Documentation/devicetree/bindings/gpio/led.txt

   1 LEDs connected to GPIO lines
   2
   3 Required properties:
   4 - compatible : should be "gpio-leds".
   5
   6 Each LED is represented as a sub-node of the gpio-leds device.  Each
   7 node's name represents the name of the corresponding LED.
   8
   9 LED sub-node properties:
  10 - gpios :  Should specify the LED's GPIO, see "Specifying GPIO information
  11   for devices" in Documentation/powerpc/booting-without-of.txt.  Active
  12   low LEDs should be indicated using flags in the GPIO specifier.
  13 - label :  (optional) The label for this LED.  If omitted, the label is
  14   taken from the node name (excluding the unit address).
  15 - linux,default-trigger :  (optional) This parameter, if present, is a
  16   string defining the trigger assigned to the LED.  Current triggers are:
  17     "backlight" - LED will act as a back-light, controlled by the framebuffer
  18                   system
  19     "default-on" - LED will turn on, but see "default-state" below
  20     "heartbeat" - LED "double" flashes at a load average based rate
  21     "ide-disk" - LED indicates disk activity
  22     "timer" - LED flashes at a fixed, configurable rate
  23 - default-state:  (optional) The initial state of the LED.  Valid
  24   values are "on", "off", and "keep".  If the LED is already on or off
  25   and the default-state property is set the to same value, then no
  26   glitch should be produced where the LED momentarily turns off (or
  27   on).  The "keep" setting will keep the LED at whatever its current
  28   state is, without producing a glitch.  The default is off if this
  29   property is not present.
  30
  31 Examples:
  32
  33 leds {
  34         compatible = "gpio-leds";
  35         hdd {
  36                 label = "IDE Activity";
  37                 gpios = <&mcu_pio 0 1>; /* Active low */
  38                 linux,default-trigger = "ide-disk";
  39         };
  40
  41         fault {
  42                 gpios = <&mcu_pio 1 0>;
  43                 /* Keep LED on if BIOS detected hardware fault */
  44                 default-state = "keep";
  45         };
  46 };
  47
  48 run-control {
  49         compatible = "gpio-leds";
  50         red {
  51                 gpios = <&mpc8572 6 0>;
  52                 default-state = "off";
  53         };
  54         green {
  55                 gpios = <&mpc8572 7 0>;
  56                 default-state = "on";
  57         };
  58 }