GPIOLED(4) FreeBSD Kernel Interfaces Manual GPIOLED(4)


gpioledGPIO led generic device driver


device gpio
device gpioled

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


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:

The gpiobus you are attaching to. Normally assigned to gpiobus0.
Arbitrary name of device in /dev/led/ to create for led(4).
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 { 
 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).


The gpioled manual page first appeared in FreeBSD 10.1.


This manual page was written by Luiz Otavio O Souza.
May 14, 2014 FreeBSD