dm: Add support for LEDs

Add a simple uclass for LEDs, so that these can be controlled by the device
tree and activated when needed. LEDs are referred to by their label.

This implementation requires a driver for each type of LED (e.g GPIO, I2C).

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/doc/device-tree-bindings/leds/common.txt b/doc/device-tree-bindings/leds/common.txt
new file mode 100644
index 0000000000..2d88816dd5
--- /dev/null
+++ b/doc/device-tree-bindings/leds/common.txt
@@ -0,0 +1,23 @@
+Common leds properties.
+
+Optional properties for child nodes:
+- label : The label for this LED.  If omitted, the label is
+  taken from the node name (excluding the unit address).
+
+- linux,default-trigger :  This parameter, if present, is a
+    string defining the trigger assigned to the LED.  Current triggers are:
+     "backlight" - LED will act as a back-light, controlled by the framebuffer
+		   system
+     "default-on" - LED will turn on (but for leds-gpio see "default-state"
+		    property in Documentation/devicetree/bindings/gpio/led.txt)
+     "heartbeat" - LED "double" flashes at a load average based rate
+     "ide-disk" - LED indicates disk activity
+     "timer" - LED flashes at a fixed, configurable rate
+
+Examples:
+
+system-status {
+	label = "Status";
+	linux,default-trigger = "heartbeat";
+	...
+};