82801DB Datasheet, PDF (354/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

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
15
14:12
11
10
9
Description
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).
Reserved
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.
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.
Reserved
354
Intel^® 82801DB ICH4 Datasheet