Advanced Configuration and Power Interface Specification

ACPI Hardware Specification
4.8.2.2.2 Sleep Button
When using the two button model, ACPI supports a second button that when pressed will request
OSPM to transition the platform between the G0 working and G1 sleeping states. Support for a sleep
button is indicated by a combination of the SLEEP_BUTTON flag and the sleep button device
object:
Table 4-14 Sleep Button Support
Indicated Support SLEEP_BUTTON Flag Sleep Button Device Object
No sleep button Set Absent
Fixed hardware sleep button Clear Absent
Control method sleep button Set Present
4.8.2.2.2.1 Fixed Hardware Sleeping Button
SLPBTN#
Debounce
Logic
SLPBTN
State machine
SLPBTN_STS
PM1x_STS.9
SLPBTN Event
SLPBTN_EN
PM1x_EN.9
Figure 4-17 Fixed Hardware Sleep Button Logic
The fixed hardware sleep button has its event programming model in the PM1x_EVT_BLK. This
logic consists of a single enable bit and sticky status bit. When the user presses the sleep button, the
sleep button status bit (SLPBTN_STS) is unconditionally set. Additionally, if the sleep button
enable bit (SLPBTN_EN) is set, and the sleep button status bit is set (SLPBTN_STS, due to a button
press) while the system is in the G0 state, then an SCI is generated. OSPM responds to the event by
clearing the SLPBTN_STS bit. The sleep button logic provides debounce logic that sets the
SLPBTN_STS bit on the button press “edge.”
While the system is sleeping (in either the S0, S1, S2, S3 or S4 states), any further sleep button press
(after the button press that caused the system transition into the sleeping state) sets the sleep button
status bit (SLPBTN_STS) and wakes the system if the SLP_EN bit is set. OSPM responds by
clearing the sleep button status bit and waking the system.
4.8.2.2.2.2 Control Method Sleeping Button
The sleep button programming model can also use the generic hardware programming model. This
allows the sleep button to reside in any of the generic hardware address spaces (for example, the
embedded controller) instead of fixed space. If the sleep button is implemented via generic
hardware, then the OEM needs to define the sleep button as a device with an _HID object value of
“PNP0C0E”, which then identifies this device as the sleep button to OSPM. The AML event handler
then generates a Notify command to notify OSPM that a sleep button event was generated. While in
the working state, a sleep button press is a user request to transition the system into the sleeping (G1)
state. In these cases the sleep button event handler issues the Notify command with the device
specific code of 0x80. This will indicate to OSPM to pass control to the sleep button driver
(PNP0C0E) with the knowledge that the user is requesting a transition out of the G0 state. Upon
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