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Documentation: gpio: documentation for optional getters functions

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Add a mention about the _optional variants of (devm_)gpiod_get*().

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Alexandre Courbot 2014-08-18 09:39:01 -07:00 committed by Linus Walleij
parent 52addcf9d6
commit 1b11a9b9e0
1 changed files with 23 additions and 1 deletions
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24
Documentation/gpio/consumer.txt
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@ -53,7 +53,20 @@ with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned
if and only if no GPIO has been assigned to the device/function/index triplet, if and only if no GPIO has been assigned to the device/function/index triplet,
other error codes are used for cases where a GPIO has been assigned but an error other error codes are used for cases where a GPIO has been assigned but an error
occurred while trying to acquire it. This is useful to discriminate between mere occurred while trying to acquire it. This is useful to discriminate between mere
errors and an absence of GPIO for optional GPIO parameters. errors and an absence of GPIO for optional GPIO parameters. For the common
pattern where a GPIO is optional, the gpiod_get_optional() and
gpiod_get_index_optional() functions can be used. These functions return NULL
instead of -ENOENT if no GPIO has been assigned to the requested function:
struct gpio_desc *gpiod_get_optional(struct device *dev,
const char *con_id,
enum gpiod_flags flags)
struct gpio_desc *gpiod_get_index_optional(struct device *dev,
const char *con_id,
unsigned int index,
enum gpiod_flags flags)
Device-managed variants of these functions are also defined: Device-managed variants of these functions are also defined:
@ -65,6 +78,15 @@ Device-managed variants of these functions are also defined:
unsigned int idx, unsigned int idx,
enum gpiod_flags flags) enum gpiod_flags flags)
struct gpio_desc *devm_gpiod_get_optional(struct device *dev,
const char *con_id,
enum gpiod_flags flags)
struct gpio_desc * devm_gpiod_get_index_optional(struct device *dev,
const char *con_id,
unsigned int index,
enum gpiod_flags flags)
A GPIO descriptor can be disposed of using the gpiod_put() function: A GPIO descriptor can be disposed of using the gpiod_put() function:
void gpiod_put(struct gpio_desc *desc) void gpiod_put(struct gpio_desc *desc)