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LPC Interface Bridge Registers (D31:F0)
8-62
82801AA and 82801AB Datasheet
8.8.3.6
LV2 — Level 2 Register
I/O Address:
PMBASE + 14h
(
ACPI P_BLK+4)
00h
No
Core
Attribute:
Size:
Usage:
RO
8 bits
ACPI or Legacy
Default Value:
Lockable:
Power Well:
8.8.3.7
GPE0_STS—General Purpose Event 0 Status Register
I/O Address:
PMBASE + 28h
(
ACPI GPE0_BLK)
0000h
No
Resume
Attribute:
Size:
Usage:
R/W
16 bits
ACPI
Default Value:
Lockable:
Power Well:
Note:
This register is symmetrical to the General Purpose Event 0 Enable Register. If the corresponding
_EN bit is set, then when the _STS bit get set, the ICH generates 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. No SCI/SMI# or wake event on
THRMOR_STS since no corresponding _EN bit. None of these bits should be reset by CF9h write.
All should be reset by RSMRST#, except for RI_STS.
Bit
Description
7:0
Reads to this register return all zeros, writes to this register have no effect. Reads to this register
generate a “enter a level 2 power state” (C2) to the clock control logic. This will cause the STPCLK#
signal to go active, and stay active until a break event occurs. Throttling (due either to THTL_EN or
THRM# override) will be ignored.
Bit
Description
15:12
Reserved.
11
PME_STS.
1 = This bit is set to 1 by hardware when the PME# signal goes active. Additionally, if the PME_EN
bit is set, and the system is in an S0 state, then the setting of the PME_STS bit generates an
SCI or SMI# (if SCI_EN is not set). If the PME_EN bit is set, and the system is in an S1-S4 state
(or S5 state due to setting SLP_TYP and SLP_EN), then the setting of the PME_STS bit
generates a wake event, and an SCI is generated. If the system is in an S5 state due to power
button override or a power failure, then PME_STS does not cause a wake event or SCI.
10:9
Reserved.
8
RI_STS.
1 = This bit is set to 1 by hardware when the RI# input signal goes active. The value of this bit must
be maintained, even through a G3 state.
0 = This bit can be reset by writing a one to this bit position.
NOTE:
This bit is not effected by a hard reset caused by a CF9h write.
7
SMB_WAK_STS.
1 = This bit is set to 1 by hardware to indicate that the wake event was caused by the ICH’s SMBus
logic.
0 = This bit is cleared by writing back a 1 to this bit position.
The SMBus controller will independently cause an SMI# or SCI, so this bit does not need to do so
(unlike the other bits in this register). This bit is in resume well.
6
TCOSCI_STS.
1 = This bit will be set to 1 by hardware when the TCO logic causes an SCI.
0 = This bit can be reset by writing a one to this bit position.