gpio: add flags argument to gpiod_get*() functions

The huge majority of GPIOs have their direction and initial value set
right after being obtained by one of the gpiod_get() functions. The
integer GPIO API had gpio_request_one() that took a convenience flags
parameter allowing to specify an direction and value applied to the
returned GPIO. This feature greatly simplifies client code and ensures
errors are always handled properly.

A similar feature has been requested for the gpiod API. Since setting
the direction of a GPIO is so often the very next action done after
obtaining its descriptor, we prefer to extend the existing functions
instead of introducing new functions that would raise the
number of gpiod getters to 16 (!).

The drawback of this approach is that all gpiod clients need to be
updated. To limit the pain, temporary macros are introduced that allow
gpiod_get*() to be called with or without the extra flags argument. They
will be removed once all consumer code has been updated.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 65 insertions, 16 deletions

diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 05e53ccb708b..b7ce0c64c6f3 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -18,30 +18,79 @@ struct gpio_desc;
 
 #ifdef CONFIG_GPIOLIB
 
+#define GPIOD_FLAGS_BIT_DIR_SET		BIT(0)
+#define GPIOD_FLAGS_BIT_DIR_OUT		BIT(1)
+#define GPIOD_FLAGS_BIT_DIR_VAL		BIT(2)
+
+/**
+ * Optional flags that can be passed to one of gpiod_* to configure direction
+ * and output value. These values cannot be OR'd.
+ */
+enum gpiod_flags {
+	GPIOD_ASIS	= 0,
+	GPIOD_IN	= GPIOD_FLAGS_BIT_DIR_SET,
+	GPIOD_OUT_LOW	= GPIOD_FLAGS_BIT_DIR_SET | GPIOD_FLAGS_BIT_DIR_OUT,
+	GPIOD_OUT_HIGH	= GPIOD_FLAGS_BIT_DIR_SET | GPIOD_FLAGS_BIT_DIR_OUT |
+			  GPIOD_FLAGS_BIT_DIR_VAL,
+};
+
 /* Acquire and dispose GPIOs */
-struct gpio_desc *__must_check gpiod_get(struct device *dev,
-					 const char *con_id);
-struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
+struct gpio_desc *__must_check __gpiod_get(struct device *dev,
+					 const char *con_id,
+					 enum gpiod_flags flags);
+#define __gpiod_get(dev, con_id, flags, ...) __gpiod_get(dev, con_id, flags)
+#define gpiod_get(varargs...) __gpiod_get(varargs, 0)
+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,
+					       unsigned int idx,
+					       enum gpiod_flags flags);
+#define __gpiod_get_index(dev, con_id, index, flags, ...)		\
+	__gpiod_get_index(dev, con_id, index, flags)
+#define gpiod_get_index(varargs...) __gpiod_get_index(varargs, 0)
+struct gpio_desc *__must_check __gpiod_get_optional(struct device *dev,
+						  const char *con_id,
+						  enum gpiod_flags flags);
+#define __gpiod_get_optional(dev, con_id, flags, ...)			\
+	__gpiod_get_optional(dev, con_id, flags)
+#define gpiod_get_optional(varargs...) __gpiod_get_optional(varargs, 0)
+struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 							const char *con_id,
-							unsigned int index);
+							unsigned int index,
+							enum gpiod_flags flags);
+#define __gpiod_get_index_optional(dev, con_id, index, flags, ...)	\
+	__gpiod_get_index_optional(dev, con_id, index, flags)
+#define gpiod_get_index_optional(varargs...)				\
+	__gpiod_get_index_optional(varargs, 0)
 
 void gpiod_put(struct gpio_desc *desc);
 
-struct gpio_desc *__must_check devm_gpiod_get(struct device *dev,
-					      const char *con_id);
-struct gpio_desc *__must_check devm_gpiod_get_index(struct device *dev,
+struct gpio_desc *__must_check __devm_gpiod_get(struct device *dev,
+					      const char *con_id,
+					      enum gpiod_flags flags);
+#define __devm_gpiod_get(dev, con_id, flags, ...)			\
+	__devm_gpiod_get(dev, con_id, flags)
+#define devm_gpiod_get(varargs...) __devm_gpiod_get(varargs, 0)
+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);
+						    unsigned int idx,
+						    enum gpiod_flags flags);
+#define __devm_gpiod_get_index(dev, con_id, index, flags, ...)		\
+	__devm_gpiod_get_index(dev, con_id, index, flags)
+#define devm_gpiod_get_index(varargs...) __devm_gpiod_get_index(varargs, 0)
+struct gpio_desc *__must_check __devm_gpiod_get_optional(struct device *dev,
+						       const char *con_id,
+						       enum gpiod_flags flags);
+#define __devm_gpiod_get_optional(dev, con_id, flags, ...)		\
+	__devm_gpiod_get_optional(dev, con_id, flags)
+#define devm_gpiod_get_optional(varargs...)				\
+	__devm_gpiod_get_optional(varargs, 0)
 struct gpio_desc *__must_check
-devm_gpiod_get_index_optional(struct device *dev, const char *con_id,
-			      unsigned int index);
+__devm_gpiod_get_index_optional(struct device *dev, const char *con_id,
+			      unsigned int index, enum gpiod_flags flags);
+#define __devm_gpiod_get_index_optional(dev, con_id, index, flags, ...)	\
+	__devm_gpiod_get_index_optional(dev, con_id, index, flags)
+#define devm_gpiod_get_index_optional(varargs...)			\
+	__devm_gpiod_get_index_optional(varargs, 0)
 
 void devm_gpiod_put(struct device *dev, struct gpio_desc *desc);