Commit abc3100f authored by Hans de Goede's avatar Hans de Goede Committed by Lee Jones
Browse files

leds: led-class: Add generic [devm_]led_get() 



Add a generic [devm_]led_get() method which can be used on both devicetree
and non devicetree platforms to get a LED classdev associated with
a specific function on a specific device, e.g. the privacy LED associated
with a specific camera sensor.

Note unlike of_led_get() this takes a string describing the function
rather then an index. This is done because e.g. camera sensors might
have a privacy LED, or a flash LED, or both and using an index
approach leaves it unclear what the function of index 0 is if there is
only 1 LED.

This uses a lookup-table mechanism for non devicetree platforms.
This allows the platform code to map specific LED class_dev-s to a specific
device,function combinations this way.

For devicetree platforms getting the LED by function-name could be made
to work using the standard devicetree pattern of adding a -names string
array to map names to the indexes.

Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarLee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230120114524.408368-5-hdegoede@redhat.com
parent 537bdca2

drivers/leds/led-class.c

+84 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
#include "leds.h"



static struct class *leds_class;

static DEFINE_MUTEX(leds_lookup_lock);

static LIST_HEAD(leds_lookup_list);



static ssize_t brightness_show(struct device *dev,

		struct device_attribute *attr, char *buf)
@@ -317,6 +319,88 @@ struct led_classdev *__must_check devm_of_led_get(struct device *dev, 
}

EXPORT_SYMBOL_GPL(devm_of_led_get);



/**

 * led_get() - request a LED device via the LED framework

 * @dev: device for which to get the LED device

 * @con_id: name of the LED from the device's point of view

 *

 * @return a pointer to a LED device or ERR_PTR(errno) on failure.

 */

struct led_classdev *led_get(struct device *dev, char *con_id)

{

	struct led_lookup_data *lookup;

	const char *provider = NULL;

	struct device *led_dev;



	mutex_lock(&leds_lookup_lock);

	list_for_each_entry(lookup, &leds_lookup_list, list) {

		if (!strcmp(lookup->dev_id, dev_name(dev)) &&

		    !strcmp(lookup->con_id, con_id)) {

			provider = kstrdup_const(lookup->provider, GFP_KERNEL);

			break;

		}

	}

	mutex_unlock(&leds_lookup_lock);



	if (!provider)

		return ERR_PTR(-ENOENT);



	led_dev = class_find_device_by_name(leds_class, provider);

	kfree_const(provider);



	return led_module_get(led_dev);

}

EXPORT_SYMBOL_GPL(led_get);



/**

 * devm_led_get() - request a LED device via the LED framework

 * @dev: device for which to get the LED device

 * @con_id: name of the LED from the device's point of view

 *

 * The LED device returned from this function is automatically released

 * on driver detach.

 *

 * @return a pointer to a LED device or ERR_PTR(errno) on failure.

 */

struct led_classdev *devm_led_get(struct device *dev, char *con_id)

{

	struct led_classdev *led;



	led = led_get(dev, con_id);

	if (IS_ERR(led))

		return led;



	return __devm_led_get(dev, led);

}

EXPORT_SYMBOL_GPL(devm_led_get);



/**

 * led_add_lookup() - Add a LED lookup table entry

 * @led_lookup: the lookup table entry to add

 *

 * Add a LED lookup table entry. On systems without devicetree the lookup table

 * is used by led_get() to find LEDs.

 */

void led_add_lookup(struct led_lookup_data *led_lookup)

{

	mutex_lock(&leds_lookup_lock);

	list_add_tail(&led_lookup->list, &leds_lookup_list);

	mutex_unlock(&leds_lookup_lock);

}

EXPORT_SYMBOL_GPL(led_add_lookup);



/**

 * led_remove_lookup() - Remove a LED lookup table entry

 * @led_lookup: the lookup table entry to remove

 */

void led_remove_lookup(struct led_lookup_data *led_lookup)

{

	mutex_lock(&leds_lookup_lock);

	list_del(&led_lookup->list);

	mutex_unlock(&leds_lookup_lock);

}

EXPORT_SYMBOL_GPL(led_remove_lookup);



static int led_classdev_next_name(const char *init_name, char *name,

				  size_t len)

{

include/linux/leds.h

+21 −0
Original line number Diff line number Diff line
@@ -39,6 +39,21 @@ enum led_default_state { 
	LEDS_DEFSTATE_KEEP	= 2,

};



/**

 * struct led_lookup_data - represents a single LED lookup entry

 *

 * @list: internal list of all LED lookup entries

 * @provider: name of led_classdev providing the LED

 * @dev_id: name of the device associated with this LED

 * @con_id: name of the LED from the device's point of view

 */

struct led_lookup_data {

	struct list_head list;

	const char *provider;

	const char *dev_id;

	const char *con_id;

};



struct led_init_data {

	/* device fwnode handle */

	struct fwnode_handle *fwnode;
@@ -211,6 +226,12 @@ void devm_led_classdev_unregister(struct device *parent, 
void led_classdev_suspend(struct led_classdev *led_cdev);

void led_classdev_resume(struct led_classdev *led_cdev);



void led_add_lookup(struct led_lookup_data *led_lookup);

void led_remove_lookup(struct led_lookup_data *led_lookup);



struct led_classdev *__must_check led_get(struct device *dev, char *con_id);

struct led_classdev *__must_check devm_led_get(struct device *dev, char *con_id);



extern struct led_classdev *of_led_get(struct device_node *np, int index);

extern void led_put(struct led_classdev *led_cdev);

struct led_classdev *__must_check devm_of_led_get(struct device *dev,