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SubjectRe: [PATCH 6/6] gpio / ACPI: Add support for ACPI GPIO operation regions
On Tue, Feb 25, 2014 at 03:55:02PM +0100, Rafael J. Wysocki wrote:
> On Monday, February 24, 2014 06:00:11 PM Mika Westerberg wrote:
> > GPIO operation regions is a new feature introduced in ACPI 5.0
> > specification. This feature adds a way for platform ASL code to call back
> > to OS GPIO driver and toggle GPIO pins.
> >
> > An example ASL code from Lenovo Miix 2 tablet with only relevant part
> > listed:
> >
> > Device (\_SB.GPO0)
> > {
> > Name (AVBL, Zero)
> > Method (_REG, 2, NotSerialized)
> > {
> > If (LEqual (Arg0, 0x08))
> > {
> > // Marks the region available
> > Store (Arg1, AVBL)
> > }
> > }
> >
> > OperationRegion (GPOP, GeneralPurposeIo, Zero, 0x0C)
> > Field (GPOP, ByteAcc, NoLock, Preserve)
> > {
> > Connection (
> > GpioIo (Exclusive, PullDefault, 0, 0, IoRestrictionOutputOnly,
> > "\\_SB.GPO0", 0x00, ResourceConsumer,,)
> > {
> > 0x003B
> > }
> > ),
> > SHD3, 1,
> > }
> > }
> >
> > Device (SHUB)
> > {
> > Method (_PS0, 0, Serialized)
> > {
> > If (LEqual (\_SB.GPO0.AVBL, One))
> > {
> > Store (One, \_SB.GPO0.SHD3)
> > Sleep (0x32)
> > }
> > }
> > Method (_PS3, 0, Serialized)
> > {
> > If (LEqual (\_SB.GPO0.AVBL, One))
> > {
> > Store (Zero, \_SB.GPO0.SHD3)
> > }
> > }
> > }
> >
> > The sensor hub (SHUB) device uses GPIO connection SHD3 to power the device
> > whenever the GPIO operation region is available.
>
> I would add more explanation of the ASL above here. Basically, how it is
> supposed to work and what's the handler's role in it.

OK, I will do that in the next revision.

> > Implement the support by registering GPIO operation region handlers for all
> > GPIO devices that have an ACPI handle. First time the GPIO is used by the
> > ASL code we make sure that the GPIO stays requested until the GPIO chip
> > driver itself is unloaded. If we find out that the GPIO is already
> > requested we just toggle it according to the value got from ASL code.
>
> The patch itself looks good to me.

Thanks for reviewing this :)


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