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LEDs connected to GPIO lines
Required properties:
- compatible : should be "gpio-leds".
Each LED is represented as a sub-node of the gpio-leds device. Each
node's name represents the name of the corresponding LED.
LED sub-node properties:
- gpios : Should specify the LED's GPIO, see "Specifying GPIO information
for devices" in Documentation/powerpc/booting-without-of.txt. Active
low LEDs should be indicated using flags in the GPIO specifier.
- label : (optional) The label for this LED. If omitted, the label is
taken from the node name (excluding the unit address).
- linux,default-trigger : (optional) 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 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:
leds {
compatible = "gpio-leds";
hdd {
label = "IDE Activity";
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";
};
}
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