leds: Add support for setting brightness in a synchronous way

There are use cases when setting a LED brightness has to
have immediate effect (e.g. setting a torch LED brightness).
This patch extends LED subsystem to support such operations.
The LED subsystem internal API __led_set_brightness is changed
to led_set_brightness_async and new led_set_brightness_sync API
is added.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

9 files changed, 54 insertions, 26 deletions

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 65722deb8d28..dbeebac38d31 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -55,7 +55,7 @@ static ssize_t brightness_store(struct device *dev,
 
         if (state == LED_OFF)
                 led_trigger_remove(led_cdev);
-        __led_set_brightness(led_cdev, state);
+        led_set_brightness(led_cdev, state);
 
         ret = size;
 unlock:
@@ -109,7 +109,7 @@ static void led_timer_function(unsigned long data)
         unsigned long delay;
 
         if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
-                __led_set_brightness(led_cdev, LED_OFF);
+                led_set_brightness_async(led_cdev, LED_OFF);
                 return;
         }
 
@@ -132,7 +132,7 @@ static void led_timer_function(unsigned long data)
                 delay = led_cdev->blink_delay_off;
         }
 
-        __led_set_brightness(led_cdev, brightness);
+        led_set_brightness_async(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 +
@@ -158,7 +158,7 @@ static void set_brightness_delayed(struct work_struct *ws)
 
         led_stop_software_blink(led_cdev);
 
-        __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
+        led_set_brightness_async(led_cdev, led_cdev->delayed_set_value);
 }
 
 /**
@@ -233,6 +233,8 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
         if (!led_cdev->max_brightness)
                 led_cdev->max_brightness = LED_FULL;
 
+        led_cdev->flags |= SET_BRIGHTNESS_ASYNC;
+
         led_update_brightness(led_cdev);
 
         INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index be6d9fa5e971..9886dace5ad2 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -42,13 +42,13 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
 
         /* never on - just set to off */
         if (!delay_on) {
-                __led_set_brightness(led_cdev, LED_OFF);
+                led_set_brightness_async(led_cdev, LED_OFF);
                 return;
         }
 
         /* never off - just set to brightness */
         if (!delay_off) {
-                __led_set_brightness(led_cdev, led_cdev->blink_brightness);
+                led_set_brightness_async(led_cdev, led_cdev->blink_brightness);
                 return;
         }
 
@@ -117,6 +117,8 @@ EXPORT_SYMBOL_GPL(led_stop_software_blink);
 void led_set_brightness(struct led_classdev *led_cdev,
                         enum led_brightness brightness)
 {
+        int ret = 0;
+
         /* delay brightness setting if need to stop soft-blink timer */
         if (led_cdev->blink_delay_on || led_cdev->blink_delay_off) {
                 led_cdev->delayed_set_value = brightness;
@@ -124,7 +126,17 @@ void led_set_brightness(struct led_classdev *led_cdev,
                 return;
         }
 
-        __led_set_brightness(led_cdev, brightness);
+        if (led_cdev->flags & SET_BRIGHTNESS_ASYNC) {
+                led_set_brightness_async(led_cdev, brightness);
+                return;
+        } else if (led_cdev->flags & SET_BRIGHTNESS_SYNC)
+                ret = led_set_brightness_sync(led_cdev, brightness);
+        else
+                ret = -EINVAL;
+
+        if (ret < 0)
+                dev_dbg(led_cdev->dev, "Setting LED brightness failed (%d)\n",
+                        ret);
 }
 EXPORT_SYMBOL(led_set_brightness);
 
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 4c50365344a9..2348dbda5269 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -17,16 +17,28 @@
 #include <linux/rwsem.h>
 #include <linux/leds.h>
 
-static inline void __led_set_brightness(struct led_classdev *led_cdev,
+static inline void led_set_brightness_async(struct led_classdev *led_cdev,
                                         enum led_brightness value)
 {
-        if (value > led_cdev->max_brightness)
-                value = led_cdev->max_brightness;
-        led_cdev->brightness = value;
+        led_cdev->brightness = min(value, led_cdev->max_brightness);
+
         if (!(led_cdev->flags & LED_SUSPENDED))
                 led_cdev->brightness_set(led_cdev, value);
 }
 
+static inline int led_set_brightness_sync(struct led_classdev *led_cdev,
+                                        enum led_brightness value)
+{
+        int ret = 0;
+
+        led_cdev->brightness = min(value, led_cdev->max_brightness);
+
+        if (!(led_cdev->flags & LED_SUSPENDED))
+                ret = led_cdev->brightness_set_sync(led_cdev,
+                                                led_cdev->brightness);
+        return ret;
+}
+
 static inline int led_get_brightness(struct led_classdev *led_cdev)
 {
         return led_cdev->brightness;
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 47e55aa9eefa..59eca17d9661 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -51,9 +51,9 @@ static int fb_notifier_callback(struct notifier_block *p,
 
         if ((n->old_status == UNBLANK) ^ n->invert) {
                 n->brightness = led->brightness;
-                __led_set_brightness(led, LED_OFF);
+                led_set_brightness_async(led, LED_OFF);
         } else {
-                __led_set_brightness(led, n->brightness);
+                led_set_brightness_async(led, n->brightness);
         }
 
         n->old_status = new_status;
@@ -89,9 +89,9 @@ static ssize_t bl_trig_invert_store(struct device *dev,
 
         /* After inverting, we need to update the LED. */
         if ((n->old_status == BLANK) ^ n->invert)
-                __led_set_brightness(led, LED_OFF);
+                led_set_brightness_async(led, LED_OFF);
         else
-                __led_set_brightness(led, n->brightness);
+                led_set_brightness_async(led, n->brightness);
 
         return num;
 }
diff --git a/drivers/leds/trigger/ledtrig-default-on.c b/drivers/leds/trigger/ledtrig-default-on.c
index 81a91be8e18d..6f38f883aaf1 100644
--- a/drivers/leds/trigger/ledtrig-default-on.c
+++ b/drivers/leds/trigger/ledtrig-default-on.c
@@ -19,7 +19,7 @@
 
 static void defon_trig_activate(struct led_classdev *led_cdev)
 {
-        __led_set_brightness(led_cdev, led_cdev->max_brightness);
+        led_set_brightness_async(led_cdev, led_cdev->max_brightness);
 }
 
 static struct led_trigger defon_led_trigger = {
diff --git a/drivers/leds/trigger/ledtrig-gpio.c b/drivers/leds/trigger/ledtrig-gpio.c
index c86c41826476..4cc7040746c6 100644
--- a/drivers/leds/trigger/ledtrig-gpio.c
+++ b/drivers/leds/trigger/ledtrig-gpio.c
@@ -54,12 +54,12 @@ static void gpio_trig_work(struct work_struct *work)
 
         if (tmp) {
                 if (gpio_data->desired_brightness)
-                        __led_set_brightness(gpio_data->led,
+                        led_set_brightness_async(gpio_data->led,
                                            gpio_data->desired_brightness);
                 else
-                        __led_set_brightness(gpio_data->led, LED_FULL);
+                        led_set_brightness_async(gpio_data->led, LED_FULL);
         } else {
-                __led_set_brightness(gpio_data->led, LED_OFF);
+                led_set_brightness_async(gpio_data->led, LED_OFF);
         }
 }
 
diff --git a/drivers/leds/trigger/ledtrig-heartbeat.c b/drivers/leds/trigger/ledtrig-heartbeat.c
index 5c8464a33172..fea6871d2609 100644
--- a/drivers/leds/trigger/ledtrig-heartbeat.c
+++ b/drivers/leds/trigger/ledtrig-heartbeat.c
@@ -74,7 +74,7 @@ static void led_heartbeat_function(unsigned long data)
                 break;
         }
 
-        __led_set_brightness(led_cdev, brightness);
+        led_set_brightness_async(led_cdev, brightness);
         mod_timer(&heartbeat_data->timer, jiffies + delay);
 }
 
diff --git a/drivers/leds/trigger/ledtrig-oneshot.c b/drivers/leds/trigger/ledtrig-oneshot.c
index cb4c7466692a..fbd02cdc3ad7 100644
--- a/drivers/leds/trigger/ledtrig-oneshot.c
+++ b/drivers/leds/trigger/ledtrig-oneshot.c
@@ -63,9 +63,9 @@ static ssize_t led_invert_store(struct device *dev,
         oneshot_data->invert = !!state;
 
         if (oneshot_data->invert)
-                __led_set_brightness(led_cdev, LED_FULL);
+                led_set_brightness_async(led_cdev, LED_FULL);
         else
-                __led_set_brightness(led_cdev, LED_OFF);
+                led_set_brightness_async(led_cdev, LED_OFF);
 
         return size;
 }
diff --git a/drivers/leds/trigger/ledtrig-transient.c b/drivers/leds/trigger/ledtrig-transient.c
index e5abc00bb00c..3c34de404d18 100644
--- a/drivers/leds/trigger/ledtrig-transient.c
+++ b/drivers/leds/trigger/ledtrig-transient.c
@@ -41,7 +41,7 @@ static void transient_timer_function(unsigned long data)
         struct transient_trig_data *transient_data = led_cdev->trigger_data;
 
         transient_data->activate = 0;
-        __led_set_brightness(led_cdev, transient_data->restore_state);
+        led_set_brightness_async(led_cdev, transient_data->restore_state);
 }
 
 static ssize_t transient_activate_show(struct device *dev,
@@ -72,7 +72,8 @@ static ssize_t transient_activate_store(struct device *dev,
         if (state == 0 && transient_data->activate == 1) {
                 del_timer(&transient_data->timer);
                 transient_data->activate = state;
-                __led_set_brightness(led_cdev, transient_data->restore_state);
+                led_set_brightness_async(led_cdev,
+                                        transient_data->restore_state);
                 return size;
         }
 
@@ -80,7 +81,7 @@ static ssize_t transient_activate_store(struct device *dev,
         if (state == 1 && transient_data->activate == 0 &&
             transient_data->duration != 0) {
                 transient_data->activate = state;
-                __led_set_brightness(led_cdev, transient_data->state);
+                led_set_brightness_async(led_cdev, transient_data->state);
                 transient_data->restore_state =
                     (transient_data->state == LED_FULL) ? LED_OFF : LED_FULL;
                 mod_timer(&transient_data->timer,
@@ -203,7 +204,8 @@ static void transient_trig_deactivate(struct led_classdev *led_cdev)
 
         if (led_cdev->activated) {
                 del_timer_sync(&transient_data->timer);
-                __led_set_brightness(led_cdev, transient_data->restore_state);
+                led_set_brightness_async(led_cdev,
+                                        transient_data->restore_state);
                 device_remove_file(led_cdev->dev, &dev_attr_activate);
                 device_remove_file(led_cdev->dev, &dev_attr_duration);
                 device_remove_file(led_cdev->dev, &dev_attr_state);