MAGMA(4) OpenBSD Programmer's Manual (SPARC64) MAGMA(4)NAME
magma - Magma Sp Serial/Parallel board device driver
SYNOPSIS
magma? at sbus?
mtty? at magma?
mbpp? at magma?
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.
The device minor numbers for this driver are encoded as follows:
+---+---+---+---+---+---+---+---+
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
+---+---+---+---+---+---+---+---+
| | | | | | | |
| | | | +---+---+---+---> port number
| | | |
| | | +-------------------> dial-out (on tty ports)
| | |
| | +-----------------------> unused
| |
+---+---------------------------> card number
Up to four cards are supported in the system.
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.
FILES
/dev/tty[mno][0-f] Serial ports
/dev/bpp[mno][0-1] Parallel ports
DIAGNOSTICS
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. If need be you can make
the ring buffer bigger by changing the MAGMA_RBUF_SIZE #define to
something bigger, but it should be a multiple of two.
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. Reducing the value of either the
MTTY_RX_FIFO_THRESHOLD or MTTY_RX_DTR_THRESHOLD #define's to something
smaller may help slow machines avoid this problem.
SEE ALSOintro(4), sbus(4), tty(4)HISTORY
The driver was loosely based upon the cy(4) Cyclades Cyclom device driver
written by Andrew Herbert and Timo Rossi.
AUTHORS
The driver was written by Iain Hibbert <plunky@skate.demon.co.uk>
TODO
CD1190 parallel support.
bpp input.
Dial-out (cua) devices are not yet supported.
mdmbuf is unsupported.
Automatic XON/XOFF handshaking could be implemented fairly easily.
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.
OpenBSD 4.9 November 29, 2008 OpenBSD 4.9