
LPC Interface Bridge Registers (D31:F0)
8-58
82801AA and 82801AB Datasheet
8.8.3.1
PM1_STS—Power Management 1 Status Register
I/O Address:
PMBASE + 00h
(
ACPI PM1a_EVT_BLK)
0000h
No
Bits 0:7: Core,
Bits 8:15: Resume,
Bit 11 still in RTC
Attribute:
Size:
Usage:
R/W
16 bits
ACPI or Legacy
Default Value:
Lockable:
Power Well:
If bit 10 or 8 in this register is set, and the corresponding _EN bit is set in the PM1_EN register,
then the ICH will generate a Wake Event. Once back in an S0 state (or if already in an S0 state
when the event occurs), the ICH 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
WAK_STS.
1 = This bit is set 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 ICH will transition the system to the ON state. This
bit is only set by hardware.
0 = Cleared by writing a one to this bit. This bit is not affected by hard resets caused by a CF9 write,
but is reset by RSMRST#.
NOTE:
If a power failure occurs (such as removed batteries) without the SLP_EN bit set, the
WAK_STS bit will not be set when power returns.
14:12
Reserved
11
PRBTNOR_STS.
1 = This bit is set by hardware anytime a Power Button Override Event occurs, which occurs when
the power button is pressed for at least 4 consecutive seconds. The power button override
causes an unconditional transition to the S5 state, as well as set the AFTERG3 bit.
0 = The BIOS or SCI handler can clear this bit by writing a 1 to it.
NOTE:
This bit is not affected by hard resets caused by a CF9 write, and will be preserved through
a power failure.
10
RTC_STS.
1 = This bit is 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.
0 = Cleared by writing a 1 to this bit position.
NOTE:
This bit is not affected by hard resets caused by a CF9 write, but is reset by RSMRST#.
9
Reserved
8
PWRBTN__STS.
This bit is set by hardware when the PWRBTN# signal is asserted Low,
independent of any other enable bit. This bit is not affected by hard resets caused by a CF9 write.
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.
If the PWRBTN# signal is held low for more than 4 seconds, the hardware clears the PWRBTN_STS
bit, sets the PWRBTNOR_STS bit, the system transitions to the S5 state, and only PWRBTN# is
enabled as a wake event.
This bit can be cleared by software by writing a one to this bit position.
7:6
Reserved