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gpio: Add helpers for optional GPIOs

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Introduce gpiod_get_optional() and gpiod_get_index_optional() helpers
that make it easier for drivers to handle optional GPIOs.

Currently in order to handle optional GPIOs, a driver needs to special
case error handling for -ENOENT, such as this:

	gpio = gpiod_get(dev, "foo");
	if (IS_ERR(gpio)) {
		if (PTR_ERR(gpio) != -ENOENT)
			return PTR_ERR(gpio);

		gpio = NULL;
	}

	if (gpio) {
		/* set up GPIO */
	}

With these new helpers the above is reduced to:

	gpio = gpiod_get_optional(dev, "foo");
	if (IS_ERR(gpio))
		return PTR_ERR(gpio);

	if (gpio) {
		/* set up GPIO */
	}

While at it, device-managed variants of these functions are also
provided.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Thierry Reding 2014-04-25 17:10:06 +02:00 • committed by Linus Walleij
commit 29a1f2333e
4 changed files with 128 additions and 0 deletions
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40
include/linux/gpio/consumer.h
View file

@ -23,6 +23,12 @@ struct gpio_desc *__must_check gpiod_get(struct device *dev,
struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
const char *con_id,
unsigned int idx);
struct gpio_desc *__must_check gpiod_get_optional(struct device *dev,
const char *con_id);
struct gpio_desc *__must_check gpiod_get_index_optional(struct device *dev,
const char *con_id,
unsigned int index);
void gpiod_put(struct gpio_desc *desc);
struct gpio_desc *__must_check devm_gpiod_get(struct device *dev,
@ -30,6 +36,12 @@ struct gpio_desc *__must_check devm_gpiod_get(struct device *dev,
struct gpio_desc *__must_check devm_gpiod_get_index(struct device *dev,
const char *con_id,
unsigned int idx);
struct gpio_desc *__must_check devm_gpiod_get_optional(struct device *dev,
const char *con_id);
struct gpio_desc *__must_check
devm_gpiod_get_index_optional(struct device *dev, const char *con_id,
unsigned int index);
void devm_gpiod_put(struct device *dev, struct gpio_desc *desc);
int gpiod_get_direction(const struct gpio_desc *desc);
@ -73,6 +85,20 @@ static inline struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
{
return ERR_PTR(-ENOSYS);
}
static inline struct gpio_desc *__must_check
gpiod_get_optional(struct device *dev, const char *con_id)
{
return ERR_PTR(-ENOSYS);
}
static inline struct gpio_desc *__must_check
gpiod_get_index_optional(struct device *dev, const char *con_id,
unsigned int index)
{
return ERR_PTR(-ENOSYS);
}
static inline void gpiod_put(struct gpio_desc *desc)
{
might_sleep();
@ -93,6 +119,20 @@ struct gpio_desc *__must_check devm_gpiod_get_index(struct device *dev,
{
return ERR_PTR(-ENOSYS);
}
static inline struct gpio_desc *__must_check
devm_gpiod_get_optional(struct device *dev, const char *con_id)
{
return ERR_PTR(-ENOSYS);
}
static inline struct gpio_desc *__must_check
devm_gpiod_get_index_optional(struct device *dev, const char *con_id,
unsigned int index)
{
return ERR_PTR(-ENOSYS);
}
static inline void devm_gpiod_put(struct device *dev, struct gpio_desc *desc)
{
might_sleep();