Advanced Configuration and Power Interface Specification

ACPI-Defined Devices and Device-Specific Objects
Return Value:
An Integer containing the current lid status
0 – The lid is closed
Non-zero –
The lid is open
9.5 Control Method Power and Sleep Button Devices
The system’s power or sleep button can either be implemented using the fixed register space as
defined in Section 4.8.2.2, “Buttons,” or implemented in AML code as a control method power
button device. In either case, the power button override function or similar unconditional system
power or reset functionality is still implemented in external hardware.
To implement a control method power-button or sleep-button device, implement AML code that
delivers two types of notifications concerning the device. The first is Notify(Object, 0x80) to signal
that the button was pressed while the system was in the S0 state to indicate that the user wants the
machine to transition from S0 to some sleeping state. The other notification is Notify(Object, 0x2) to
signal that the button was pressed while the system was in an S1 to S4 state and to cause the system
to wake. When the button is used to wake the system, the wake notification (Notify(Object, 0x2))
must occur after OSPM actually wakes, and a button-pressed notification (Notify(Object, 0x80))
must not occur.
The Wake Notification indicates that the system is awake because the user pressed the button and
therefore a complete system resume should occur (for example, turn on the display immediately, and
so on).
9.6 Embedded Controller Device
Operation of the embedded controller host controller register interface requires that the embedded
controller driver has ACPI-specific knowledge. Specifically, the driver needs to provide an
“operational region” of its embedded controller address space, and needs to use an ACPI event to
service the host controller interface. For more information about an ACPI-compatible embedded
controller device, see Section 12, “ACPI Embedded Controller Interface Specification.”
The embedded controller device object provides the _HID of an ACPI-integrated embedded
controller device of PNP0C09 and the host controller register locations using the device standard
methods. In addition, the embedded controller must be declared as a named device object that
includes a set of control methods. For more information, see Section 12.11, “Defining an Embedded
Controller Device in ACPI Namespace”).
9.7 Generic Container Device
A generic container device is a bridge that does not require a special OS driver because the bridge
does not provide or require any features not described within the normal ACPI device functions. The
resources the bridge requires are specified via normal ACPI resource mechanisms. Device
enumeration for child devices is supported via ACPI namespace device enumeration and OS drivers
require no other features of the bus. Such a bridge device is identified with the Plug and Play ID of
PNP0A05 or PNP0A06.
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