.\"-
.\" Copyright (c) 2012 Robert N. M. Watson
.\" All rights reserved.
.\"
.\" This software was developed by SRI International and the University of
.\" Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
.\" ("CTSRD"), as part of the DARPA CRASH research programme.
.\"
.\" 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.
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.\" $FreeBSD$
.\"
.Dd August 18, 2012
.Dt ALTERA_AVGEN 4
.Os
.Sh NAME
.Nm altera_avgen
.Nd driver for generic Altera Avalon-bus-attached, memory-mapped devices
.Sh SYNOPSIS
.Cd "device altera_avgen"
.Pp
In
.Pa /boot/device.hints :
.Cd hint.altera_avgen.0.at="nexus0"
.Cd hint.altera_avgen.0.maddr=0x7f00a000
.Cd hint.altera_avgen.0.msize=20
.Cd hint.altera_avgen.0.width=4
.Cd hint.altera_avgen.0.fileio="rw"
.Cd hint.altera_avgen.0.devname="berirom"
.Sh DESCRIPTION
The
.Nm
device driver provides generic support for memory-mapped devices on the
Altera Avalon bus.
.Pa device.hints
entries configure the address, size, I/O disposition, and
.Pa /dev
device node name that will be used.
The
.Xr open 2 ,
.Xr read 2 ,
.Xr write 2 ,
and
.Xr mmap 2
system calls (and variations) may be used on
.Nm
device nodes, subject to constraints imposed using
.Pa device.hints
entries.
Although reading and writing mapped memory is supported,
.Nm
does not currently support directing device interrupts to userspace.
.Pp
A number of
.Pa device.hints
sub-fields are available to configure
.Nm
device instances:
.Bl -tag -width devunit
.It maddr
base physical address of the memory region to export; must be aligned to
.Li width
.It msize
length of the memory region export; must be aligned to
.Li width
.It width
Granularity at which
.Xr read 2
and
.Xr write 2
operations will be performed.
Larger requests will be broken down into
.Li width -sized
operations; smaller requests will be rejected.
I/O operations must be aligned to
.Li width .
.It fileio
allowed file descriptor operations;
.Li r
authorizes
.Xr read 2 ;
.Li w
authorizes
.Xr write 2 .
.It mmapio
allowed
.Xr mmap 2
permissions;
.Li w
authorizes
.Dv PROT_WRITE ;
.Li r
authorizes
.Dv PROT_READ ;
.Li x
authorizes
.Dv PROT_EXEC .
.It devname
specifies a device name relative to
.Pa /dev .
.It devunit
specifies a device unit number; no unit number is used if this is unspecified.
.El
.Sh SEE ALSO
.Xr mmap 2 ,
.Xr open 2 ,
.Xr read 2 ,
.Xr write 2
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 10.0 .
.Sh AUTHORS
The
.Nm
device driver and this manual page were
developed by SRI International and the University of Cambridge Computer
Laboratory under DARPA/AFRL contract
.Pq FA8750-10-C-0237
.Pq Do CTSRD Dc ,
as part of the DARPA CRASH research programme.
This device driver was written by
.An Robert N. M. Watson .
.Sh BUGS
.Nm
is intended to support the writing of userspace device drivers; however, it
does not permit directing interrupts to userspace, only memory-mapped I/O.
.Pp
.Nm
supports only a
.Li nexus
bus attachment, which is appropriate for system-on-chip busses such as
Altera's Avalon bus.
If the target device is off of another bus type, then additional bus
attachments will be required.