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.\" Copyright (c) 2020 Andriy Gapon <avg@FreeBSD.org>
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.Dd August 5, 2020
.Dt GPIOKEYS 4
.Os
.Sh NAME
.Nm gpiokeys
.Nd GPIO keys device driver
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "options FDT"
.Cd "device gpio"
.Cd "device gpiokeys"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
gpiokeys_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides a way to represent a set of general purpose inputs as a
.Xr keyboard 4
device.
At the moment the driver supports only
.Xr FDT 4
based systems.
The DTS determines what pins are mapped to buttons and what key codes are
generated for each virtual button.
The
.Xr keyboard 4
device can be used from userland to monitor for input changes.
.Pp
On an
.Xr FDT 4
based system
the DTS part for a
.Nm
device usually looks like:
.Bd -literal
/ {

	...

	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>
		};
	};
};
.Ed
.Pp
For more details about the
.Va gpios
property, please consult
.Pa /usr/src/sys/dts/bindings-gpio.txt .
.Pp
The
.Nm
driver supports two properties for specifying a key code.
.Pp
The property
.Va freebsd,code
specifies a
.Fx
native scancode compatible with
.Xr kbdmap 5
keyboard maps.
.Pp
The property
.Va 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.
.Pp
The property
.Va 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.
.Pp
The property
.Va autorepeat
determines whether autorepeat is enabled for a button.
.Pp
The property
.Va debounce-interval
defines debouncing interval time in milliseconds.
If not specified the interval defaults to 5.
.Sh SEE ALSO
.Xr fdt 4 ,
.Xr gpio 4 ,
.Xr keyboard 4 ,
.Xr kbdmap 5
.Sh HISTORY
The
.Nm
manual page first appeared in
.Fx 12.2 .
.Sh AUTHORS
The
.Nm
driver was written by
.An Oleksandr Tymoshenko Aq Mt gonzo@FreeBSD.org .
This
manual page was written by
.An Andriy Gapon Aq Mt avg@FreeBSD.org .