[PATCH 04/12] gpiolib: add support for gpiod_get_index and gpiod_get_index_optional

[Marco Felsch <m.felsch@pengutronix.de>]

Add Linux compatible APIs to make it easier to port code from Linux to
barebox. This aligns the GPIO label naming scheme with Linux too.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
 drivers/gpio/gpiolib.c        | 62 +++++++++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h | 26 +++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 146eaf9af138..55beaba6acbc 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -22,6 +22,8 @@ struct gpio_desc {
 	u32 flags; /* OR-d enum of_gpio_flags */
 };
 
+#define gpiod_not_found(desc)           (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)
+
 /*
  * This descriptor validation needs to be inserted verbatim into each
  * function taking a descriptor, so we need to use a preprocessor
@@ -1053,6 +1055,66 @@ struct gpio_desc *dev_gpiod_get_index(struct device *dev,
 	return ret ? ERR_PTR(ret): desc;
 }
 
+/**
+ * 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
+ * @idx:	index of the GPIO to obtain in the consumer
+ * @flags:	optional GPIO initialization flags
+ *
+ * This variant of gpiod_get() allows to access GPIOs other than the first
+ * defined one for functions that define several GPIOs.
+ *
+ * Returns:
+ * A valid GPIO descriptor, -ENOENT if no GPIO has been assigned to the
+ * requested function and/or index, or another IS_ERR() code if an error
+ * occurred while trying to acquire the GPIO.
+ */
+struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
+					       const char *con_id,
+					       unsigned int idx,
+					       enum gpiod_flags flags)
+{
+	struct device_node *np = dev_of_node(dev);
+	const char *devname = dev ? dev_name(dev) : "?";
+	const char *label = con_id ?: devname;
+
+	return dev_gpiod_get_index(dev, np, con_id, idx, flags, label);
+}
+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
+ * @flags: optional GPIO initialization flags
+ *
+ * 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.
+ *
+ * Returns:
+ * A valid GPIO descriptor, NULL if no GPIO has been assigned to the
+ * requested function and/or index, or another IS_ERR() code if an error
+ * occurred while trying to acquire the GPIO.
+ */
+struct gpio_desc *__must_check gpiod_get_index_optional(struct device *dev,
+							const char *con_id,
+							unsigned int index,
+							enum gpiod_flags flags)
+{
+	struct gpio_desc *desc;
+
+	desc = gpiod_get_index(dev, con_id, index, flags);
+	if (gpiod_not_found(desc))
+		return NULL;
+
+	return desc;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_index_optional);
+
 /**
  * gpiod_count - return the number of GPIOs associated with a device / function
  *		or -ENOENT if no GPIO has been assigned to the requested function
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index f0d5bf7b255b..34e5795cbc07 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -86,6 +86,16 @@ void gpiod_put(struct gpio_desc *desc);
 
 int gpiod_count(struct device *dev, const char *con_id);
 
+struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
+					       const char *con_id,
+					       unsigned int idx,
+					       enum gpiod_flags flags);
+
+struct gpio_desc *__must_check gpiod_get_index_optional(struct device *dev,
+							const char *con_id,
+							unsigned int index,
+							enum gpiod_flags flags);
+
 struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
 						const char *con_id,
 						enum gpiod_flags flags);
@@ -167,6 +177,22 @@ static inline int gpiod_count(struct device *dev, const char *con_id)
 	return 0;
 }
 
+static inline struct gpio_desc *__must_check
+gpiod_get_index(struct device *dev,
+		const char *con_id,
+		unsigned int idx,
+		enum gpiod_flags flags)
+{
+	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, enum gpiod_flags flags)
+{
+	return NULL;
+}
+
 static inline struct gpio_descs *__must_check
 gpiod_get_array(struct device *dev, const char *con_id, enum gpiod_flags flags)
 {
-- 
2.39.5