leds: triggers: send uevent when changing triggers

Some triggers create sysfs files when they are enabled. Send a uevent
"change" notification whenever the trigger is changed to allow userspace
processes such as udev to modify permissions on the new files.

A change notification will also be sent during registration of led class
devices or led triggers if the default trigger of an led class device
is found.

(bryan.wu@canonical.com: rename trigger to trig to fix the build error)

Signed-off-by: Colin Cross <ccross@android.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index b53bf54023f6..262eb4193710 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -102,6 +102,12 @@ EXPORT_SYMBOL_GPL(led_trigger_show);
 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
 {
         unsigned long flags;
+        char *event = NULL;
+        char *envp[2];
+        const char *name;
+
+        name = trig ? trig->name : "none";
+        event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 
         /* Remove any existing trigger */
         if (led_cdev->trigger) {
@@ -124,6 +130,13 @@ void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
                 if (trig->activate)
                         trig->activate(led_cdev);
         }
+
+        if (event) {
+                envp[0] = event;
+                envp[1] = NULL;
+                kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
+                kfree(event);
+        }
 }
 EXPORT_SYMBOL_GPL(led_trigger_set);