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     cy — Cyclades Cyclom-Y serial driver


     For one ISA card:
           device cy

           In /boot/device.hints:

     For two ISA cards:
           device cy

           In /boot/device.hints:

     For PCI cards:
           device cy
           options CY_PCI_FASTINTR

           No lines are required in /boot/device.hints for PCI cards.

     Minor numbering:
             MMMMMMMMMMMMMMMM           MMMMMMinor


     The cy driver provides support for Cirrus Logic CD1400-based EIA RS-232C (CCITT V.24)
     communications interfaces (ports) on Cyclades Cyclom-Y boards.  Each CD1400 provides 4
     ports.  Cyclom-Y boards with various numbers of CD1400's are available.  This driver
     supports up to 8 CD1400's (32 ports) per board.

     Input and output for each line may set independently to the following speeds: 50, 75, 110,
     134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, or 115200 bps.
     Other speeds of up to 150000 are supported by the termios interface but not by the sgttyb
     compatibility interface.  The CD1400 is not fast enough to handle speeds above 115200 bps
     effectively.  It can transmit on a single line at slightly more than 115200 bps, but when 4
     lines are active in both directions its limit is about 90000 bps on each line.

     Serial ports controlled by the cy driver can be used for both `callin' and `callout'.  For
     each port there is a callin device and a callout device.  The minor number of the callout
     device is 128 higher than that of the corresponding callin port.  The callin device is
     general purpose.  Processes opening it normally wait for carrier and for the callout device
     to become inactive.  The callout device is used to steal the port from processes waiting for
     carrier on the callin device.  Processes opening it do not wait for carrier and put any
     processes waiting for carrier on the callin device into a deeper sleep so that they do not
     conflict with the callout session.  The callout device is abused for handling programs that
     are supposed to work on general ports and need to open the port without waiting but are too
     stupid to do so.

     The cy driver also supports an initial-state and a lock-state control device for each of the
     callin and the callout "data" devices.  The minor number of the initial-state device is 32
     higher than that of the corresponding data device.  The minor number of the lock-state
     device is 64 higher than that of the corresponding data device.  The termios settings of a
     data device are copied from those of the corresponding initial-state device on first opens
     and are not inherited from previous opens.  Use stty(1) in the normal way on the initial-
     state devices to program initial termios states suitable for your setup.

     The lock termios state acts as flags to disable changing the termios state.  E.g., to lock a
     flag variable such as CRTSCTS, use stty crtscts on the lock-state device.  Speeds and
     special characters may be locked by setting the corresponding value in the lock-state device
     to any nonzero value.

     Correct programs talking to correctly wired external devices work with almost arbitrary
     initial states and almost no locking, but other setups may benefit from changing some of the
     default initial state and locking the state.  In particular, the initial states for non
     (POSIX) standard flags should be set to suit the devices attached and may need to be locked
     to prevent buggy programs from changing them.  E.g., CRTSCTS should be locked on for devices
     that support RTS/CTS handshaking at all times and off for devices that do not support it at
     all.  CLOCAL should be locked on for devices that do not support carrier.  HUPCL may be
     locked off if you do not want to hang up for some reason.  In general, very bad things
     happen if something is locked to the wrong state, and things should not be locked for
     devices that support more than one setting.  The CLOCAL flag on callin ports should be
     locked off for logins to avoid certain security holes, but this needs to be done by getty if
     the callin port is used for anything else.

   Kernel Configuration Options
     The CY_PCI_FASTINTR option should be used to avoid suboptimal interrupt handling for PCI
     Cyclades boards.  The PCI BIOS must be configured with the cy interrupt not shared with any
     other active device for this option to work.  This option is not the default because it is
     currently harmful in certain cases where it does not work.


     /dev/ttyc??   for callin ports
     /dev/ttylc??  corresponding callin initial-state and lock-state devices

     /dev/cuac??   for callout ports
     /dev/cualc??  corresponding callout initial-state and lock-state devices

     /etc/rc.serial  examples of setting the initial-state and lock-state devices

     The first question mark in these device names is short for the card number (a decimal number
     between 0 and 65535 inclusive).  The second question mark is short for the port number (a
     letter in the range [0-9a-v]).


     cy%d: silo overflow.  Problem in the interrupt handler.

     cy%d: interrupt-level buffer overflow.  Problem in the bottom half of the driver.

     cy%d: tty-level buffer overflow.  Problem in the application.  Input has arrived faster than
     the given module could process it and some has been lost.


     stty(1), termios(4), tty(4), comcontrol(8), pstat(8)


     The cy driver is derived from the sio driver and the NetBSD cy driver and is currently under


     Serial consoles are not implemented.