All rights reserved.
This code is derived from software contributed to Berkeley by
the Systems Programming Group of the University of Utah Computer
Science Department.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
must display the following acknowledgement:
This product includes software developed by the University of
California, Berkeley and its contributors.
4. Neither the name of the University nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
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 15, 1994 .Dt SIO 4 i386 .Os FreeBSD .Sh NAME .Nm sio .Nd fast interrupt driven asynchronous serial communications interface .Sh SYNOPSIS For single lines: .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 .Cd "" For multiport cards: .Cd "options" "COM_MULTIPORT" .Cd "device sio4 at isa? port 0x2a0 tty irq 6 flags 0x0701 vector siointr" .Cd "device sio5 at isa? port 0x2a8 tty flags 0x0701 vector siointr" .Cd "device sio6 at isa? port 0x2b0 tty flags 0x0701 vector siointr" .Cd "device sio7 at isa? port 0x2b8 tty flags 0x0701 vector siointr" .Cd "" For bidirectional use of sio devices: .Cd "options" "COM_BIDIR" .Sh DESCRIPTION The .Nm sio driver provides support for NS8250-, NS16450-, NS16550 and NS16550A-based (and true compatibles) .Tn EIA .Tn RS-232C
f ( Tn CCITT .Tn V.24 ) communications interfaces. The NS8250 and NS16450 have single character buffers, the NS16550 has broken FIFO buffers and the NS16550A has a 16 character FIFO buffer.
p 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. The hardware implementation of your serial interface card may limit your choice of baud rates. To be precise: the frequency of the baud rate clock signal fed into the NSxx50 chips determines which baudrates you can select, not the NSxx50 chips themselves.
p All I/O addresses and IRQ levels listed in the config file must exactly match the actual setup of the hardware. Note that the AT bus does not support multiple cards on a single IRQ line.
p For multiport cards the .Nm flags keyword in the kernel configuration file determines which device of your multiport card is the master device and also indicates that the device is part of a multiport card. The master device is the device which has the register through which all interrupts of the card are funneled. All devices of a multiport card report pending interrupts using this single register. The master device is indicated .Nm bitwise using bits 8-15. All sio entries in the kernel config file that are part of a multiport card must include the correct .Nm flags specification. The requirement to have a .Nm flags value on each sio line entry for a multiport card device allows multiple multiport cards to be configured in one system. It does .Nm not imply that the hardware can share the same physical interrupt line! In the synopsis .Nm flags 0x0701 means that the device with minor number .Nm 7 is the multiport card's master device (so the MSB of the flags), and that the devices are on a multiport card (the LSB of the flags, actually only the LS .Nm bit ) is used to indicate this. So, in this example the last device of the multiport card is the masterdevice. Note that if you also have non-multiport serial devices controlled by sio, as in the .Nm Synopsis , they do not require .Nm flags entries but .Nm do count as serial devices for the calculation of the multiport card's master device. Which device the master device is depends on the card type. Consult the hardware documentation of your card to obtain this info. If you want to disable the FIFO buffers on a sio line with a NS16550A chip, you can specify a .Nm flags value of 0x0002 for a non-multiport line, or OR 0x0002 to the .Nm flags entry of a multiport line. You can specify this also for a device that has no FIFO buffers and it will simply have no effect. Serial devices controlled by the .Nm sio driver can be used for both dialin and dialout. Use .Nm comcontrol command to enable/disable bidirectional use of the .Nm sio devices. The minor number of the dialout device is 128 higher than that of the corresponding dialin device. Use .Nm stty(1) to enable or disable modem control as required by your setup. .Sh FILES l -tag -width Pa t Pa /dev/tty00 for dialin t Pa /dev/ttyd00 for dialout .El .Sh DIAGNOSTICS l -diag t sio%d: silo overflow. The single-character input .Dq silo has overflowed and incoming data has been lost. t sio%d: interrupt-level buffer overflow. The kernel was too busy to read the interrupt-level buffer in time. t sio%d: tty-level buffer overflow. The application was too busy to read the tty-level buffer in time or the system was too busy to give the application enough time to read the tty-level buffer. .El .Sh SEE ALSO .Xr tty 4 .Xr comcontrol 1 .Xr stty 1 .Sh HISTORY The .Nm driver is derived from the .Nm HP9000/300 .Nm dca driver and is d .Sh BUGS Data loss is not nearly as likely on busy systems as it is with the .Xr com 4 driver but can still occur at very high baud rates on slow systems. The use of NS16550A's helps to handle high baud rates on multiple lines.
p Stay away from NS16550 (so without the trailing A). These are early implementations of the chip with non-functional FIFO hardware.
p The constants which define the locations of the various serial devices are holdovers from .Nm DOS . As shown, hex addresses can be and for clarity probably should be used instead.
p Rumour has it that not all 16550 clones work correctly. Hard evidence is difficult to come by.
p The meaning of the .Nm flags value has changed between FreeBSD 1.0.2 and 1.1. On FreeBSD 1.0.2, it was sufficient to have the .Nm flags value on only one sio line for each multiport card, although it really should have been on all lines even for 1.0.2. For 1.1 you must have .Nm flags entries on each line that is part of a multiport card. Take care when you want to re-use 1.0.2. config files on 1.1. The multiport example is based on an AST/4 card, your mileage may vary however. Note that on the AST/4 the card's dip switches should .Nm not be set to use interrupt sharing. AST/4-like interrupt sharing is only used when .Nm multiple AST/4 cards are installed in the same system. The sio driver does not support more than 1 AST/4 card on one IRQ. It looks like the AST/4 sometimes needs a power cycle to reset itself correctly. Symptoms: devices are probed by the kernel as being present but do not work correctly. Getting multiport cards to work can prematurely turn your hair grey. The hardware documentation generally increases the greying rate.
p This man page can not replace the Ultimate Doc(tm): the source.
p Bugs in this man page can be reported to: wilko@idca.tds.philips.nl