leds: convert blink timer to workqueue

This patch converts the blink timer from led-core to workqueue which is more
suitable for this kind of non-priority operations. Moreover, timer may lead to
errors when a LED setting function use a scheduling function such as pinctrl
which is using mutex.

Signed-off-by: Vincent Donnefort <[e-mail]>
Signed-off-by: Bryan Wu <[e-mail]>

drivers/leds/led-class.c

···
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/device.h>
-#include <linux/timer.h>
 #include <linux/err.h>
 #include <linux/ctype.h>
 #include <linux/leds.h>
+#include <linux/workqueue.h>
 #include "leds.h"
 
 static struct class *leds_class;
···
 	NULL,
 };
 
-static void led_timer_function(unsigned long data)
+static void led_work_function(struct work_struct *ws)
 {
-	struct led_classdev *led_cdev = (void *)data;
+	struct led_classdev *led_cdev =
+		container_of(ws, struct led_classdev, blink_work.work);
 	unsigned long brightness;
 	unsigned long delay;
 
···
 		}
 	}
 
-	mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
+	queue_delayed_work(system_wq, &led_cdev->blink_work,
+			   msecs_to_jiffies(delay));
 }
 
 static void set_brightness_delayed(struct work_struct *ws)
···
 
 	INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
 
-	init_timer(&led_cdev->blink_timer);
-	led_cdev->blink_timer.function = led_timer_function;
-	led_cdev->blink_timer.data = (unsigned long)led_cdev;
+	INIT_DELAYED_WORK(&led_cdev->blink_work, led_work_function);
 
 #ifdef CONFIG_LEDS_TRIGGERS
 	led_trigger_set_default(led_cdev);

drivers/leds/led-core.c

···
 #include <linux/module.h>
 #include <linux/rwsem.h>
 #include <linux/leds.h>
+#include <linux/workqueue.h>
 #include "leds.h"
 
 DECLARE_RWSEM(leds_list_lock);
···
 		return;
 	}
 
-	mod_timer(&led_cdev->blink_timer, jiffies + 1);
+	queue_delayed_work(system_wq, &led_cdev->blink_work, 1);
 }
 
 
···
 		   unsigned long *delay_on,
 		   unsigned long *delay_off)
 {
-	del_timer_sync(&led_cdev->blink_timer);
+	cancel_delayed_work_sync(&led_cdev->blink_work);
 
 	led_cdev->flags &= ~LED_BLINK_ONESHOT;
 	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
···
 			   int invert)
 {
 	if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
-	     timer_pending(&led_cdev->blink_timer))
+	     delayed_work_pending(&led_cdev->blink_work))
 		return;
 
 	led_cdev->flags |= LED_BLINK_ONESHOT;
···
 
 void led_stop_software_blink(struct led_classdev *led_cdev)
 {
-	del_timer_sync(&led_cdev->blink_timer);
+	cancel_delayed_work_sync(&led_cdev->blink_work);
 	led_cdev->blink_delay_on = 0;
 	led_cdev->blink_delay_off = 0;
 }
···
 void led_set_brightness(struct led_classdev *led_cdev,
 			enum led_brightness brightness)
 {
-	/* delay brightness setting if need to stop soft-blink timer */
+	/* delay brightness setting if need to stop soft-blink work */
 	if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
 		led_cdev->delayed_set_value = brightness;
 		schedule_work(&led_cdev->set_brightness_work);

include/linux/leds.h

···
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/rwsem.h>
-#include <linux/timer.h>
 #include <linux/workqueue.h>
 
 struct device;
···
 	const char		*default_trigger;	/* Trigger to use */
 
 	unsigned long		 blink_delay_on, blink_delay_off;
-	struct timer_list	 blink_timer;
+	struct delayed_work	 blink_work;
 	int			 blink_brightness;
 
 	struct work_struct	set_brightness_work;