[PATCH 1/2] leds: add DT support for LEDs wired to supply and default brightness

[Russell King]

Some PWM outputs are wired such that the LED they're controlling is
connected to supply rather than ground.  Therefore, the duty cycle
needs to be inverted to make the LED behave as it should do.

We also provide a way to specify the default brightness when a
trigger is not specified.

Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
---
 Documentation/devicetree/bindings/leds/leds-pwm.txt |  3 +++
 drivers/leds/leds-pwm.c                             | 15 +++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/leds/leds-pwm.txt b/Documentation/devicetree/bindings/leds/leds-pwm.txt
index 7297107cf832..ffcb74ab61fd 100644
--- a/Documentation/devicetree/bindings/leds/leds-pwm.txt
+++ b/Documentation/devicetree/bindings/leds/leds-pwm.txt
@@ -13,6 +13,9 @@ node's name represents the name of the corresponding LED.
   For the pwms and pwm-names property please refer to:
   Documentation/devicetree/bindings/pwm/pwm.txt
 - max-brightness : Maximum brightness possible for the LED
+- default-brightness : (optional) Default brightness for the LED
+- active-low : (optional) For PWMs where the LED is wired to supply
+  rather than ground.
 - label :  (optional)
   see Documentation/devicetree/bindings/leds/common.txt
 - linux,default-trigger :  (optional)
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index 605047428b5a..fe2cd849b593 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -70,6 +70,10 @@ static void led_pwm_set(struct led_classdev *led_cdev,
 
 	duty *= brightness;
 	do_div(duty, max);
+
+	if (led_dat->active_low)
+		duty = led_dat->period - duty;
+
 	led_dat->duty = duty;
 
 	if (led_dat->can_sleep)
@@ -93,6 +97,10 @@ static int led_pwm_create_of(struct platform_device *pdev,
 	for_each_child_of_node(pdev->dev.of_node, child) {
 		struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
 
+		led_dat->cdev.brightness_set = led_pwm_set;
+		led_dat->cdev.brightness = LED_OFF;
+		led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+
 		led_dat->cdev.name = of_get_property(child, "label",
 						     NULL) ? : child->name;
 
@@ -110,10 +118,9 @@ static int led_pwm_create_of(struct platform_device *pdev,
 						"linux,default-trigger", NULL);
 		of_property_read_u32(child, "max-brightness",
 				     &led_dat->cdev.max_brightness);
-
-		led_dat->cdev.brightness_set = led_pwm_set;
-		led_dat->cdev.brightness = LED_OFF;
-		led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+		of_property_read_u32(child, "default-brightness",
+				     &led_dat->cdev.brightness);
+		led_dat->active_low = of_property_read_bool(child, "active-low");
 
 		led_dat->can_sleep = pwm_can_sleep(led_dat->pwm);
 		if (led_dat->can_sleep)
-- 
1.8.3.1