backlight: introduce backlight_device_registered
[cascardo/linux.git] / drivers / video / backlight / backlight.c
index 94a403a..5d05555 100644 (file)
@@ -21,6 +21,9 @@
 #include <asm/backlight.h>
 #endif
 
+static struct list_head backlight_dev_list;
+static struct mutex backlight_dev_list_mutex;
+
 static const char *const backlight_types[] = {
        [BACKLIGHT_RAW] = "raw",
        [BACKLIGHT_PLATFORM] = "platform",
@@ -349,10 +352,32 @@ struct backlight_device *backlight_device_register(const char *name,
        mutex_unlock(&pmac_backlight_mutex);
 #endif
 
+       mutex_lock(&backlight_dev_list_mutex);
+       list_add(&new_bd->entry, &backlight_dev_list);
+       mutex_unlock(&backlight_dev_list_mutex);
+
        return new_bd;
 }
 EXPORT_SYMBOL(backlight_device_register);
 
+bool backlight_device_registered(enum backlight_type type)
+{
+       bool found = false;
+       struct backlight_device *bd;
+
+       mutex_lock(&backlight_dev_list_mutex);
+       list_for_each_entry(bd, &backlight_dev_list, entry) {
+               if (bd->props.type == type) {
+                       found = true;
+                       break;
+               }
+       }
+       mutex_unlock(&backlight_dev_list_mutex);
+
+       return found;
+}
+EXPORT_SYMBOL(backlight_device_registered);
+
 /**
  * backlight_device_unregister - unregisters a backlight device object.
  * @bd: the backlight device object to be unregistered and freed.
@@ -364,6 +389,10 @@ void backlight_device_unregister(struct backlight_device *bd)
        if (!bd)
                return;
 
+       mutex_lock(&backlight_dev_list_mutex);
+       list_del(&bd->entry);
+       mutex_unlock(&backlight_dev_list_mutex);
+
 #ifdef CONFIG_PMAC_BACKLIGHT
        mutex_lock(&pmac_backlight_mutex);
        if (pmac_backlight == bd)
@@ -499,6 +528,8 @@ static int __init backlight_class_init(void)
 
        backlight_class->dev_groups = bl_device_groups;
        backlight_class->pm = &backlight_class_dev_pm_ops;
+       INIT_LIST_HEAD(&backlight_dev_list);
+       mutex_init(&backlight_dev_list_mutex);
        return 0;
 }