Advanced Configuration and Power Interface Specification

ACPI-Defined Devices and Device-Specific Objects
9.18.5 _GWS (Get Wake alarm status)
This object is required and enables the OSPM to read the status of wake alarms. Expired wake timers
will wake the platform even if the transition to a sleep state was completed after the wake timer has
expired. This method enables the OSPM to retrieve the status of wake timers and clear any of them if
needed.
Arguments: (1)
Arg0 - Timer Identifier (Integer (DWORD)): indicates the timer to be cleared:
0x00000000 - AC Timer
0x00000001 - DC Timer
Return Value:
An Integer (DWORD) containing current expired timers in bit field
Bit [0]- 1 = timer expired, 0 = timer did not expired
Bit [ 1]- 1= timer caused a platform wake, 0 = timer did not cause a platform wake
Bit [31:2] reserved and should be 0.
9.18.6 _CWS (Clear Wake alarm status)
This object is required and enables the OSPM to clear the status of wake alarms. Expired wake
timers will wake the platform even if the transition to a sleep state was completed after the wake
timer has expired. This method enables the OSPM to clear the status of expired wake timers.
Arguments: (1)
Arg0 - Timer Identifier (Integer (DWORD)): indicates the timer to be cleared:
0x00000000 - AC Timer
0x00000001 - DC Timer
Return Value:
An Integer (DWORD) containing current expired timer wake policy:
0x00000000 - Success
0x00000001 - Failure
9.18.7 _STP (Set Expired Timer Wake Policy)
This object is required and sets the expired timer wake policy. The policy is applied when a
corresponding timer expired but the wake signal was not asserted as a result of the power source.
The platform accumulates elapsed time on the power source and asserts the wake signal when the
elapsed timer on the power source exceeds the expired timer wake policy value. Power source
transitions do not reset the expired timer wake policy values. When the Wake Alarm device asserts
the wake, the expired timer wake policy values of both the AC timer and DC timer are reset to
0xFFFFFFFF automatically by hardware.
Arguments: (2)
Arg0 – TimerIdentifier (Integer(DWORD)): indicates the timer to be set:
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