.\"	$NetBSD: swsensor.4,v 1.13 2016/06/01 02:15:26 pgoyette Exp $
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Paul Goyette.
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.Dd June 1, 2016
.Dt SWSENSOR 4
.Os
.Sh NAME
.Nm swsensor
.Nd software environmental sensor
.Sh SYNOPSIS
.Cd "pseudo-device swsensor"
.Sh DESCRIPTION
The
.Nm
driver provides a software environmental sensor that works with
.Xr  sysctl 8
and
.Xr envstat 8 .
The driver is intended to be loaded as a kernel module.
One can, however, include the
.Nm
driver directly in a kernel using the configuration from the synopsis.
By default, the sensor is of type
.Dv ENVSYS_UNITS_INTEGER .
.Pp
The following values can be specified in the
.Xr modload 8
command when loading the
.Nm
module to alter the driver's behavior.
.Pp
.Bl -tag -width "percentage"
.It Sy "Variable" Sy "Usage"
.It Li "mode"
Controls whether or not
.Nm
provides internally-maintained limits and limit checking
.Bl -tag -width "Value"
.It Sy "Value" Sy "Meaning"
.It Li "0"
sensor has no internally-maintained limits
.It Li "1"
sensor provides its own internal limit value
.It Li "2"
sensor maintains an internal adjustable limit and performs its own
comparison between the sensor's limit and its current value
.El
.It Li "limit"
The initial alarm limit value, if limit emulation is selected (i.e., if
.Dv mode
is set to 1 or 2)
.It Li "value_max"
.It Li "value_min"
The maximum and minimum values.
The corresponding
.Dv ENVSYS_FVALID_MAX
and
.Dv ENVSYS_FVALID_MIN
flags are implicitly set.
.It Li "percentage"
This boolean value controls the setting of the
.Dv ENVSYS_FPERCENT
flag.
.It Li "type"
Define the sensor's unit/type.
By default, a Temperature sensor is created.
Any of the string values from the following table can be specified:
.Bl -column "Battery capacity" "Battery charge" "Ampere hour"
.It "Temperature"      Ta "Fan"       Ta "Voltage AC"
.It "Voltage DC"       Ta "Ohms"      Ta "Watts"
.It "Ampere"           Ta "Watt hour" Ta "Ampere hour"
.It "Indicator"        Ta "Integer"   Ta "Drive"
.It "Battery capacity" Ta "Battery charge" Ta ""
.El
(Values are case-sensitive, and spaces must be included.)
.It Li "value"
Provide an initial value for the sensor.
If this is omitted, the sensor's initial value is set to zero.
.El
.Pp
For example,
.Dl Ic modload -s type=Voltage\e DC swsensor
will create a sensor of type
.Dv ENVSYS_UNITS_SVOLTS_DC ,
while
.Dl Ic modload -i mode=1 -i limit=50 swsensor
will create a sensor which has an initial, device-provided limit of 50.
.Pp
The sensor's raw value and state can be manually updated by modifying the
.Xr sysctl 8
variables
.Dq hw.swsensor.cur_value
and
.Dq hw.swsensor.state
variables respectively.
.Sh SEE ALSO
.Xr modctl 2 ,
.Xr envstat 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
driver was written by
.An Paul Goyette
and first appeared in
.Nx 6.0 .
.Sh BUGS
The
.Nm
driver emulates a device with only a single sensor.
.Pp
The
.Nm
driver can only emulate one hardware-managed limit; this is assumed to
be the
.Dv critical-min
limit.