Datasheet 505
LPC Interface Bridge Registers (D31:F0)
13.7.5 RST_CNT—Reset Control Register
I/O Address: CF9h Attribute: R/W
Default Value: 00h Size: 8-bit
Lockable: No Power Well: Core
Bit Description
7:4 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 = 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.
2
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).
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 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).
0 Reserved
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