freebsd-skq/share/man/man4/sio.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
.\"	$Id: sio.4,v 1.1 1993/08/28 12:41:23 rgrimes Exp $
.\"
.Dd February 9, 1994
.Dt SIO 4 i386
.Os FreeBSD
.Sh NAME
.Nm sio
.Nd
fast interrupt driven asynchronous serial communications interface
.Sh SYNOPSIS
For standard ports:
.Cd "device sio0 at isa? port" \&"IO_COM1\&" tty irq 4 vector siointr
.Cd "device sio1 at isa? port" \&"IO_COM2\&" tty irq 3 vector siointr
.Cd "device sio2 at isa? port" \&"IO_COM3\&" tty irq 5 vector siointr
.Cd "device sio3 at isa? port" \&"IO_COM4\&" tty irq 9 vector siointr
.sp
For multiport cards:
.Cd "options" \&"COM_MULTIPORT\&"
.Cd "device sio4 at isa? port 0x2a0 tty irq 12 vector siointr flags 0x401"
.Cd "device sio5 at isa? port 0x2a8 tty vector siointr flags 0x401"
.Cd "device sio6 at isa? port 0x2b0 tty vector siointr flags 0x401"
.Cd "device sio7 at isa? port 0x2b8 tty vector siointr flags 0x401"
.sp
For bidirectional use of ports:
.Cd "options" \&"COM_BIDIR\&"
.sp
For control FIFO trigger:
.Cd "options" \&"FIFO_TRIGGER=FIFO_TRIGGER_14\&"
.sp
Use 0x02 bit in flags field to disable FIFO on specified port.
.Sh DESCRIPTION
The
.Nm sio
driver provides support for NS8250-, NS16450-, NS16550 and NS16550A-based
.Tn EIA
.Tn RS-232C
.Pf ( Tn CCITT
.Tn V.24 )
communications interfaces.  The NS8250 and NS16450 have single character
buffers, the NS16550A has a 16 character FIFO buffer.
.Pp
Input and output for each line may set to one of following baud rates;
50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
19200, 38400, 57600, or 115200. Your hardware may limit your baud
rate choices.
.Pp
For multiport cards the 
.Nm flags
keyword in the kernel configuration file determines which port of 
your multiport card is the master device, and whether the 
port is part of a multiport card. The master device is the port with 
the shared interrupt register.
All ports of a multiport card report
pending interrupts using this single register.
.Pp
In the synopsis the 
.Nm flags 0x401
means that the 4th port (sio4) is the master
device (so the MSB of the flags), and that the ports are part of a 
multiport card (the LSB of the flags, actually only the LS 
.Nm bit
).
F.e. if you have only two standard ports in addition to multiport
card, this
.Nm flags
will be
.Nm 0x201 .
.Pp
Which port is the master device depends on the card type. Consult
the hardware documentation of your card.
If you are shure, that your master device fully compatible with
standard port, you can ommit
.Nm flags
field from master device description line.
.Pp
Serial ports controlled by the 
.Nm sio
driver can be used for both dialin and dialout. Use 
.Xr comcontrol 8
to enable/disable bidirectional use of the 
.Nm sio
ports. The minor number of the dialout
port is 128 higher than that of the corresponding dialin port. Use 
.Xr stty 1
to enable or disable modem control as required by your setup.
.Sh FILES
.Bl -tag -width Pa
.It Pa /dev/tty0? for dialin
.It Pa /dev/cua0? for dialout
.El
.Sh DIAGNOSTICS
.Bl -diag
.It sio%d: silo overflow.
The single-character input
.Dq silo
has overflowed and incoming data has been lost.
.\".It com%d: weird interrupt: %x.
.\"The device has generated an unexpected interrupt
.\"with the code listed.
.El
.Sh SEE ALSO
.Xr tty 4 ,
.Xr comcontrol 8 ,
.Xr stty 1 .
.Sh HISTORY
The
.Nm
driver is derived from the
.Nm HP9000/300
.Nm dca
driver and is
.Ud
.Sh BUGS
Data loss is not near as likely on busy systems
but they still can occur at very high baud rates on slow systems. The
use of NS16550A's helps lot to handle high baud rates.
.Pp
The constants which define the locations
of the various serial ports are holdovers from
.Nm DOS .
As shown, hex addresses can be used instead.
.Pp
As usual, you get what you pay for; cheap NS16550 clones generally don't work.
.Pp
The multiport example has been successfully tested with an AST/4 card, your
mileage may vary however.
.Pp
This man page can not replace the Ultimate Doc(tm): the source.