gpio: add parameter to allow the use named gpios

The gpio binding document says that new code should always use named
gpios. Patch 40b73183 added support to parse a list of gpios from child
nodes, but does not make it possible to use named gpios. This patch adds
the con_id property and implements it is done in gpiolib.c, where the
old-style of using unnamed gpios still works.
Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Acked-by: Bryan Wu <cooloney@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/devres.c

@@ -111,23 +111,39 @@ EXPORT_SYMBOL(__devm_gpiod_get_index);
 /**
  * devm_get_gpiod_from_child - get a GPIO descriptor from a device's child node
  * @dev:	GPIO consumer
+ * @con_id:	function within the GPIO consumer
  * @child:	firmware node (child of @dev)
  *
  * GPIO descriptors returned from this function are automatically disposed on
  * driver detach.
  */
 struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
+					    const char *con_id,
 					    struct fwnode_handle *child)
 {
+	static const char const *suffixes[] = { "gpios", "gpio" };
+	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);
 
-	desc = fwnode_get_named_gpiod(child, "gpios");
+	for (i = 0; i < ARRAY_SIZE(suffixes); i++) {
+		if (con_id)
+			snprintf(prop_name, sizeof(prop_name), "%s-%s",
+					    con_id, suffixes[i]);
+		else
+			snprintf(prop_name, sizeof(prop_name), "%s",
+							       suffixes[i]);
+
+		desc = fwnode_get_named_gpiod(child, prop_name);
+		if (!IS_ERR(desc) || (PTR_ERR(desc) == -EPROBE_DEFER))
+			break;
+	}
 	if (IS_ERR(desc)) {
 		devres_free(dr);
 		return desc;

drivers/input/keyboard/gpio_keys_polled.c

@@ -125,7 +125,7 @@ static struct gpio_keys_platform_data *gpio_keys_polled_get_devtree_pdata(struct
 	device_for_each_child_node(dev, child) {
 		struct gpio_desc *desc;
 
-		desc = devm_get_gpiod_from_child(dev, child);
+		desc = devm_get_gpiod_from_child(dev, NULL, child);
 		if (IS_ERR(desc)) {
 			error = PTR_ERR(desc);
 			if (error != -EPROBE_DEFER)

drivers/leds/leds-gpio.c

@@ -184,7 +184,7 @@ static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
 		struct gpio_led led = {};
 		const char *state = NULL;
 
-		led.gpiod = devm_get_gpiod_from_child(dev, child);
+		led.gpiod = devm_get_gpiod_from_child(dev, NULL, child);
 		if (IS_ERR(led.gpiod)) {
 			fwnode_handle_put(child);
 			ret = PTR_ERR(led.gpiod);

include/linux/gpio/consumer.h

@@ -110,6 +110,7 @@ struct fwnode_handle;
 struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
 					 const char *propname);
 struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
+					    const char *con_id,
 					    struct fwnode_handle *child);
 #else /* CONFIG_GPIOLIB */