the D3cold state. This value can be written by BIOS when a more accurate value is
known.
5
DSI — R/W-Special. The ICH4 reports 0, indicating that no device-specific initialization is required.
4
Reserved
3
PME Clock — R/W-Special. The ICH4 reports 0, indicating that no PCI clock is required to generate
PME#.
2:0
Version — R/W-Special. The ICH4 reports 010b, indicating that it complies with Revision 1.1 of the
PCI Power Management Specification.
NOTES:
1. Normally, this register is read-only to report capabilities to the power management software. To report
different power management capabilities, depending on the system in which the ICH4ICH4 is used, bits 15:11
and 8:6 in this register are writable when the WRT_RDONLY bit is set. The value written to this register does
not affect the hardware other than changing the value returned during a read.
2. Reset: core well, but not D3-to-D0 warm reset.
424
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.1.19
PWR_CNTL_STS—Power Management Control/Status
Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
54–55h
0000h
Bit
Attribute:
Size:
R/WC, R/W
16 bits
Description
PME Status — R/WC.
15
0 = Writing a 1 to this bit clears it and causes the internal PME to deassert (if enabled). Writing a 0
has no effect.
1 = This bit is set when the ICH4 EHC would normally assert the PME# signal independent of the
state of the PME_En bit.
NOTE: This bit must be explicitly cleared by the operating system each time the operating system
is loaded.
14:13
Data Scale — RO. Hardwired to 00b; ICH4 does not support the associated Data register.
12:9
Data Select — RO. Hardwired to 0000b; ICH4 does not support the associated Data register.
8
PME Enable — R/W.
0 = Disable.
1 = Enables the ICH4 EHC to generate an internal PME signal when PME_Status is 1.
NOTE: This bit must be explicitly cleared by the operating system each time it is initially loaded.
7:2
Reserved
1:0
Power State — R/W. This 2-bit field is used both to determine the current power state of EHC
function and to set a new power state. The definition of the field values are:
00 = D0 state
11 = D3 hot state
If software attempts to write a value of 10b or 01b in to this field, the write operation must complete
normally; however, the data is discarded and no state change occurs. When in the D3 hot state, the
ICH4 must not accept accesses to the EHC memory range; but the configuration space must still be
accessible. When not in the D0 state, the generation of the interrupt output is blocked. Specifically,
the PIRQ[H] is not asserted by the ICH4 when not in the D0 state.
When software changes this value from the D3 hot state to the D0 state, an internal warm (soft)
reset is generated, and software must re-initialize the function.
NOTE: Reset (bits 15, 8): suspend well, and not D3-to-D0 warm reset nor core well reset.
12.1.20
DEBUG_CAPID—Debug Port Capability ID Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
Bit
7:0
58h
0Ah
Attribute:
Size:
RO
8 bits
Description
Debug Port Capability ID — RO. Hardwired to 0Ah; indicates that this is the start of a Debug Port
Capability structure.
Intel® 82801DB ICH4 Datasheet
425
EHCI Controller Registers (D29:F7)
12.1.21
NXT_PTR2—Next Item Pointer #2 Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
12.1.22
59h
00h
Description
7:0
Next Item Pointer 2 Capability — RO. Hardwired to 00h: indicates that there are no more capability
structures in this function.
DEBUG_BASE—Debug Port Base Offset Register
(USB EHCI—D29:F7)
5Ah–5Bh
2080h
Bit
Attribute:
Size:
RO
16 bits
Description
15:13
BAR Number — RO. Hardwired to 001b: indicates the memory BAR begins at offset 10h in the
EHCI configuration space.
12:0
Debug Port Offset — RO. Hardwired to 080h; indicates that the Debug Port registers begin at offset
80h in the EHCI memory range.
USB_RELNUM—USB Release Number Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
Bit
7:0
426
RO
8 bits
Bit
Address Offset:
Default Value:
12.1.23
Attribute:
Size:
60h
20h
Attribute:
Size:
RO
8 bits
Description
USB Release Number — RO. A value of 20h indicates that this controller follows the Universal
Serial Bus (USB) Specification, Revision 2.0 .
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.1.24
FL_ADJ—Frame Length Adjustment Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
61h
20h
Bit
Attribute:
Size:
R/W
8 bits
Description
7:6
Reserved — RO. These bits are reserved for future use and should read as 00b.
5:0
Frame Length Timing Value — R/W. Each decimal value change to this register corresponds to 16
high-speed bit times. The SOF cycle time (number of SOF counter clock periods to generate a SOF
micro-frame length) is equal to 59488 + value in this field. The default value is decimal 32 (20h),
which gives a SOF cycle time of 60000.
Frame Length (# 480 MHz Clocks)
FLADJ Value
decimal (hex)
59488
0 (00h)
59504
1 (01h)
59520
2 (02h)
…
59984
31 (1Fh)
60000
32 (20h)
…
60480
62 (3Eh)
60496
63 (3Fh)
NOTE: This feature is used to adjust any offset from the clock source that generates the clock that drives the
SOF counter. When a new value is written into these six bits, the length of the frame is adjusted. Its
initial programmed value is system dependent based on the accuracy of hardware USB clock and is
initialized by system BIOS. This register should only be modified when the HChalted bit in the
EHCI_STS register is a 1. Changing value of this register while the host controller is operating yields
undefined results. It should not be reprogrammed by USB system software unless the default or BIOS
programmed values are incorrect, or the system is restoring the register while returning from a
suspended state.
12.1.25
PWAKE_CAP—Port Wake Capability Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
62–63h
7Fh
Bit
Attribute:
Size:
R/W
16 bits
Description
15:7
Reserved — RO.
6:1
Port Wake Up Capability Mask — R/W. Bit positions 1 through 6 correspond to a physical port
implemented on this host controller. For example, bit position 1 corresponds to port 1, bit position 2
corresponds to port 2, bit position 3 corresponds to port 3, etc.
0
Port Wake Implemented — R/W. A 1 in bit 0 indicates that this register is implemented to software.
NOTE: This register is in the suspend power well. The intended use of this register is to establish a policy about
which ports are to be used for wake events. Bit positions 1–6 in the mask correspond to a physical port
implemented on the current EHCI controller. A 1 in a bit position indicates that a device connected
below the port can be enabled as a wake-up device and the port may be enabled for disconnect/connect
or over-current events as wake-up events. This is an information-only mask register. The bits in this
register do not affect the actual operation of the EHCI host controller. The system-specific policy can be
established by BIOS initializing this register to a system-specific value. System software uses the
information in this register when enabling devices and ports for remote wake-up.
Intel® 82801DB ICH4 Datasheet
427
EHCI Controller Registers (D29:F7)
12.1.26
LEG_EXT_CAP—USB EHCI Legacy Support Extended
Capability Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
Power Well:
68–6Bh
00000001h
Suspend
Bit
31:25
24
23:17
12.1.27
Attribute:
Size:
R/W, RO
32 bits
Description
Reserved — RO. Hardwired to 00h
HC OS Owned Semaphore — R/W. System software sets this bit to request ownership of the EHCI
controller. Ownership is obtained when this bit reads as 1 and the HC BIOS Owned Semaphore bit
reads as clear.
Reserved — RO. Hardwired to 00h
16
HC BIOS Owned Semaphore — R/W. The BIOS sets this bit to establish ownership of the EHCI
controller. System BIOS will clear this bit in response to a request for ownership of the EHCI
controller by system software.
15:8
Next EHCI Capability Pointer — RO. A value of 00h indicates that there are no EHCI Extended
Capability structures in this device.
7:0
Capability ID — RO. A value of 01h indicates that this EHCI Extended Capability is the Legacy
Support Capability.
LEG_EXT_CS—USB EHCI Legacy Support Extended
Control / Status Register (USB EHCI—D29:F7)
Address Offset:
Default Value:
Power Well:
6C–6Fh
00000000h
Suspend
Bit
Attribute:
Size:
R/W, R/WC, RO
32 bits
Description
31
SMI on BAR—R/WC.
0 = Software clears this bit by writing a 1 to this bit location.
1 = This bit is set to 1 whenever the Base Address Register (BAR) is written.
30
SMI on PCI Command — R/WC.
0 = Software clears this bit by writing a 1 to this bit location.
1 = This bit is set to 1 whenever the PCI Command Register is written.
29
SMI on OS Ownership Change — R/WC.
0 = Software clears this bit by writing a 1 to this bit location.
1 = HC OS Owned Semaphore bit in the USB EHCI Legacy Support Extended Capability register
transitioned from 1-to-0 or 0-to-1.
28:22
Reserved — RO. Hardwired to 00h
SMI on Async Advance — RO. Shadow bit of the Interrupt on Async Advance bit in the EHCI_STS
register.
21
NOTE: To clear this bit system software must write a 1 to the Interrupt on Async Advance bit in the
EHCI_STS register.
SMI on Host System Error — RO. Shadow bit of Host System Error bit in the EHCI_STS register.
20
428
NOTE: To clear this bit system software must write a 1 to the Host System Error bit in the
EHCI_STS register.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
Bit
Description
SMI on Frame List Rollover — RO. Shadow bit of Frame List Rollover bit in the EHCI_STS register.
19
NOTE: To clear this bit system software must write a 1 to the Frame List Rollover bit in the
EHCI_STS register.
18
NOTE: To clear this bit system software must write a 1 to the Port Change Detect bit in the
EHCI_STS register.
SMI on Port Change Detect — RO. Shadow bit of Port Change Detect bit in the EHCI_STS register.
SMI on USB Error — RO. Shadow bit of USB Error Interrupt (USBERRINT) bit in the EHCI_STS
register.
17
NOTE: To clear this bit system software must write a 1 to the USB Error Interrupt bit in the
EHCI_STS register.
SMI on USB Complete — RO. Shadow bit of USB Interrupt (USBINT) bit in the EHCI_STS register.
16
NOTE: To clear this bit system software must write a 1 to the USB Interrupt bit in the EHCI_STS
register.
15
SMI on BAR Enable — R/W.
0 = Disable.
1 = Enable. When this bit is 1 and SMI on BAR is 1, then the host controller will issue an SMI.
14
SMI on PCI Command Enable — R/W.
0 = Disable.
1 = Enable. When this bit is 1 and SMI on PCI Command is 1, then the host controller will issue an
SMI.
13
SMI on OS Ownership Enable — R/W.
0 = Disable.
1 = Enable. When this bit is a 1 AND the OS Ownership Change bit is 1, the host controller will
issue an SMI.
12:6
Reserved — RO. Hardwired to 00h
5
SMI on Async Advance Enable — R/W.
0 = Disable.
1 = Enable. When this bit is a 1, and the SMI on Async Advance bit is a 1, the host controller will
issue an SMI immediately.
4
SMI on Host System Error Enable — R/W.
0 = Disable.
1 = Enable. When this bit is a 1, and the SMI on Host System Error is a 1, the host controller will
issue an SMI.
3
SMI on Frame List Rollover Enable — R/W.
0 = Disable.
1 = Enable. When this bit is a 1, and the SMI on Frame List Rollover bit is a 1, the host controller
will issue an SMI.
2
SMI on Port Change Enable — R/W.
0 = Disable.
1 = Enable. When this bit is a 1, and the SMI on Port Change Detect bit is a 1, the host controller
will issue an SMI.
1
SMI on USB Error Enable — R/W.
0 = Disable.
1 = Enable. When this bit is a 1, and the SMI on USB Error bit is a 1, the host controller will issue an
SMI immediately.
0
SMI on USB Complete Enable — R/W.
0 = Disable.
1 = Enable. When this bit is a 1, and the SMI on USB Complete bit is a 1, the host controller will
issue an SMI immediately.
Intel® 82801DB ICH4 Datasheet
429
EHCI Controller Registers (D29:F7)
12.1.28
SPECIAL_SMI—Intel Specific USB EHCI SMI Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
Power Well:
70–73h
00000000h
Suspend
Attribute:
Size:
R/WC, R/W
32 bits
This register provides a mechanism for BIOS to provide USB EHCI related bug fixes and
workarounds. Writing a 1 to that bit location clears bits that are marked as Read/Write-Clear
(R/WC). Software should clear all SMI status bits prior to setting the global SMI enable bit and
individual SMI enable bit to prevent spurious SMI when returning from a powerdown.
Bit
31:28
Reserved — RO. Hardwired to 00h
27:22
SMI on PortOwner — R/WC.
0 = Software clears these bits by writing a 1 to the bit location.
1 = Bits 27:22 correspond to the Port Owner bits for ports 1 (22) through 6 (27). These bits are set
to 1 whenever the associated Port Owner bits transition from 0-to-1 or 1-to-0.
21
SMI on PMCSR — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = Software modified the Power State bits in the Power Management Control/Status (PMCSR)
register.
20
SMI on Async — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = Async Schedule Enable bit transitioned from 1->0 or 0->1.
19
SMI on Periodic — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = Periodic Schedule Enable bit transitioned from 1-to-0 or 0-to-1
18
SMI on CF — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = Configure Flag (CF) transitioned from 1-to-0 or 0-to-1.
17
SMI on HCHalted — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = HCHalted transitions to 1 (as a result of the Run/Stop bit being cleared).
16
SMI on HCReset — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = HCRESET transitioned to 1.
15:12
430
Description
Reserved — RO. Hardwired to 00h
11:6
SMI on PortOwner Enable — R/W.
0 = Disable
1 = Enable. When any of these bits are 1 and the corresponding SMI on PortOwner bits are 1, the
host controller will issue an SMI. Unused ports should have their corresponding bits cleared.
5
SMI on PMSCR Enable — R/W.
0 = Disable
1 = Enable. When this bit is 1 and SMI on PMSCR is 1, then the host controller will issue an SMI.
4
SMI on Async Enable — R/W.
0 = Disable
1 = Enable. When this bit is 1 and SMI on Async is 1, then the host controller will issue an SMI.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
Bit
12.1.29
Description
3
SMI on Periodic Enable — R/W.
0 = Disable
1 = Enable. When this bit is 1 and SMI on Periodic is 1, then the host controller will issue an SMI.
2
SMI on CF Enable — R/W.
0 = Disable
1 = Enable. When this bit is 1 and SMI on CF is 1, then the host controller will issue an SMI.
1
SMI on HCHalted Enable — R/W.
0 = Disable
1 = Enable. When this bit is a 1 and SMI on HCHalted is 1, then the host controller will issue an
SMI.
0
SMI on HCReset Enable — R/W.
0 = Disable
1 = Enable. When this bit is a 1 and SMI on HCReset is 1, then host controller will issue an SMI—
R/W.
ACCESS_CNTL—Access Control Register
(USB EHCI—D29:F7)
Address Offset:
Default Value:
80h
00h
Bit
7:1
0
12.1.30
Attribute:
Size:
R/W
8 bits
Description
Reserved
WRT_RDONLY — R/W.
0 = Disable
1 = Enables a select group of normally read-only registers in the EHC function to be written by
software. Registers that may only be written when this mode is entered are noted in the
summary tables and detailed description as “Read/Write-Special”. The registers fall into two
categories:
- System-configured parameters, and
- Status bits
HS_Ref_V—USB HS Reference Voltage Register
(USB EHCI—D29:F7)
Offset Address:
Default Value:
Lockable:
DC–DFh
00000000h
No
Bit
Attribute:
Size:
Power Well:
R/W
32 bit
Resume
Description
31:22
Reserved— RO.
21:16
USB HS Ref Voltage — RW. BIOS should always program this register to the recommended value
of 111111. All other values are reserved
15:0
Reserved— RO.
Intel® 82801DB ICH4 Datasheet
431
EHCI Controller Registers (D29:F7)
12.2
Memory-Mapped I/O Registers
The USB 2.0 EHCI memory-mapped I/O space is composed of two sets of registers: Capability
Registers and Operational Registers.
Note:
12.2.1
When the USB EHCI function is in the D3 PCI power state, accesses to the USB EHCI memory
range are ignored and result in a master abort. Similarly, if the Memory Space Enable (MSE) bit is
not set in the Command register in configuration space, the memory range will not be decoded by
the ICH4 Enhanced Host Controller (EHC). If the MSE bit is not set, the ICH4 must default to
allowing any memory accesses for the range specified in the BAR to go to PCI. This is because the
range may not be valid and, therefore, the cycle must be made available to any other targets that
may be currently using that range.
Host Controller Capability Registers
These registers specify the limits, restrictions and capabilities of the host controller
implementation. Within the Host Controller Capability Registers, only the Structural Parameters
register is writable. This register is implemented in the Suspend well and is only reset by the
standard suspend-well hardware reset, not by HCRESET or the D3-to-D0 reset.
Table 12-2. Enhanced Host Controller Capability Registers
Offset
Mnemonic
Register Name
Default
Type
00h
CAPLENGTH
Capabilities Registers Length
20h
RO
02–03h
HCIVERSION
Host Controller Interface Version Number
0100h
RO
04–07h
HCSPARAMS
Host Controller Structural Parameters
00103206h
R/W-Special
08–0Bh
HCCPARAMS
Host Controller Capability Parameters
00006871h
RO
NOTE: “Read/Write-Special” means that the register is normally read-only, but may be written when the
WRT_RDONLY bit is set. Because these registers are expected to be programmed by BIOS during
initialization, their contents must not get modified by HCRESET or D3-to-D0 internal reset.
12.2.1.1
CAPLENGTH—Capability Registers Length Register
Offset:
Default Value:
Bit
7:0
432
00h
20h
Attribute:
Size:
RO
8 bits
Description
Capability Register Length Value — RO. This register is used as an offset to add to the Memory
Base Register to find the beginning of the Operational Register Space. This is fixed at 20h,
indicating that the Operation Registers begin at offset 20h.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.2.1.2
HCIVERSION—Host Controller Interface Version Number Register
Offset:
Default Value:
02–03h
0100h
Bit
15:0
12.2.1.3
RO
16 bits
Description
This is a two-byte register containing a BCD encoding of the version number of interface that this
host controller interface conforms.
HCSPARAMS—Host Controller Structural Parameters Register
Offset:
Default Value:
Note:
Attribute:
Size:
04–07h
00103206h
Attribute:
Size:
R/W-Special
32 bits
This register is reset by a suspend well reset and not a D3-to-D0 reset or HCRESET.
Bit
Description
31:24
Reserved — RO. Default=0h.
23:20
Debug Port Number (DP_N) — R/W-Special. Hardwired to 1h; indicates that the Debug Port is on
the lowest numbered port on the ICH4.
19:17
Reserved
16
Reserved. Should be written to 0.
15:12
Number of Companion Controllers (N_CC) — R/W-Special. This field indicates the number of
companion controllers associated with this USB ECHI host controller.
A 0h in this field indicates there are no companion host controllers. Port-ownership hand-off is not
supported. Only high-speed devices are supported on the host controller root ports.
A value larger than 1 in this field indicates there are companion USB UHCI host controller(s). Portownership hand-offs are supported. High, Full- and Low-speed devices are supported on the host
controller root ports.
The ICH4 allows the default value of 3h to be over-written by BIOS. Since the ICH4 cannot support
more than 3 companion host controllers, bits 15:14 are implemented as read-only 00b. When
removing classic controllers, they should be disabled in the following order: Function 2, Function 1,
and Function 0, which correspond to ports 5:4, 3:2, and 1:0, respectively.
11:8
Number of Ports per Companion Controller (N_PCC) — RO. Hardwired to 0010. This field indicates
the number of ports supported per companion host controller. It is used to indicate the port routing
configuration to system software.
7:4
Reserved. These bits are reserved and default to 0h.
3:0
N_PORTS — R/W-Special. This field specifies the number of physical downstream ports
implemented on this host controller. The value of this field determines how many port registers are
addressable in the Operational Register Space. Valid values are in the range of 1h to Fh. The default
is 0110 (6h). However, software may write a value less than 6 for some platform configurations. A 0h
in this field is undefined. Bit 3 is always hardwired to 0.
NOTE: This register is writable when the WRT_RDONLY bit is set.
Intel® 82801DB ICH4 Datasheet
433
EHCI Controller Registers (D29:F7)
12.2.1.4
HCCPARAMS—Host Controller Capability Parameters Register
Offset:
Default Value:
08–0Bh
00006871h
Bit
Attribute:
Size:
RO
32 bits
Description
31:16
Reserved
15:8
EHCI Extended Capabilities Pointer (EECP) — RO. Hardwired to 68h, indicating that the EHCI
capabilities list exists and begins at offset 68h in the PCI configuration space.
7:4
Isochronous Scheduling Threshold — RO. Hardwired to 7h (0111). This field indicates, relative to the
current position of the executing host controller, where software can reliably update the isochronous
schedule.
When bit 7 is 0, the value of the least significant 3 bits indicates the number of micro-frames a host
controller hold a set of isochronous data structures (one or more) before flushing the state.
When bit 7 is a 1, host software assumes the host controller may cache an isochronous data
structure for an entire frame. Refer to the EHCI specification for details on how software uses this
information for scheduling isochronous transfers.
3
Reserved. Should be set to 0.
2
Asynchronous Schedule Park Capability — RO. Hardwired to 0, indicating that the Host controller
does not support this optional feature
1
Programmable Frame List Flag — RO.
0 = System software must use a frame list length of 1024 elements with this host controller. The
USBCMD register Frame List Size field is a read-only register and must be set to zero.
1 = System software can specify and use a smaller frame list and configure the host controller via
the USBCMD register Frame List Size field. The frame list must always be aligned on a 4K page
boundary. This requirement ensures that the frame list is always physically contiguous.
0
64-bit Addressing Capability— RO. Hardwired to 1. This field documents the addressing range
capability of this implementation. The value of this field determines whether software should use the
32-bit or 64-bit data structures. Values for this field have the following interpretation:
0 = Data structures using 32-bit address memory pointers
1 = Data structures using 64-bit address memory pointers
NOTE: The ICH4 only implements 44 bits of addressing. Bits 63:44 will always be 0.
434
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.2.2
Host Controller Operational Registers
This section defines the enhanced host controller operational registers. These registers are located
after the capabilities registers. The operational register base must be DWord-aligned and is
calculated by adding the value in the first capabilities register (CAPLENGTH) to the base address
of the enhanced host controller register address space. All registers are 32 bits in length.
Table 12-3. Enhanced Host Controller Operational Registers
Offset
(CAPLEN
GTH+)
Mnemonic
00–03h
EHCI_CMD
USB EHCI Command
00080000h
R/W, RO
04–07h
EHCI_STS
USB EHCI Status
00001000h
R/WC, RO
08–0Bh
EHCI_INTR
0C–0Fh
FRINDEX
10–13h
Default
Special
Notes
Type
USB EHCI Interrupt Enable
00000000h
R/W
USB EHCI Frame Index
00000000h
R/W
CTRLDSSEGMENT
Control Data Structure
Segment
00000000h
R/W
14–17h
PERIODICLISTBASE
Period Frame List Base
Address
00000000h
R/W
18–1Bh
ASYNCLISTADDR
Next Asynchronous List
Address
00000000h
R/W
40–43h
CONFIGFLAG
Configure Flag Register
00000000h
Suspend
R/W
44–47h
PORTSC0
Port 0 Status and Control
00003000h
Suspend
R/WC,
R/W, RO
48–4Bh
PORTSC1
Port 1 Status and Control
00003000h
Suspend
R/WC,
R/W, RO
4C–4Fh
PORTSC2
Port 2 Status and Control
00003000h
Suspend
R/WC,
R/W, RO
50–53h
PORTSC3
Port 3 Status and Control
00003000h
Suspend
R/WC,
R/W, RO
54–57h
PORTSC4
Port 4 Status and Control
00003000h
Suspend
R/WC,
R/W, RO
58–5Bh
PORTSC5
Port 5 Status and Control
00003000h
Suspend
R/WC,
R/W, RO
1C–3Fh
Reserved
0h
RO
5C–5Fh
Reserved
Undefined
RO
60–73h
Debug Port Registers
Undefined
RO
Reserved
Undefined
RO
74–3FFh
Note:
Register Name
Software must read and write these registers using only DWord accesses.These registers are
divided into two sets. The first set at offset 00:3Fh are implemented in the core power well. Unless
otherwise noted, the core-well registers are reset by the assertion of any of the following:
• core well hardware reset
• HCRESET
• D3-to-D0 reset
The second set at offset 40h to the end of the implemented register space are implemented in the
Suspend power well. Unless otherwise noted, the suspend-well registers are reset by the assertion
of either of the following:
• suspend well hardware reset
• HCRESET
Intel® 82801DB ICH4 Datasheet
435
EHCI Controller Registers (D29:F7)
12.2.2.1
EHCI_CMD—USB EHCI Command Register
Offset:
Default Value:
CAPLENGTH + 00–03h
00080000h
Bit
Attribute:
Size:
R/W, RO
32 bits
Description
31:24
Reserved. Should be set to 0s.
23:16
Interrupt Threshold Control  R/W. This field is used by system software to select the maximum
rate at which the host controller will issue interrupts. The only valid values are defined below. If
software writes an invalid value to this register, the results are undefined.
00h = Reserved
01h = 1 micro-frame
02h = 2 micro-frames
04h = 4 micro-frames
08h = 8 micro-frames (default, equates to 1 ms)
10h = 16 micro-frames (2 ms)
20h = 32 micro-frames (4 ms)
40h = 64 micro-frames (8 ms)
15:8
Reserved. Should be set to 0s.
11:8
Unimplemented Asynchronous Park Mode Bits — RO. Hardwired to 000b; the host controller does
not support this optional feature.
7
6
Light Host Controller Reset — RO. Hardwired to 0; the ICH4 does not implement this optional reset.
Interrupt on Async Advance Doorbell — R/W. This bit is used as a doorbell by software to tell the
host controller to issue an interrupt the next time it advances asynchronous schedule.
0 = The host controller sets this bit to a 0 after it has set the Interrupt on Async Advance status bit in
the EHCI_STS register to a 1.
1 = Software must write a 1 to this bit to ring the doorbell. When the host controller has evicted all
appropriate cached schedule state, it sets the Interrupt on Async Advance status bit in the
EHCI_STS register. If the Interrupt on Async Advance Enable bit in the USBINTR register is a 1
then the host controller will assert an interrupt at the next interrupt threshold. See the Enhanced
Host Controller Interface (EHCI) Specification for Universal Serial Bus for operational details.
Software should not write a 1 to this bit when the asynchronous schedule is inactive. Doing this
will yield undefined results.
5
Asynchronous Schedule Enable  R/W. This bit controls whether the host controller skips
processing the Asynchronous Schedule.
0 = Do not process the Asynchronous Schedule (Default)
1 = Use the ASYNCLISTADDR register to access the Asynchronous Schedule.
4
Periodic Schedule Enable  R/W. This bit controls whether the host controller skips processing
the Periodic Schedule.
0 = Do not process the Periodic Schedule (Default)
1 = Use the PERIODICLISTBASE register to access the Periodic Schedule.
3:2
436
Frame List Size  RO. Hardwired to 00; ICH4 only supports the 1024-element frame list size.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
Bit
Description
Host Controller Reset (HCRESET)  R/W. This control bit used by software to reset the host
controller. The effects of this on Root Hub registers are similar to a Chip Hardware Reset
(i.e., RSMRST# assertion and PWROK deassertion on the ICH4).
0 = This bit is set to 0 by the Host controller when the reset process is complete. Software cannot
terminate the reset process early by writing a 0 to this bit.
1 = When software writes a 1 to this bit, the Host controller resets its internal pipelines, timers,
counters, state machines, etc. to their initial value. Any transaction currently in progress on
USB is immediately terminated. A USB reset is not driven on downstream ports.
1
All operational registers, including port registers and port state machines are set to their initial
values. Port ownership reverts to the companion host controller(s), with the side effects
described in the EHCI spec. Software must re-initialize the host controller in order to return the
host controller to an operational state.
Software should not set this bit to a 1 when the HCHalted bit in the EHCI_STS register is a 0.
Attempting to reset an actively running host controller will result in undefined behavior. This
reset me be used to leave EHCI port test modes.
NOTE: PCI Configuration registers and Host Controller Capability Registers are not effected by this
reset.
Run/Stop (RS)  R/W.
0 = Stop (Default)
1 = Run. When set to a 1, the Host controller proceeds with execution of the schedule. The Host
controller continues execution as long as this bit is set. When this bit is set to 0, the Host
controller completes the current transaction on the USB and then halts. The HC Halted bit in the
status register indicates when the Host controller has finished the transaction and has entered
the stopped state.
0
NOTE: Software should not write a 1 to this field unless the host controller is in the Halted state
(i.e., HCHalted in the EHCI_STS register is a 1). The Halted bit is cleared immediately when
the Run bit is set.
The following table explains how the different combinations of Run and Halted should be interpreted:
Halted
Interpretation
0
0
Valid- in the process of halting
0
1
Valid- halted
1
0
Valid- running
1
1
Invalid- the HCHalted bit clears immediately.
Memory read cycles initiated by the EHC that receive any status other than Successful will result in
this bit being cleared.
Run/Stop
NOTE: The Command Register indicates the command to be executed by the serial bus host controller. Writing
to the register causes a command to be executed.
Intel® 82801DB ICH4 Datasheet
437
EHCI Controller Registers (D29:F7)
12.2.2.2
EHCI_STS—USB EHCI Status Register
Offset:
Default Value:
CAPLENGTH + 04–07h
00001000h
Attribute:
Size:
R/WC, RO
32 bits
This register indicates pending interrupts and various states of the Host controller. The status
resulting from a transaction on the serial bus is not indicated in this register. Software sets a bit to 0
in this register by writing a 1 to it. See the Interrupts description in Chapter 4 of the Enhanced Host
Controller Interface (EHCI) Specification for Universal Serial Bus for additional information
concerning USB EHCI interrupt conditions.
Bit
31:16
Description
Reserved. Should be set to 0s.
15
Asynchronous Schedule Status  RO. This bit reports the current real status of the Asynchronous
Schedule. The Host controller is not required to immediately disable or enable the Asynchronous
Schedule when software transitions the Asynchronous Schedule Enable bit in the USBCMD register.
When this bit and the Asynchronous Schedule Enable bit are the same value, the Asynchronous
Schedule is either enabled (1) or disabled (0).
0 = Disable. (Default)
1 = Enable. The status of the Asynchronous Schedule is enabled.
14
Periodic Schedule Status  RO. This bit reports the current real status of the Periodic Schedule.
The Host controller is not required to immediately disable or enable the Periodic Schedule when
software transitions the Periodic Schedule Enable bit in the USBCMD register. When this bit and the
Periodic Schedule Enable bit are the same value, the Periodic Schedule is either enabled (1) or
disabled (0).
0 = Disable. (Default).
1 = Enable. The status of the Periodic Schedule is enabled.
13
Reclamation  RO. (Defaults to 1). This bit is used to detect an empty asynchronous schedule. The
operational model and valid transitions for this bit are described in Section 4 of the EHCI
Specification.
12
HCHalted  RO.
0 = This bit is a 0 when the Run/Stop bit is a 1.
1 = The Host controller sets this bit to 1 after it has stopped executing as a result of the Run/Stop bit
being set to 0, either by software or by the Host controller hardware (e.g., internal error).
(Default)
11:6
5
4
Reserved
Interrupt on Async Advance — R/WC. 0=Default.
0 = Interrupt not occurred (source not asserted).
1 = Interrupt occurred (source asserted). System software can force the host controller to issue an
interrupt the next time the host controller advances the asynchronous schedule by writing a 1 to
the Interrupt on Async Advance Doorbell bit in the USBCMD register. This bit indicates the
assertion of that interrupt source.
Host System Error — RO.
0 = No host system error during access of the Host controller module.
1 = Host system error. The Host controller sets this bit to 1 when a serious error occurs during a
host system access involving the Host controller module. A hardware interrupt is generated to
the system. Memory read cycles initiated by the EHC that receive any status other than
Successful will result in this bit being set.
When this error occurs, the Host controller clears the Run/Stop bit in the Command register to
prevent further execution of the scheduled TDs. A hardware interrupt is generated to the
system (if enabled in the Interrupt Enable Register).
438
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
Bit
Description
3
Frame List Rollover — R/WC.
0 = No rollover.
1 = Frame List Rollover. The Host controller sets this bit to a 1 when the Frame List Index (see
Section) rolls over from its maximum value to zero. Since the ICH4 only supports the 1024entry Frame List Size, the Frame List Index rolls over every time FRNUM[13] toggles.
2
Port Change Detect — R/WC.
0 = Not Detected.
1 = Port Change Detected. The Host controller sets this bit to a 1 when any port for which the Port
Owner bit is set to 0 has a change bit transition from 0 to 1 or a Force Port Resume bit transition
from 0 to 1 as a result of a J-K transition detected on a suspended port.
1
USB Error Interrupt (USBERRINT) — R/WC.
0 = No Error.
1 = Error Condition. The Host controller sets this bit to 1 when completion of a USB transaction
results in an error condition (e.g., error counter underflow). If the TD on which the error interrupt
occurred also had its IOC bit set, both this bit and Bit 0 are set. See the EHCI specification for a
list of the USB errors that will result in this interrupt being asserted.
0
USB Interrupt (USBINT) — R/WC.
0 = Software clears this bit by writing a 1 to the bit location.
1 = The Host controller sets this bit to 1 when one of the following occurs:
• The cause of an interrupt is a completion of a USB transaction whose Transfer Descriptor
had its IOC bit set.
• The Host controller also sets this bit to 1 when a short packet is detected (actual number of
bytes received was less than the expected number of bytes).
Intel® 82801DB ICH4 Datasheet
439
EHCI Controller Registers (D29:F7)
12.2.2.3
EHCI_INTR—USB EHCI Interrupt Enable Register
Offset:
Default Value:
CAPLENGTH + 08–0Bh
00000000h
Attribute:
Size:
R/W
32 bits
This register enables and disables reporting of the corresponding interrupt to the software. When a
bit is set and the corresponding interrupt is active, an interrupt is generated to the host. Interrupt
sources that are disabled in this register still appear in the Status Register to allow the software to
poll for events. Each interrupt enable bit description indicates whether it is dependent on the
interrupt threshold mechanism, or not (see Chapter 4 of the Enhanced Host Controller Interface
(EHCI) Specification for Universal Serial Bus).
Bit
31:6
Description
Reserved. Should be 0s.
5
Interrupt on Async Advance Enable — R/W. When this bit is a 1, and the Interrupt on Async
Advance bit in the EHCI_STS register is a 1, the host controller will issue an interrupt at the next
interrupt threshold. The interrupt is acknowledged by software clearing the Interrupt on Async
Advance bit in the EHCI_STS register.
0 = Disable
1 = Enable
4
Host System Error Enable — R/W. When this bit is a 1, and the Host System Error Status bit in the
EHCI_STS register is a 1, the host controller will issue an interrupt. The interrupt is acknowledged
by software clearing the Host System Error bit in the EHCI_STS register.
0 = Disable
1 = Enable
3
Frame List Rollover Enable — R/W. When this bit is a 1, and the Frame List Rollover bit in the
EHCI_STS register is a 1, the host controller will issue an interrupt. The interrupt is acknowledged
by software clearing the Frame List Rollover bit in the EHCI_STS register.
0 = Disable
1 = Enable
2
Port Change Interrupt Enable — R/W. When this bit is a 1, and the Port Change Detect bit in the
EHCI_STS register is a 1, the host controller will issue an interrupt. The interrupt is acknowledged
by software clearing the Port Change Detect bit in the EHCI_STS register.
0 = Disable
1 = Enable
1
USB Error Interrupt Enable — R/W. When this bit is a 1, and the USBERRINT bit in the EHCI_STS
register is a 1, the host controller will issue an interrupt at the next interrupt threshold. The interrupt
is acknowledged by software by clearing the USBERRINT bit in the EHCI_STS register.
0 = Disable
1 = Enable
0
USB Interrupt Enable — R/W. When this bit is a 1, and the USBINT bit in the EHCI_STS register is
a 1, the host controller will issue an interrupt at the next interrupt threshold. The interrupt is
acknowledged by software by clearing the USBINT bit in the EHCI_STS register.
0 = Disable
1 = Enable
440
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.2.2.4
FRINDEX—Frame Index Register
Offset:
Default Value:
CAPLENGTH + 0C–0Fh
00000000h
Attribute:
Size:
R/W
32 bits
The SOF frame number value for the bus SOF token is derived or alternatively managed from this
register. Refer to Section 4 of the EHCI specification for a detailed explanation of the SOF value
management requirements on the host controller. The value of FRINDEX must be within 125 µs
(1 micro-frame) ahead of the SOF token value. The SOF value may be implemented as an 11-bit
shadow register. For this discussion, this shadow register is 11 bits and is named SOFV. SOFV
updates every 8 micro-frames. (1 millisecond). An example implementation to achieve this
behavior is to increment SOFV each time the FRINDEX[2:0] increments from 0 to 1.
Software must use the value of FRINDEX to derive the current micro-frame number, both for highspeed isochronous scheduling purposes and to provide the get micro-frame number function
required to client drivers. Therefore, the value of FRINDEX and the value of SOFV must be kept
consistent if chip is reset or software writes to FRINDEX. Writes to FRINDEX must also writethrough FRINDEX[13:3] to SOFV[10:0]. In order to keep the update as simple as possible,
software should never write a FRINDEX value where the three least significant bits are 111b or
000b.
Note:
This register is used by the host controller to index into the periodic frame list. The register updates
every 125 microseconds (once each micro-frame). Bits [12:3] are used to select a particular entry in
the Periodic Frame List during periodic schedule execution. The number of bits used for the index
is fixed at 10 for the ICH4 since it only supports 1024-entry frame lists. This register must be
written as a DWord. Word and byte writes produce undefined results. This register cannot be
written unless the Host controller is in the Halted state as indicated by the HCHalted bit (USB
EHCI STS register). A write to this register while the Run/Stop bit is set to a 1 (USB EHCI CMD
register) produces undefined results. Writes to this register also effect the SOF value. For details,
see Chapter 4 of the Enhanced Host Controller Interface (EHCI) Specification for Universal Serial
Bus.
Bit
Description
31:14
Reserved
13:0
Frame List Current Index/Frame Number — R/W. The value in this register increments at the end
of each time frame (e.g., micro-frame). Bits [12:3] are used for the Frame List current index. This
means that each location of the frame list is accessed 8 times (frames or micro-frames) before
moving to the next index.
Intel® 82801DB ICH4 Datasheet
441
EHCI Controller Registers (D29:F7)
12.2.2.5
CTRLDSSEGMENT—Control Data Structure Segment Register
Offset:
Default Value:
CAPLENGTH + 10–13h
00000000h
Attribute:
Size:
R/W
32 bits
This 32-bit register corresponds to the most significant address bits [63:32] for all EHCI data
structures. Since the ICH4 hardwires the 64-bit Addressing Capability field in HCCPARAMS to
1s, then this register is used with the link pointers to construct 64-bit addresses to EHCI control
data structures. This register is concatenated with the link pointer from either the
PERIODICLISTBASE, ASYNCLISTADDR, or any control data structure link field to construct a
64-bit address. This register allows the host software to locate all control data structures within the
same 4 GB memory segment.
Bit
31:12
11:0
12.2.2.6
Description
Upper Address [63:44] — R/W. These bits are hardwired, read-only to 0 in the ICH4. The ICH4
EHC is only capable of generating addresses up to 16 terabytes (44 bits of address).
Upper Address [43:32] — R/W. This 12-bit field corresponds to address bits 43:32 when forming a
control data structure address.
PERIODICLISTBASE—Periodic Frame List Base Address Register
Offset:
Default Value:
CAPLENGTH + 14–17h
00000000h
Attribute:
Size:
R/W
32 bits
This 32-bit register contains the beginning address of the Periodic Frame List in the system
memory. Since the ICH4 host controller operates in 64-bit mode (as indicated by the one in the
64-bit Addressing Capability field in the HCCSPARAMS register), then the most significant
32 bits of every control data structure address comes from the CTRLDSSEGMENT register. HCD
loads this register prior to starting the schedule execution by the Host controller. The memory
structure referenced by this physical memory pointer is assumed to be 4-KB aligned. The contents
of this register are combined with the Frame Index Register (FRINDEX) to enable the Host
controller to step through the Periodic Frame List in sequence.
Bit
31:12
11:0
442
Description
Base Address (Low) — R/W. These bits correspond to memory address signals [31:12],
respectively.
Reserved. Must be written as 0s. During runtime, the value of these bits are undefined.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.2.2.7
ASYNCLISTADDR—Current Asynchronous List Address Register
Offset:
Default Value:
CAPLENGTH + 18–1Bh
00000000h
Attribute:
Size:
R/W
32 bits
This 32-bit register contains the address of the next asynchronous queue head to be executed. Since
the ICH4 host controller operates in 64-bit mode (as indicated by a one in 64-bit Addressing
Capability field in the HCCPARAMS register), then the most significant 32 bits of every control
data structure address comes from the CTRLDSSEGMENT register. Bits [4:0] of this register
cannot be modified by system software and will always return zeros when read. The memory
structure referenced by this physical memory pointer is assumed to be 32-byte aligned.
Bit
12.2.2.8
Description
31:5
Link Pointer Low (LPL) — R/W. These bits correspond to memory address signals [31:5],
respectively. This field may only reference a Queue Head (QH).
4:0
Reserved. These bits are reserved and their value has no effect on operation.
CONFIGFLAG—Configure Flag Register
Offset:
Default Value:
CAPLENGTH + 40–43h
00000000h
Attribute:
Size:
R/W
32 bits
This 32-bit register contains the address of the next asynchronous queue head to be executed. Since
the ICH4 host controller operates in 64-bit mode (as indicated by a one in 64-bit Addressing
Capability field in the HCCPARAMS register), then the most significant 32 bits of every control
data structure address comes from the CTRLDSSEGMENT register. Bits [4:0] of this register
cannot be modified by system software and will always return zeros when read. The memory
structure referenced by this physical memory pointer is assumed to be 32-byte aligned.
Bit
31:1
0
Description
Reserved. Read from this field will always return 0.
Configure Flag (CF) — R/W. Host software sets this bit as the last action in its process of
configuring the Host controller. This bit controls the default port-routing control logic. Bit values and
side-effects are listed below. For operation details, see Chapter 4 of the Enhanced Host Controller
Interface (EHCI) Specification for Universal Serial Bus.
0 = Port routing control logic default-routes each port to the classic host controllers. (Default)
1 = Port routing control logic default-routes all ports to this host controller.
Intel® 82801DB ICH4 Datasheet
443
EHCI Controller Registers (D29:F7)
12.2.2.9
PORTSC—Port N Status and Control Register
Offset:
Attribute:
Default Value:
Port 0 CAPLENGTH + 44–47h
Port 1 CAPLENGTH + 48–4Bh
Port 2 CAPLENGTH + 4C–4Fh
Port 3 CAPLENGTH + 50–53h
Port 4 CAPLENGTH + 54–57h
Port 5 CAPLENGTH + 58–5Bh
R/W, R/WC, RO
00003000h
Size:
32 bits
A host controller must implement one or more port registers. Software uses the N_Port information
from the Structural Parameters Register to determine how many ports need to be serviced. All ports
have the structure defined below. Software must not write to unreported Port Status and Control
Registers.
This register is in the suspend power well. It is only reset by hardware when the suspend power is
initially applied or in response to a host controller reset. The initial conditions of a port are:
• No device connected,
• Port disabled.
When a device is attached, the port state transitions to the attached state and system software will
process this as with any status change notification. Refer to Chapter 4 of the Enhanced Host
Controller Interface (EHCI) Specification for Universal Serial Bus for operational requirements
for how change events interact with port suspend mode.
Bit
31:23
Reserved. These bits are reserved for future use and will return a value of 0s when read.
22
Wake on Over-current Enable (WKOC_E) — RW.
0 = Disable. (Default)
1 = Enable. Writing this bit to a 1 enables the setting of the PME Status bit in the Power
Management Control/Status Register (offset 54, bit 15) when the Over-current Active bit (bit 4
of this register) is set to 1.
21
Wake on Disconnect Enable (WKDSCNNT_E) — RW. Default = 0b.
0 = Disable. (Default)
1 = Enable. Writing this bit to a 1 enables the setting of the PME Status bit in the Power
Management Control/Status Register (offset 54, bit 15) when the Current Connect Status
changes from connected to disconnected (i.e., bit 0 of this register changes from 1 to 0).
20
Wake on Connect Enable (WKCNNT_E) — RW.
0 = Disable. (Default)
1 = Enable. Writing this bit to a 1 enables the setting of the PME Status bit in the Power
Management Control/Status Register (offset 54, bit 15) when the Current Connect Status
changes from disconnected to connected (i.e., bit 0 of this register changes from 0 to 1).
19:16
444
Description
Port Test Control — RW. When this field is 0, the port is NOT operating in a test mode. A non-zero
value indicates that it is operating in test mode and the specific test mode is indicated by the specific
value. Refer to Universal Serial Bus (USB) Specification, Revision 2.0, Chapter 7 for details on each
test mode.
Bits
Test Mode
0000
Test mode Not enabled (Default)
0001
Test J_STATE
0010
Test K_STATE
0011
Test SE0_NAK
0100
Test Packet
0101
Test FORCE_ENABLE
0110–1111
Reserved
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
Bit
15:14
Description
Reserved — RW. Should be written to =00b.
13
Port Owner — RW. Default = 1b. This bit unconditionally goes to a 0 when the Configured Flag bit in
the CONFIGFLAG register makes a 0-to-1 transition.
System software uses this field to release ownership of the port to a selected host controller (in the
event that the attached device is not a high-speed device). Software writes a 1 to this bit when the
attached device is not a high-speed device. A 1 in this bit means that a companion host controller
owns and controls the port. For operational details, see Chapter 4 of the Enhanced Host Controller
Interface (EHCI) Specification for Universal Serial Bus.
12
Port Power (PP)  RO. Hardwired to 1. This indicates that the port does have power.
Line Status— RO.These bits reflect the current logical levels of the D+ (bit 11) and D- (bit 10) signal
lines. These bits are used for detection of low-speed USB devices prior to the port reset and enable
sequence. This field is valid only when the port enable bit is 0 and the current connect status bit is
set to a 1.
11:10
9
00 = SE0
10 = J-state
01 = K-state
11 = Undefined
Reserved. This bit will return a 0 when read.
Port Reset — RW. When software writes a 1 to this bit (from a 0), the bus reset sequence as
defined in the Universal Serial Bus (USB) Specification, Revision 2.0 is started. Software writes a 0
to this bit to terminate the bus reset sequence. Software must keep this bit at a 1 long enough to
ensure the reset sequence completes, as specified in the Universal Serial Bus (USB) Specification,
Revision 2.0.
0 = Port is not in Reset. (Default)
1 = Port is in Reset.
8
NOTE: When software writes this bit to a 1, it must also write a 0 to the Port Enable bit. When
software writes a 0 to this bit, there may be a delay before the bit status changes to a 0. The
bit status will not read as a 0 until after the reset has completed. If the port is in high-speed
mode after reset is complete, the host controller will automatically enable this port (e.g., set
the Port Enable bit to a 1). A host controller must terminate the reset and stabilize the state
of the port within 2 milliseconds of software transitioning this bit from 1 to 0.
For example: if the port detects that the attached device is high-speed during reset, then the
host controller must have the port in the enabled state within 2 ms of software writing this bit
to a 0. The HCHalted bit in the EHCI_STS register should be a 0 before software attempts
to use this bit. The host controller may hold Port Reset asserted to a 1 when the HCHalted
bit is a 1. This field is 0 if Port Power is 0.
Warning: System software should not attempt to reset a port if the HCHalted bit in the EHCI_STS
register is a 1. Doing so will result in undefined behavior.
Suspend — RW.
7
0 = Port not in suspend state. (Default).
1 = Port in suspend state.
Port Enabled Bit and Suspend bit of this register define the port states as follows:
Bits [Port Enabled, Suspend]
Port State
0X
Disable
10
Enable
11
Suspend
• When in suspend state, downstream propagation of data is blocked on this port, except for port
reset. Note that the bit status does not change until the port is suspended and that there may be
a delay in suspending a port depending on the activity on the port.
• The host controller will unconditionally set this bit to a 0 when software sets the Force Port
Resume bit to a 0 (from a 1). A write of 0 to this bit is ignored by the host controller.
• If host software sets this bit to a 1 when the port is not enabled (i.e., Port enabled bit is a 0) the
results are undefined.
Intel® 82801DB ICH4 Datasheet
445
EHCI Controller Registers (D29:F7)
Bit
6
Description
Force Port Resume — RW. Software sets this bit to a 1 to drive resume signaling. The Host
controller sets this bit to a 1 if a J-to-K transition is detected while the port is in the Suspend state.
When this bit transitions to a 1 because a J-to-K transition is detected, the Port Change Detect bit in
the EHCI_STS register is also set to a 1. If software sets this bit to a 1, the host controller must not
set the Port Change Detect bit.
0 = No resume (K-state) detected/driven on port. (Default).
1 = Resume detected/driven on port.
NOTE: When the EHCI controller owns the port, the resume sequence follows the defined
sequence documented in the Universal Serial Bus (USB) Specification, Revision 2.0. The
resume signaling (Full-speed 'K') is driven on the port as long as this bit remains a 1.
Software must appropriately time the Resume and set this bit to a 0 when the appropriate
amount of time has elapsed. Writing a 0 (from 1) causes the port to return to high-speed
mode (forcing the bus below the port into a high-speed idle). This bit will remain 1 until the
port has switched to the high-speed idle.
446
5
Overcurrent Change— R/WC. Default = 0. The functionality of this bit is not dependent upon the
port owner.
0 = Software clears this bit by writing a 1 to this bit position.
1 = There is a change to Over-current Active.
4
Overcurrent Active — RO. The ICH4 automatically disables the port when the over-current active bit
is 1.
0 = This port does not have an over-current condition. This bit will automatically transition from a
1-to-0 when the over current condition is removed. (Default)
1 = This port currently has an over-current condition.
3
Port Enable/Disable Change — R/WC. For the root hub, this bit gets set to a 1 only when a port is
disabled due to the appropriate conditions existing at the EOF2 point (See Chapter 11 of the
Universal Serial Bus (USB) Specification, Revision 2.0 for the definition of a port error). This bit is
not set due to the Disabled-to-Enabled transition, nor due to a disconnect.
0 = No change in status. (Default). Software clears this bit by writing a 1 to it.
1 = Port enabled/disabled status has changed.
2
Port Enabled/Disabled — R/W. Ports can only be enabled by the host controller as a part of the
reset and enable. Software cannot enable a port by writing a 1 to this field. Ports can be disabled by
either a fault condition (disconnect event or other fault condition) or by host software. Note that the
bit status does not change until the port state actually changes. There may be a delay in disabling or
enabling a port due to other host controller and bus events.
0 = Disable. (Default)
1 = Enable.
1
Connect Status Change — R/WC. A 1 indicates a change has occurred in the port’s Current
Connect Status. The host controller sets this bit for all changes to the port device connect status,
even if system software has not cleared an existing connect status change. For example, the
insertion status changes twice before system software has cleared the changed condition, hub
hardware will be “setting” an already-set bit (i.e., the bit will remain set).
0 = No change. (Default). Software sets this bit to 0 by writing a 1 to it.
1 = Change in Current Connect Status.
0
Current Connect Status — RO. This value reflects the current state of the port, and may not
correspond directly to the event that caused the Connect Status Change bit (Bit 1) to be set.
0 = No device is present. (Default)
1 = Device is present on port.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.2.3
USB 2.0-Based Debug Port Register
The Debug port’s registers are located in the same memory area, defined by the Base Address
Register (BAR), as the standard EHCI registers. The base offset for the debug port registers (80h)
is declared in the Debug Port Base Offset Capability Register at Configuration offset 5Ah. The
specific EHCI port that supports this debug capability is indicated by a 4-bit field (bits 20–23) in
the HCSPARAMS register of the EHCI controller.
The map of the Debug Port registers is shown in Table 12-4. Each register is defined individually
below.
Table 12-4. Debug Port Register Address Map
Offset
00h
Register Name
Type
Control/Status
R/W, RO
04h
USB PIDs
R/W, RO
08h
Data Buffer (Bytes 3:0)
R/W
0Ch
Data Buffer (Bytes 7:4)
R/W
10h
Config Register
R/W
NOTES:
1. All of these registers are implemented in the core well and reset by PCIRST#, EHC HCRESET, and a EHC
D3-to-D0 transition.
2. The hardware associated with this register provides no checks to ensure that software programs the interface
correctly. How the hardware behaves when programmed illegally is undefined.
12.2.3.1
Control/Status Register
Offset:
Default Value:
00h
00000000h
Attribute:
Size:
R/W, RO
32 bits
Note:
Software should do Read-Modify-Write operations to this register to preserve the contents of bits
not being modified. This include Reserved bits.
Note:
To preserve the usage of RESERVED bits in the future, software should always write the same
value read from the bit until it is defined. Reserved bits will always return 0 when read.
Bit
Description
31
Reserved
30
OWNER_CNT — R/W.
0 = Default.
1 = Ownership of the debug port is forced to the EHCI controller (i.e., immediately taken away
from the companion Classic USB Host controller). If the port was already owned by the EHCI
controller, then setting this bit has no effect. This bit overrides all of the ownership-related bits
in the standard EHCI registers.
29
Reserved
Intel® 82801DB ICH4 Datasheet
447
EHCI Controller Registers (D29:F7)
Bit
Description
28
ENABLED_CNT — R/W.
0 = Software can clear this bit by writing a 0 to it. Hardware clears the bit for the same conditions
where the Port Enable/Disable Change bit (in the PORTSC register) is set. (Default)
1 = Enable debug port for operation. Software can directly set this bit if the port is already enabled
in the associated Port Status and Control register (this is enforced by the hardware).
27:17
Reserved
DONE_STS — R/WC.
16
15:12
0 = Not Done (Default). Software clears this bit by writing a 1 to it.
1 = This bit is set by hardware to indicate that the request is complete.
LINK_ID_STS — RO. Hardwired to 0000. This field identifies the link interface. It is hardwired to 0h
to indicate that it is a USB Debug Port.
11
Reserved. This bit will return 0 when read. Writes will have no effect.
10
IN_USE_CNT — R/W. (This bit has no affect on hardware.)
0 = Not in Use. Cleared by software to indicate that the port is free and may be used by other
software. (Default)
1 = In Use. Set by software to indicate that the port is in use.
9:7
EXCEPTION_STS — RO. Default=000b This field indicates the exception when the
ERROR_GOOD#_STS bit is set. This field should be ignored if the ERROR_GOOD#_STS bit is 0.
000 =No Error. Note: this should not be seen, since this field should only be checked if there is an
error.
001 =Transaction error: indicates the USB EHCI transaction had an error (CRC, bad PID, timeout,
etc.)
010 =HW error. Request was attempted (or in progress) when port was suspended or reset.
All Others = Reserved
ERROR_GOOD#_STS — RO.
6
5
0 = Hardware clears this bit upon the proper completion of a read or write. (Default)
1 = Error Occurred. The hardware sets this bit to indicate that an error has occurred. Details on
the nature of the error are provided in the Exception field.
GO_CNT — WO.
0 = Hardware clears this bit when hardware sets the DONE_STS bit. (Default)
1 = Causes hardware to perform a read or write request. Writing a 1 to this bit when it is already
set may result in undefined behavior.
WRITE_READ#_CNT — R/W.
4
0 = Read. Software clears this bit to indicate that the current request is a read. (Default)
1 = Write. Software sets this bit to indicate that the current request is a write.
DATA_LEN_CNT — R/W. This field is used to indicate the size of the data to be transferred.
(default = 0h).
3:0
448
For write operations, this field is set by software to indicate to the hardware how many bytes of data
in Data Buffer are to be transferred to the console. A value of 0h indicates that a zero-length packet
should be sent. A value of 1–8h indicates 1–8 bytes are to be transferred. Values 9–Fh are illegal
and how hardware behaves if used is undefined.
For read operations, this field is set by hardware to indicate to software how many bytes in Data
Buffer are valid in response to a read operation. A value of 0h indicates that a zero length packet
was returned and the state of Data Buffer is not defined. A value of 1–8 indicates 1–8 bytes were
received. Hardware does not return values 9–Fh.
The transferring of data always starts with byte 0 in the data area and moves toward byte 7 until the
transfer size is reached.
Intel® 82801DB ICH4 Datasheet
EHCI Controller Registers (D29:F7)
12.2.3.2
USB PIDs Register
Offset:
Default Value:
04h
00000000h
Attribute:
Size:
R/W, RO
32 bits
This DWord register is used to communicate PID information between the USB debug driver and
the USB debug port. The debug port uses some of these fields to generate USB packets, and uses
other fields to return PID information to the USB debug driver.
Bit
12.2.3.3
Description
31:24
Reserved. These bits will return 0 when read. Writes will have no effect.
23:16
RECEIVED_PID_STS [23:16] — RO. The hardware updates this field with the received PID for
transactions in either direction. When the controller is writing data, this field is updated with the
handshake PID that is received from the device. When the host controller is reading data, this field
is updated with the data packet PID (if the device sent data), or the handshake PID (if the device
NAKs the request). This field is valid when the hardware clears the GO_DONE#_CNT bit.
15:8
SEND_PID_CNT [15:8] — R/W. The hardware sends this PID to begin the data packet when
sending data to USB (i.e., WRITE_READ#_CNT is asserted). Software will typically set this field to
either DATA0 or DATA1 PID values.
7:0
TOKEN_PID_CNT [7:0] — R/W. Hardware sends this PID as the Token PID for each USB
transaction. Software typically sets this field to either IN, OUT, or SETUP PID values.
Data Buffer Bytes 7:0 Register
Offset:
Default Value:
08h
0000000000000000h
Attribute:
Size:
R/W
64 bits
This register can be accessed as 8 separate 8-bit registers or 2 separate 32-bit register.
Bit
63:0
Description
DATA_BUFFER [63:0] — R/W. These are the 8 bytes of the data buffer. The bytes in the Data
Buffer must be written with data before software initiates a write request. For a read request, the
Data Buffer contains valid data when DONE_STS bit is cleared by the hardware,
ERROR_GOOD#_STS is cleared by the hardware, and the DATA_LENGTH_CNT field indicates
the number of bytes that are valid.
Bits 63:56
Correspond to the most significant byte (byte 7).
...
...
Bits 7:0
Correspond to least significant byte (byte 0).
Intel® 82801DB ICH4 Datasheet
449
EHCI Controller Registers (D29:F7)
12.2.3.4
Configuration Register
Offset:
Default Value:
Bit
450
10h
00007F01h
Attribute:
Size:
R/W
32 bits
Description
31:15
Reserved
14:8
USB_ADDRESS_CNF — R/W. This 7-bit field that identifies the USB device address used by the
controller for all Token PID generation. (Default = 7Fh)
7:4
Reserved
3:0
USB_ENDPOINT_CNF — R/W. This 4-bit field identifies the endpoint used by the controller for all
Token PID generation. (Default=01h)
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
SMBus Controller Registers (D31:F3) 13
13.1
PCI Configuration Registers (SMBUS—D31:F3)
Note:
Registers that are not shown in Table 13-1 should be treated as Reserved (See Section 6.2 for
details).
Table 13-1. SMBus Controller PCI Configuration Register Address Map (SMBUS—D31:F3)
Offset
Mnemonic
Register Name
Default
Type
00–01h
VID
Vendor ID
8086
RO
02–03h
DID
Device ID
24C3h
RO
04–05h
CMD
Command Register
0000h
R/W, RO
06–07h
STA
Device Status
0280h
R/WC, RO
08h
RID
09h
PI
Revision ID
See Note
RO
00h
RO
Programming Interface
0Ah
SCC
Sub Class Code
05h
RO
0Bh
BCC
Base Class Code
0Ch
RO
20–23h
SMB_BASE
SMBus Base Address
00000001h
R/W
2C–2Dh
SVID
Subsystem Vendor ID
00h
RO
2E–2Fh
SID
Subsystem ID
00h
RO
3Ch
INTR_LN
Interrupt Line
00h
R/W
3Dh
INTR_PN
Interrupt Pin
02h
RO
40h
HOSTC
Host Configuration
00h
R/W
NOTE: Refer to the ICH4 Specification Update for the value of the Revision ID Register.
13.1.1
VID—Vendor Identification Register (SMBUS—D31:F3)
Address:
Default Value:
00–01h
8086h
Bit
15:0
13.1.2
Attribute:
Size:
RO
16 bits
Description
Vendor Identification Value — RO. This is a 16-bit value assigned to Intel
DID—Device Identification Register (SMBUS—D31:F3)
Address:
Default Value:
02–03h
24C3h
Bit
15:0
Attribute:
Size:
RO
16 bits
Description
Device Identification Value — RO.
Intel® 82801DB ICH4 Datasheet
451
SMBus Controller Registers (D31:F3)
13.1.3
CMD—Command Register (SMBUS—D31:F3)
Address:
Default Value:
04–05h
0000h
Bit
15:10
13.1.4
RO R/W
16 bits
Description
Reserved
9
Fast Back to Back Enable (FBE) — RO. Reserved as 0.
8
SERR# Enable (SERR_EN) — RO. Reserved as 0.
7
Wait Cycle Control (WCC) — RO. Reserved as 0.
6
Parity Error Response (PER) — RO. Reserved as 0.
5
VGA Palette Snoop (VPS) — RO. Reserved as 0.
4
Postable Memory Write Enable (PMWE) — RO. Reserved as 0.
3
Special Cycle Enable (SCE) — RO. Reserved as 0.
2
Bus Master Enable (BME) — RO. Reserved as 0.
1
Memory Space Enable (MSE) — RO. Reserved as 0.
0
I/O Space Enable (IOSE) — R/W.
0 = Disable
1 = Enables access to the SM Bus I/O space registers as defined by the Base Address Register.
STA—Device Status Register (SMBUS—D31:F3)
Address:
Default Value:
Bit
06–07h
0280h
Attributes:
Size:
RO R/WC
16 bits
Description
15
Detected Parity Error (DPE) — RO. Reserved as 0.
14
Signaled System Error (SSE) — RO. Reserved as 0.
13
Received Master Abort (RMA) — RO. Reserved as 0.
12
Received Target Abort (RTA) — RO. Reserved as 0.
11
Signaled Target Abort (STA) — R/WC.
Set when the function is targeted with a transaction that the ICH4 terminates with a target abort.
Software resets STA to 0 by writing a 1 to this bit location.
10:9
DEVSEL# Timing Status (DEV_STS) — RO. This 2-bit field defines the timing for DEVSEL#
assertion for positive decode.
01 = Medium timing.
8
Data Parity Error Detected (DPED) — RO. Reserved as 0.
7
Fast Back to Back Capable (FB2BC) — RO. Reserved as 1.
6
User Definable Features (UDF) — RO. Reserved as 0.
5
66 MHz Capable (66MHZ_CAP) — RO. Reserved as 0.
4:0
452
Attributes:
Size:
Reserved
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
13.1.5
REVID—Revision ID Register (SMBUS—D31:F3)
Offset Address:
Default Value:
08h
See Bit Description
Bit
7:0
13.1.6
Revision Identification Value — RO. Refer to the ICH4 Specification Update for the value of the
Revision ID Register.
SCC—Sub Class Code Register (SMBUS—D31:F3)
0Ah
05h
Bit
7:0
Attributes:
Size:
RO
8 bits
Description
Sub Class Code — RO.
05h = SM Bus serial controller
BCC—Base Class Code Register (SMBUS—D31:F3)
Address Offset:
Default Value:
0Bh
0Ch
Bit
7:0
13.1.8
RO
8 bits
Description
Address Offset:
Default Value:
13.1.7
Attribute:
Size:
Attributes:
Size:
RO
8 bits
Description
Base Class Code — RO.
0Ch = Serial controller.
SMB_BASE—SMBUS Base Address Register
(SMBUS—D31:F3)
Address Offset:
Default Value:
20–23h
00000001h
Bit
Attribute:
Size:
R/W, RO
32-bits
Description
31:16
Reserved — RO
15:5
Base Address — R/W. Provides the 32-byte system I/O base address for the ICH4 SMB logic.
4:1
Reserved — RO
0
I/O Space Indicator — RO. This read-only bit is always 1, indicating that the SMB logic is I/O
mapped.
Intel® 82801DB ICH4 Datasheet
453
SMBus Controller Registers (D31:F3)
13.1.9
SVID — Subsystem Vendor ID (SMBUS—D31:F2/F4)
Address Offset:
Default Value:
Lockable:
2Ch–2Dh
00h
No
Bit
15:0
13.1.10
Subsystem Vendor ID (SVID) — RO. The SVID register, in combination with the Subsystem ID
(SID) register, enables the operating system (OS) to distinguish subsystems from each other. The
value returned by reads to this register is the same as that which was written by BIOS into the
IDE_SVID register.
SID — Subsystem ID (SMBUS—D31:F2/F4)
Attribute:
Size:
Power Well:
RO
16 bits
Core
Description
15:0
Subsystem ID (SID) — R/Write-Once. The SID register, in combination with the SVID register,
enables the operating system (OS) to distinguish subsystems from each other. The value returned
by reads to this register is the same as that which was written by BIOS into the IDE_SID register.
INTR_LN—Interrupt Line Register (SMBUS—D31:F3)
3Ch
00h
Attributes:
Size:
R/W
8 bits
Bit
Description
7:0
Interrupt Line (INT_LN) — R/W. This data is not used by the ICH4. It is to communicate to software
the interrupt line that the interrupt pin is connected to PIRQB#.
INTR_PN—Interrupt Pin Register (SMBUS—D31:F3)
Address Offset:
Default Value:
Bit
7:0
454
2Eh–2Fh
00h
No
Bit
Address Offset:
Default Value:
13.1.12
RO
16 bits
Core
Description
Address Offset:
Default Value:
Lockable:
13.1.11
Attribute:
Size:
Power Well:
3Dh
02h
Attributes:
Size:
RO
8 bits
Description
Interrupt Pin (INT_PN) — RO.
02h = Indicates that the ICH4 SMBus controller will drive PIRQB# as its interrupt line.
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
13.1.13
HOSTC—Host Configuration Register (SMBUS—D31:F3)
Address Offset:
Default Value:
Bit
7:3
40h
00h
Attribute:
Size:
R/W
8 bits
Description
Reserved
2
I2C_EN — R/W.
0 = SMBus behavior.
1 = The ICH4 is enabled to communicate with I2C devices. This will change the formatting of some
commands.
1
SMB_SMI_EN — R/W. This bit needs to be set for SMBALERT# to be enabled.
0 = SMBus interrupts will not generate an SMI#.
1 = Any source of an SMB interrupt will instead be routed to generate an SMI#. Refer to
Section 5.18.4 (Interrupts / SMI#).
0
SMBus Host Enable (HST_EN) — R/W.
0 = Disable the SMBus Host controller.
1 = Enable. The SMB Host controller interface is enabled to execute commands. The INTREN bit
needs to be enabled for the SMB Host controller to interrupt or SMI#. Note that the SMB Host
controller will not respond to any new requests until all interrupt requests have been cleared.
Intel® 82801DB ICH4 Datasheet
455
SMBus Controller Registers (D31:F3)
13.2
SMBUS I/O Registers
Table 13-2. SMB I/O Registers
13.2.1
Offset
Mnemonic
00h
HST_STS
Register Name
Host Status
Default
Type
00h
R/WC,
RO
02h
HST_CNT
Host Control
00h
R/W, WO
03h
HST_CMD
Host Command
00h
R/W
04h
XMIT_SLVA
Transmit Slave Address
00h
R/W
05h
HST_D0
Host Data 0
00h
R/W
Host Data 1
00h
R/W
Host Block Data Byte
00h
R/W
06h
HST_D1
07h
HOST_BLOCK_DB
08h
PEC
09h
RCV_SLVA
Packet Error Check
00h
R/W
Receive Slave Address
44h
R/W
0Ah
SLV_DATA
Slave Data
0Ch
AUX_STS
Auxiliary Status
0000h
R/W
00h
R/WC
0Dh
AUX_CTL
Auxiliary Control
00h
R/W
0Eh
SMLINK_PIN_CTL
SMLink Pin Control
04h
R/W, RO
0Fh
SMBUS_PIN_CTL
SMBus Pin Control
04h
R/W, RO
10h
SLV_STS
Slave Status
00h
R/WC
Slave Command
00h
R/W
Notify Device Address
00h
RO
11h
SLV_CMD
14h
NOTIFY_DADDR
16h
NOTIFY_DLOW
Notify Data Low Byte
00h
RO
17h
NOTIFY_DHIGH
Notify Data High Byte
00h
RO
HST_STS—Host Status Register
Register Offset:
Default Value:
00h
00h
Attribute:
Size:
R/WC, RO
8-bits
All status bits are set by hardware and cleared by the software writing a one to the particular bit
position. Writing a zero to any bit position has no effect.
Bit
7
Description
Byte Done Status (DS) — R/WC. This bit will be set to 1 when the host controller has received a
byte (for Block Read commands) or if it has completed transmission of a byte (for Block Write
commands) when the 32-byte buffer is not being used. Note that this bit will be set, even on the last
byte of the transfer. Software clears the bit by writing a 1 to the bit position. This bit is not set when
transmission is due to the D110 interface heartbeat.
This bit has no meaning for block transfers when the 32-byte buffer is enabled.
NOTE: When the last byte of a block message is received, the host controller will set this bit.
However, it will not immediately set the INTR bit (bit 1 in this register). When the interrupt
handler clears the BYTE_DONE_STS bit, the message is considered complete, and the
host controller will then set the INTR bit (and generate another interrupt). Thus, for a block
message of n bytes, the Intel ICH4 will generate n+1 interrupts. The interrupt handler needs
to be implemented to handle these cases.
456
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
Bit
Description
6
INUSE_STS — R/WC (special). This bit is used as semaphore among various independent
software threads that may need to use the ICH4’s SMBus logic, and has no other effect on
hardware.
0 = After a full PCI reset, a read to this bit returns a 0.
1 = After the first read, subsequent reads will return a 1. A write of a 1 to this bit will reset the next
read value to 0. Writing a 0 to this bit has no effect. Software can poll this bit until it reads a 0,
and will then own the usage of the host controller.
5
SMBALERT_STS — R/WC. If the signal is programmed as a GPIO, then this bit will never be set.
0 = Interrupt or SMI# was not generated by SMBALERT#. This bit is only cleared by software
writing a 1 to the bit position or by RSMRST# going low.
1 = The source of the interrupt or SMI# was the SMBALERT# signal.
4
FAILED — R/WC.
0 = Cleared by writing a 1 to the bit position.
1 = The source of the interrupt or SMI# was a failed bus transaction. This bit is set in response to
the KILL bit being set to terminate the host transaction.
3
BUS_ERR — R/WC.
0 = Cleared by writing a 1 to the bit position.
1 = The source of the interrupt of SMI# was a transaction collision.
DEV_ERR — R/WC.
2
0 = Software resets this bit by writing a 1 to this location. The ICH4 will then deassert the interrupt
or SMI#.
1 = The source of the interrupt or SMI# was due to one of the following:
• Illegal Command Field,
• Unclaimed Cycle (host initiated),
• Host Device Time-out Error.
1
INTR — R/WC (special). This bit can only be set by termination of a command. INTR is not
dependent on the INTREN bit of the Host Controller Register (offset 02h). It is only dependent on
the termination of the command. If the INTREN bit is not set, then the INTR bit will be set, although
the interrupt will not be generated. Software can poll the INTR bit in this non-interrupt case.
0 = Software resets this bit by writing 1 to this location. The ICH4 will then deassert the interrupt or
SMI#.
1 = The source of the interrupt or SMI# was the successful completion of its last command.
0
HOST_BUSY — RO.
0 = Cleared by the ICH4 when the current transaction is completed.
1 = Indicates that the ICH4 is running a command from the host interface. No SMB registers should
be accessed while this bit is set, except the BLOCK DATA BYTE Register. The BLOCK DATA
BYTE Register can be accessed when this bit is set only when the SMB_CMD bits in the Host
Control Register are programmed for Block command or I2C Read command. This is
necessary in order to check the DONE_STS bit.
Intel® 82801DB ICH4 Datasheet
457
SMBus Controller Registers (D31:F3)
13.2.2
HST_CNT—Host Control Register
Register Offset:
Default Value:
Note:
02h
00h
Attribute:
Size:
R/W, WO
8-bits
A read to this register will clear the byte pointer of the 32-byte buffer.
Bit
Description
PEC_EN — R/W.
0 = SMBus host controller does not perform the transaction with the PEC phase appended.
7
6
1 = Causes the host controller to perform the SMBus transaction with the Packet Error Checking
phase appended. For writes, the value of the PEC byte is transferred from the PEC Register.
For reads, the PEC byte is loaded in to the PEC Register. This bit must be written prior to the
write in which the START bit is set.
START — WO.
0 = This bit will always return 0 on reads. The HOST_BUSY bit in the Host Status register (offset
00h) can be used to identify when the ICH4 has finished the command.
1 = Writing a 1 to this bit initiates the command described in the SMB_CMD field. All registers
should be setup prior to writing a 1 to this bit position.
LAST_BYTE — WO. This bit is used for Block Read commands.
1 = Software sets this bit to indicate that the next byte will be the last byte to be received for the
block. This causes the ICH4 to send a NACK (instead of an ACK) after receiving the last byte.
5
4:2
458
NOTE: Once the SECOND_TO_STS bit in TCO2_STS register (D31:F0, TCOBASE+6h, bit 1) is
set, the LAST_BYTE bit also gets set. While the SECOND_TO_STS bit is set, the
LAST_BYTE bit cannot be cleared. This prevents the ICH4 from running some of the
SMBus commands (Block Read/Write, I2C Read, Block I2C Write).
SMB_CMD — R/W. The bit encoding below indicates which command the ICH4 is to perform. If
enabled, the ICH4 will generate an interrupt or SMI# when the command has completed If the value
is for a non-supported or reserved command, the ICH4 will set the device error (DEV_ERR) status
bit and generate an interrupt when the START bit is set. The ICH4 will perform no command, and will
not operate until DEV_ERR is cleared.
000 = Quick: The slave address and read/write value (bit 0) are stored in the transmit slave address
register.
001 = Byte: This command uses the transmit slave address and command registers. Bit 0 of the
slave address register determines if this is a read or write command.
010 = Byte Data: This command uses the transmit slave address, command, and DATA0 registers.
Bit 0 of the slave address register determines if this is a read or write command. If it is a read,
the DATA0 register will contain the read data.
011 = Word Data: This command uses the transmit slave address, command, DATA0 and DATA1
registers. Bit 0 of the slave address register determines if this is a read or write command. If it
is a read, after the command completes, the DATA0 and DATA1 registers will contain the read
data.
100 = Process Call: This command uses the transmit slave address, command, DATA0 and DATA1
registers. Bit 0 of the slave address register determines if this is a read or write command.
After the command completes, the DATA0 and DATA1 registers will contain the read data.
101 = Block: This command uses the transmit slave address, command, DATA0 registers, and the
Block Data Byte register. For block write, the count is stored in the DATA0 register and
indicates how many bytes of data will be transferred. For block reads, the count is received
and stored in the DATA0 register. Bit 0 of the slave address register selects if this is a read or
write command. For writes, data is retrieved from the first n (where n is equal to the specified
count) addresses of the SRAM array. For reads, the data is stored in the Block Data Byte
register.
110 = I2C Read: This command uses the transmit slave address, command, DATA0, DATA1
registers, and the Block Data Byte register. The read data is stored in the Block Data Byte
register. The ICH4 will continue reading data until the NAK is received.
111 = Reserved
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
Bit
Description
KILL — R/W.
1
0
13.2.3
0 = Normal SMBus Host controller functionality.
1 = When set, kills the current host transaction taking place, sets the FAILED status bit, and
asserts the interrupt (or SMI#). This bit, once set, must be cleared by software to allow the
SMBus Host controller to function normally.
INTREN — R/W.
0 = Disable.
1 = Enable the generation of an interrupt or SMI# upon the completion of the command.
HST_CMD—Host Command Register
Register Offset:
Default Value:
13.2.4
03h
00h
Attribute:
Size:
R/W
8 bits
Bit
Description
7:0
This 8-bit field is transmitted by the host controller in the command field of the SMBus protocol during
the execution of any command.
XMIT_SLVA—Transmit Slave Address Register
Register Offset:
Default Value:
04h
00h
Attribute:
Size:
R/W
8 bits
This register is transmitted by the host controller in the slave address field of the SMBus protocol.
Bit
7:1
0
13.2.5
Description
ADDRESS — R/W. 7-bit address of the targeted slave.
RW — R/W. Direction of the host transfer.
0 = Write
1 = Read
HST_D0—Data 0 Register
Register Offset:
Default Value:
05h
00h
Attribute:
Size:
R/W
8 bits
Bit
Description
7:0
DATA0/COUNT — R/W. This field contains the eight bit data sent in the DATA0 field of the SMBus
protocol. For block write commands, this register reflects the number of bytes to transfer. This register
should be programmed to a value between 1 and 32 for block counts. A count of 0 or a count above 32
will result in unpredictable behavior. The host controller does not check or log illegal block counts.
Intel® 82801DB ICH4 Datasheet
459
SMBus Controller Registers (D31:F3)
13.2.6
HST_D1—Data 1 Register
Register Offset:
Default Value:
13.2.7
R/W
8 bits
Description
7:0
DATA1 — R/W. This eight bit register is transmitted in the DATA1 field of the SMBus protocol during
the execution of any command.
Host_BLOCK_DB—Host Block Data Byte Register
07h
00h
Attribute:
Size:
R/W
8 bits
Bit
Description
7:0
Block Data (BDTA)— R/W. This is either a register, or a pointer into a 32-byte block array, depending
upon whether the E32B bit is set in the Auxiliary Control register. When the E32B bit is cleared, this is
a register containing a byte of data to be sent on a block write or read from on a block read, just as it
behaved on the ICH3.
When the E32B bit is set, reads and writes to this register are used to access the 32-byte block data
storage array. An internal index pointer is used to address the array, which is reset to 0 by reading the
HCTL register (offset 02h). The index pointer then increments automatically upon each access to this
register. The transfer of block data into (read) or out of (write) this storage array during an SMBus
transaction always starts at index address 0.
When the E2B bit is set, for writes, software will write up to 32-bytes to this register as part of the
setup for the command. After the Host controller has sent the Address, Command, and Byte Count
fields, it will send the bytes in the SRAM pointed to by this register. After the byte count has been
exhausted, the controller will set the DONE_STS bit (see definition above).
When the E2B bit is cleared for writes, software will place a single byte in this register. After the host
controller has sent the address, command, and byte count fields, it will send the byte in this register. If
there is more data to send, software will write the next series of bytes to the SRAM pointed to by this
register and clear the DONE_STS bit. The controller will then send the next byte. During the time
between the last byte being transmitted to the next byte being transmitted, the controller will insert
wait-states on the interface.
When the E2B bit is set for reads, after receiving the byte count into the Data0 register, the first series
of data bytes go into the SRAM pointed to by this register. If the byte count has been exhausted or the
32-byte SRAM has been filled, the controller will generate an SMI# or interrupt (depending on
configuration) and set the DONE_STS bit. Software will then read the data. During the time between
when the last byte is read from the SRAM to when the DONE_STS bit is cleared, the controller will
insert wait-states on the interface.
PEC—Packet Error Check (PEC) Register
Register Offset:
Default Value:
460
Attribute:
Size:
Bit
Register Offset:
Default Value:
13.2.8
06h
00h
08h
00h
Attribute:
Size:
R/W
8 bits
Bit
Description
7:0
PEC_DATA — R/W. This 8-bit register is written with the 8-bit CRC value that is used as the SMBus
PEC data prior to a write transaction. For read transactions, the PEC data is loaded from the SMBus
into this register and is then read by software. Software must ensure that the INUSE_STS bit is
properly maintained to avoid having this field over-written by a write transaction following a read
transaction.
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
13.2.9
RCV_SLVA—Receive Slave Address Register
Register Offset:
Default Value:
Lockable:
09h
44h
No
Bit
7
6:0
13.2.10
Attribute:
Size:
Power Well:
R/W
8 bits
Resume
Description
Reserved
SLAVE_ADDR — R/W. This field is the slave address that the ICH4 decodes for read and write
cycles. the default is not 0, so the SMBus Slave Interface can respond even before the processor
comes up (or if the processor is dead). This register is cleared by RSMRST#, but not by PCIRST#.
SLV_DATA—Receive Slave Data Register
Register Offset:
Default Value:
Lockable:
0Ah
0000h
No
Attribute:
Size:
Power Well:
RO
16 bits
Resume
This register contains the 16-bit data value written by the external SMBus master. The processor
can then read the value from this register. This register is reset by RSMRST#, but not PCIRST#.
.
Bit
13.2.11
Description
15:8
Data Message Byte 1 (DATA_MSG1) — RO. See Section 5.18.7 for a discussion of this field.
7:0
Data Message Byte 0 (DATA_MSG0) — RO. See Section 5.18.7 for a discussion of this field.
AUX_STS—Auxiliary Status Register
Register Offset:
Default Value:
Lockable:
0Ch
00h
No
Attribute:
Size:
Power Well:
RW/C
8 bits
Resume
.
Bit
7:1
0
Description
Reserved
CRC Error (CRCE) — R/WC.
0 = Software clears this bit by writing a 1 to it.
1 = This bit is set if a received message contained a CRC error. When this bit is set, the DERR bit of
the host status register will also be set. This bit will be set by the controller if a software abort
occurs in the middle of the CRC portion of the cycle or an abort happens after the ICH4 has
received the final data bit transmitted by an external slave.
Intel® 82801DB ICH4 Datasheet
461
SMBus Controller Registers (D31:F3)
13.2.12
AUX_CTL—Auxiliary Control Register
Register Offset:
Default Value:
Lockable:
0Dh
00h
No
Attribute:
Size:
Power Well:
R/W
8 bits
Resume
.
Bit
7:2
Description
Reserved
Enable 32-byte Buffer (E32B)— R/W.
1
0
13.2.13
0 = Disable.
1 = Enable. The Host Block Data register is a pointer into a 32-byte buffer, as opposed to a single
register. This enables the block commands to transfer or receive up to 32-bytes before the ICH4
generates an interrupt.
Automatically Append CRC (AAC) — R/W.
0 = Disable.
1 = Enable. The ICH4 automatically appends the CRC. This bit must not be changed during SMBus
transactions, or undetermined behavior will result
SMLINK_PIN_CTL—SMLink Pin Control Register
Register Offset:
Default Value:
Note:
0Eh
See below
Attribute:
Size:
R/W, RO
8 bits
This register is in the resume well and is reset by RSMRST#.
Bit
7:3
Description
Reserved
SMLINK_CLK_CTL — R/W.
2
462
0 = ICH4 drives the SMLINK[0] pin low, independent of what the other SMLINK logic would otherwise
indicate for the SMLINK[0] pin.
1 = The SMLINK[0] pin is not overdriven low. The other SMLINK logic controls the state of the pin.
(Default)
1
SMLINK1_CUR_STS — R/W. This pin returns the value on the SMLINK[1] pin. This allows software
to read the current state of the pin. Default value is dependent on an external signal level.
0 = Low
1 = High
0
SMLINK0_CUR_STS — RO. This pin returns the value on the SMLINK[0] pin. This allows software to
read the current state of the pin. Default value is dependent on an external signal level.
0 = Low
1 = High
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
13.2.14
SMBUS_PIN_CTL—SMBUS Pin Control Register
Register Offset:
Default Value:
Note:
0Fh
See below
Attribute:
Size:
R/W, RO
8 bits
This register is in the resume well and is reset by RSMRST#.
Bit
7:3
Description
Reserved
SMBCLK_CTL — R/W.
2
13.2.15
0 = ICH4 will drive the SMBCLK pin low, independent of what the other SMB logic would otherwise
indicate for the SMBCLK pin.
1 = The SMBCLK pin is not overdriven low. The other SMBus logic controls the state of the pin.
(Default)
1
SMBDATA_CUR_STS — RO. This pin returns the value on the SMBDATA pin. This allows software to
read the current state of the pin. Default value is dependent on an external signal level.
0 = Low
1 = High
0
SMBCLK_CUR_STS — RO. This pin returns the value on the SMBCLK pin. This allows software to
read the current state of the pin. Default value is dependent on an external signal level.
0 = Low
1 = High
SLV_STS—Slave Status Register
Register Offset:
Default Value:
Note:
10h
00h
Attribute:
Size:
R/WC
8 bits
This register is in the resume well and is reset by RSMRST#.
All bits in this register are implemented in the 64 kHz clock domain. Therefore, software must poll
this register until a write takes effect before assuming that a write has completed internally.
Bit
7:1
0
Description
Reserved
HOST_NOTIFY_STS — R/WC. The ICH4 sets this bit to a 1 when it has completely received a
successful Host Notify Command on the SMLink pins. Software reads this bit to determine that the
source of the interrupt or SMI# was the reception of the Host Notify Command. Software clears this bit
after reading any information needed from the Notify address and data registers by writing a 1 to this
bit. Note that the ICH4 will allow the Notify Address and Data registers to be over-written once this bit
has been cleared. When this bit is 1, the ICH4 will NACK the first byte (host address) of any new “Host
Notify” commands on the SMLink. Writing a 0 to this bit has no effect.
Intel® 82801DB ICH4 Datasheet
463
SMBus Controller Registers (D31:F3)
13.2.16
SLV_CMD—Slave Command Register
Register Offset:
Default Value:
Note:
11h
00h
7:2
Description
Reserved
2
SMBALERT_DIS — R/W.
0 = Allows the generation of the interrupt or SMI#.
1 = Software sets this bit to block the generation of the interrupt or SMI# due to the SMBALERT#
source. This bit is logically inverted and ANDed with the SMBALERT_STS bit. The resulting
signal is distributed to the SMI# and/or interrupt generation logic. This bit does not effect the
wake logic.
1
HOST_NOTIFY_WKEN — R/W.
0 = Disable.
1 = Enables the reception of a Host Notify command as a wake event. When enabled this event is
“OR”ed in with the other SMBus wake events and is reflected in the SMB_WAK_STS bit of the
General Purpose Event 0 Status register.
0
HOST_NOTIFY_INTREN — R/W.
0 = Disable
1 = Enables the generation of interrupt or SMI# when HOST_NOTIFY_STS is 1. This enable does
not affect the setting of the HOST_NOTIFY_STS bit. When the interrupt is generated, either
PIRQ[B]# or SMI# is generated, depending on the value of the SMB_SMI_EN bit (D31, F3,
Off40h, B1). If the HOST_NOTIFY_STS bit is set when this bit is written to a 1, then the interrupt
(or SMI#) will be generated. The interrupt (or SMI#) is logically generated by AND’ing the STS
and INTREN bits.
NOTIFY_DADDR—Notify Device Address
Register Offset:
Default Value:
Note:
14h
00h
Attribute:
Size:
RO
8 bits
This register is in the resume well and is reset by RSMRST#
Bit
Description
7:1
DEVICE_ADDRESS — RO. This field contains the 7-bit device address received during the Host
Notify protocol of the SMBus 2.0 Specification. Software should only consider this field valid when the
HOST_NOTIFY_STS bit is set to 1.
0
464
R/W
8 bits
This register is in the resume well and is reset by RSMRST#
Bit
13.2.17
Attribute:
Size:
Reserved
Intel® 82801DB ICH4 Datasheet
SMBus Controller Registers (D31:F3)
13.2.18
NOTIFY_DLOW—Notify Data Low Byte Register
Register Offset:
Default Value:
Note:
13.2.19
Attribute:
Size:
RO
8 bits
This register is in the resume well and is reset by RSMRST#
Bit
Description
7:0
DATA_LOW_BYTE — RO. This field contains the first (low) byte of data received during the Host
Notify protocol of the SMBus 2.0 Specification. Software should only consider this field valid when the
HOST_NOTIFY_STS bit is set to 1.
NOTIFY_DHIGH—Notify Data High Byte Register
Register Offset:
Default Value:
Note:
16h
00h
17h
00h
Attribute:
Size:
RO
8 bits
This register is in the resume well and is reset by RSMRST#
Bit
Description
7:0
DATA_HIGH_BYTE — RO. This field contains the second (high) byte of data received during the Host
Notify protocol of the SMBus 2.0 Specification. Software should only consider this field valid when the
HOST_NOTIFY_STS bit is set to 1.
Intel® 82801DB ICH4 Datasheet
465
SMBus Controller Registers (D31:F3)
This page is intentionally left blank.
466
Intel® 82801DB ICH4 Datasheet
AC ’97 Audio Controller Registers (D31:F5)
AC ’97 Audio Controller Registers
(D31:F5)
14.1
14
AC ’97 Audio PCI Configuration Space (D31:F5)
Note:
Registers address locations not shown in Table 14-1 should be treated as Reserved.
Table 14-1. AC ‘97 Audio PCI Configuration Register Address Map (Audio—D31:F5)
Offset
Mnemonic
00–01h
VID
Register
Default
Access
Vendor Identification
8086h
RO
Device Identification
02–03h
DID
24C5h
RO
04–05h
PCICMD
PCI Command
0000
R/W, RO
06–07h
PCISTS
PCI Device Status
0280h
R/WC, RO
08h
RID
Revision Identification
See Note
RO
09h
PI
Programming Interface
00
RO
0Ah
SCC
Sub Class Code
01h
RO
0Bh
BCC
Base Class Code
04h
RO
0Eh
HEDT
Header Type
00
RO
10–13h
NAMBBAR
Native Audio Mixer Base Address
00000001h
R/W, RO
14–17h
NAMBBAR
Native Audio Bus Mastering Base Address
00000001h
R/W, RO
18–1Bh
MMBAR
Mixer Base Address(Mem)
00000000h
R/W, RO
1C–1Fh
MBBAR
Bus Master Base Address(Mem)
00000000h
R/W, RO
2C–2Dh
SVID
Subsystem Vendor ID
0000h
R/WO
2E–2Fh
SID
Subsystem ID
0000h
R/WO
34h
CAP_PTR
Capabilities Pointer
50h
RO
3Ch
INTR_LN
Interrup