zs - Zilog 8530 SCC serial communications driver


     #include <fcntl.h>

     #include <sys/termios.h>

     open("/dev/term/n", mode);

     open("/dev/ttyn", mode);

     open("/dev/cua/n", mode);


     The Zilog 8530 provides  two  serial  input/output  channels
     capable  of supporting a variety of communication protocols.
     A typical system uses two or more of these devices to imple-
     ment essential functions, including RS-423 ports (which also
     support most RS-232 equipment), and the console keyboard and
     mouse devices.

     The zs module is a loadable  STREAMS  driver  that  provides
     basic  support  for  the Zilog 8530 hardware and basic asyn-
     chronous communication  support.  The  driver  supports  the
     termio(7I)  device  control  functions specified by flags in
     the c_cflag word of the termios structure and by the IGNBRK,
     IGNPAR,  PARMRK,  or  INPCK  flags  in the c_iflag word. All
     other termio(7I) functions  must  be  performed  by  STREAMS
     modules pushed atop the driver. When a device is opened, the
     ldterm(7M) and ttcompat(7M) STREAMS  modules  are  automati-
     cally  pushed  on  top of the stream, providing the standard
     termio( 7I) interface.

     The character-special devices  /dev/term/a  and  /dev/term/b
     are used to access the two serial ports on the CPU board.

     Valid name space entries are /dev/cua/[a-z], /dev/term/[a-z]
     and  /dev/tty[a-z].  The  number  of  entries used in a name
     space are machine dependent.

     The /dev/tty[n] device names only exist  if  the  SunOS  4.x
     Binary  Compatibility  Package is installed. The /dev/tty[n]
     device names are created by the ucblinks command,  which  is
     available only with the SunOS 4.x Binary Compatibility Pack-

     To allow a single tty line to be connected to  a  modem  and
     used for both incoming and outgoing calls, a special feature
     is available that is controlled by the minor device  number.
     By  accessing  character-special  devices  with names of the
     form  /dev/cua/[n], it is possible to open  a  port  without
     the  Carrier  Detect  signal  being asserted, either through
     hardware or an equivalent software mechanism.  These devices
     are commonly known as dial-out lines.

     Once a /dev/cua/[n] line is opened,  the  corresponding  tty
     line cannot be opened until the /dev/cua/n line is closed. A
     blocking open will  wait  until  the  /dev/cua/[n]  line  is
     closed  (which  will  drop  Data Terminal Ready, and Carrier
     Detect) and carrier is detected again. A  non-blocking  open
     will  return  an error. If the tty line has been opened suc-
     cessfully (usually only when carrier is  recognized  on  the
     modem)  ,  the  corresponding  /dev/cua/[n]  line  cannot be
     opened. This allows a modem to be attached to  /dev/term/[n]
     (renamed from /dev/tty[n]) and used for dial-in (by enabling
     the line for login in /etc/inittab) and also used for  dial-
     out  (by  tip(1) or uucp(1C)) as /dev/cua/[n] when no one is
     logged in on the line.


          This module is affected  by  the  setting  of  specific
          eeprom  variables.  For  information on parameters that
          are persistent across reboots, see the  eeprom(1M)  man


     The zs module supports the standard set  of  termio  ioctl()

     If the CRTSCTS flag in the c_cflag field is set, output will
     be generated only if CTS is high; if CTS is low, output will
     be frozen. If the CRTSCTS flag is clear, the  state  of  CTS
     has no effect.

     If the CRTSXOFF flag in the  c_cflag  field  is  set,  input
     will  be  received only if RTS is high; if RTS is low, input
     will be frozen. If the  CRTSXOFF flag is clear, the state of
     RTS has no effect.

     The termios CRTSCTS (respectively  CRTSXOFF) flag  and  ter-
     miox  CTSXON (respectively RTSXOFF) can be used interchange-

     Breaks  can  be  generated  by  the  TCSBRK,  TIOCSBRK,  and
     TIOCCBRK ioctl() calls.

     The state of the DCD, CTS, RTS, and  DTR  interface  signals
     may  be queried through the use of the TIOCM_CAR, TIOCM_CTS,
     TIOCM_RTS, and TIOCM_DTR arguments  to  the  TIOCMGET  ioctl
     command,  respectively.   Due  to hardware limitations, only
     the RTS and DTR signals may be set through their  respective
     arguments  to  the  TIOCMSET,  TIOCMBIS,  and TIOCMBIC ioctl

     The input and output line speeds may be set to  any  of  the
     speeds supported by termio. The input and output line speeds
     cannot be set independently; for example, when you  set  the
     the  output  speed,  the input speed is automatically set to
     the same speed.

     When the driver is used to service the serial console  port,
     it  supports  a  BREAK  condition  that allows the system to
     enter the debugger or the monitor. The  BREAK  condition  is
     generated  by hardware and it is usually enabled by default.
     A BREAK condition originating from erroneous electrical sig-
     nals  cannot  be distinguished from one deliberately sent by
     remote DCE. The Alternate Break  sequence  can  be  used  to
     remedy this.

     Due to a risk of incorrect sequence  interpretation,  binary
     protocols  such  as  PPP, SLIP, and others should not be run
     over the serial console port when Alternate  Break  sequence
     is  in  effect.  By default, the Alternate Break sequence is
     three characters: carriage return, tilde and control-B (CR ~
     CTRL-B), but may be changed by the driver. For more informa-
     tion on breaking (entering  the  debugger  or  monitor,  see
     kbd(1) and kb(7M).


     An open will fail under the following conditions:

     ENXIO The unit being opened does not exist.

     EBUSY The dial-out device is being opened  and  the  dial-in
           device is already open, or the dial-in device is being
           opened with a no-delay open and the dial-out device is
           already open.

     EBUSY The port is in use by another serial protocol.

     EBUSY The unit has been marked as exclusive-use  by  another
           process with a TIOCEXCL ioctl() call.

     EINTR The open was interrupted by the delivery of a signal.


           dial-out tty lines

           dial-in tty lines

           binary compatibility package device names


     See attributes(5) for descriptions of the  following  attri-

    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    | Architecture                | SPARC                       |


     eeprom(1M),   kadb(1M),   tip(1),   ucblinks(1B),    cu(1C),
     uucp(1C),   ports(1M),   ioctl(2),  open(2),  attributes(5),
     zsh(7D),   termio(7I)ldterm(7M),    ttcompat(7M),    kb(7M),


     zsn: silo overflow.
           The Zilog 8530 character input silo overflowed  before
           it could be serviced.

     zsn: ring buffer overflow.
           The driver's character input  ring  buffer  overflowed
           before it could be serviced.

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