NetBSD-5.0.2/share/man/man4/man4.sparc/magma.4

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.\" Copyright (c) 1998 Iain Hibbert
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.Dd April 21, 1998
.Dt MAGMA 4 sparc
.Sh NAME
.Nm magma
.Nd
Magma Sp Serial/Parallel board device driver
.Sh SYNOPSIS
.Cd "magma* at sbus? slot ? offset ?"
.Cd "mtty* at magma?"
.Cd "mbpp* at magma?"
.Sh DESCRIPTION
The
.Nm
driver provides an interface to Magma LC2+1Sp, 2+1Sp, 4+1Sp, 8+2Sp,
4Sp, 8Sp, 12Sp, 16Sp, 1P and 2P 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:
.Pp
.Bd -literal
    +---+---+---+---+---+---+---+---+
    | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
    +---+---+---+---+---+---+---+---+
      |   |   |   |   |   |   |   |
      |   |   |   |   +---+---+---+---\*[Gt] port number
      |   |   |   |
      |   |   |   +-------------------\*[Gt] dial-out (on tty ports)
      |   |   |
      |   |   +-----------------------\*[Gt] unused
      |   |
      +---+---------------------------\*[Gt] 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 Pa /dev/tty[0-3][0-a]
Serial ports
.It Pa /dev/bpp[0-3][0-1]
Parallel ports
.El
.Sh DIAGNOSTICS
.Bl -diag
.It "mtty%d%x: 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.
.Pp
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 "mtty%d%x: 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.
.Pp
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 read 2 ,
.Xr termios 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 .
.Sh TO DO
CD1190 parallel support.
.Pp
.Qq bpp
input.
.Pp
Dial-out (cua) devices are not yet supported.
.Pp
.Qq mdmbuf
is unsupported (see
.Xr tty 4
and
.Xr termios 4 ) .
.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.