[PATCH v2] gpio / ACPI: Add label to the gpio request

[Tobias Diedrich <ranma+kernel@xxxxxxxxxxxx>]

In leds-gpio.c create_gpio_led only the legacy path propagates the label
by passing it into devm_gpio_request_one. Similarily gpio_keys_polled.c
also neglects to propagate the name to the gpio subsystem.

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 take an additonal (optional) label
argument and propagate it so it will show up in /sys/kernel/debug/gpio.

So instead of:

GPIOs 288-511, platform/PRP0001:00, AMD SBX00:
 gpio-475 (?                   ) in  hi
 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-475 (switch1             ) in  hi
 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 ++++--
 drivers/input/keyboard/gpio_keys_polled.c |  9 +++++----
 drivers/leds/leds-gpio.c                  | 20 +++++++++++---------
 include/linux/gpio/consumer.h             |  6 ++++--
 5 files changed, 28 insertions(+), 19 deletions(-)

diff --git a/drivers/gpio/devres.c b/drivers/gpio/devres.c
index 07ba823..40a6089 100644
--- a/drivers/gpio/devres.c
+++ b/drivers/gpio/devres.c
@@ -127,13 +127,15 @@ EXPORT_SYMBOL(__devm_gpiod_get_index);
  * @dev:	GPIO consumer
  * @con_id:	function within the GPIO consumer
  * @child:	firmware node (child of @dev)
+ * @label:	a literal description string of this GPIO
  *
  * 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)
+					    struct fwnode_handle *child,
+					    const char *label)
 {
 	static const char * const suffixes[] = { "gpios", "gpio" };
 	char prop_name[32]; /* 32 is max size of property name */
@@ -154,7 +156,7 @@ struct gpio_desc *devm_get_gpiod_from_child(struct device *dev,
 			snprintf(prop_name, sizeof(prop_name), "%s",
 							       suffixes[i]);
 
-		desc = fwnode_get_named_gpiod(child, prop_name);
+		desc = fwnode_get_named_gpiod(child, prop_name, label);
 		if (!IS_ERR(desc) || (PTR_ERR(desc) == -EPROBE_DEFER))
 			break;
 	}
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 6bc612b..b3f2e5c 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:	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/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
index 097d721..4cf3d23 100644
--- a/drivers/input/keyboard/gpio_keys_polled.c
+++ b/drivers/input/keyboard/gpio_keys_polled.c
@@ -124,8 +124,12 @@ static struct gpio_keys_platform_data *gpio_keys_polled_get_devtree_pdata(struct
 
 	device_for_each_child_node(dev, child) {
 		struct gpio_desc *desc;
+		button = &pdata->buttons[pdata->nbuttons++];
+
+		fwnode_property_read_string(child, "label", &button->desc);
 
-		desc = devm_get_gpiod_from_child(dev, NULL, child);
+		desc = devm_get_gpiod_from_child(dev, NULL, child,
+						 button->desc);
 		if (IS_ERR(desc)) {
 			error = PTR_ERR(desc);
 			if (error != -EPROBE_DEFER)
@@ -136,7 +140,6 @@ static struct gpio_keys_platform_data *gpio_keys_polled_get_devtree_pdata(struct
 			return ERR_PTR(error);
 		}
 
-		button = &pdata->buttons[pdata->nbuttons++];
 		button->gpiod = desc;
 
 		if (fwnode_property_read_u32(child, "linux,code", &button->code)) {
@@ -146,8 +149,6 @@ static struct gpio_keys_platform_data *gpio_keys_polled_get_devtree_pdata(struct
 			return ERR_PTR(-EINVAL);
 		}
 
-		fwnode_property_read_string(child, "label", &button->desc);
-
 		if (fwnode_property_read_u32(child, "linux,input-type",
 					     &button->type))
 			button->type = EV_KEY;
diff --git a/drivers/leds/leds-gpio.c b/drivers/leds/leds-gpio.c
index 15eb3f8..082ad40 100644
--- a/drivers/leds/leds-gpio.c
+++ b/drivers/leds/leds-gpio.c
@@ -184,13 +184,6 @@ 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, NULL, child);
-		if (IS_ERR(led.gpiod)) {
-			fwnode_handle_put(child);
-			ret = PTR_ERR(led.gpiod);
-			goto err;
-		}
-
 		np = of_node(child);
 
 		if (fwnode_property_present(child, "label")) {
@@ -198,9 +191,18 @@ static struct gpio_leds_priv *gpio_leds_create(struct platform_device *pdev)
 		} else {
 			if (IS_ENABLED(CONFIG_OF) && !led.name && np)
 				led.name = np->name;
-			if (!led.name)
-				return ERR_PTR(-EINVAL);
 		}
+		if (!led.name)
+			return ERR_PTR(-EINVAL);
+
+		led.gpiod = devm_get_gpiod_from_child(dev, NULL, child,
+						      led.name);
+		if (IS_ERR(led.gpiod)) {
+			fwnode_handle_put(child);
+			ret = PTR_ERR(led.gpiod);
+			goto err;
+		}
+
 		fwnode_property_read_string(child, "linux,default-trigger",
 					    &led.default_trigger);
 
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 3a7c9ff..51654cf 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -134,10 +134,12 @@ 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);
+					    struct fwnode_handle *child,
+					    const char *label);
 #else /* CONFIG_GPIOLIB */
 
 static inline int gpiod_count(struct device *dev, const char *con_id)
-- 
2.1.4

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