Documentation: gpio: documentation for optional getters functions
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>
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@ -53,7 +53,20 @@ with IS_ERR() (they will never return a NULL pointer). -ENOENT will be returned
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if and only if no GPIO has been assigned to the device/function/index triplet,
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other error codes are used for cases where a GPIO has been assigned but an error
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occurred while trying to acquire it. This is useful to discriminate between mere
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errors and an absence of GPIO for optional GPIO parameters.
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errors and an absence of GPIO for optional GPIO parameters. For the common
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pattern where a GPIO is optional, the gpiod_get_optional() and
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gpiod_get_index_optional() functions can be used. These functions return NULL
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instead of -ENOENT if no GPIO has been assigned to the requested function:
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struct gpio_desc *gpiod_get_optional(struct device *dev,
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const char *con_id,
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enum gpiod_flags flags)
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struct gpio_desc *gpiod_get_index_optional(struct device *dev,
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const char *con_id,
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unsigned int index,
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enum gpiod_flags flags)
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Device-managed variants of these functions are also defined:
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@ -65,6 +78,15 @@ Device-managed variants of these functions are also defined:
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unsigned int idx,
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enum gpiod_flags flags)
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struct gpio_desc *devm_gpiod_get_optional(struct device *dev,
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const char *con_id,
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enum gpiod_flags flags)
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struct gpio_desc * devm_gpiod_get_index_optional(struct device *dev,
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const char *con_id,
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unsigned int index,
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enum gpiod_flags flags)
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A GPIO descriptor can be disposed of using the gpiod_put() function:
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void gpiod_put(struct gpio_desc *desc)
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