gpiolib: introduce fwnode_gpiod_get_index()

This introduces fwnode_gpiod_get_index() that iterates through common gpio
suffixes when trying to locate a GPIO within a given firmware node.

We also switch devm_fwnode_gpiod_get_index() to call
fwnode_gpiod_get_index() instead of iterating through GPIO suffixes on
its own.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20190913032240.50333-3-dmitry.torokhov@gmail.com
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib-devres.c

@@ -205,29 +205,15 @@ struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 					      enum gpiod_flags flags,
 					      const char *label)
 {
-	char prop_name[32]; /* 32 is max size of property name */
 	struct gpio_desc **dr;
 	struct gpio_desc *desc;
-	unsigned int i;
 
 	dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *),
 			  GFP_KERNEL);
 	if (!dr)
 		return ERR_PTR(-ENOMEM);
 
-	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+	desc = fwnode_gpiod_get_index(fwnode, con_id, index, flags, label);
-		if (con_id)
-			snprintf(prop_name, sizeof(prop_name), "%s-%s",
-					    con_id, gpio_suffixes[i]);
-		else
-			snprintf(prop_name, sizeof(prop_name), "%s",
-					    gpio_suffixes[i]);
-
-		desc = fwnode_get_named_gpiod(fwnode, prop_name, index, flags,
-					      label);
-		if (!IS_ERR(desc) || (PTR_ERR(desc) != -ENOENT))
-			break;
-	}
 	if (IS_ERR(desc)) {
 		devres_free(dr);
 		return desc;

drivers/gpio/gpiolib.c

@@ -4324,6 +4324,54 @@ static int platform_gpio_count(struct device *dev, const char *con_id)
 	return count;
 }
 
+/**
+ * fwnode_gpiod_get_index - obtain a GPIO from firmware node
+ * @fwnode:	handle of the firmware node
+ * @con_id:	function within the GPIO consumer
+ * @index:	index of the GPIO to obtain for the consumer
+ * @flags:	GPIO initialization flags
+ * @label:	label to attach to the requested GPIO
+ *
+ * This function can be used for drivers that get their configuration
+ * from opaque firmware.
+ *
+ * The function properly finds the corresponding GPIO using whatever is the
+ * underlying firmware interface and then makes sure that the GPIO
+ * descriptor is requested before it is returned to the caller.
+ *
+ * Returns:
+ * On successful request the GPIO pin is configured in accordance with
+ * provided @flags.
+ *
+ * In case of error an ERR_PTR() is returned.
+ */
+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 *desc;
+	char prop_name[32]; /* 32 is max size of property name */
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
+		if (con_id)
+			snprintf(prop_name, sizeof(prop_name), "%s-%s",
+					    con_id, gpio_suffixes[i]);
+		else
+			snprintf(prop_name, sizeof(prop_name), "%s",
+					    gpio_suffixes[i]);
+
+		desc = fwnode_get_named_gpiod(fwnode, prop_name, index, flags,
+					      label);
+		if (!IS_ERR(desc) || (PTR_ERR(desc) != -ENOENT))
+			break;
+	}
+
+	return desc;
+}
+EXPORT_SYMBOL_GPL(fwnode_gpiod_get_index);
+
 /**
  * gpiod_count - return the number of GPIOs associated with a device / function
  *		or -ENOENT if no GPIO has been assigned to the requested function

include/linux/gpio/consumer.h

@@ -176,6 +176,10 @@ struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
 					 const char *propname, int index,
 					 enum gpiod_flags dflags,
 					 const char *label);
+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_index(struct device *dev,
 					      struct fwnode_handle *child,
 					      const char *con_id, int index,
@@ -531,6 +535,15 @@ struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
 	return ERR_PTR(-ENOSYS);
 }
 
+static inline
+struct gpio_desc *fwnode_gpiod_get_index(struct fwnode_handle *fwnode,
+					 const char *con_id, int index,
+					 enum gpiod_flags flags,
+					 const char *label)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
 static inline
 struct gpio_desc *devm_fwnode_gpiod_get_index(struct device *dev,
 					      struct fwnode_handle *fwnode,