Reading /sys/class/leds/<led>/trigger returns all available LED triggers. However, this violates the "one value per file" rule of sysfs. This makes led_triggers "real" devices and provides an /sys/devices/virtual/led-trigger/ directory that contains a sub-directoriy for each LED trigger device. The name of the sub-directory matches the LED trigger name. We can find all available LED triggers by listing this directory contents. Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> Cc: Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> Cc: Pavel Machek <pavel@xxxxxx> Cc: Dan Murphy <dmurphy@xxxxxx> Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx> --- .../ABI/testing/sysfs-devices-virtual-led-trigger | 8 +++ drivers/leds/led-triggers.c | 57 ++++++++++++++++++++++ include/linux/leds.h | 3 ++ 3 files changed, 68 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-devices-virtual-led-trigger diff --git a/Documentation/ABI/testing/sysfs-devices-virtual-led-trigger b/Documentation/ABI/testing/sysfs-devices-virtual-led-trigger new file mode 100644 index 0000000..b8eb8f3 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-virtual-led-trigger @@ -0,0 +1,8 @@ +What: /sys/devices/virtual/leds-trigger/ +Date: September 2019 +KernelVersion: 5.5 +Contact: linux-leds@xxxxxxxxxxxxxxx +Description: + This directory contains a sub-directoriy for each LED trigger + device. The name of the sub-directory matches the LED trigger + name. diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c index 79e30d2..0b810cf 100644 --- a/drivers/leds/led-triggers.c +++ b/drivers/leds/led-triggers.c @@ -267,21 +267,76 @@ void led_trigger_rename_static(const char *name, struct led_trigger *trig) } EXPORT_SYMBOL_GPL(led_trigger_rename_static); +struct ledtrig_device { + struct device dev; +}; + +static void ledtrig_device_release(struct device *dev) +{ + struct ledtrig_device *trig_dev = + container_of(dev, struct ledtrig_device, dev); + + kfree(trig_dev); +} + +static struct bus_type led_trigger_subsys = { + .name = "led-trigger", +}; + +static int led_trigger_subsys_init(void) +{ + static DEFINE_MUTEX(init_mutex); + static bool init_done; + int ret = 0; + + mutex_lock(&init_mutex); + if (!init_done) { + ret = subsys_virtual_register(&led_trigger_subsys, NULL); + if (!ret) + init_done = true; + } + mutex_unlock(&init_mutex); + + return ret; +} + /* LED Trigger Interface */ int led_trigger_register(struct led_trigger *trig) { struct led_classdev *led_cdev; struct led_trigger *_trig; + struct ledtrig_device *trig_dev; + int ret; rwlock_init(&trig->leddev_list_lock); INIT_LIST_HEAD(&trig->led_cdevs); + ret = led_trigger_subsys_init(); + if (ret) + return ret; + trig_dev = kzalloc(sizeof(*trig_dev), GFP_KERNEL); + if (!trig_dev) + return -ENOMEM; + + trig_dev->dev.bus = &led_trigger_subsys; + trig_dev->dev.release = ledtrig_device_release; + dev_set_name(&trig_dev->dev, "%s", trig->name); + + ret = device_register(&trig_dev->dev); + if (ret) { + put_device(&trig_dev->dev); + return ret; + } + + trig->trig_dev = trig_dev; + down_write(&triggers_list_lock); /* Make sure the trigger's name isn't already in use */ list_for_each_entry(_trig, &trigger_list, next_trig) { if (!strcmp(_trig->name, trig->name)) { up_write(&triggers_list_lock); + device_unregister(&trig_dev->dev); return -EEXIST; } } @@ -327,6 +382,8 @@ void led_trigger_unregister(struct led_trigger *trig) up_write(&led_cdev->trigger_lock); } up_read(&leds_list_lock); + + device_unregister(&trig->trig_dev->dev); } EXPORT_SYMBOL_GPL(led_trigger_unregister); diff --git a/include/linux/leds.h b/include/linux/leds.h index da78b27..d63c8e7 100644 --- a/include/linux/leds.h +++ b/include/linux/leds.h @@ -336,6 +336,8 @@ static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev) #define TRIG_NAME_MAX 50 +struct ledtrig_device; + struct led_trigger { /* Trigger Properties */ const char *name; @@ -350,6 +352,7 @@ struct led_trigger { struct list_head next_trig; const struct attribute_group **groups; + struct ledtrig_device *trig_dev; }; /* -- 2.7.4