[PATCH] LED: add LED trigger tupport

Add support for LED triggers to the LED subsystem.  "Triggers" are events
which change the state of an LED.  Two kinds of trigger are available, simple
ones which can be added to exising code with minimum disruption and complex
ones for implementing new or more complex functionality.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/include/linux/leds.h b/include/linux/leds.h
index 6812640b39cc..404575c3dd5a 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -40,6 +40,14 @@ struct led_classdev {
 
         /* Trigger data */
         char *default_trigger;
+#ifdef CONFIG_LEDS_TRIGGERS
+        rwlock_t trigger_lock;
+        /* Protects the trigger data below */
+
+        struct led_trigger *trigger;
+        struct list_head trig_list;
+        void *trigger_data;
+#endif
 };
 
 extern int led_classdev_register(struct device *parent,
@@ -48,4 +56,48 @@ extern void led_classdev_unregister(struct led_classdev *led_cdev);
 extern void led_classdev_suspend(struct led_classdev *led_cdev);
 extern void led_classdev_resume(struct led_classdev *led_cdev);
 
+/*
+ * LED Triggers
+ */
+#ifdef CONFIG_LEDS_TRIGGERS
+
+#define TRIG_NAME_MAX 50
+
+struct led_trigger {
+        /* Trigger Properties */
+        const char *name;
+        void (*activate)(struct led_classdev *led_cdev);
+        void (*deactivate)(struct led_classdev *led_cdev);
+
+        /* LEDs under control by this trigger (for simple triggers) */
+        rwlock_t leddev_list_lock;
+        struct list_head led_cdevs;
+
+        /* Link to next registered trigger */
+        struct list_head next_trig;
+};
+
+/* Registration functions for complex triggers */
+extern int led_trigger_register(struct led_trigger *trigger);
+extern void led_trigger_unregister(struct led_trigger *trigger);
+
+/* Registration functions for simple triggers */
+#define DEFINE_LED_TRIGGER(x)           static struct led_trigger *x;
+#define DEFINE_LED_TRIGGER_GLOBAL(x)    struct led_trigger *x;
+extern void led_trigger_register_simple(const char *name,
+                                struct led_trigger **trigger);
+extern void led_trigger_unregister_simple(struct led_trigger *trigger);
+extern void led_trigger_event(struct led_trigger *trigger,
+                                enum led_brightness event);
+
+#else
+
+/* Triggers aren't active - null macros */
+#define DEFINE_LED_TRIGGER(x)
+#define DEFINE_LED_TRIGGER_GLOBAL(x)
+#define led_trigger_register_simple(x, y) do {} while(0)
+#define led_trigger_unregister_simple(x) do {} while(0)
+#define led_trigger_event(x, y) do {} while(0)
+
+#endif
 #endif          /* __LINUX_LEDS_H_INCLUDED */