svn commit: r355548 - head/share/man/man4

[Ian Lepore]

Author: ian
Date: Mon Dec  9 03:02:54 2019
New Revision: 355548
URL: https://svnweb.freebsd.org/changeset/base/355548

Log:
  Add a man page for the gpioths(4) driver.

Added:
  head/share/man/man4/gpioths.4   (contents, props changed)

Added: head/share/man/man4/gpioths.4
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ head/share/man/man4/gpioths.4	Mon Dec  9 03:02:54 2019	(r355548)
@@ -0,0 +1,152 @@
+.\"-
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.\" Copyright (c) 2019 Ian Lepore <ian at freebsd.org>
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd December 8, 2019
+.Dt GPIOTHS 4
+.Os
+.Sh NAME
+.Nm gpioths
+.Nd driver for DHTxx and AM320x temperature and humidity sensors
+.Sh SYNOPSIS
+To compile this driver into the kernel,
+place the following line in your
+kernel configuration file:
+.Bd -ragged -offset indent
+.Cd "device gpioths"
+.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
+gpioths_load="YES"
+.Ed
+.Sh DESCRIPTION
+The
+.Nm
+driver supports the DHTxx and AM320x family of
+temperature and humidity sensors.
+The driver automatically reads the values from the sensor
+once every 5 seconds, and makes the results available via
+.Xr sysctl 8
+variables.
+.Sh HARDWARE
+The
+.Nm
+driver provides support for the following devices:
+.Pp
+.Bl -column -compact -offset indent "XXXXXXXX" "XXXXXXXX"
+.It DHT11  Ta DHT12
+.It DHT21  Ta DHT22
+.It AM3201 Ta AM3202
+.El
+.Pp
+The supported devices are all similar to each other, varying
+primarily in accuracy and resolution.
+The devices require a single wire for data communications, using a
+custom protocol which is not compatible with Maxim's 1-wire(tm).
+The AM320x devices also support connection to an i2c bus,
+but this driver supports only the single-wire connection option.
+.Sh SYSCTL VARIABLES
+Sysctl variables are used to access the most recent temperature and
+humidity measurements.
+.Bl -tag -width indent
+.It Va dev.gpioths.<unit>.temp
+The current temperature in integer deciKelvins.
+Note that
+.Xr sysctl 8
+will convert those units to display in decimal degrees Celcius.
+.It Va dev.gpioths.<unit>.hum
+The current relative humidity, as an integer percentage.
+.It Va dev.gpioths.<unit>.fails
+The number of failed attempts to communicate with the sensor since
+the last good access.
+Cleared whenever a set of measurements is successfully retrieved.
+.El
+.Sh FDT CONFIGURATION
+On an
+.Xr fdt 4
+based system, a
+.Nm
+device node is typically defined directly under the root node, or under
+a simplebus node that represents a collection of devices on a board.
+.Pp
+The following properties are required in the
+.Nm
+device subnode:
+.Bl -tag -width indent
+.It Va compatible
+Must be "dht11".
+.It Va gpios
+A reference to the gpio device and pin for data communications.
+.El
+.Ss Example of adding a sensor with an overlay
+.Bd -unfilled -offset indent
+/dts-v1/;
+/plugin/;
+#include <dt-bindings/gpio/gpio.h>
+
+/ {
+    compatible = "wand,imx6q-wandboard";
+};
+
+&{/} {
+    dht0 {
+        compatible = "dht11";
+        gpios = <&gpio5 15 GPIO_ACTIVE_HIGH>;
+    };
+};
+.Ed
+.Sh HINTS CONFIGURATION
+On a
+.Xr device.hints 5
+based system, such as
+.Li MIPS ,
+these values are configurable for
+.Nm :
+.Bl -tag -width indent
+.It Va hint.gpioths.<unit>.at
+The
+.Xr gpiobus 4
+instance the
+.Nm
+instance is attached to.
+.It Va hint.gpioths.pins
+A bitmask with a single bit set to indicate which gpio pin on the
+.Xr gpiobus 4
+to use for data communications.
+.El
+.Sh SEE ALSO
+.Xr fdt 4 ,
+.Xr gpiobus 4 ,
+.Xr sysctl 8
+.Sh HISTORY
+The
+.Nm
+driver first appeared in
+.Fx 11.1 .