leds: Add options to have GPIO LEDs start on or keep their state

[safe/jmp/linux-2.6] / Documentation / powerpc / dts-bindings / gpio / led.txt

diff --git a/Documentation/powerpc/dts-bindings/gpio/led.txt b/Documentation/powerpc/dts-bindings/gpio/led.txt
index 4fe14de..064db92 100644 (file)
--- a/Documentation/powerpc/dts-bindings/gpio/led.txt
+++ b/Documentation/powerpc/dts-bindings/gpio/led.txt
@@ -16,10 +16,17 @@ LED sub-node properties:
   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
+    "default-on" - LED will turn on, but see "default-state" below
     "heartbeat" - LED "double" flashes at a load average based rate
     "ide-disk" - LED indicates disk activity
     "timer" - LED flashes at a fixed, configurable rate
+- default-state:  (optional) The initial state of the LED.  Valid
+  values are "on", "off", and "keep".  If the LED is already on or off
+  and the default-state property is set the to same value, then no
+  glitch should be produced where the LED momentarily turns off (or
+  on).  The "keep" setting will keep the LED at whatever its current
+  state is, without producing a glitch.  The default is off if this
+  property is not present.
 
 Examples:
 
@@ -30,14 +37,22 @@ leds {
                gpios = <&mcu_pio 0 1>; /* Active low */
                linux,default-trigger = "ide-disk";
        };
+
+       fault {
+               gpios = <&mcu_pio 1 0>;
+               /* Keep LED on if BIOS detected hardware fault */
+               default-state = "keep";
+       };
 };
 
 run-control {
        compatible = "gpio-leds";
        red {
                gpios = <&mpc8572 6 0>;
+               default-state = "off";
        };
        green {
                gpios = <&mpc8572 7 0>;
+               default-state = "on";
        };
 }