[PATCH] gpio / ACPI: Add label to the gpio request

[Tobias Diedrich <ranma+kernel@xxxxxxxxxxxx>]

In create_gpio_led only the legacy pass propagates the label by passing it into
devm_gpio_request_one.

On the newer devicetree/acpi path the label is lost as far as the GPIO
subsystem goes (it is only retained as name in struct gpio_led.

Amend devm_get_gpiod_from_child to also pass the label into the GPIO layer, so
it will show up in /sys/kernel/debug/gpio, so instead of:

GPIOs 288-511, platform/PRP0001:00, AMD SBX00:
 gpio-477 (?                   ) out hi
 gpio-478 (?                   ) out lo
 gpio-479 (?                   ) out hi

we get the much nicer output:

GPIOs 288-511, platform/PRP0001:00, AMD SBX00:
 gpio-477 (led1                ) out hi
 gpio-478 (led2                ) out lo
 gpio-479 (led3                ) out hi

Signed-off-by: Tobias Diedrich <ranma+kernel@xxxxxxxxxxxx>
---
 drivers/gpio/devres.c         | 6 +++++-
 drivers/gpio/gpiolib.c        | 6 ++++--
 include/linux/gpio/consumer.h | 3 ++-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/devres.c b/drivers/gpio/devres.c
index 07ba823..089db97 100644
--- a/drivers/gpio/devres.c
+++ b/drivers/gpio/devres.c
@@ -103,13 +103,17 @@ struct gpio_desc *__must_check __devm_gpiod_get_index(struct device *dev,
 {
 	struct gpio_desc **dr;
 	struct gpio_desc *desc;
+	const char *label = NULL;
 
 	dr = devres_alloc(devm_gpiod_release, sizeof(struct gpio_desc *),
 			  GFP_KERNEL);
 	if (!dr)
 		return ERR_PTR(-ENOMEM);
 
-	desc = gpiod_get_index(dev, con_id, idx, flags);
+	if (fwnode_property_present(child, "label"))
+		fwnode_property_read_string(child, "label", &label);
+
+	desc = gpiod_get_index(dev, con_id, idx, flags, label);
 	if (IS_ERR(desc)) {
 		devres_free(dr);
 		return desc;
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 6bc612b..fb2be68 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2017,6 +2017,7 @@ EXPORT_SYMBOL_GPL(__gpiod_get_index);
  * fwnode_get_named_gpiod - obtain a GPIO from firmware node
  * @fwnode:	handle of the firmware node
  * @propname:	name of the firmware property representing the GPIO
+ * @label:	optional label for the GPIO
  *
  * This function can be used for drivers that get their configuration
  * from firmware.
@@ -2028,7 +2029,8 @@ EXPORT_SYMBOL_GPL(__gpiod_get_index);
  * In case of error an ERR_PTR() is returned.
  */
 struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
-					 const char *propname)
+					 const char *propname,
+					 const char *label)
 {
 	struct gpio_desc *desc = ERR_PTR(-ENODEV);
 	bool active_low = false;
@@ -2056,7 +2058,7 @@ struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
 	if (IS_ERR(desc))
 		return desc;
 
-	ret = gpiod_request(desc, NULL);
+	ret = gpiod_request(desc, label);
 	if (ret)
 		return ERR_PTR(ret);
 
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 3a7c9ff..ef7d322 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -134,7 +134,8 @@ int desc_to_gpio(const struct gpio_desc *desc);
 struct fwnode_handle;
 
 struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
-					 const char *propname);
+					 const char *propname,
+					 const char *label);
 struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
 					    const char *con_id,
 					    struct fwnode_handle *child);
-- 
2.1.4

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