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Date: Fri, 25 Apr 2014 17:10:06 +0200
From: Thierry Reding <thierry.reding@...il.com>
To: Linus Walleij <linus.walleij@...aro.org>,
Alexandre Courbot <gnurou@...il.com>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] gpio: Add helpers for optional GPIOs
From: Thierry Reding <treding@...dia.com>
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@...dia.com>
---
Documentation/driver-model/devres.txt | 2 ++
drivers/gpio/devres.c | 43 +++++++++++++++++++++++++++++++++++
drivers/gpio/gpiolib.c | 43 +++++++++++++++++++++++++++++++++++
include/linux/gpio/consumer.h | 40 ++++++++++++++++++++++++++++++++
4 files changed, 128 insertions(+)
diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index 7b7d1c4d06bf..4796e2ab3349 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -314,4 +314,6 @@ SPI
GPIO
devm_gpiod_get()
devm_gpiod_get_index()
+ devm_gpiod_get_optional()
+ devm_gpiod_get_index_optional()
devm_gpiod_put()
diff --git a/drivers/gpio/devres.c b/drivers/gpio/devres.c
index 307464fd015f..65978cf85f79 100644
--- a/drivers/gpio/devres.c
+++ b/drivers/gpio/devres.c
@@ -52,6 +52,22 @@ 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
* @con_id: function within the GPIO consumer
@@ -87,6 +103,33 @@ 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
*
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index f284e23c78ef..431fddb0dfec 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2732,6 +2732,22 @@ 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
* @con_id: function within the GPIO consumer
@@ -2794,6 +2810,33 @@ 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
*
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index bed128e8f4b1..6a37ef0dc59c 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -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();
--
1.9.2
--
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