diff options
| -rw-r--r-- | Documentation/gpio/consumer.txt | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt index 76546324e968..6ce544191ca6 100644 --- a/Documentation/gpio/consumer.txt +++ b/Documentation/gpio/consumer.txt @@ -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, 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 -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: @@ -65,6 +78,15 @@ Device-managed variants of these functions are also defined: unsigned int idx, 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: void gpiod_put(struct gpio_desc *desc) |