.\" Copyright (c) 2020 Emmanuel Vadot <manu@freebsd.org>
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.Dd October 2, 2020
.Dt BACKLIGHT 9
.Os
.Sh NAME
.Nm backlight ,
.Nm backlight_register ,
.Nm backlight_destroy ,
.Nm BACKLIGHT_GET_STATUS ,
.Nm BACKLIGHT_SET_STATUS ,
.Nd BACKLIGHT methods
.Sh SYNOPSIS
.Cd "device backlight"
.In "backlight_if.h"
.In "sys/sys/backlight.h"
.Ft int
.Fn BACKLIGHT_GET_STATUS "device_t bus" "struct backlight_props *props"
.Ft int
.Fn BACKLIGHT_SET_STATUS "device_t bus" "struct backlight_props *props"
.Ft struct cdev *
.Fn backlight_register "const char *name" "device_t dev"
.Ft int
.Fn backlight_destroy "struct cdev *cdev"
.Sh DESCRIPTION
The backlight driver provides a generic way for handling a panel backlight.
.Pp
Drivers for backlight system register themselves globally using the
.Fn backlight_register
function.
They must define two methods,
.Fn BACKLIGHT_GET_STATUS
which is used to query the current brightness level and
.Fn BACKLIGHT_SET_STATUS
which is used to update it.
.Sh INTERFACE
.Bl -tag -width indent
.It Fn BACKLIGHT_GET_STATUS "device_t bus" "struct backlight_props *props"
Driver fills the current brightless level and the optional supported levels.
.It Fn BACKLIGHT_SET_STATUS "device_t bus" "struct backlight_props *props"
Driver update the backlight level based on the brightness member of the props
struct.
.El
.Sh FILES
.Bl -tag -width "/dev/backlight/*"
.It Pa /dev/backlight/*
.Sh HISTORY
The
.Nm backlight
interface first appear in
.Fx 13.0 .
The
.Nm backlight
driver and manual page was written by
.An Emmanuel Vadot Aq Mt manu@FreeBSD.org .