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CY(4) Device Drivers Manual CY(4)

cyCyclades Cyclom-{4, 8, 16}Y asynchronous comms board device driver

cy0 at isa? iomem 0xd4000 irq 12
cy* at pci?

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

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.

com(4), intro(4), isa(4), pci(4), termios(4), tty(4)

Some ideas for the architecture of this driver's two-layer processing model were derived from the fas 2.10 driver by Uwe Doering <> and the high-performance com driver by Bruce Evans <>.

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.

The driver was written by Andrew Herbert <>.

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.

July 23, 2020 OpenBSD-7.1