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CY(4)                    BSD Kernel Interfaces Manual                    CY(4)

     cy -- Cyclades 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: tty input queue overflow  Incoming characters have been discarded
     due to a buffer overflow.  This is caused by the process in control of
     the device not read(2)'ing characters fast enough.

     cy0: receive fifo overrun  Incoming characters have been discarded due to
     a CD1400 channel overrun.  This is caused by interrupts not being ser-
     viced sufficiently quickly to prevent the 12 byte receive FIFO on a
     serial channel from overflowing.  Reducing the value of the RxFifoThresh-
     old #define from 8 to something smaller may help slow machines avoid this
     problem.  The driver must have been compiled with the LogOverruns option
     defined (the default) in order for this condition to be logged.

     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
     <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

     The driver was written by Andrew Herbert <andrew@werple.apana.org.au>.

     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.

BSD                              July 16, 2013                             BSD