leds: Add support for hardware accelerated LED flashing
Extends the leds subsystem with a blink_set() callback function which can
be optionally implemented by a LED driver. If implemented, the driver can use
the hardware acceleration for blinking a LED.
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
diff --git a/drivers/leds/ledtrig-timer.c b/drivers/leds/ledtrig-timer.c
index ed9ff02..82c55d6 100644
--- a/drivers/leds/ledtrig-timer.c
+++ b/drivers/leds/ledtrig-timer.c
@@ -77,8 +77,21 @@
count++;
if (count == size) {
- timer_data->delay_on = state;
- mod_timer(&timer_data->timer, jiffies + 1);
+ if (timer_data->delay_on != state) {
+ /* the new value differs from the previous */
+ timer_data->delay_on = state;
+
+ /* deactivate previous settings */
+ del_timer_sync(&timer_data->timer);
+
+ /* try to activate hardware acceleration, if any */
+ if (!led_cdev->blink_set ||
+ led_cdev->blink_set(led_cdev,
+ &timer_data->delay_on, &timer_data->delay_off)) {
+ /* no hardware acceleration, blink via timer */
+ mod_timer(&timer_data->timer, jiffies + 1);
+ }
+ }
ret = count;
}
@@ -110,8 +123,21 @@
count++;
if (count == size) {
- timer_data->delay_off = state;
- mod_timer(&timer_data->timer, jiffies + 1);
+ if (timer_data->delay_off != state) {
+ /* the new value differs from the previous */
+ timer_data->delay_off = state;
+
+ /* deactivate previous settings */
+ del_timer_sync(&timer_data->timer);
+
+ /* try to activate hardware acceleration, if any */
+ if (!led_cdev->blink_set ||
+ led_cdev->blink_set(led_cdev,
+ &timer_data->delay_on, &timer_data->delay_off)) {
+ /* no hardware acceleration, blink via timer */
+ mod_timer(&timer_data->timer, jiffies + 1);
+ }
+ }
ret = count;
}
@@ -143,6 +169,13 @@
if (rc)
goto err_out_delayon;
+ /* If there is hardware support for blinking, start one
+ * user friendly blink rate chosen by the driver.
+ */
+ if (led_cdev->blink_set)
+ led_cdev->blink_set(led_cdev,
+ &timer_data->delay_on, &timer_data->delay_off);
+
return;
err_out_delayon: