NAME
cy —
Cyclades Cyclom-{4, 8, 16}Y
asynchronous comms board device driver
SYNOPSIS
cy0 at isa? iomem 0xd4000 irq 12
cy* at pci?
DESCRIPTION
This driver provides an interface to Cyclades Cyclom-4Y, Cyclom-8Y and Cyclom-16Y asynchronous multiport serial boards. These boards are based around Cirrus Logic CD1400 communication controllers.
The device minor numbers for this driver are encoded as follows:
d c c u u u u u - bits in the minor device number
bits meaning
---- -------
uuuuu physical serial line (i.e., unit) to use
0-7 on a cyclom-8Y, 0-15 on a cyclom-16Y
cc card number
d dial-out flag
DIAGNOSTICS
- cy0: port 0 ibuf overrun
- Incoming characters have been discarded due to a buffer overflow.
- cy0: port 0 fifo overrun
- 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 the
RX_FIFO_THRESHOLD#define from 6 to something smaller may help slow machines avoid this problem.
SEE ALSO
HISTORY
Some ideas for the architecture of this driver's two-layer processing model were derived from the fas 2.10 driver by Uwe Doering <gemini@geminix.in-berlin.de> and the high-performance com driver by Bruce Evans <bde@kralizec.zeta.org.au>.
This work was made possible through the donation of a Cyclom-8Y board by the manufacturer, Cyclades Corporation. However, neither Cyclades nor the author make any warranties regarding this software, nor guarantees of support.
AUTHORS
The driver was written by Andrew Herbert <andrew@werple.apana.org.au>.
BUGS
There is currently no BREAK handling - breaks are ignored. There is no support for bad-character reporting, except via PARMRK. The Cyclom-[48]Y boards do not listen to the RTS signal for receiver flow control. FIFO overruns are only logged when the termios IGNPAR setting is enabled.