1 .\" Copyright (c) 1990, 1991 The Regents of the University of California.
2 .\" All rights reserved.
4 .\" This code is derived from software contributed to Berkeley by
5 .\" the Systems Programming Group of the University of Utah Computer
6 .\" Science Department.
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35 .\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91
36 .\" from: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp
37 .\" $FreeBSD: src/share/man/man4/sio.4,v 1.34.2.4 2002/12/18 13:31:17 keramida Exp $
44 .Nd "fast interrupt driven asynchronous serial communications interface"
47 .Cd "device sio0 at isa? port IO_COM1 irq 4"
48 .Cd "device sio1 at isa? port IO_COM2 irq 3"
49 .Cd "device sio2 at isa? port IO_COM3 irq 5"
50 .Cd "device sio3 at isa? port IO_COM4 irq 9"
52 For AST compatible multiport cards with 4 ports:
53 .Cd "options COM_MULTIPORT"
54 .Cd "device sio4 at isa? port 0x2a0 flags 0x701"
55 .Cd "device sio5 at isa? port 0x2a8 flags 0x701"
56 .Cd "device sio6 at isa? port 0x2b0 flags 0x701"
57 .Cd "device sio7 at isa? port 0x2b8 flags 0x701 irq 12"
59 For Boca Board compatible multiport cards with 8 ports:
60 .Cd "options COM_MULTIPORT"
61 .Cd "device sio4 at isa? port 0x100 flags 0xb05"
63 .Cd "device sio11 at isa? port 0x138 flags 0xb05 irq 12"
65 For Netmos Nm9845 multiport cards with 6 ports:
66 .Cd "options COM_MULTIPORT"
67 .Cd "device sio4 at isa? port 0xb000 flags 0x901"
68 .Cd "device sio5 at isa? port 0xb400 flags 0x901"
69 .Cd "device sio6 at isa? port 0xb800 flags 0x901"
70 .Cd "device sio7 at isa? port 0xbc00 flags 0x901"
71 .Cd "device sio8 at isa? port 0xc000 flags 0x901"
72 .Cd "device sio9 at isa? port 0xac00 flags 0x901 irq 12"
80 .Bl -tag -offset indent -compact -width 0x000000
86 no AST/4 compatible IRQ control register
88 recover sooner from lost output interrupts
90 device is potential system console
92 device is forced to become system console
94 device is reserved for low-level IO (e. g. for remote kernel debugging)
96 use this port for remote kernel debugging
97 .It 0x0 Ns Em ?? Ns 00
98 minor number of master port
100 device is assumed to use a 16650A-type (extended FIFO) chip
114 driver provides support for NS8250-, NS16450-, NS16550 and NS16550A-based
119 communications interfaces. The NS8250 and NS16450 have single character
120 buffers, the NS16550A has 16 character FIFO input and output buffers.
122 Input and output for each line may set to one of following baud rates;
123 50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
124 19200, 38400, 57600, or 115200. Your hardware may limit your baud
127 The driver supports `multiport' cards.
128 Multiport cards are those that have one or more groups of ports
129 that share an Interrupt Request (IRQ) line per group.
130 Shared IRQs on different cards are not supported.
131 Frequently 4 ports share 1 IRQ; some 8 port cards have 2 groups of 4 ports,
133 Some cards allow the first 2 serial ports to have separate IRQs per port
134 (as per DOS PC standard).
136 Some cards have an IRQ control register for each group.
137 Some cards require special initialization related to such registers.
138 Only AST/4 compatible IRQ control registers are supported.
139 Some cards have an IRQ status register for each group.
140 The driver does not require or use such registers yet.
141 To work, the control and status registers for a group, if any,
142 must be mapped to the scratch register (register 7)
143 of a port in the group.
144 Such a port is called a
150 keyword may be used on each
152 line in the kernel configuration file
153 to disable the FIFO on 16550A UARTs
155 Disabling the FIFO should rarely be necessary.
161 be used for all ports that are part of an IRQ sharing group.
162 One bit specifies IRQ sharing; another bit specifies whether the port does
164 require AST/4 compatible initialization.
165 The minor number of the device corresponding a master port
166 for the group is encoded as a bitfield in the high byte.
167 The same master port must be specified for all ports in a group.
171 specification must be given for master ports
172 and for ports that are not part of an IRQ sharing group,
173 and not for other ports.
177 means that the 8th port (sio7) is the master
178 port, and that the port is on a multiport card with shared IRQs
179 and an AST/4 compatible IRQ control register.
182 means that the 12th port (sio11) is the master
183 port, and that the port is on a multiport card with shared IRQs
184 and no special IRQ control register.
186 Which port is the master port depends on the card type.
187 Consult the hardware documentation of your card.
188 Since IRQ status registers are never used,
189 and IRQ control registers are only used for AST/4 compatible cards,
190 and some cards map the control/status registers to all ports in a group,
191 any port in a group will sometimes do for the master port.
192 Choose a port containing an IRQ status register for forwards compatibility,
193 and the highest possible port for consistency.
195 Serial ports controlled by the
197 driver can be used for both `callin' and `callout'.
198 For each port there is a callin device and a callout device.
199 The minor number of the callout device is 128 higher
200 than that of the corresponding callin port.
201 The callin device is general purpose.
202 Processes opening it normally wait for carrier
203 and for the callout device to become inactive.
204 The callout device is used to steal the port from
205 processes waiting for carrier on the callin device.
206 Processes opening it do not wait for carrier
207 and put any processes waiting for carrier on the callin device into
208 a deeper sleep so that they do not conflict with the callout session.
209 The callout device is abused for handling programs that are supposed
210 to work on general ports and need to open the port without waiting
211 but are too stupid to do so.
215 driver also supports an initial-state and a lock-state control
216 device for each of the callin and the callout "data" devices.
217 The minor number of the initial-state device is 32 higher
218 than that of the corresponding data device.
219 The minor number of the lock-state device is 64 higher
220 than that of the corresponding data device.
221 The termios settings of a data device are copied
222 from those of the corresponding initial-state device
223 on first opens and are not inherited from previous opens.
226 in the normal way on the initial-state devices to program
227 initial termios states suitable for your setup.
229 The lock termios state acts as flags to disable changing
230 the termios state. E.g., to lock a flag variable such as
233 on the lock-state device. Speeds and special characters
234 may be locked by setting the corresponding value in the lock-state
235 device to any nonzero value.
237 Correct programs talking to correctly wired external devices
238 work with almost arbitrary initial states and almost no locking,
239 but other setups may benefit from changing some of the default
240 initial state and locking the state.
241 In particular, the initial states for non (POSIX) standard flags
242 should be set to suit the devices attached and may need to be
243 locked to prevent buggy programs from changing them.
244 E.g., CRTSCTS should be locked on for devices that support
245 RTS/CTS handshaking at all times and off for devices that don't
246 support it at all. CLOCAL should be locked on for devices
247 that don't support carrier. HUPCL may be locked off if you don't
248 want to hang up for some reason. In general, very bad things happen
249 if something is locked to the wrong state, and things should not
250 be locked for devices that support more than one setting. The
251 CLOCAL flag on callin ports should be locked off for logins
252 to avoid certain security holes, but this needs to be done by
253 getty if the callin port is used for anything else.
255 .Bl -tag -width /dev/ttyid? -compact
260 corresponding callin initial-state and lock-state devices
266 corresponding callout initial-state and lock-state devices
269 .Bl -tag -width /etc/rc.serial -compact
270 .It Pa /etc/rc.serial
271 examples of setting the initial-state and lock-state devices
274 The device numbers are made from the set [0-9a-v] so that more than
275 10 ports can be supported.
278 .It sio%d: silo overflow.
279 Problem in the interrupt handler.
282 .It sio%d: interrupt-level buffer overflow.
283 Problem in the bottom half of the driver.
286 .It sio%d: tty-level buffer overflow.
287 Problem in the application.
288 Input has arrived faster than the given module could process it
289 and some has been lost.
292 .\" .It sio%d: reduced fifo trigger level to %d.
293 .\" Attempting to avoid further silo overflows.
303 driver is derived from the
309 Data loss may occur at very high baud rates on slow systems,
310 or with too many ports on any system,
311 or on heavily loaded systems when crtscts cannot be used.
312 The use of NS16550A's reduces system load and helps to avoid data loss.
314 Stay away from plain NS16550's. These are early
315 implementations of the chip with non-functional FIFO hardware.
317 The constants which define the locations
318 of the various serial ports are holdovers from
320 As shown, hex addresses can be and for clarity probably should be used instead.
322 Note that on the AST/4 the card's dipswitches should
324 be set to use interrupt sharing.
325 AST/4-like interrupt sharing is only used when
327 AST/4 cards are installed in the same system. The sio driver does not
328 support more than 1 AST/4 on one IRQ.
330 The examples in the synopsis are too vendor-specific.