AMD SB600 - Manual (Page 181)

©2008 Advanced Micro Devices, Inc. SMBus Module and ACPI Block (Device 20, Function 0)
AMD SB600 Register Reference Manual Proprietary Page 181
2.3.4 WatchDogTimer Registers
WatchDogTimer base address is defined in PM_Reg 6F:6Ch.
Register Name Offset Address
WatchDogControl 00h
WatchDogCount 04h
WatchDogControl - RW - 32 bits - [WD_Mem_Reg: 00h]
Field Name Bits Default Description
WatchDogRunStopB 0 0b This bit is used to control or indicate whether the watchdog is
in the Running and Stopped states.
1 = Watchdog is in the Running state
0 = Watchdog is in the Stopped state
If the watchdog is in the Stopped state and a 1 is written to bit
0, the watchdog moves to the Running state, but a count
interval is not started until a 1 is written to bit 7.
If the watchdog is in the Running state, writing a 1 to bit 0 has
no effect.
The bit is only valid when the watchdog is enabled.
WatchDogFired 1 0b A value of “1” indicates that the watchdog timer has expired
and caused the current restart. The bit is cleared by writing a
“1” to bit 1 in the Watchdog Control register. Writing a “0” has
no effect.
The bit is cleared by a power cycle or by the operating
system and it must remain cleared for any restart that is not
caused by the watchdog timer firing.
The bit is only valid when the watchdog is enabled.
WatchDogAction 2 0b This bit determines the action to be taken when the watchdog
timer expires.
0=system reset
1=system power off
The bit is only valid when the watchdog is enabled.
WatchDogDisable 3 Same as
PM IO x69,
bit 0
This bit reflects the state of the watchdog timer hardware.
0=Enable
1=Disable
Reserved 6:4 000b
WatchDogTrigger (WO) 7 0b Write only. Setting this bit triggers the watchdog to start a
new count interval, counting down from the value that was
last written to the Watchdog Count Register.
This bit is always read as zero. Setting this bit has no effect if
the watchdog is disabled or stopped.
Reserved 31:8 000000h
WatchDogCount - RW - 32 bits - [WD_Mem_Reg: 04h]
Field Name Bits Default Description
WatchDogCount 15:0 ---- This defines the countdown time for the counter. The units
are defined in the Units field in the Watchdog Resource Table
(WDRT). The maximum value is defined in the Max Count
field in the WDRT.
Reading this register returns in the current counter value.
Reserved 31:16 0000h