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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
parent 91329132c9
commit 29a1f2333e
4 changed files with 128 additions and 0 deletions
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2
Documentation/driver-model/devres.txt
View file

@ -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()

43
drivers/gpio/devres.c
View file

@ -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

43
drivers/gpio/gpiolib.c
View file

@ -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

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();