+
+#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
+ defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
+/* This callback gets called when something important happens inside a
+ * framebuffer driver. We're looking if that important event is blanking,
+ * and if it is, we're switching backlight power as well ...
+ */
+static int fb_notifier_callback(struct notifier_block *self,
+ unsigned long event, void *data)
+{
+ struct backlight_device *bd;
+ struct fb_event *evdata = data;
+
+ /* If we aren't interested in this event, skip it immediately ... */
+ if (event != FB_EVENT_BLANK)
+ return 0;
+
+ bd = container_of(self, struct backlight_device, fb_notif);
+ down(&bd->sem);
+ if (bd->props)
+ if (!bd->props->check_fb ||
+ bd->props->check_fb(evdata->info)) {
+ bd->props->fb_blank = *(int *)evdata->data;
+ if (likely(bd->props && bd->props->update_status))
+ bd->props->update_status(bd);
+ }
+ up(&bd->sem);
+ return 0;
+}
+
+static int backlight_register_fb(struct backlight_device *bd)
+{
+ memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
+ bd->fb_notif.notifier_call = fb_notifier_callback;
+
+ return fb_register_client(&bd->fb_notif);
+}
+
+static void backlight_unregister_fb(struct backlight_device *bd)
+{
+ fb_unregister_client(&bd->fb_notif);
+}
+#else
+static inline int backlight_register_fb(struct backlight_device *bd)
+{
+ return 0;
+}
+
+static inline void backlight_unregister_fb(struct backlight_device *bd)
+{
+}
+#endif /* CONFIG_FB */
+