leds: core: add managed version of led_trigger_register

Complementing devm_led_classdev_register add a managed version of
led_trigger_register.

I omit a managed version of led_classdev_unregister as the equivalent
devm_led_classdev_unregister isn't used in the kernel as of today.

Signed-off-by: Heiner Kallweit <[e-mail]>
Signed-off-by: Jacek Anaszewski <[e-mail]>

drivers/leds/led-triggers.c

···
 }
 EXPORT_SYMBOL_GPL(led_trigger_unregister);
 
+static void devm_led_trigger_release(struct device *dev, void *res)
+{
+	led_trigger_unregister(*(struct led_trigger **)res);
+}
+
+int devm_led_trigger_register(struct device *dev,
+			      struct led_trigger *trig)
+{
+	struct led_trigger **dr;
+	int rc;
+
+	dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
+			  GFP_KERNEL);
+	if (!dr)
+		return -ENOMEM;
+
+	*dr = trig;
+
+	rc = led_trigger_register(trig);
+	if (rc)
+		devres_free(dr);
+	else
+		devres_add(dev, dr);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(devm_led_trigger_register);
+
 /* Simple LED Tigger Interface */
 
 void led_trigger_event(struct led_trigger *trig,

include/linux/leds.h

···
 /* Registration functions for complex triggers */
 extern int led_trigger_register(struct led_trigger *trigger);
 extern void led_trigger_unregister(struct led_trigger *trigger);
+extern int devm_led_trigger_register(struct device *dev,
+				     struct led_trigger *trigger);
 
 extern void led_trigger_register_simple(const char *name,
 				struct led_trigger **trigger);