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: Linus Walleij <linus.walleij@xxxxxxxxxx> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- Changes in v5: - Rename lookup-table names to match those from the gpio and reset lookups: s/led_name/provider/ s/consumer_dev_name/dev_id/ s/consumer_function/con_id/ Changes in v4: - Split out support for led_get() devicetree name-based lookup support into a separate RFC patch as there currently are no users for this - Use kstrdup_const() / kfree_const() for the led_name --- drivers/leds/led-class.c | 84 ++++++++++++++++++++++++++++++++++++++++ include/linux/leds.h | 21 ++++++++++ 2 files changed, 105 insertions(+) diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c index 4904d140a560..0c4b8d8d2b4f 100644 --- a/drivers/leds/led-class.c +++ b/drivers/leds/led-class.c @@ -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) { diff --git a/include/linux/leds.h b/include/linux/leds.h index ba4861ec73d3..8d6767072ebf 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -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, -- 2.39.0