Intel 6 SERIES CHIPSET - DATASHEET 01-2011 Datasheet page 505

LPC Interface Bridge Registers (D31:F0)
13.7.5 RST_CNT—Reset Control Register
I/O Address:
Default Value:
Lockable:
Bit
7:4
3
2
1
0
Datasheet
CF9h
00h
No
Reserved
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 = PCH will keep SLP_S3#, SLP_S4# and SLP_S5# high.
1 = PCH will drive SLP_S3#, SLP_S4# and SLP_S5# low for 3 – 5 seconds.
NOTE: When this bit is set, it also causes the full power cycle (SLP_S3/4/5# assertion)
in response to SYS_RESET#, PWROK#, and Watchdog timer reset sources.
Reset Processor (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).
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 PCH performs a soft reset by activating
INIT# for 16 PCI clocks.
1 = When RST_CPU bit goes from 0 to 1, the PCH performs a hard reset by activating
PLTRST# and SUS_STAT# active for a minimum of about 1 milliseconds. In this
case, SLP_S3#, SLP_S4# and SLP_S5# state (assertion or deassertion) depends
on FULL_RST bit setting. The PCH main power well is reset when this bit is 1. It
also resets the resume well bits (except for those noted throughout this
document).
Reserved
Attribute: R/W
Size: 8-bit
Power Well: Core
Description
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