.\"	$OpenBSD: sensor_add.9,v 1.2 2006/05/29 10:39:29 jmc Exp $
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.\" Copyright (c) 2006 Michael Knudsen <mk@openbsd.org>
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.Dd April 23, 2006
.Dt SENSOR_ADD 9
.Os
.Sh NAME
.Nm sensor_add ,
.Nm sensor_del ,
.Nm sensor_get ,
.Nm sensor_task_register ,
.Nm sensor_task_unregister
.Nd sensor framework
.Sh SYNOPSIS
.Fd #include <sys/sensors.h>
.Ft void
.Fn "sensor_add" "struct sensor *sens"
.Ft void
.Fn "sensor_del" "struct sensor *sens"
.Ft struct sensor
.Fn "*sensor_get" "int num"
.Ft int
.Fn "sensor_task_register" "void *arg" "void (*func)(void *)" "int period"
.Ft void
.Fn "sensor_task_unregister" "void *arg"
.Sh DESCRIPTION
The
.Nm sensor
framework API provides a mechanism to manipulate the sensor framework
available under the
.Va hw.sensors
.Xr sysctl 8 .
.Pp
.Fn sensor_add
adds a sensor specified by the
.Pa sens
argument.
.Fn sensor_del
removes a sensor previously added by
.Fn sensor_add .
Both
.Fn sensor_add
and
.Fn sensor_del
take an argument of a pointer to a
.Vt struct sensor ,
defined in
.Aq Pa sys/sensors.h ,
as:
.Bd -literal
struct sensor {
	SLIST_ENTRY(sensor) list;
	int num;			/* sensor number */
	char device[16];		/* device name */
	enum sensor_type type;		/* sensor type */
	char desc[32];			/* sensor description */
	int64_t value;			/* current value */
	u_int rfact;			/* resistor factor */
	enum sensor_status status;	/* sensor status */
	int flags;			/* sensor flags */
	struct timeval tv;		/* sensor value last change time */
};
.Ed
.Pp
.Fn sensor_get
takes an index parameter and returns a pointer to the corresponding
.Vt struct sensor ,
or
.Dv NULL
if no such sensor exists.
.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 .
.Sh SEE ALSO
.Xr sysctl 8
.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 .