Date: Sat, 7 Apr 2018 23:31:55 +0000 (UTC) From: Ian Lepore <ian@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r332261 - head/share/man/man4 Message-ID: <201804072331.w37NVt7w081169@repo.freebsd.org>
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Author: ian Date: Sat Apr 7 23:31:55 2018 New Revision: 332261 URL: https://svnweb.freebsd.org/changeset/base/332261 Log: Add a manpage for spigen(4). Added: head/share/man/man4/spigen.4 (contents, props changed) Added: head/share/man/man4/spigen.4 ============================================================================== --- /dev/null 00:00:00 1970 (empty, because file is newly added) +++ head/share/man/man4/spigen.4 Sat Apr 7 23:31:55 2018 (r332261) @@ -0,0 +1,206 @@ +.\" +.\" 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 April 7, 2018 +.Dt SPIGEN 4 +.Os +.Sh NAME +.Nm spigen +.Nd SPI generic I/O device driver +.Sh SYNOPSIS +To compile this driver into the kernel, +place the following lines in your +kernel configuration file: +.Bd -ragged -offset indent +.Cd "device spi" +.Cd "device spibus" +.Cd "device spigen" +.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 +spigen_load="YES" +.Ed +.Sh DESCRIPTION +The +.Nm +driver provides direct access to a slave device on the SPI bus. +Each instance of a +.Nm +device is associated with a single chip-select +line on the bus, and all I/O performed through that instance is done +with that chip-select line asserted. +.Pp +SPI data transfers are inherently bi-directional; there are not separate +read and write operations. +When commands and data are sent to a device, data also comes back from +the device, although in some cases the data may not be useful (or even +documented or predictable for some devices). +Likewise on a read operation, whatever data is in the buffer at the start +of the operation is sent to (and typically ignored by) the device, with each +outgoing byte then replaced in the buffer by the corresponding incoming byte. +Thus, all buffers passed to the transfer functions are both input and +output buffers. +.Pp +The +.Nm +driver provides access to the SPI slave device with the following +.Xr ioctl 2 +calls, defined in +.In sys/spigenio.h : +.Bl -tag -width indent +.It Dv SPIGENIOC_TRANSFER Pq Vt "struct spigen_transfer" +Transfer a command and optional associated data to/from the device, +using the buffers described by the st_command and st_data fields in the +.Vt spigen_transfer . +Set +.Vt st_data.iov_len +to zero if there is no data associated with the command. +.Bd -literal +struct spigen_transfer { + struct iovec st_command; + struct iovec st_data; +}; +.Ed +.It Dv SPIGENIOC_TRANSFER_MMAPPED Pq Vt "spigen_transfer_mmapped" +Transfer a command and optional associated data to/from the device. +The buffers for the transfer are a previously-mmap'd region. +The length of the command and data within that region are described by the +.Vt stm_command_length +and +.Vt stm_data_length +fields of +.Vt spigen_transfer_mmapped . +If +.Vt stm_data_length +is non-zero, the data appears in the memory region immediately +following the command (that is, at offset +.Vt stm_command_length +from the start of the mapped region). +.Bd -literal +struct spigen_transfer_mmapped { + size_t stm_command_length; + size_t stm_data_length; +}; +.Ed +.It Dv SPIGENIOC_GET_CLOCK_SPEED Pq Vt uint32_t +Get the maximum clock speed (bus frequency in Hertz) to be used +when communicating with this slave device. +.It Dv SPIGENIOC_SET_CLOCK_SPEED Pq Vt uint32_t +Set the maximum clock speed (bus frequency in Hertz) to be used +when communicating with this slave device. +The setting remains in effect for subsequent transfers; it +is not necessary to reset this before each transfer. +The actual bus frequency may be lower due to hardware limitiations +of the SPI bus controller device. +.It Dv SPIGENIOC_GET_SPI_MODE Pq Vt uint32_t +Get the SPI mode (clock polarity and phase) to be used +when communicating with this device. +.It Dv SPIGENIOC_SET_SPI_MODE Pq Vt uint32_t +Set the SPI mode (clock polarity and phase) to be used +when communicating with this device. +The setting remains in effect for subsequent transfers; it +is not necessary to reset this before each transfer. +.El +.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.spigen.%d.at +The spibus the +.Nm +instance is attached to. +.It Va hint.spigen.%d.clock +The maximum bus frequency to use when communicating with this device. +Actual bus speed may be lower, depending on the capabilities of the SPI +bus controller hardware. +.It Va hint.spigen.%d.cs +The chip-select number to assert when performing I/O for this device. +Set the high bit (1 << 31) to invert the logic level of the chip select line. +.It Va hint.spigen.%d.mode +The SPI mode (0-3) to use when communicating with this device. +.El +.Sh FDT CONFIGURATION +On an +.Xr fdt 4 +based system, the spigen device is defined as a slave device subnode +of the SPI bus controller node. +All properties documented in the +.Va spibus.txt +bindings document can be used with the +.Nm +device. +The most commonly-used ones are documented below. +.Pp +The following properties are required in the +.Nm +device subnode: +.Bl -tag -width indent +.It Va compatible +Must be the string "freebsd,spigen". +.It Va reg +Chip select address of device. +.It Va spi-max-frequency +The maximum bus frequency to use when communicating with this slave device. +Actual bus speed may be lower, depending on the capabilities of the SPI +bus controller hardware. +.El +.Pp +The following properties are optional for the +.Nm +device subnode: +.Bl -tag -width indent +.It Va spi-cpha +Empty property indicating the slave device requires shifted clock +phase (CPHA) mode. +.It Va spi-cpol +Empty property indicating the slave device requires inverse clock +polarity (CPOL) mode. +.It Va spi-cs-high +Empty property indicating the slave device requires chip select active high. +.El +.Sh FILES +.Bl -tag -width -compact +.It Pa /dev/spigen* +.El +.Sh SEE ALSO +.Xr fdt 4 , +.Xr device.hints 5 +.Sh HISTORY +The +.Nm +driver +appeared in +.Fx 11.0 . +FDT support appeared in +.Fx 11.2 .
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