led-class: always implement blinking

Currently, blinking LEDs can be awkward because it is not guaranteed that
all LEDs implement blinking.  The trigger that wants it to blink then
needs to implement its own timer solution.

Rather than require that, add led_blink_set() API that triggers can use.
This function will attempt to use hw blinking, but if that fails
implements a timer for it.  To stop blinking again, brightness_set() also
needs to be wrapped into API that will stop the software blink.

As a result of this, the timer trigger becomes a very trivial one, and
hopefully we can finally see triggers using blinking as well because it's
always easy to use.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-by: Richard Purdie <rpurdie@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 104 insertions, 1 deletions

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 26066007650..211e21f34bd 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -81,6 +81,79 @@ static struct device_attribute led_class_attrs[] = {
         __ATTR_NULL,
 };
 
+static void led_timer_function(unsigned long data)
+{
+        struct led_classdev *led_cdev = (void *)data;
+        unsigned long brightness;
+        unsigned long delay;
+
+        if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
+                led_set_brightness(led_cdev, LED_OFF);
+                return;
+        }
+
+        brightness = led_get_brightness(led_cdev);
+        if (!brightness) {
+                /* Time to switch the LED on. */
+                brightness = led_cdev->blink_brightness;
+                delay = led_cdev->blink_delay_on;
+        } else {
+                /* Store the current brightness value to be able
+                 * to restore it when the delay_off period is over.
+                 */
+                led_cdev->blink_brightness = brightness;
+                brightness = LED_OFF;
+                delay = led_cdev->blink_delay_off;
+        }
+
+        led_set_brightness(led_cdev, brightness);
+
+        mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
+}
+
+static void led_stop_software_blink(struct led_classdev *led_cdev)
+{
+        /* deactivate previous settings */
+        del_timer_sync(&led_cdev->blink_timer);
+        led_cdev->blink_delay_on = 0;
+        led_cdev->blink_delay_off = 0;
+}
+
+static void led_set_software_blink(struct led_classdev *led_cdev,
+                                   unsigned long delay_on,
+                                   unsigned long delay_off)
+{
+        int current_brightness;
+
+        current_brightness = led_get_brightness(led_cdev);
+        if (current_brightness)
+                led_cdev->blink_brightness = current_brightness;
+        if (!led_cdev->blink_brightness)
+                led_cdev->blink_brightness = led_cdev->max_brightness;
+
+        if (delay_on == led_cdev->blink_delay_on &&
+            delay_off == led_cdev->blink_delay_off)
+                return;
+
+        led_stop_software_blink(led_cdev);
+
+        led_cdev->blink_delay_on = delay_on;
+        led_cdev->blink_delay_off = delay_off;
+
+        /* never on - don't blink */
+        if (!delay_on)
+                return;
+
+        /* never off - just set to brightness */
+        if (!delay_off) {
+                led_set_brightness(led_cdev, led_cdev->blink_brightness);
+                return;
+        }
+
+        mod_timer(&led_cdev->blink_timer, jiffies + 1);
+}
+
+
 /**
  * led_classdev_suspend - suspend an led_classdev.
  * @led_cdev: the led_classdev to suspend.
@@ -148,6 +221,10 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 
         led_update_brightness(led_cdev);
 
+        init_timer(&led_cdev->blink_timer);
+        led_cdev->blink_timer.function = led_timer_function;
+        led_cdev->blink_timer.data = (unsigned long)led_cdev;
+
 #ifdef CONFIG_LEDS_TRIGGERS
         led_trigger_set_default(led_cdev);
 #endif
@@ -157,7 +234,6 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 
         return 0;
 }
-
 EXPORT_SYMBOL_GPL(led_classdev_register);
 
 /**
@@ -175,6 +251,9 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
         up_write(&led_cdev->trigger_lock);
 #endif
 
+        /* Stop blinking */
+        led_brightness_set(led_cdev, LED_OFF);
+
         device_unregister(led_cdev->dev);
 
         down_write(&leds_list_lock);
@@ -183,6 +262,30 @@ void led_classdev_unregister(struct led_classdev *led_cdev)
 }
 EXPORT_SYMBOL_GPL(led_classdev_unregister);
 
+void led_blink_set(struct led_classdev *led_cdev,
+                   unsigned long *delay_on,
+                   unsigned long *delay_off)
+{
+        if (led_cdev->blink_set &&
+            led_cdev->blink_set(led_cdev, delay_on, delay_off))
+                return;
+
+        /* blink with 1 Hz as default if nothing specified */
+        if (!*delay_on && !*delay_off)
+                *delay_on = *delay_off = 500;
+
+        led_set_software_blink(led_cdev, *delay_on, *delay_off);
+}
+EXPORT_SYMBOL(led_blink_set);
+
+void led_brightness_set(struct led_classdev *led_cdev,
+                        enum led_brightness brightness)
+{
+        led_stop_software_blink(led_cdev);
+        led_cdev->brightness_set(led_cdev, brightness);
+}
+EXPORT_SYMBOL(led_brightness_set);
+
 static int __init leds_init(void)
 {
         leds_class = class_create(THIS_MODULE, "leds");