gpiolib: Implement devm_gpio_request_one()

Allow drivers to use the modern request and configure idiom together
with devres.

As with plain gpio_request() and gpio_request_one() we can't implement
the old school version in terms of _one() as this would force the
explicit selection of a direction in gpio_request() which could break
systems if we pick the wrong one.  Implementing devm_gpio_request_one()
in terms of devm_gpio_request() would needlessly complicate things or
lead to duplication from the unmanaged version depending on how it's
done.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

3 files changed, 37 insertions, 0 deletions

diff --git a/drivers/gpio/devres.c b/drivers/gpio/devres.c
index 3dd29399cef5..d21a9ff38551 100644
--- a/drivers/gpio/devres.c
+++ b/drivers/gpio/devres.c
@@ -71,6 +71,35 @@ int devm_gpio_request(struct device *dev, unsigned gpio, const char *label)
 EXPORT_SYMBOL(devm_gpio_request);
 
 /**
+ *      devm_gpio_request_one - request a single GPIO with initial setup
+ *      @dev:   device to request for
+ *      @gpio:  the GPIO number
+ *      @flags: GPIO configuration as specified by GPIOF_*
+ *      @label: a literal description string of this GPIO
+ */
+int devm_gpio_request_one(struct device *dev, unsigned gpio,
+                          unsigned long flags, const char *label)
+{
+        unsigned *dr;
+        int rc;
+
+        dr = devres_alloc(devm_gpio_release, sizeof(unsigned), GFP_KERNEL);
+        if (!dr)
+                return -ENOMEM;
+
+        rc = gpio_request_one(gpio, flags, label);
+        if (rc) {
+                devres_free(dr);
+                return rc;
+        }
+
+        *dr = gpio;
+        devres_add(dev, dr);
+
+        return 0;
+}
+
+/**
  *      devm_gpio_free - free an interrupt
  *      @dev: device to free gpio for
  *      @gpio: gpio to free
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 5f52690c3c8f..4ead12332c66 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -179,6 +179,8 @@ extern void gpio_free_array(const struct gpio *array, size_t num);
 
 /* bindings for managed devices that want to request gpios */
 int devm_gpio_request(struct device *dev, unsigned gpio, const char *label);
+int devm_gpio_request_one(struct device *dev, unsigned gpio,
+                          unsigned long flags, const char *label);
 void devm_gpio_free(struct device *dev, unsigned int gpio);
 
 #ifdef CONFIG_GPIO_SYSFS
diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index 7a8816a1a0d8..f07fc2d08159 100644
--- a/include/linux/gpio.h
+++ b/include/linux/gpio.h
@@ -106,6 +106,12 @@ static inline int gpio_request_one(unsigned gpio,
         return -ENOSYS;
 }
 
+static inline int devm_gpio_request_one(struct device *dev, unsigned gpio,
+                                        unsigned long flags, const char *label)
+{
+        return -ENOSYS;
+}
+
 static inline int gpio_request_array(const struct gpio *array, size_t num)
 {
         return -ENOSYS;