leds: support automatic start of blinking with ledtrig-timer

By setting initial values blink_delay_on and blink_delay_off in a
led_classdev struct, this change starts the blinking when the led is
initialized.

With this patch, you can initialize blink_delay_on and blink_delay_off in
led_classdev with default_trigger set to "timer", and the led will start
up blinking.  The current ledtrig-timer implementation ignores any initial
blink_delay_on/blink_delay_off settings, and requires setting
blink_delay_on/blink_delay_off (typically from userspace) before the led
blinks.

Signed-off-by: Esben Haabendal <eha@doredevelopment.dk>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/leds/led-class.c

@@ -131,7 +131,8 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
 	if (!led_cdev->blink_brightness)
 		led_cdev->blink_brightness = led_cdev->max_brightness;
 
-	if (delay_on == led_cdev->blink_delay_on &&
+	if (led_get_trigger_data(led_cdev) &&
+	    delay_on == led_cdev->blink_delay_on &&
 	    delay_off == led_cdev->blink_delay_off)
 		return;
 

drivers/leds/leds.h

@@ -40,10 +40,17 @@ void led_trigger_set_default(struct led_classdev *led_cdev);
 void led_trigger_set(struct led_classdev *led_cdev,
 			struct led_trigger *trigger);
 void led_trigger_remove(struct led_classdev *led_cdev);
+
+static inline void *led_get_trigger_data(struct led_classdev *led_cdev)
+{
+	return led_cdev->trigger_data;
+}
+
 #else
 #define led_trigger_set_default(x) do {} while (0)
 #define led_trigger_set(x, y) do {} while (0)
 #define led_trigger_remove(x) do {} while (0)
+#define led_get_trigger_data(x) (NULL)
 #endif
 
 ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,

drivers/leds/ledtrig-timer.c

@@ -91,6 +91,9 @@ static void timer_trig_activate(struct led_classdev *led_cdev)
 	if (rc)
 		goto err_out_delayon;
 
+	led_blink_set(led_cdev, &led_cdev->blink_delay_on,
+		      &led_cdev->blink_delay_off);
+
 	led_cdev->trigger_data = (void *)1;
 
 	return;