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ALTERA_AVGEN(4)        FreeBSD Kernel Interfaces Manual        ALTERA_AVGEN(4)

NAME
     altera_avgen - driver for generic Altera Avalon-bus-attached, memory-
     mapped devices

SYNOPSIS
     device altera_avgen

     In /boot/device.hints:
     hint.altera_avgen.0.at="nexus0"
     hint.altera_avgen.0.maddr=0x7f00a000
     hint.altera_avgen.0.msize=20
     hint.altera_avgen.0.width=4
     hint.altera_avgen.0.fileio="rw"
     hint.altera_avgen.0.devname="berirom"

DESCRIPTION
     The altera_avgen device driver provides generic support for memory-mapped
     devices on the Altera Avalon bus.  device.hints entries configure the
     address, size, I/O disposition, and /dev device node name that will be
     used.  The open(2), read(2), write(2), and mmap(2) system calls (and
     variations) may be used on altera_avgen device nodes, subject to
     constraints imposed using device.hints entries.  Although reading and
     writing mapped memory is supported, altera_avgen does not currently
     support directing device interrupts to userspace.

     A number of device.hints sub-fields are available to configure
     altera_avgen device instances:

     maddr    base physical address of the memory region to export; must be
              aligned to width

     msize    length of the memory region export; must be aligned to width

     width    Granularity at which read(2) and write(2) operations will be
              performed.  Larger requests will be broken down into width
              -sized operations; smaller requests will be rejected.  I/O
              operations must be aligned to width.

     fileio   allowed file descriptor operations; r authorizes read(2); w
              authorizes write(2).

     mmapio   allowed mmap(2) permissions; w authorizes PROT_WRITE; r
              authorizes PROT_READ; x authorizes PROT_EXEC.

     devname  specifies a device name relative to /dev.

     devunit  specifies a device unit number; no unit number is used if this
              is unspecified.

SEE ALSO
     mmap(2), open(2), read(2), write(2)

HISTORY
     The altera_avgen device driver first appeared in FreeBSD 10.0.

AUTHORS
     The altera_avgen device driver and this manual page were 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.  This device driver was written by Robert N. M.
     Watson.

BUGS
     altera_avgen is intended to support the writing of userspace device
     drivers; however, it does not permit directing interrupts to userspace,
     only memory-mapped I/O.

     altera_avgen supports only a 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.

FreeBSD 11.1-RELEASE-p4         August 18, 2012        FreeBSD 11.1-RELEASE-p4
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