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authorMika Westerberg <mika.westerberg@linux.intel.com>2013-10-10 11:01:11 +0300
committerLinus Walleij <linus.walleij@linaro.org>2013-10-19 23:32:50 +0200
commit45f394391f93596782c6a5ec14f0a5428f60f9b3 (patch)
tree12e3c0a5b9f141ce53131cfd47bfda5cd63b428a /Documentation/acpi
parente01f440a689aeb2d0e81c696fe2069f8d01d5d49 (diff)
downloadkernel-45f394391f93596782c6a5ec14f0a5428f60f9b3.tar.gz
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/acpi')
-rw-r--r--Documentation/acpi/enumeration.txt26
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.