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| author | Mika Westerberg <mika.westerberg@linux.intel.com> | 2013-10-10 11:01:11 +0300 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2013-10-19 23:32:50 +0200 |
| commit | 45f394391f93596782c6a5ec14f0a5428f60f9b3 (patch) | |
| tree | 12e3c0a5b9f141ce53131cfd47bfda5cd63b428a /Documentation | |
| parent | e01f440a689aeb2d0e81c696fe2069f8d01d5d49 (diff) | |
| download | linux-rpi3-45f394391f93596782c6a5ec14f0a5428f60f9b3.tar.gz linux-rpi3-45f394391f93596782c6a5ec14f0a5428f60f9b3.tar.bz2 linux-rpi3-45f394391f93596782c6a5ec14f0a5428f60f9b3.zip | |
gpiolib / ACPI: document the GPIO descriptor based interface
In addition to the existing ACPI specific GPIO interface, document the new
descriptor based GPIO interface in Documentation/acpi/enumeration.txt, so
it is clear that this new interface is preferred over the ACPI specific
version.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/acpi/enumeration.txt | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt index aca4e69121b7..b994bcb32b92 100644 --- a/Documentation/acpi/enumeration.txt +++ b/Documentation/acpi/enumeration.txt @@ -295,10 +295,6 @@ These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0" specifies the path to the controller. In order to use these GPIOs in Linux we need to translate them to the Linux GPIO numbers. -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 @@ -322,3 +318,25 @@ suitable to the gpiolib before passing them. In case of GpioInt resource an additional call to gpio_to_irq() must be done before calling request_irq(). + +Note that the above API is ACPI specific and not recommended for drivers +that need to support non-ACPI systems. The recommended way is to use +the descriptor based GPIO interfaces. The above example looks like this +when converted to the GPIO desc: + + #include <linux/gpio/consumer.h> + ... + + struct gpio_desc *irq_desc, *power_desc; + + irq_desc = gpiod_get_index(dev, NULL, 1); + if (IS_ERR(irq_desc)) + /* handle error */ + + power_desc = gpiod_get_index(dev, NULL, 0); + if (IS_ERR(power_desc)) + /* handle error */ + + /* Now we can use the GPIO descriptors */ + +See also Documentation/gpio.txt. |