gpioled4

Usage

Overview

The gpioled driver provides glue to attach a led(4) compatible device to a GPIO pin. Each LED in the system has a name which is used to export a device as /dev/led/<name>. The GPIO pin can then be controlled by writing to this device as described in led(4).

On a device.hints(5) based system, like MIPS, these values are configurable for gpioled:

hint.gpioled.%d.at

The gpiobus you are attaching to. Normally assigned to gpiobus0.

hint.gpioled.%d.name

Arbitrary name of device in /dev/led/ to create for led(4).

hint.gpioled.%d.pins

Which pin on the GPIO interface to map to this instance. Please note that this mask should only ever have one bit set (any other bits - i.e., pins - will be ignored).

hint.gpioled.%d.invert

Use pin inversion. If set to 1, the pin will be set to 0 to light the LED, and 1 to clear it.

hint.gpioled.%d.invmode

Whether or not to use hardware support when pin inversion is requested. Must be one of:

auto

Use hardware pin inversion if available, else fallback to software pin inversion. This is the default.

hw

Use hardware pin inversion.

sw

Use software pin inversion.

hint.gpioled.%d.state

The initial state of the LED when the driver takes control over it. If set to 1 or 0, the LED will be on or off correspondingly. If set to -1, the LED will be kept in its original state.

On a FDT(4) based system, like ARM, the DTS part for a gpioled device usually looks like:

gpio: gpio {
	gpio-controller;
	...
	led0 {
		compatible = "gpioled";
		gpios = <&gpio 16 2 0>;		/* GPIO pin 16. */
		name = "ok";
	};
	led1 {
		compatible = "gpioled";
		gpios = <&gpio 17 2 0>;		/* GPIO pin 17. */
		name = "user-led1";
	};
};

Optionally, you can choose to combine all the LEDs under a single “gpio-leds” compatible node:

simplebus0 {
	...
	leds {
		compatible = "gpio-leds";
		led0 {
			gpios = <&gpio 16 2 0>;
			name = "ok"
		};
		led1 {
			gpios = <&gpio 17 2 0>;
			name = "user-led1"
		};
	};
};

Both methods are equally supported and it is possible to have the LEDs defined with any sort of mix between the methods. The only restriction is that a GPIO pin cannot be mapped by two different (gpio)leds.

For more details about the gpios property, please consult /usr/src/sys/dts/bindings-gpio.txt.

The property name is the arbitrary name of the device in /dev/led/ to create for led(4).