GPIOLED(4)

NAME
gpioled - GPIO led generic device driver

SYNOPSIS
device gpio
device gpioled

This driver attaches a led(4) device to a GPIO pin.

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

On a hint based system, like MIPS, these values are configureable 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 others bits - i.e., pins - will be ignored).

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";
    	};
    };

And optionally, you can choose 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/boot/fdt/dts/bindings-gpio.txt.

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

SEE ALSO
fdt(4), gpio(4), led(4), gpioiic(4)

HISTORY
The gpioled manual page first appeared in FreeBSD 10.1.

AUTHORS
This manual page was written by Luiz Otavio O Souza.