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).

     hint.gpioled.%d.invert
                            If set to 1, the pin will be set to 0 to light the LED, and 1 to
                            clear it.

     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).

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.