leds: leds-pwm: Add device tree bindings

The DT binding for the pwm-leds devices are similar to the gpio-leds type.
LEDs are represented as sub-nodes of the pwm-leds device.
The code for handling the DT boot is based on the code found in the
leds-gpio driver and adapted to use PWMs instead of GPIOs.
To avoid having custom cleanup code in case of DT boot the newly created
devm_of_pwm_get() API is used to get the correct PWM instance.

For usage see:
Documentation/devicetree/bindings/leds/leds-pwm.txt

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/leds/leds-pwm.txt b/Documentation/devicetree/bindings/leds/leds-pwm.txt
new file mode 100644
index 000000000000..7297107cf832
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-pwm.txt
@@ -0,0 +1,48 @@
+LED connected to PWM
+
+Required properties:
+- compatible : should be "pwm-leds".
+
+Each LED is represented as a sub-node of the pwm-leds device.  Each
+node's name represents the name of the corresponding LED.
+
+LED sub-node properties:
+- pwms : PWM property to point to the PWM device (phandle)/port (id) and to
+  specify the period time to be used: <&phandle id period_ns>;
+- pwm-names : (optional) Name to be used by the PWM subsystem for the PWM device
+  For the pwms and pwm-names property please refer to:
+  Documentation/devicetree/bindings/pwm/pwm.txt
+- max-brightness : Maximum brightness possible for the LED
+- label :  (optional)
+  see Documentation/devicetree/bindings/leds/common.txt
+- linux,default-trigger :  (optional)
+  see Documentation/devicetree/bindings/leds/common.txt
+
+Example:
+
+twl_pwm: pwm {
+        /* provides two PWMs (id 0, 1 for PWM1 and PWM2) */
+        compatible = "ti,twl6030-pwm";
+        #pwm-cells = <2>;
+};
+
+twl_pwmled: pwmled {
+        /* provides one PWM (id 0 for Charing indicator LED) */
+        compatible = "ti,twl6030-pwmled";
+        #pwm-cells = <2>;
+};
+
+pwmleds {
+        compatible = "pwm-leds";
+        kpad {
+                label = "omap4::keypad";
+                pwms = <&twl_pwm 0 7812500>;
+                max-brightness = <127>;
+        };
+
+        charging {
+                label = "omap4:green:chrg";
+                pwms = <&twl_pwmled 0 7812500>;
+                max-brightness = <255>;
+        };
+};