leds: add oneshot blink functions

Add two new functions, led_blink_set_oneshot and
led_trigger_blink_oneshot, to be used by triggers for one-shot blink of
led devices.

This is implemented extending the existing software-blink code, and uses
the same timer and handler function.

The behavior of the code is to do a blink-on, blink-off sequence when
the function is called, ignoring other calls until the sequence is
completed so that the leds keep blinking at constant rate if the
functions are called repeatedly.

This is meant to be used by drivers which needs to trigger on sporadic
event, but doesn't have clear busy/idle trigger points.

After the blink sequence the led remains off. This behavior can be
inverted setting the "invert" argument, which blink the led off, than on
and leave the led on after the sequence.

(bryan.wu@canonical.com: rebase to commit 'leds: don't disable blinking
when writing the same value to delay_on or delay_off')

Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Acked-by: Shuah Khan <shuahkhan@gmail.com>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>

3 files changed, 83 insertions, 11 deletions

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index e663e6f413e9..81eb0916b44a 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -86,6 +86,11 @@ static void led_timer_function(unsigned long data)
                 return;
         }
 
+        if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
+                led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
+                return;
+        }
+
         brightness = led_get_brightness(led_cdev);
         if (!brightness) {
                 /* Time to switch the LED on. */
@@ -102,6 +107,20 @@ static void led_timer_function(unsigned long data)
 
         led_set_brightness(led_cdev, brightness);
 
+        /* Return in next iteration if led is in one-shot mode and we are in
+         * the final blink state so that the led is toggled each delay_on +
+         * delay_off milliseconds in worst case.
+         */
+        if (led_cdev->flags & LED_BLINK_ONESHOT) {
+                if (led_cdev->flags & LED_BLINK_INVERT) {
+                        if (brightness)
+                                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
+                } else {
+                        if (!brightness)
+                                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
+                }
+        }
+
         mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
 }
 
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index d65353d8d3fc..a6f4d910ca08 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -27,7 +27,6 @@ EXPORT_SYMBOL_GPL(leds_list);
 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;
 }
@@ -61,13 +60,12 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
 }
 
 
-void led_blink_set(struct led_classdev *led_cdev,
-                   unsigned long *delay_on,
-                   unsigned long *delay_off)
+void led_blink_setup(struct led_classdev *led_cdev,
+                     unsigned long *delay_on,
+                     unsigned long *delay_off)
 {
-        del_timer_sync(&led_cdev->blink_timer);
-
-        if (led_cdev->blink_set &&
+        if (!(led_cdev->flags & LED_BLINK_ONESHOT) &&
+            led_cdev->blink_set &&
             !led_cdev->blink_set(led_cdev, delay_on, delay_off))
                 return;
 
@@ -77,8 +75,41 @@ void led_blink_set(struct led_classdev *led_cdev,
 
         led_set_software_blink(led_cdev, *delay_on, *delay_off);
 }
+
+void led_blink_set(struct led_classdev *led_cdev,
+                   unsigned long *delay_on,
+                   unsigned long *delay_off)
+{
+        del_timer_sync(&led_cdev->blink_timer);
+
+        led_cdev->flags &= ~LED_BLINK_ONESHOT;
+        led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
+
+        led_blink_setup(led_cdev, delay_on, delay_off);
+}
 EXPORT_SYMBOL(led_blink_set);
 
+void led_blink_set_oneshot(struct led_classdev *led_cdev,
+                           unsigned long *delay_on,
+                           unsigned long *delay_off,
+                           int invert)
+{
+        if ((led_cdev->flags & LED_BLINK_ONESHOT) &&
+             timer_pending(&led_cdev->blink_timer))
+                return;
+
+        led_cdev->flags |= LED_BLINK_ONESHOT;
+        led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
+
+        if (invert)
+                led_cdev->flags |= LED_BLINK_INVERT;
+        else
+                led_cdev->flags &= ~LED_BLINK_INVERT;
+
+        led_blink_setup(led_cdev, delay_on, delay_off);
+}
+EXPORT_SYMBOL(led_blink_set_oneshot);
+
 void led_brightness_set(struct led_classdev *led_cdev,
                         enum led_brightness brightness)
 {
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index b449ed8d8712..fa0b9be019ea 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -230,9 +230,11 @@ void led_trigger_event(struct led_trigger *trig,
 }
 EXPORT_SYMBOL_GPL(led_trigger_event);
 
-void led_trigger_blink(struct led_trigger *trig,
-                       unsigned long *delay_on,
-                       unsigned long *delay_off)
+void led_trigger_blink_setup(struct led_trigger *trig,
+                             unsigned long *delay_on,
+                             unsigned long *delay_off,
+                             int oneshot,
+                             int invert)
 {
         struct list_head *entry;
 
@@ -244,12 +246,32 @@ void led_trigger_blink(struct led_trigger *trig,
                 struct led_classdev *led_cdev;
 
                 led_cdev = list_entry(entry, struct led_classdev, trig_list);
-                led_blink_set(led_cdev, delay_on, delay_off);
+                if (oneshot)
+                        led_blink_set_oneshot(led_cdev, delay_on, delay_off,
+                                              invert);
+                else
+                        led_blink_set(led_cdev, delay_on, delay_off);
         }
         read_unlock(&trig->leddev_list_lock);
 }
+
+void led_trigger_blink(struct led_trigger *trig,
+                       unsigned long *delay_on,
+                       unsigned long *delay_off)
+{
+        led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
+}
 EXPORT_SYMBOL_GPL(led_trigger_blink);
 
+void led_trigger_blink_oneshot(struct led_trigger *trig,
+                               unsigned long *delay_on,
+                               unsigned long *delay_off,
+                               int invert)
+{
+        led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
+}
+EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
+
 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
 {
         struct led_trigger *trig;