136 lines
4.4 KiB
Groff
136 lines
4.4 KiB
Groff
.\"
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.\" Copyright (c) 2014 Marcel Moolenaar
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd April 29, 2014
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.Dt PROTO 4
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.Os
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.\"
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.Sh NAME
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.Nm proto
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.Nd Driver for prototyping and H/W diagnostics
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.\"
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device proto"
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.Ed
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.Pp
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Alternatively, to load the driver as a
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module at boot time, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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proto_load="YES"
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.Ed
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.\"
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.Sh DESCRIPTION
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The
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.Nm
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device driver attaches to PCI devices when no other device drivers are
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present and creates device special files for all resources associated
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with the device.
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The driver itself has no knowledge of the device it attaches to.
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Programs can open these device special files and perform register-level
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reads and writes.
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As such, the
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.Nm
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device driver is nothing but a conduit or gateway between user space
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programs and the hardware device.
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.Pp
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Examples for why this is useful include hardware diagnostics and prototyping.
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In both these use cases, it is far more convenient to develop and run the
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logic in user space.
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Especially hardware diagnostics requires a somewhat user-friendly interface
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and adequate reporting.
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Neither is done easily as kernel code.
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.\"
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.Sh FILES
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All device special files corresponding to a PCI device are located under
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.Pa /dev/proto/pci<d>:<b>:<s>:<f>
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with
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.Pa pci<d>:<b>:<s>:<f>
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representing the location of the PCI device in the PCI hierarchy.
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A location includes:
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.Pp
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.Bl -tag -width XXXXXX -compact
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.It <d>
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The PCI domain number
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.It <b>
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The PCI bus number
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.It <s>
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The PCI slot or device number
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.It <f>
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The PCI function number
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.El
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.Pp
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Every PCI device has a device special file called
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.Pa pcicfg .
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This device special file gives access to the PCI configuration space.
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For each valid base address register (BAR), a device special file is created
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that contains the BAR offset and the resource type.
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A resource type can be either
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.Pa io
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or
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.Pa mem
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representing I/O port or memory mapped I/O space (resp.)
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.\"
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.Sh EXAMPLES
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A single function PCI device in domain 0, on bus 1, in slot 2 and having a
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single memory mapped I/O region will have the following device special files:
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.Pp
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.Bl -tag -width XXXXXX -compact
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.It Pa /dev/proto/pci0:1:2:0/10.mem
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.It Pa /dev/proto/pci0:1:2:0/pcicfg
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.El
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.\"
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.Sh AUTHORS
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The
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.Nm
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device driver and this manual page were written by
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.An Marcel Moolenaar Aq Mt marcel@xcllnt.net .
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.Sh SECURITY CONSIDERATIONS
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Because programs have direct access to the hardware, the
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.Nm
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driver is inherently insecure.
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It is not advisable to use this driver on a production machine.
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.\"
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.Sh MISSING FUNCTIONALITY
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The
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.Nm
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driver does not yet support interrupts.
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Since interrupts cannot be handled by the driver itself, they must be converted
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into signals and delivered to the program that has registered for interrupts.
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.Pp
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In order to test the transmission or reception of data, some means of doing
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direct memory access (DMA) by the device must be possible.
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This too must be under the control of the program.
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The details of how a program can set up and
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initiate DMA still need to be fleshed out.
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.Pp
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Support for non-PCI devices has not been implemented yet.
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