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>

1 files changed, 26 insertions, 4 deletions

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;