[PATCH v3 1/2] gpio: Add devm_fwnode_gpiod_get_optional() helpers

[Krzysztof Kozlowski <krzk@kernel.org>]

Add devm_fwnode_gpiod_get_optional() and
devm_fwnode_gpiod_get_index_optional() helpers, similar to regular
devm_gpiod optional versions.  Drivers getting GPIOs from a firmware
node might use it to remove some boilerplate code.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

---

Changes since v2:
1. Return NULL

Changes since v1:
1. New patch
---
 drivers/gpio/gpiolib-devres.c | 71 +++++++++++++++++++++++++++++++++++
 include/linux/gpio/consumer.h | 30 +++++++++++++++
 2 files changed, 101 insertions(+)

diff --git a/drivers/gpio/gpiolib-devres.c b/drivers/gpio/gpiolib-devres.c
index 7dbce4c4ebdf..f8476f6a65cc 100644
--- a/drivers/gpio/gpiolib-devres.c
+++ b/drivers/gpio/gpiolib-devres.c
@@ -184,6 +184,37 @@ struct gpio_desc *devm_gpiod_get_from_of_node(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_gpiod_get_from_of_node);
 
+/**
+ * devm_fwnode_gpiod_get_optional - Resource-managed fwnode_gpiod_get_index()
+ *                                  for optional GPIO
+ * @dev:	GPIO consumer
+ * @fwnode:	firmware node containing GPIO reference
+ * @con_id:	function within the GPIO consumer
+ * @flags:	GPIO initialization flags
+ * @label:	label to attach to the requested GPIO
+ *
+ * GPIO descriptors returned from this function are automatically disposed on
+ * driver detach.
+ *
+ * This is equivalent to devm_fwnode_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.
+ *
+ * On successful request the GPIO pin is configured in accordance with
+ * provided @flags.
+ */
+struct gpio_desc *devm_fwnode_gpiod_get_optional(struct device *dev,
+						 struct fwnode_handle *fwnode,
+						 const char *con_id,
+						 enum gpiod_flags flags,
+						 const char *label)
+{
+	return devm_fwnode_gpiod_get_index_optional(dev, fwnode, con_id, 0,
+						    flags, label);
+}
+EXPORT_SYMBOL_GPL(devm_fwnode_gpiod_get_optional);
+
 /**
  * devm_fwnode_gpiod_get_index - get a GPIO descriptor from a given node
  * @dev:	GPIO consumer
@@ -226,6 +257,46 @@ struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_fwnode_gpiod_get_index);
 
+/**
+ * devm_fwnode_gpiod_get_index_optional - Resource-managed fwnode_gpiod_get_index()
+ *                                        for optional GPIO
+ * @dev:	GPIO consumer
+ * @fwnode:	firmware node containing GPIO reference
+ * @con_id:	function within the GPIO consumer
+ * @index:	index of the GPIO to obtain in the consumer
+ * @flags:	GPIO initialization flags
+ * @label:	label to attach to the requested GPIO
+ *
+ * GPIO descriptors returned from this function are automatically disposed on
+ * driver detach.
+ *
+ * This is equivalent to devm_fwnode_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.
+ *
+ * On successful request the GPIO pin is configured in accordance with
+ * provided @flags.
+ */
+struct gpio_desc *devm_fwnode_gpiod_get_index_optional(struct device *dev,
+						       struct fwnode_handle *fwnode,
+						       const char *con_id, int index,
+						       enum gpiod_flags flags,
+						       const char *label)
+{
+	struct gpio_desc *desc;
+
+	desc = devm_fwnode_gpiod_get_index(dev, fwnode, con_id, index, flags,
+					   label);
+	if (IS_ERR(desc)) {
+		if (PTR_ERR(desc) == -ENOENT)
+			return NULL;
+	}
+
+	return desc;
+}
+EXPORT_SYMBOL_GPL(devm_fwnode_gpiod_get_index_optional);
+
 /**
  * devm_gpiod_get_index_optional - Resource-managed gpiod_get_index_optional()
  * @dev: GPIO consumer
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 901aab89d025..7854d80b1e9a 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -183,11 +183,21 @@ struct gpio_desc *fwnode_gpiod_get_index(struct fwnode_handle *fwnode,
 					 const char *con_id, int index,
 					 enum gpiod_flags flags,
 					 const char *label);
+struct gpio_desc *devm_fwnode_gpiod_get_optional(struct device *dev,
+						 struct fwnode_handle *fwnode,
+						 const char *con_id,
+						 enum gpiod_flags flags,
+						 const char *label);
 struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 					      struct fwnode_handle *child,
 					      const char *con_id, int index,
 					      enum gpiod_flags flags,
 					      const char *label);
+struct gpio_desc *devm_fwnode_gpiod_get_index_optional(struct device *dev,
+						       struct fwnode_handle *fwnode,
+						       const char *con_id, int index,
+						       enum gpiod_flags flags,
+						       const char *label);
 
 #else /* CONFIG_GPIOLIB */
 
@@ -562,6 +572,16 @@ struct gpio_desc *fwnode_gpiod_get_index(struct fwnode_handle *fwnode,
 	return ERR_PTR(-ENOSYS);
 }
 
+static inline
+struct gpio_desc *devm_fwnode_gpiod_get_optional(struct device *dev,
+						 struct fwnode_handle *fwnode,
+						 const char *con_id,
+						 enum gpiod_flags flags,
+						 const char *label)
+{
+	return NULL;
+}
+
 static inline
 struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 					      struct fwnode_handle *fwnode,
@@ -572,6 +592,16 @@ struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 	return ERR_PTR(-ENOSYS);
 }
 
+static inline
+struct gpio_desc *devm_fwnode_gpiod_get_index_optional(struct device *dev,
+						       struct fwnode_handle *fwnode,
+						       const char *con_id, int index,
+						       enum gpiod_flags flags,
+						       const char *label)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_GPIOLIB */
 
 static inline
-- 
2.17.1