Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
4.8.4.1.2.1 General-Purpose Event 1 Status Register
Register Location: System I/O or System Memory Space
Default Value:
00h
Attribute:
Read/Write
Size:
GPE1_BLK_LEN/2
The general -purpose event 1 status register contains the general-purpose event status bits. Each
available status bit in this register corresponds to the bit with the same bit position in the GPE1_EN
register. Each available status bit in this register is set when the event is active, and can only be
cleared by software writing a “1” to its respective bit position. For the general-purpose event
registers, unimplemented bits are ignored by the operating system.
Each status bit can optionally wake the system if asserted when the system is in a sleeping state with
its respective enable bit set.
OSPM accesses GPE registers through byte accesses (regardless of their length).
4.8.4.1.2.2 General-Purpose Event 1 Enable Register
Register Location: System I/O or System Memory Space
Default Value:
00h
Attribute:
Read/Write
Size:
GPE1_BLK_LEN/2
The general-purpose event 1 enable register contains the general-purpose event enable. Each
available enable bit in this register corresponds to the bit with the same bit position in the
GPE1_STS register. The enable bits work similarly to how the enable bits in the fixed-event
registers are defined: When the enable bit is set, a set status bit in the corresponding status bit will
generate an SCI bit.
OSPM accesses GPE registers through byte accesses (regardless of their length).
4.8.4.2 Example Generic Devices
This section points out generic devices with specific ACPI driver support.
4.8.4.2.1 Lid Switch
The Lid switch is an optional feature present in most “clam shell” style mobile computers. It can be
used by the OS as policy input for sleeping the system, or for waking the system from a sleeping
state. If used, then the OEM needs to define the lid switch as a device with an _HID object value of
“PNP0C0D”, which identifies this device as the lid switch to OSPM. The Lid device needs to
contain a control method that returns its status. The Lid event handler AML code reconfigures the lid
hardware (if it needs to) to generate an event in the other direction, clear the status, and then notify
OSPM of the event.
Example hardware and ASL code is shown below for such a design.
Momentary Normally
Open push button
LID_POL
8 ms
Debounce
LID_STS
Figure 4-22 Example Generic Address Space Lid Switch Logic
98 April, 2015 Version 6.0