102 lines
3.6 KiB
Groff
102 lines
3.6 KiB
Groff
.\" Copyright (c) 1990, 1991 The Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the Systems Programming Group of the University of Utah Computer
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.\" Science Department.
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91
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.\" $NetBSD: com.4,v 1.5 1999/03/16 01:19:20 garbled Exp $
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.\"
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.Dd July 28, 1995
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.Dt COM 4 arm32
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.Os
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.Sh NAME
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.Nm com
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.Nd
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serial communications interface
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.Sh SYNOPSIS
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.Cd "com0 at mainbus? base 0x00210fe0"
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.Cd "com1 at mainbus? base 0x00210be0"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for NS8250-, NS16450-, and NS16550-based
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.Tn EIA
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.Tn RS-232C
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.Pf ( Tn CCITT
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.Tn V.28 )
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communications interfaces. The NS8250 and NS16450 have single character
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buffers, and the NS16550 has a 16 character buffer.
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.Pp
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Input and output for each line may set to one of following baud rates;
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50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
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19200, 38400, 57600, or 115200, or any other baud rate which is a factor
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of 115200.
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.Pp
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If
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.Dq flags 1
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is specified, the
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.Nm
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driver will not set the MCR_IENABLE bit on the UART. This is mainly for
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use on AST multiport boards, where the MCR_IENABLE bit is used to control
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whether or not the devices use a shared interrupt.
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.Sh FILES
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.Bl -tag -width Pa
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.It Pa /dev/tty00
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.It Pa /dev/tty01
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.El
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.Sh DIAGNOSTICS
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.Bl -diag
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.It com%d: %d silo overflows
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The input
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.Dq silo
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has overflowed and incoming data has been lost.
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.It com%d: weird interrupt: iir=%x
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The device has generated an unexpected interrupt
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with the code listed.
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.El
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.Sh SEE ALSO
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.Xr tty 4
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.Sh HISTORY
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The
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.Nm
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driver was originally derived from the
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.Nm i386
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.Nm com
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driver and is
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.Ud
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.Sh BUGS
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Data loss is possible on busy systems with unbuffered UARTs at high speed.
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.Pp
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The name of this driver and the constants which define the locations
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of the various serial ports are holdovers from
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.Nm DOS .
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