.\"	$OpenBSD: sensor_attach.9,v 1.3 2006/12/28 11:36:14 jmc Exp $
.\"
.\" Copyright (c) 2006 Michael Knudsen <mk@openbsd.org>
.\" Copyright (c) 2006 Constantine A. Murenin <cnst+openbsd@bugmail.mojo.ru>
.\" All rights reserved.
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.Dd December 23, 2006
.Dt SENSOR_ATTACH 9
.Os
.Sh NAME
.Nm sensor_attach ,
.Nm sensor_detach ,
.Nm sensor_find ,
.Nm sensordev_install ,
.Nm sensordev_deinstall ,
.Nm sensordev_get ,
.Nm sensor_task_register ,
.Nm sensor_task_unregister
.Nd sensors framework
.Sh SYNOPSIS
.Fd #include <sys/sensors.h>
.Ft void
.Fn "sensordev_install" "struct sensordev *sensdev"
.Ft void
.Fn "sensordev_deinstall" "struct sensordev *sensdev"
.Ft struct sensordev
.Fn "*sensordev_get" "int devnum"
.Pp
.Ft void
.Fn "sensor_attach" "struct sensordev *sensdev" "struct sensor *sens"
.Ft void
.Fn "sensor_detach" "struct sensordev *sensdev" "struct sensor *sens"
.Ft struct sensor
.Fn "*sensor_find" "int devnum" "enum sensor_type stype" "int numt"
.Pp
.Ft int
.Fn "sensor_task_register" "void *arg" "void (*func)(void *)" "int period"
.Ft void
.Fn "sensor_task_unregister" "void *arg"
.Sh DESCRIPTION
The
sensors
framework API provides a mechanism for manipulation of hardware sensors
that are available under the
.Va hw.sensors
.Xr sysctl 8
tree.
.Pp
.Fn sensor_attach
adds the sensor specified by the
.Pa sens
argument to the sensor device specified by the
.Pa sensdev
argument.
.Fn sensor_detach
can be used to remove sensors previously added by
.Fn sensor_attach .
.Pp
.Fn sensordev_install
registers the sensor device specified by the
.Pa sensdev
argument so that all sensors that are attached to the device become
accessible via the sysctl interface.
.Fn sensordev_deinstall
can be used to remove sensor devices previously registered by
.Fn sensordev_install .
.Pp
.Fn sensordev_get
takes ordinal number
.Pa devnum
specifying a sensor device and
returns a pointer to the corresponding
.Vt struct sensordev ,
or
.Dv NULL
if no such sensor device exists.
.Pp
.Fn sensor_find
takes ordinal number
.Pa devnum
specifying a sensor device, sensor type
.Pa stype
and ordinal number of sensor of such type
.Pa numt ,
and returns a pointer to the corresponding
.Vt struct sensor ,
or
.Dv NULL
if no such sensor exists.
.Fn sensor_find
will always return
.Dv NULL
if the corresponding sensor devices are not registered by
.Fn sensordev_install .
.Pp
Drivers are responsible for retrieving, interpreting, and normalising
sensor values and updating the sensor struct periodically.
If the driver needs process context, for example to sleep, it can
register a task with the sensor framework.
.Pp
.Fn sensor_task_register
is used to register a periodic task to update sensors.
The
.Fa func
argument is a pointer to the function to run with an interval of
.Fa period
seconds.
The
.Fa arg
parameter is the argument given to the
.Fa func
function.
The
.Fn sensor_task_unregister
removes all tasks previously registered with
.Fn sensor_task_register
with an argument of
.Fa arg .
.Pp
All the functions in the sensor framework must be called during
.Xr autoconf 9
or from a process context.
Additionally,
.Fn sensor_task_unregister
must not be called while a function previously registered with
.Fn sensor_task_register
is running.
.Sh SEE ALSO
.Xr sysctl 8 ,
.Xr autoconf 9
.Sh HISTORY
The sensor framework was written by
.An Alexander Yurchenko Aq grange@openbsd.org
and first appeared in
.Ox 3.4 .
.An David Gwynne Aq dlg@openbsd.org
later extended it for
.Ox 3.8 .
.An Constantine A. Murenin Aq cnst+openbsd@bugmail.mojo.ru
extended it even further by introducing the concept of sensor devices in
.Ox 4.1 .