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Add a manpage for the imx_spi driver.

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Ian Lepore 2018-07-09 19:00:13 +00:00
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.\"
.\" Copyright (c) 2018 Ian Lepore <ian@freebsd.org>
.\" All rights reserved.
.\"
.\" 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 ``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 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 July 9, 2018
.Dt IMX_SPI 4
.Os
.Sh NAME
.Nm imx_spi
.Nd device driver for the NXP i.MX family Serial Peripheral Interface (SPI)
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following line in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device imx_spi"
.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
imx_spi_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides support for the
.Sq ECSPI
(Enhanced Configurable SPI) hardware present on the NXP i.MX family
of processors.
While the ECSPI hardware supports both master and slave mode,
this driver currently operates only in master mode.
.Pp
Due to hardware quirks, the
.Nm
driver requires that all chip select pins be configured as GPIO pins.
Use the FDT property
.Sq cs-gpios
to specify which pins to use as chip selects.
You may use any GPIO pins, including the ones that the hardware would
normally use as SPI select pins; just configure them as GPIO in the
.Xr fdt_pinctrl 4
data.
.Pp
.Sh SYSCTL VARIABLES
The following variables are available via
.Xr sysctl 8 ,
and as
.Xr loader 8
tunables:
.Bl -tag -width indent
.It Va dev.imx_spi.%d.debug
Output debugging info when non-zero.
A value of 1 displays information about bus transfers,
2 adds information about bus clock frequency and chip select activity,
and 3 adds information about interrupt handling.
.El
.Sh SEE ALSO
.Xr fdt 4 ,
.Xr fdt_pinctrl 4 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 12.0 .