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Commit 29a1f233 authored by Thierry Reding's avatar Thierry Reding Committed by Linus Walleij
Browse files

gpio: Add helpers for optional GPIOs 



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: default avatarThierry Reding <treding@nvidia.com>
Reviewed-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 91329132

Documentation/driver-model/devres.txt

+2 −0
Original line number Diff line number Diff line
@@ -312,4 +312,6 @@ SPI 
GPIO

  devm_gpiod_get()

  devm_gpiod_get_index()

  devm_gpiod_get_optional()

  devm_gpiod_get_index_optional()

  devm_gpiod_put()

drivers/gpio/devres.c

+43 −0
Original line number Diff line number Diff line
@@ -51,6 +51,22 @@ struct gpio_desc *__must_check devm_gpiod_get(struct device *dev, 
}

EXPORT_SYMBOL(devm_gpiod_get);



/**

 * devm_gpiod_get_optional - Resource-managed gpiod_get_optional()

 * @dev: GPIO consumer

 * @con_id: function within the GPIO consumer

 *

 * Managed gpiod_get_optional(). GPIO descriptors returned from this function

 * are automatically disposed on driver detach. See gpiod_get_optional() for

 * detailed information about behavior and return values.

 */

struct gpio_desc *__must_check devm_gpiod_get_optional(struct device *dev,

						       const char *con_id)

{

	return devm_gpiod_get_index_optional(dev, con_id, 0);

}

EXPORT_SYMBOL(devm_gpiod_get_optional);



/**

 * devm_gpiod_get_index - Resource-managed gpiod_get_index()

 * @dev:	GPIO consumer
@@ -86,6 +102,33 @@ struct gpio_desc *__must_check devm_gpiod_get_index(struct device *dev, 
}

EXPORT_SYMBOL(devm_gpiod_get_index);



/**

 * devm_gpiod_get_index_optional - Resource-managed gpiod_get_index_optional()

 * @dev: GPIO consumer

 * @con_id: function within the GPIO consumer

 * @index: index of the GPIO to obtain in the consumer

 *

 * Managed gpiod_get_index_optional(). GPIO descriptors returned from this

 * function are automatically disposed on driver detach. See

 * gpiod_get_index_optional() for detailed information about behavior and

 * return values.

 */

struct gpio_desc *__must_check devm_gpiod_get_index_optional(struct device *dev,

							     const char *con_id,

							     unsigned int index)

{

	struct gpio_desc *desc;



	desc = devm_gpiod_get_index(dev, con_id, index);

	if (IS_ERR(desc)) {

		if (PTR_ERR(desc) == -ENOENT)

			return NULL;

	}



	return desc;

}

EXPORT_SYMBOL(devm_gpiod_get_index_optional);



/**

 * devm_gpiod_put - Resource-managed gpiod_put()

 * @desc:	GPIO descriptor to dispose of

drivers/gpio/gpiolib.c

+43 −0
Original line number Diff line number Diff line
@@ -2737,6 +2737,22 @@ struct gpio_desc *__must_check gpiod_get(struct device *dev, const char *con_id) 
}

EXPORT_SYMBOL_GPL(gpiod_get);



/**

 * gpiod_get_optional - obtain an optional GPIO for a given GPIO function

 * @dev: GPIO consumer, can be NULL for system-global GPIOs

 * @con_id: function within the GPIO consumer

 *

 * This is equivalent to gpiod_get(), except that when no GPIO was assigned to

 * the requested function it will return NULL. This is convenient for drivers

 * that need to handle optional GPIOs.

 */

struct gpio_desc *__must_check gpiod_get_optional(struct device *dev,

						  const char *con_id)

{

	return gpiod_get_index_optional(dev, con_id, 0);

}

EXPORT_SYMBOL_GPL(gpiod_get_optional);



/**

 * gpiod_get_index - obtain a GPIO from a multi-index GPIO function

 * @dev:	GPIO consumer, can be NULL for system-global GPIOs
@@ -2799,6 +2815,33 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev, 
}

EXPORT_SYMBOL_GPL(gpiod_get_index);



/**

 * gpiod_get_index_optional - obtain an optional GPIO from a multi-index GPIO

 *                            function

 * @dev: GPIO consumer, can be NULL for system-global GPIOs

 * @con_id: function within the GPIO consumer

 * @index: index of the GPIO to obtain in the consumer

 *

 * This is equivalent to gpiod_get_index(), except that when no GPIO with the

 * specified index was assigned to the requested function it will return NULL.

 * This is convenient for drivers that need to handle optional GPIOs.

 */

struct gpio_desc *__must_check gpiod_get_index_optional(struct device *dev,

							const char *con_id,

							unsigned int index)

{

	struct gpio_desc *desc;



	desc = gpiod_get_index(dev, con_id, index);

	if (IS_ERR(desc)) {

		if (PTR_ERR(desc) == -ENOENT)

			return NULL;

	}



	return desc;

}

EXPORT_SYMBOL_GPL(gpiod_get_index_optional);



/**

 * gpiod_put - dispose of a GPIO descriptor

 * @desc:	GPIO descriptor to dispose of

include/linux/gpio/consumer.h

+40 −0
Original line number Diff line number Diff line
@@ -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();