GPIOKEYS(4)            FreeBSD Kernel Interfaces Manual            GPIOKEYS(4)

NAME
     gpiokeys - GPIO keys device driver

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

           options FDT
           device gpio
           device gpiokeys

     Alternatively, to load the driver as a module at boot time, place the
     following line in loader.conf(5):

           gpiokeys_load="YES"

DESCRIPTION
     The gpiokeys driver provides a way to represent a set of general purpose
     inputs as a keyboard(4) device.  At the moment the driver supports only
     FDT(4) based systems.  The DTS determines what pins are mapped to buttons
     and what key codes are generated for each virtual button.  The
     keyboard(4) device can be used from userland to monitor for input
     changes.

     On an FDT(4) based system the DTS part for a gpiokeys device usually
     looks like:

     / {

             ...

             gpio_keys {
                     compatible = "gpio-keys";

                     btn1 {
                             label = "button1";
                             linux,code = <KEY_1>;
                             gpios = <&gpio 0 3 GPIO_ACTIVE_LOW>
                     };

                     btn2 {
                             label = "button2";
                             linux,code = <KEY_2>;
                             gpios = <&gpio 0 4 GPIO_ACTIVE_LOW>
                     };
             };
     };

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

     The gpiokeys driver supports two properties for specifying a key code.

     The property freebsd,code specifies a FreeBSD native scancode compatible
     with kbdmap(5) keyboard maps.

     The property linux,code specifies an evdev scancode.  That scancode is
     internally translated to a native scancode.  Note that not all evdev
     scancodes have corresponding native scancodes.  If a scancode cannot be
     translated, then a diagnostic message is printed and the input is
     ignored.

     The property label is a descriptive name of a button.  It is used for
     diagnostic messages only.  This property is optional.  If not set, the
     node name is used in its place.

     The property autorepeat determines whether autorepeat is enabled for a
     button.

     The property debounce-interval defines debouncing interval time in
     milliseconds.  If not specified the interval defaults to 5.

SEE ALSO
     fdt(4), gpio(4), keyboard(4), kbdmap(5)

HISTORY
     The gpiokeys manual page first appeared in FreeBSD 12.2.

AUTHORS
     The gpiokeys driver was written by Oleksandr Tymoshenko
     <gonzo@FreeBSD.org>.  This manual page was written by
     Andriy Gapon <avg@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6         August 5, 2020         FreeBSD 13.1-RELEASE-p6