HardenedBSD/share/man/man4/cy.4

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.\"     from: @(#)dca.4	5.2 (Berkeley) 3/27/91
.\"	from: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp
.\"	from: sio.4,v 1.16 1995/06/26 06:05:30 bde Exp $
.\"	$FreeBSD$
.\"
.Dd October 10, 1995
.Dt CY 4 i386
.Os FreeBSD
.Sh NAME
.Nm cy
.Nd
Cyclades Cyclom-8Y and Cyclom-16Y serial driver
.Sh SYNOPSIS
.Cd "device cy0 at isa? tty irq 10 iomem 0xd4000 iosiz 0x2000 vector cyintr
.Cd "device cy1 at isa? tty irq 11 iomem 0xd6000 iosiz 0x2000 vector cyintr
.sp
Minor numbering:
.br
0b\fIOLIMMMMM\fR
.br
  call\fBO\fRut
.br
   \fBL\fRock
.br
    \fBI\fRnitial
.br
     \fBMMMMMM\fRinor
.Sh DESCRIPTION
The
.Nm cy
driver provides support for Cyrix CD1400-based
.Tn EIA
.Tn RS-232C
.Pf ( Tn CCITT
.Tn V.24 )
communications interfaces (ports) on Cyclades Cyclom-Y boards.
Each CD1400 provides 4 ports.
Each Cyclom-8Y has 2 CD1400's giving 8 ports.
Each Cyclom-16Y's has 4 CD1400's giving 16 ports.
.Pp
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.
.\" XXX the following should be true for all serial drivers and
.\" should not be repeated in the man pages for all serial drivers.
.\" It was copied from sio.4.  The only change was s/sio/cy/g.
.Pp
Serial ports controlled by the
.Nm 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.
.Pp
The
.Nm 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
.Xr stty 1
in the normal way on the initial-state devices to program
initial termios states suitable for your setup.
.sp
The lock termios state acts as flags to disable changing
the termios state.  E.g., to lock a flag variable such as
CRTSCTS, use
.Nm 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.
.sp
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 don't
support it at all.  CLOCAL should be locked on for devices
that don't support carrier.  HUPCL may be locked off if you don't
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.
.Sh FILES
.Bl -tag -width /dev/ttyic? -compact
.\" XXX more cloning: s/d/c/g.
.It Pa /dev/ttyc?
for callin ports
.It Pa /dev/ttyic?
.It Pa /dev/ttylc?
corresponding callin initial-state and lock-state devices
.sp
.\" XXX more cloning: s/a/c/g.  No consistency :-(.
.It Pa /dev/cuac?
for callout ports
.It Pa /dev/cuaic?
.It Pa /dev/cualc?
corresponding callout initial-state and lock-state devices
.El
.sp
.Bl -tag -width /etc/rc.serial -compact
.It Pa /etc/rc.serial
examples of setting the initial-state and lock-state devices
.\" XXX no examples in rc.serial for cy ports specifically.
for sio ports (change the device names for cy ports)
.El
.Pp
The devices numbers are made from the set [0-9a-v] so that more than
10 ports can be supported.
.\" XXX this is for cy only.
[0-9a-f] are for the cy0 and [g-v] are for cy1.
For Cyclom-8Y's, only the first 8 of these are used.
.Sh DIAGNOSTICS
.Bl -diag
.\" XXX back to s/sio/cy/g.
.It cy%d: silo overflow.
Problem in the interrupt handler.
.El
.Bl -diag
.It cy%d: interrupt-level buffer overflow.
Problem in the bottom half of the driver.
.El
.Bl -diag
.It 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.
.El
.\" .Bl -diag
.\" .It sio%d: reduced fifo trigger level to %d.
.\" Attempting to avoid further silo overflows.
.\" .El
.Sh SEE ALSO
.Xr stty 1 ,
.Xr termios 4 ,
.Xr tty 4 ,
.Xr comcontrol 8
.Sh HISTORY
The
.Nm
driver is derived from the
.Nm sio
driver and the NetBSD
.Nm
driver and is
.Ud
.Sh BUGS
The naming scheme and the minor numbering scheme limit the number
of ports to 32.
.Pp
BREAK is not yet implemented.
.Pp
Serial consoles are not implemented.
.Pp
Data loss may occur at very high baud rates on slow systems,
or with too many ports on any system,
or on heavily loaded systems when crtscts cannot be used.
.Pp
There are too many compile-time-only flags.
The CD1400 has slightly smaller fifos than the NS16550 (12 bytes
instead of 16), so it needs pseudo-dma more than a NS16550.  The
default configuration is optimized for generality at about a 30%
relative cost in efficiency.  These compile-time defines may be
changed for higher efficiency:
.Pp
RxFifoThreshold: default 6; on a 486DX-33, this works for 8 ports
talking to each other at 115200 bps; 11 works for 8 ports talking
to each other at 57600 bps.  The low threshold is not for FreeBSD,
it's for the CD1400, which can't really keep up with 115200 bps.
.Pp
PollMode: required for Cyclom-16Y's; costs 10-20% relative efficiency
on Cyclom-8Y's (more with a low RxFifoThreshold).
.Pp
SOFT_HOTCHAR: required in addition to the small RxFifoThreshold
to avoid overruns with SLIP and PPP for 8 ports at 115200 bps.
Costs 5% relative efficiency.