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Documentation / devicetree / bindings / gpio / led.txt




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Based on kernel version 3.7. Page generated on 2012-12-12 10:00 EST.

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 "gpios property" in
11	  Documentation/devicetree/bindings/gpio/gpio.txt.  Active low LEDs should be
12	  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	};
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