freebsd man page for gpioled

GPIOLED(4)						   BSD Kernel Interfaces Manual 						GPIOLED(4)

NAME
     gpioled -- GPIO LED generic device driver

SYNOPSIS
     To compile this driver into the kernel, place the following lines in your kernel configuration file:

	   device gpio
	   device gpioled

DESCRIPTION
     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).

     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 restric-
     tion 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 the device in /dev/led/ to create for led(4).

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

HISTORY
     The gpioled manual page first appeared in FreeBSD 10.1.

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

BSD
								   May 14, 2014 							       BSD