leds: allow led-drivers to use a variable range of brightness values

This patch allows drivers to override the default maximum brightness value
of 255.  We take care to preserve backwards-compatibility as much as
possible, so that user-space ABI doesn't change for existing drivers.
LED trigger code has also been updated to use the per-LED maximum.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

7 files changed, 29 insertions, 8 deletions

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 52f82e3ea13a..f2cc13d76810 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -64,7 +64,16 @@ static ssize_t led_brightness_store(struct device *dev,
         return ret;
 }
 
+static ssize_t led_max_brightness_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct led_classdev *led_cdev = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%u\n", led_cdev->max_brightness);
+}
+
 static DEVICE_ATTR(brightness, 0644, led_brightness_show, led_brightness_store);
+static DEVICE_ATTR(max_brightness, 0444, led_max_brightness_show, NULL);
 #ifdef CONFIG_LEDS_TRIGGERS
 static DEVICE_ATTR(trigger, 0644, led_trigger_show, led_trigger_store);
 #endif
@@ -138,6 +147,13 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
         list_add_tail(&led_cdev->node, &leds_list);
         up_write(&leds_list_lock);
 
+        if (!led_cdev->max_brightness)
+                led_cdev->max_brightness = LED_FULL;
+
+        rc = device_create_file(led_cdev->dev, &dev_attr_max_brightness);
+        if (rc)
+                goto err_out_attr_max;
+
         led_update_brightness(led_cdev);
 
 #ifdef CONFIG_LEDS_TRIGGERS
@@ -155,9 +171,11 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
 
 #ifdef CONFIG_LEDS_TRIGGERS
 err_out_led_list:
+        device_remove_file(led_cdev->dev, &dev_attr_max_brightness);
+#endif
+err_out_attr_max:
         device_remove_file(led_cdev->dev, &dev_attr_brightness);
         list_del(&led_cdev->node);
-#endif
 err_out:
         device_unregister(led_cdev->dev);
         return rc;
@@ -172,6 +190,7 @@ EXPORT_SYMBOL_GPL(led_classdev_register);
  */
 void led_classdev_unregister(struct led_classdev *led_cdev)
 {
+        device_remove_file(led_cdev->dev, &dev_attr_max_brightness);
         device_remove_file(led_cdev->dev, &dev_attr_brightness);
 #ifdef CONFIG_LEDS_TRIGGERS
         device_remove_file(led_cdev->dev, &dev_attr_trigger);
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 5edbf52c4fa7..2dd8ecbfdc31 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -20,8 +20,8 @@
 static inline void led_set_brightness(struct led_classdev *led_cdev,
                                         enum led_brightness value)
 {
-        if (value > LED_FULL)
-                value = LED_FULL;
+        if (value > led_cdev->max_brightness)
+                value = led_cdev->max_brightness;
         led_cdev->brightness = value;
         if (!(led_cdev->flags & LED_SUSPENDED))
                 led_cdev->brightness_set(led_cdev, value);
diff --git a/drivers/leds/ledtrig-default-on.c b/drivers/leds/ledtrig-default-on.c
index 92995e40cfa4..a4ef54b9d508 100644
--- a/drivers/leds/ledtrig-default-on.c
+++ b/drivers/leds/ledtrig-default-on.c
@@ -19,7 +19,7 @@
 
 static void defon_trig_activate(struct led_classdev *led_cdev)
 {
-        led_set_brightness(led_cdev, LED_FULL);
+        led_set_brightness(led_cdev, led_cdev->max_brightness);
 }
 
 static struct led_trigger defon_led_trigger = {
diff --git a/drivers/leds/ledtrig-heartbeat.c b/drivers/leds/ledtrig-heartbeat.c
index 4bf8cec8b8c1..c1c1ea6f817b 100644
--- a/drivers/leds/ledtrig-heartbeat.c
+++ b/drivers/leds/ledtrig-heartbeat.c
@@ -47,7 +47,7 @@ static void led_heartbeat_function(unsigned long data)
                         msecs_to_jiffies(heartbeat_data->period);
                 delay = msecs_to_jiffies(70);
                 heartbeat_data->phase++;
-                brightness = LED_FULL;
+                brightness = led_cdev->max_brightness;
                 break;
         case 1:
                 delay = heartbeat_data->period / 4 - msecs_to_jiffies(70);
@@ -56,7 +56,7 @@ static void led_heartbeat_function(unsigned long data)
         case 2:
                 delay = msecs_to_jiffies(70);
                 heartbeat_data->phase++;
-                brightness = LED_FULL;
+                brightness = led_cdev->max_brightness;
                 break;
         default:
                 delay = heartbeat_data->period - heartbeat_data->period / 4 -
diff --git a/drivers/leds/ledtrig-ide-disk.c b/drivers/leds/ledtrig-ide-disk.c
index 883a577b1b97..ec099fcbcb00 100644
--- a/drivers/leds/ledtrig-ide-disk.c
+++ b/drivers/leds/ledtrig-ide-disk.c
@@ -37,7 +37,8 @@ static void ledtrig_ide_timerfunc(unsigned long data)
 {
         if (ide_lastactivity != ide_activity) {
                 ide_lastactivity = ide_activity;
-                led_trigger_event(ledtrig_ide, LED_FULL);
+                /* INT_MAX will set each LED to its maximum brightness */
+                led_trigger_event(ledtrig_ide, INT_MAX);
                 mod_timer(&ledtrig_ide_timer, jiffies + msecs_to_jiffies(10));
         } else {
                 led_trigger_event(ledtrig_ide, LED_OFF);
diff --git a/drivers/leds/ledtrig-timer.c b/drivers/leds/ledtrig-timer.c
index 3d6531396dda..3b83406de752 100644
--- a/drivers/leds/ledtrig-timer.c
+++ b/drivers/leds/ledtrig-timer.c
@@ -166,7 +166,7 @@ static void timer_trig_activate(struct led_classdev *led_cdev)
 
         timer_data->brightness_on = led_get_brightness(led_cdev);
         if (timer_data->brightness_on == LED_OFF)
-                timer_data->brightness_on = LED_FULL;
+                timer_data->brightness_on = led_cdev->max_brightness;
         led_cdev->trigger_data = timer_data;
 
         init_timer(&timer_data->timer);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 24489da701e3..17d277e0c4a6 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -30,6 +30,7 @@ enum led_brightness {
 struct led_classdev {
         const char              *name;
         int                      brightness;
+        int                      max_brightness;
         int                      flags;
 
         /* Lower 16 bits reflect status */