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18 .Dd August 31, 2018
19 .Dt PRNIO 7I
20 .Os
21 .Sh NAME
22 .Nm prnio
23 .Nd generic printer interface
24 .Sh SYNOPSIS
25 .In sys/prnio.h
26 .Sh DESCRIPTION
27 The
28 .Nm
29 generic printer interface defines ioctl commands and data
30 structures for printer device drivers.
31 .Pp
32 .Nm
33 defines and provides facilities for five basic phases of the printing process:
34 .Bl -bullet -offset indent
35 .It
36 Identification \(em Retrieve device information/attributes
37 .It
38 Setup \(em Set device attributes
39 .It
40 Transfer \(em Transfer data to or from the device
41 .It
42 Cleanup \(em Transfer phase conclusion
43 .It
44 Abort \(em Transfer phase interruption
45 .El
46 .Pp
47 During the Identification phase, the application retrieves a set of device
48 capabilities and additional information using the
49 .Dv PRNIOC_GET_IFCAP ,
50 .Dv PRNIOC_GET_STATUS ,
51 .Dv PRNIOC_GET_TIMEOUTS ,
52 .Dv PRNIOC_GET_IFINFO ,
53 and
54 .Dv PRNIOC_GET_1284_DEVID
55 commands.
56 .Pp
57 During the Setup phase the application sets some interface attributes and
58 probably resets the printer as described in the
59 .Dv PRNIOC_SET_IFCAP ,
60 .Dv PRNIOC_SET_TIMEOUTS ,
61 and
62 .Dv PRNIOC_RESET
63 sections.
64 .Pp
65 During the Transfer phase, data is transferred in a forward (host to
66 peripheral) or reverse direction (peripheral to host).
67 Transfer is accomplished
68 using
69 .Xr write 2
70 and
71 .Xr read 2
72 system calls.
73 For
74 .Nm
75 compliant
76 printer drivers, forward transfer support is mandatory, while reverse transfer
77 support is optional.
78 Applications can also use
79 .Dv PRNIOC_GET_STATUS
80 and
81 .Dv PRNIOC_GET_1284_STATUS
82 commands during the transfer to monitor the device state.
83 .Pp
84 The Cleanup phase is accomplished by closing the device using
85 .Xr close 2 .
86 Device drivers supporting
87 .Nm
88 may set non-zero error code as appropriate.
89 Applications should explicitly
90 .Xr close 2
91 a device before
92 exiting and check
93 .Va errno
94 value.
95 .Pp
96 The Abort phase is accomplished by interrupting the
97 .Xr write 2
98 and
99 .Xr read 2
100 system calls.
101 The application can perform some additional cleanup
102 during the Abort phase as described in
103 .Dv PRNIOC_GET_IFCAP
104 section.
105 .Sh IOCTLS
106 .Bl -tag -width PRNIOC_GET_IFINFO
107 .It Dv PRNIOC_GET_IFCAP
108 Application can retrieve printer interface capabilities using this command.
109 The
110 .Xr ioctl 2
111 argument is a pointer to
112 .Vt uint_t ,
113 a bit field representing
114 a set of properties and services provided by a printer driver.
115 Set bit means supported capability.
116 The following values are defined:
117 .Bl -tag -width PRN_1284_STATUS
118 .It Dv PRN_BIDI
119 When this bit is set, the interface operates in a
120 bidirectional mode, instead of forward-only mode.
121 .It Dv PRN_HOTPLUG
122 If this bit is set, the interface allows device hot-plugging.
123 .It Dv PRN_1284_DEVID
124 If this bit is set, the device is capable of returning
125 .Em 1284
126 device ID (see
127 .Dv PRNIOC_GET_1284_DEVID ) .
128 .It Dv PRN_1284_STATUS
129 If this bit is set, the device driver can return device
130 status lines (see
131 .Dv PRNIOC_GET_1284_STATUS ) .
132 Some devices support this
133 ioctl in unidirectional mode only.
134 .It Dv PRN_TIMEOUTS
135 If this bit is set the peripheral may stall during the
136 transfer phase and the driver can timeout and return from the
137 .Xr write 2
138 and
139 .Xr read 2
140 returning the number of bytes that have been transferred.
141 If
142 .Dv PRN_TIMEOUTS
143 is set, the driver supports this functionality and the
144 timeout values can be retrieved and modified via the
145 .Dv PRNIOC_GET_TIMEOUTS
146 and
147 .Dv PRNIOC_SET_TIMEOUTS
148 ioctls.
149 Otherwise, applications can implement
150 their own timeouts and abort phase.
151 .It Dv PRN_STREAMS
152 This bit impacts the application abort phase behaviour.
153 If the device claimed
154 .Dv PRN_STREAMS
155 capability, the application must issue an
156 .Dv I_FLUSH
157 .Xr ioctl 2
158 before
159 .Xr close 2
160 to dismiss the untransferred
161 data.
162 Only STREAMS drivers can support this capability.
163 .El
164 .It Dv PRNIOC_SET_IFCAP
165 This ioctl can be used to change interface capabilities.
166 The argument is a pointer to
167 .Vt uint_t
168 bit field that is described in detail in the
169 .Dv PRNIOC_GET_IFCAP
170 section.
171 Capabilities should be set one at a time;
172 otherwise the command will return
173 .Er EINVAL .
174 The following capabilities can be changed by this ioctl:
175 .Bl -tag -width PRN_BIDI
176 .It Dv PRN_BIDI
177 When this capability is set, the interface operates in a
178 bidirectional mode, instead of forward-only mode.
179 Devices that support only one
180 mode will not return error; applications should use
181 .Dv PRNIOC_GET_IFCAP
182 to check if the mode was successfully changed.
183 Because some capabilities may be
184 altered as a side effect of changing other capabilities, this command should be
185 followed by
186 .Dv PRNIOC_GET_IFCAP .
187 .El
188 .It Dv PRNIOC_GET_IFINFO
189 This command can be used to retrieve printer interface info string, which is an
190 arbitrary format string usually describing the bus type.
191 The argument is a
192 pointer to
193 .Vt struct prn_interface_info
194 as described below.
195 .Bd -literal -offset 2n
196 struct prn_interface_info {
197 uint_t if_len; /* length of buffer */
198 uint_t if_rlen; /* actual info length */
199 char *if_data; /* buffer address */
200 };
201 .Ed
202 .Pp
203 The application allocates a buffer and sets
204 .Fa if_data
205 and
206 .Fa if_len
207 values to its address and length, respectively.
208 The driver returns the string
209 to this buffer and sets
210 .Fa if_len
211 to its length.
212 If
213 .Fa if_len
214 is less
215 than
216 .Fa if_rlen ,
217 the driver must return the first
218 .Fa if_len
219 bytes of the string.
220 The application may then repeat the command with a bigger buffer.
221 .Pp
222 Although
223 .Nm
224 does not limit the contents of the interface info string,
225 some values are recommended and defined in
226 .In sys/prnio.h
227 by the following macros:
228 .Pp
229 .Bl -tag -width PRN_PARALLEL -compact
230 .It Dv PRN_PARALLEL
231 Centronics or
232 .Em IEEE 1284
233 compatible devices
234 .It Dv PRN_SERIAL
235 EIA-232/EIA-485 serial ports
236 .It Dv PRN_USB
237 Universal Serial Bus printers
238 .It Dv PRN_1394
239 .Em IEEE 1394
240 peripherals
241 .El
242 .Pp
243 Printer interface info string is for information only: no implications should
244 be made from its value.
245 .It Dv PRNIOC_RESET
246 Some applications may want to reset the printer state during Setup and/or
247 Cleanup phase using
248 .Dv PRNIOC_RESET
249 command.
250 Reset semantics are
251 device-specific, and in general, applications using this command should be
252 aware of the printer type.
253 .Pp
254 Each
255 .Nm
256 compliant driver is required to accept this request, although
257 performed actions are completely driver-dependent.
258 More information on the
259 .Dv PRNIOC_RESET
260 implementation for the particular driver is available in the
261 corresponding man page and printer manual.
262 .It Dv PRNIOC_GET_1284_DEVID
263 This command can be used to retrieve printer device ID as defined by
264 .Em IEEE 1284-1994 .
265 The
266 .Xr ioctl 2
267 argument is a pointer to
268 .Vt struct prn_1284_device_id
269 as described below.
270 .Bd -literal -offset 2n
271 struct prn_1284_device_id {
272 uint_t id_len; /* length of buffer */
273 uint_t id_rlen; /* actual ID length */
274 char *id_data; /* buffer address */
275 };
276 .Ed
277 .Pp
278 For convenience, the two-byte length field is not considered part of device ID
279 string and is not returned in the user buffer.
280 Instead,
281 .Fa id_rlen
282 value shall be set to (length - 2) by the driver, where length is the ID
283 length field value.
284 If buffer length is less than
285 .Fa id_rlen ,
286 the driver returns the first
287 .Fa id_len
288 bytes of the ID.
289 .Pp
290 The printer driver must return the most up-to-date value of the device ID.
291 .It Dv PRNIOC_GET_STATUS
292 This command can be used by applications to retrieve current device status.
293 The argument is a pointer to
294 .Vt uint_t ,
295 where the status word is returned.
296 Status is a combination of the following bits:
297 .Bl -tag -width PRN_ONLINE
298 .It Dv PRN_ONLINE
299 For devices that support
300 .Dv PRN_HOTPLUG
301 capability, this bit is set when the device is online, otherwise the device is
302 offline.
303 Devices without
304 .Dv PRN_HOTPLUG
305 support should always have this bit set.
306 .It Dv PRN_READY
307 This bit indicates if the device is ready to receive/send data.
308 Applications may use this bit for an outbound flow control.
309 .El
310 .It Dv PRNIOC_GET_1284_STATUS
311 Devices that support
312 .Dv PRN_1284_STATUS
313 capability accept this ioctl to
314 retrieve the device status lines defined in
315 .Em IEEE 1284
316 for use in Compatibility mode.
317 The following bits may be set by the driver:
318 .Pp
319 .Bl -tag -width PRN_1284_NOFAULT -compact
320 .It Dv PRN_1284_NOFAULT
321 Device is not in error state
322 .It Dv PRN_1284_SELECT
323 Device is selected
324 .It Dv PRN_1284_PE
325 Paper error
326 .It Dv PRN_1284_BUSY
327 Device is busy
328 .El
329 .It Dv PRNIOC_GET_TIMEOUTS
330 This command retrieves current transfer timeout values for the driver.
331 The argument is a pointer to
332 .Vt struct prn_timeouts
333 as described below.
334 .Bd -literal -offset 2n
335 struct prn_timeouts {
336 uint_t tmo_forward; /* forward transfer timeout */
337 uint_t tmo_reverse; /* reverse transfer timeout */
338 };
339 .Ed
340 .Pp
341 .Fa tmo_forward
342 and
343 .Fa tmo_reverse
344 define forward and reverse transfer timeouts in seconds.
345 This command is only valid for drivers that support
346 .Dv PRN_TIMEOUTS
347 capability.
348 .It Dv PRNIOC_SET_TIMEOUTS
349 This command sets current transfer timeout values for the driver.
350 The argument is a pointer to
351 .Vt struct prn_timeouts .
352 See
353 .Sx PRNIOC_GET_TIMEOUTS
354 for description of this structure.
355 This command is only valid for drivers that support
356 .Dv PRN_TIMEOUTS
357 capability.
358 .El
359 .Sh SEE ALSO
360 .Xr close 2 ,
361 .Xr ioctl 2 ,
362 .Xr read 2 ,
363 .Xr write 2 ,
364 .Xr attributes 5 ,
365 .Xr ecpp 7D ,
366 .Xr lp 7D ,
367 .Xr usbprn 7D
368 .Rs
369 .%T IEEE Std 1284-1994
370 .Re