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.\" $OpenBSD: magma.4,v 1.13 2013/07/16 16:05:50 schwarze Exp $
.\"
.\"
.\" Copyright (c) 1998 Iain Hibbert
.\" 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.
.\"
.Dd $Mdocdate: July 16 2013 $
.Dt MAGMA 4 sparc64
.Os
.Sh NAME
.Nm magma
.Nd Magma Sp Serial/Parallel board device driver
.Sh SYNOPSIS
.Cd "magma? at sbus?"
.Cd "mtty? at magma?"
.Cd "mbpp? at magma?"
.Sh DESCRIPTION
This driver provides an interface to Magma LC2+1Sp, 2+1Sp, 4+1Sp, 8+2Sp,
4Sp, 8Sp, 12Sp, 16Sp, 1P, 2P, and 2+1HS boards.
These boards are based around the Cirrus Logic CD1400 serial/parallel
communications engine and the Cirrus Logic CD1190 parallel communications
engine.
.Pp
The device minor numbers for this driver are encoded as follows:
.Bd -literal
+---+---+---+---+---+---+---+---+
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
+---+---+---+---+---+---+---+---+
| | | | | | | |
| | | | +---+---+---+---> port number
| | | |
| | | +-------------------> dial-out (on tty ports)
| | |
| | +-----------------------> unused
| |
+---+---------------------------> card number
.Ed
.Pp
Up to four cards are supported in the system.
.Pp
All tty ports have full automatic hardware (RTS/CTS) flow control available
and a 12 byte FIFO on the chip in each direction so errors should be minimal.
.Sh FILES
.Bl -tag -width /dev/bpp[0-3][0-1] -compact
.It /dev/tty[mno][0-f]
Serial ports
.It /dev/bpp[mno][0-1]
Parallel ports
.El
.Sh DIAGNOSTICS
.Bl -diag
.It "mtty0X: ring buffer overflow"
Incoming characters have been discarded due to a buffer overflow.
This is caused by the process in control of the device not reading characters
fast enough.
If need be you can make the ring buffer bigger by changing the
.Dv MAGMA_RBUF_SIZE
#define to something bigger, but it should be a multiple of two.
.It "mtty0X: fifo overflow"
Incoming characters have been discarded due to a CD1400 channel overrun.
This is caused by interrupts not being serviced sufficiently quickly to prevent
the 12 byte receive FIFO on a serial channel from overflowing.
Reducing the value of either the
.Dv MTTY_RX_FIFO_THRESHOLD
or
.Dv MTTY_RX_DTR_THRESHOLD
#define's to something smaller may help slow machines avoid this problem.
.El
.Sh SEE ALSO
.Xr intro 4 ,
.Xr sbus 4 ,
.Xr tty 4
.Sh HISTORY
The driver was loosely based upon the
.Xr cy 4
Cyclades Cyclom device driver written
by Andrew Herbert and Timo Rossi.
.Sh AUTHORS
The driver was written by
.An Iain Hibbert Aq Mt plunky@skate.demon.co.uk
.Sh TODO
CD1190 parallel support.
.Pp
bpp input.
.Pp
Dial-out (cua) devices are not yet supported.
.Pp
mdmbuf is unsupported.
.Pp
Automatic XON/XOFF handshaking could be implemented fairly easily.
.Pp
It would be good if the tty port waited for the FIFO to empty before allowing
a close, so that I could turn off the channel interrupts at that time.
It can be done.
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