zs(7D) Devices zs(7D)NAMEzs - Zilog 8530 SCC serial communications driver
SYNOPSIS
#include <fcntl.h>
#include <sys/termios.h>
open("/dev/term/n", mode);
open("/dev/ttyn", mode);
open("/dev/cua/n", mode);
DESCRIPTION
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 implement essential functions, includ‐
ing 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 asynchronous communication sup‐
port. The driver supports the termio(7I) device control functions spec‐
ified 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 automatically pushed on top of the stream, provid‐
ing 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.
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 com‐
monly 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 Termi‐
nal Ready, and Carrier Detect) and carrier is detected again. A non-
blocking open will return an error. If the tty line has been opened
successfully (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.
Note -
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 page.
IOCTLS
The zs module supports the standard set of termio ioctl() calls.
If the CRTSCTS flag in the c_cflag field is set, output will be gener‐
ated 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 termiox CTSXON
(respectively RTSXOFF) can be used interchangeably.
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 commands.
The input and output line speeds may be set to any of the speeds sup‐
ported by termio. The input and output line speeds cannot be set inde‐
pendently; 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 elec‐
trical signals 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, SLIP and certain
other binary protocols should not be run over the serial console port
when Alternate Break sequence is in effect. Although PPP is a binary
protocol, it is able to avoid these sequences using the ACCM feature in
RFC 1662. For Solaris PPP 4.0, you do this by adding the following line
to the /etc/ppp/options file (or other configuration files used for the
connection; see pppd(1M) for details):
asyncmap 0x00002000
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 information on breaking (entering the debugger or mon‐
itor), see kbd(1) and kb(7M).
ERRORS
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.
FILES
/dev/cua/[a-z] dial-out tty lines
/dev/term/[a-z] dial-in tty lines
/dev/tty[a-z] binary compatibility package device names
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Architecture │SPARC │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOeeprom(1M), kmdb(1), tip(1), cu(1C), uucp(1C), ports(1M), pppd(1M),
ioctl(2), open(2), attributes(5), zsh(7D), termio(7I), kb(7M),
ldterm(7M), ttcompat(7M)DIAGNOSTICS
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.
SunOS 5.11 16 Jul 2009 zs(7D)
