ACPICA 20101209:

Completed the major overhaul of the GPE support code that was begun in July
2010. Major features include: removal of _PRW execution in ACPICA (host
executes _PRWs anyway), cleanup of "wake" GPE interfaces and processing,
changes to existing interfaces, simplification of GPE handler operation, and
a handful of new interfaces:

    AcpiUpdateAllGpes
    AcpiFinishGpe
    AcpiSetupGpeForWake
    AcpiSetGpeWakeMask

ACPICA 20100331:

Completed a major update for the GPE support in order to improve support for
shared GPEs and to simplify both host OS and ACPICA code. Added a reference
count mechanism to support shared GPEs that require multiple device drivers.
Several external interfaces have changed. One external interface has been
removed. One new external interface was added. Most of the GPE external
interfaces now use the GPE spinlock instead of the events mutex (and the
Flags parameter for many GPE interfaces has been removed.) See the updated
ACPICA Programmer Reference for details. Matthew Garrett, Bob Moore, Rafael
Wysocki. ACPICA BZ 831.

Changed:
    AcpiEnableGpe, AcpiDisableGpe, AcpiClearGpe, AcpiGetGpeStatus
Removed:
    AcpiSetGpeType
New:
    AcpiSetGpe

ACPICA 20100702:

Implemented several updates to the recently added GPE reference count
support. The model for "wake" GPEs is changing to give the host OS complete
control of these GPEs. Eventually, the ACPICA core will not execute any _PRW
methods, since the host already must execute them. Also, additional changes
were made to help ensure that the reference counts are kept in proper
synchronization with reality. Rafael J. Wysocki.

1) Ensure that GPEs are not enabled twice during initialization.
2) Ensure that GPE enable masks stay in sync with the reference count.
3) Do not inadvertently enable GPEs when writing GPE registers.
4) Remove the internal wake reference counter and add new AcpiGpeWakeup
interface. This interface will set or clear individual GPEs for wakeup.
5) Remove GpeType argument from AcpiEnable and AcpiDisable. These interfaces
are now used for "runtime" GPEs only.

(jruoho)