On Thu, Apr 4, 2013 at 11:38 AM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> On Thu, Apr 04, 2013 at 11:19:53AM +0200, Benjamin Tissoires wrote:
>> Hi Mika,
>>
>> On Wed, Apr 3, 2013 at 12:56 PM, Mika Westerberg
>> <mika.westerberg@xxxxxxxxxxxxxxx> wrote:
>> > Instead of open-coding ACPI GPIO resource lookup in each driver, we provide
>> > a helper function analogous to Device Tree version that allows drivers to
>> > specify which GPIO resource they are interested (using an index to the GPIO
>> > resources). The function then finds out the correct resource, translates
>> > the ACPI GPIO number to the corresponding Linux GPIO number and returns
>> > that.
>> >
>> > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
>> > ---
>> > Documentation/acpi/enumeration.txt | 32 ++++++++++++++-
>> > drivers/gpio/gpiolib-acpi.c | 77 ++++++++++++++++++++++++++++++++++++
>> > include/linux/acpi_gpio.h | 17 ++++++++
>> > 3 files changed, 125 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
>> > index 94a6561..b0d5410 100644
>> > --- a/Documentation/acpi/enumeration.txt
>> > +++ b/Documentation/acpi/enumeration.txt
>> > @@ -199,6 +199,8 @@ the device to the driver. For example:
>> > {
>> > Name (SBUF, ResourceTemplate()
>> > {
>> > + ...
>> > + // Used to power on/off the device
>> > GpioIo (Exclusive, PullDefault, 0x0000, 0x0000,
>> > IoRestrictionOutputOnly, "\\_SB.PCI0.GPI0",
>> > 0x00, ResourceConsumer,,)
>> > @@ -206,10 +208,20 @@ the device to the driver. For example:
>> > // Pin List
>> > 0x0055
>> > }
>> > +
>> > + // Interrupt for the device
>> > + GpioInt (Edge, ActiveHigh, ExclusiveAndWake, PullNone,
>> > + 0x0000, "\\_SB.PCI0.GPI0", 0x00, ResourceConsumer,,)
>>
>> Sorry for coming late in the GPIO ACPI discussion, but when I see this
>> documentation, I wonder:
>> wouldn't it be feasible to find the correct GPIO by its type? Here, we
>> have a GpioIo and a GpioInt, and I bet this would be sometime more
>> useful to request the first GpioInt without knowing the correct order
>> of declarations.
>
> Why not. But then again you can always check the type returned in the
> acpi_gpio_info structure and pick the first GpioInt (if you have multiple
> GPIO resources).
>
>> It may be feasible by walking the tree, but a helper would be of great
>> help (thinking at i2c-hid here, which can not rely on indexes in the
>> DSDT).
>
> Well, index is the only thing we can rely on unfortunately. There's nothing
> like names or anything like that.
>
> What I've seen from ACPI enumerated i2c-hid devices there is only one GPIO
> resource (GpioInt) declared.
Ok, thanks for the answer. I guess the idea would be to pick the index
0, check the type, and try indexes 1 or 2 if it's not GpioInt. I bet
there will be devices with more than one Gpio as most of I2C input
device have a reset line (except if Microsoft forces them not to have
one).
Cheers,
Benjamin
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