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.
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).
Cheers,
Benjamin
> + {
> + // Pin list
> + 0x0058
> + }
> +
> ...
>
> - Return (SBUF)
> }
> +
> + Return (SBUF)
> }
>
> These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0"
> @@ -220,6 +232,24 @@ The driver can do this by including <linux/acpi_gpio.h> and then calling
> acpi_get_gpio(path, gpio). This will return the Linux GPIO number or
> negative errno if there was no translation found.
>
> +In a simple case of just getting the Linux GPIO number from device
> +resources one can use acpi_get_gpio_by_index() helper function. It takes
> +pointer to the device and index of the GpioIo/GpioInt descriptor in the
> +device resources list. For example:
> +
> + int gpio_irq, gpio_power;
> + int ret;
> +
> + gpio_irq = acpi_get_gpio_by_index(dev, 1, NULL);
> + if (gpio_irq < 0)
> + /* handle error */
> +
> + gpio_power = acpi_get_gpio_by_index(dev, 0, NULL);
> + if (gpio_power < 0)
> + /* handle error */
> +
> + /* Now we can use the GPIO numbers */
> +
> Other GpioIo parameters must be converted first by the driver to be
> suitable to the gpiolib before passing them.
>
[snipped]
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