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6 .TH ECPP 7D "May 17, 2020"
7 .SH NAME
8 ecpp \- IEEE 1284 compliant parallel port driver
9 .SH SYNOPSIS
10 .nf
11 #include <sys/types.h>
12 .fi
13
14 .LP
15 .nf
16 #include <sys/ecppio.h>
17 .fi
18
19 .LP
20 .nf
21 ecpp@unit-address
22 .fi
23
24 .SH DESCRIPTION
25 The \fBecpp\fR driver provides a bi-directional interface to \fIIEEE 1284\fR
26 compliant devices as well as a forward single-directional interface to
27 Centronics devices. In addition to the Centronics protocol, the \fBecpp\fR
28 driver supports the \fIIEEE 1284\fR Compatibility, Nibble, and ECP protocols.
29 \fBECPP_COMPAT_MODE\fR and \fBECPP_CENTRONICS\fR modes of operation have
30 logically identical handshaking protocols, however devices that support
31 \fBECPP_COMPAT_MODE\fR are \fIIEEE 1284\fR compliant devices. \fIIEEE 1284\fR
32 compliant devices support at least \fBECPP_COMPAT_MODE\fR and
33 \fBECPP_NIBBLE_MODE\fR. Centronics devices support only \fBECPP_CENTRONICS\fR
34 mode.
35 .sp
36 .LP
37 By default, \fBECPP_COMPAT_MODE\fR devices have a strobe handshaking pulse
38 width of 500ns. For this mode, forward data transfers are conducted by DMA. By
39 default, the strobe pulse width for \fBECPP_CENTRONICS\fR devices is two
40 microseconds. Forward transfers for these devices are managed through PIO. The
41 default characteristics for both \fBECPP_COMPAT_MODE\fR and
42 \fBECPP_CENTRONICS\fR devices may be changed through tunable variables defined
43 in \fBecpp.conf\fR.
44 .sp
45 .LP
46 The \fBecpp\fR driver is an \fIexclusive-use\fR device, meaning that if the
47 device is already open, subsequent opens fail with \fBEBUSY\fR.
48 .SS "Default Operation"
49 Each time the \fBecpp\fR device is opened, the device is marked as \fBEBUSY\fR
50 and the configuration variables are set to their default values. The
51 \fBwrite_timeout\fR period is set to 90 seconds.
52 .sp
53 .LP
54 The driver sets the mode variable according to the following algorithm: The
55 driver initially attempts to negotiate the link into \fBECPP_ECP_MODE\fR during
56 \fBopen\fR(2). If it fails, the driver tries to negotiate into
57 \fBECPP_NIBBLE_MODE\fR mode. If that fails, the driver operates in
58 \fBECPP_CENTRONICS\fR mode. Upon successfully opening the device, \fIIEEE
59 1284\fR compliant devices will be left idle in either reverse idle phase of
60 \fBECPP_ECP_MODE\fR or in \fBECPP_NIBBLE_MODE\fR. Subsequent calls to
61 \fBwrite\fR(2) invokes the driver to move the link into either
62 \fBECPP_COMPAT_MODE\fR or the forward phase of \fBECPP_ECP_MODE\fR. After the
63 transfer completes, the link returns to idle state.
64 .sp
65 .LP
66 The application may attempt to negotiate the device into a specific mode or set
67 the \fBwrite_timeout\fR values through the \fBECPPIOC_SETPARMS\fR
68 \fBioctl\fR(2) call. For mode negotiation to be successful, both the host
69 workstation and the peripheral must support the requested mode.
70 .SS "Tunables"
71 Characteristics of the \fBecpp\fR driver may be tuned by the variables
72 described in \fB/kernel/drv/ecpp.conf\fR. These variables are read by the
73 kernel during system startup. To tune the variables, edit the \fBecpp.conf\fR
74 file and invoke \fBupdate_drv\fR(1M) to have the kernel read the file again.
75 .sp
76 .LP
77 Some Centronics peripherals and certain \fIIEEE 1284\fR compatible peripherals
78 will not operate with the parallel port operating in a fast handshaking mode.
79 If printing problems occur, set "fast-centronics" and "fast-1284-compatible" to
80 "false." See \fB/kernel/drv/ecpp.conf\fR for more information.
81 .SS "Read/Write Operation"
82 The \fBecpp\fR driver is a full duplex STREAMS device driver. While an
83 application is writing to an \fIIEEE 1284\fR compliant device, another thread
84 may read from it.
85 .SS "Write Operation"
86 A \fBwrite\fR(2) operation returns the number of bytes successfully written to
87 the stream head. If a failure occurs while a Centronics device is transferring
88 data, the content of the status bits will be captured at the time of the error
89 and can be retrieved by the application program using the \fBBPPIOC_GETERR\fR
90 \fBioctl\fR(2) call. The captured status information is overwritten each time
91 an attempted transfer or a \fBBPPIOC_TESTIO\fR \fBioctl\fR(2) occurs.
92 .SS "Read Operation"
93 If a failure or error condition occurs during a \fBread\fR(2), the number of
94 bytes successfully read is returned (short read). When attempting to read a
95 port that has no data currently available, \fBread\fR(2) returns \fB0\fR if
96 \fBO_NDELAY\fR is set. If \fBO_NONBLOCK\fR is set, \fBread\fR(2) returns
97 \fB-1\fR and sets errno to \fBEAGAIN.\fR If \fBO_NDELAY\fR and \fBO_NONBLOCK\fR
98 are clear, \fBread\fR(2) blocks until data become available.
99 .SH IOCTLS
100 The \fBioctl\fR(2) calls described below are supported. Note that when
101 \fBecpp\fR is transferring data, the driver waits until the data has been sent
102 to the device before processing the \fBioctl\fR(2) call.
103 .sp
104 .LP
105 The ecpp driver supports \fBprnio\fR(7I) interfaces.
106 .LP
107 Note -
108 .sp
109 .RS 2
110 The \fBPRNIOC_RESET\fR command toggles the \fBnInit\fR signal for 2 ms,
111 followed by default negotiation.
112 .RE
113 .sp
114 .LP
115 The following \fBioctl\fR(2) calls are supported for backward compatibility and
116 are not recommended for new applications:
117 .sp
118 .ne 2
119 .na
120 \fB\fBECPPIOC_GETPARMS\fR\fR
121 .ad
122 .RS 20n
123 Get current transfer parameters. The argument is a pointer to a struct
124 \fBecpp_transfer_parms\fR. See below for a description of the elements of this
125 structure. If no parameters have been configured since the device was opened,
126 the structure will be set to its default configuration. See Default Operation
127 above for more information.
128 .RE
129
130 .sp
131 .ne 2
132 .na
133 \fB\fBECPPIOC_SETPARMS\fR\fR
134 .ad
135 .RS 20n
136 Set transfer parameters. The argument is a pointer to a struct
137 \fBecpp_transfer_parms\fR. If a parameter is out of range, \fBEINVAL\fR is
138 returned. If the peripheral or host device cannot support the requested mode,
139 \fBEPROTONOSUPPORT\fR is returned. See below for a description of
140 \fBecpp_transfer_parms\fR and its valid parameters.
141 .sp
142 The Transfer Parameters Structure is defined in <\fBsys/ecppio.h\fR>.
143 .sp
144 .in +2
145 .nf
146 struct ecpp_transfer_parms {
147 int write_timeout;
148 int mode;
149 };
150 .fi
151 .in -2
152
153 The \fBwrite_timeout\fR field is set to the value of
154 \fBecpp-transfer-timeout\fR specified in the \fBecpp.conf\fR. The
155 \fBwrite_timeout\fR field specifies how long the driver will wait for the
156 peripheral to respond to a transfer request. The value must be greater than
157 \fB0\fR and less than \fBECPP_MAX_TIMEOUT.\fR All other values are out of
158 range.
159 .sp
160 The mode field reflects the \fIIEEE 1284\fR mode to which the parallel port is
161 currently configured. The mode may be set to one of the following values only:
162 \fBECPP_CENTRONICS\fR, \fBECPP_COMPAT_MODE\fR, \fBECPP_NIBBLE_MODE\fR,
163 \fBECPP_ECP_MODE\fR. All other values are invalid. If the requested mode is not
164 supported, \fBECPPIOC_SETPARMS\fR will return \fBEPROTONOSUPPORT\fR and the
165 mode will be set to \fBECPP_CENTRONICS\fR mode. Afterwards, the application may
166 change the mode back to the original mode with \fBECPPIOC_SETPARMS\fR.
167 .RE
168
169 .sp
170 .ne 2
171 .na
172 \fB\fBECPPIOC_GETDEVID\fR\fR
173 .ad
174 .RS 20n
175 This ioctl gets the \fIIEEE 1284\fR device ID from the peripheral in specified
176 mode. Currently, the device ID can be retrieved only in Nibble mode. A pointer
177 to the structure defined in \fB<sys/ecppsys.h>\fR must be passed as an
178 argument.
179 .sp
180 The 1284 device ID structure:
181 .sp
182 .in +2
183 .nf
184 struct ecpp_device_id {
185 int mode; /* mode to use for reading device id */
186 int len; /* length of buffer */
187 int rlen; /* actual length of device id string */
188 char *addr; /* buffer address */
189 };
190 .fi
191 .in -2
192
193 The mode is the \fIIEEE 1284\fR mode into which the port will be negotiated to
194 retrieve device ID information. If the peripheral or host do not support the
195 mode, \fBEPROTONOSUPPORT\fR is returned. Applications should set mode to
196 \fBECPP_NIBBLE_MODE\fR. \fBlen\fR is the length of the buffer pointed to by
197 \fBaddr\fR. \fBrlen\fR is the actual length of the device ID string returned
198 from the peripheral. If the returned \fBrlen\fR is greater than \fBlen\fR, the
199 application can call \fBECPPIOC_GETDEVID\fR again with a buffer length equal or
200 greater than \fBrlen\fR. Note that the two length bytes of the \fIIEEE 1284\fR
201 device ID are not taken into account and are not returned in the user buffer.
202 .sp
203 After \fBECPPIOC_GETDEVID\fR successfully completes, the driver returns the
204 link to \fBECPP_COMPAT_MODE\fR. The application is responsible for determining
205 the previous mode the link was operating in and returning the link to that
206 mode.
207 .RE
208
209 .sp
210 .ne 2
211 .na
212 \fB\fBBPPIOC_TESTIO\fR\fR
213 .ad
214 .RS 20n
215 Tests the forward transfer readiness of a peripheral operating in Centronics or
216 Compatibility mode.
217 .sp
218 \fBTESTIO\fR determines if the peripheral is ready to receive data by checking
219 the open flags and the Centronics status signals. If the current mode of the
220 device is \fBECPP_NIBBLE_MODE\fR, the driver negotiates the link into
221 \fBECPP_COMPAT_MODE\fR, check the status signals and then return the link to
222 \fBECPP_NIBBLE_MODE\fR mode. If the current mode is \fBECPP_CENTRONICS\fR or
223 \fBECPP_COMPAT_MODE\fR, \fBTESTIO\fR examines the Centronics status signals in
224 the current mode. To receive data, the device must have the \fBnErr\fR and
225 \fBSelect\fR signals asserted and must not have the \fBPE\fR and \fBBusy\fR
226 signals asserted. If \fBecpp\fR is transferring data, \fBTESTIO\fR waits until
227 the previous data sent to the driver is delivered before executing
228 \fBTESTIO\fR. However if an error condition occurs while a \fBTESTIO\fR is
229 waiting, \fBTESTIO\fR returns immediately. If \fBTESTIO\fR determines that the
230 conditions are ok, \fB0\fR is returned. Otherwise, \fB-1\fR is returned, errno
231 is set to \fBEIO\fR and the state of the status pins is captured. The captured
232 status can be retrieved using the \fBBPPIOC_GETERR\fR \fBioctl\fR(2) call. The
233 \fBtimeout_occurred\fR and \fBbus_error\fR fields will never be set by this
234 \fBioctl\fR(2).
235 .RE
236
237 .sp
238 .ne 2
239 .na
240 \fB\fBBPPIOC_GETERR\fR\fR
241 .ad
242 .RS 20n
243 Get last error status. The argument is a pointer to a \fBstruct
244 bpp_error_status\fR defined in \fB<sys/bpp_io.h>\fR header file. The error
245 status structure is:
246 .sp
247 .in +2
248 .nf
249 struct bpp_error_status {
250 char timeout_occurred; /* 1=timeout */
251 char bus_error; /* not used */
252 uchar_t pin_status; /* status of pins which
253 /* could cause error */
254 };
255 .fi
256 .in -2
257
258 The pin_status field indicates possible error conditions. The valid bits for
259 pin_status are: \fBBPP_ERR_ERR\fR, \fBBPP_SLCT_ERR\fR, \fBBPP_PE_ERR\fR,
260 \fBBPP_BUSY_ERR\fR. A set bit indicates that the associated pin is asserted.
261 .sp
262 This structure indicates the status of all the appropriate status bits at the
263 time of the most recent error condition during a \fBwrite\fR(2) call, or the
264 status of the bits at the most recent \fBBPPIOC_TESTIO\fR \fBioctl\fR(2)call.
265 .sp
266 \fBpin_status\fR indicates possible error conditions under
267 \fBECPP_CENTRONICS\fR or \fBECPP_COMPAT_MODE\fR. Under these modes, the state
268 of the status pins will indicate the state of the device. For instance, many
269 Centronics printers lower the \fBnErr\fR signal when a paper jam occurs. The
270 behavior of the status pins depends on the device. Additional status
271 information may be retrieved through the backchannel.
272 .sp
273 The \fBtimeout_occurred\fR value is set when a timeout occurs during
274 \fBwrite\fR(2). \fBbus_error\fR is not used in this interface.
275 .RE
276
277 .sp
278 .LP
279 The following ioctls are used to directly read and write the parallel port
280 status and control signals. If the current mode of the device is
281 \fBECPP_ECP_MODE\fR or \fBECPP_NIBBLE_MODE\fR, the driver negotiates the link
282 into \fBECPP_COMPAT_MODE\fR, gets or sets the registers and then returns the
283 link to \fBECPP_NIBBLE_MODE\fR. If the current mode is \fBECPP_CENTRONICS\fR or
284 \fBECPP_COMPAT_MODE\fR, these ioctls will get/set the register values in the
285 current mode.
286 .sp
287 .ne 2
288 .na
289 \fB\fBECPPIOC_GETREGS\fR\fR
290 .ad
291 .RS 19n
292 Read register values. The argument is a pointer to a \fBstruct ecpp_regs\fR.
293 See below for a description of this structure.
294 .RE
295
296 .sp
297 .ne 2
298 .na
299 \fB\fBECPPIOC_SETREGS\fR\fR
300 .ad
301 .RS 19n
302 Set \fBecpp\fR register values. The argument is a pointer to a \fBstruct
303 ecpp_regs\fR. See below for a description of this structure. If a parameter is
304 out of range, \fBEINVAL\fR is returned.
305 .sp
306 The Port Register Structure is defined in <\fBsys/ecppio.h\fR>.
307 .sp
308 .in +2
309 .nf
310 struct ecpp_regs {
311 uchar dsr; /* status reg */
312 u_char dcr; /* control reg */
313 };
314 .fi
315 .in -2
316
317 The status register is read-only. The \fBECPPIOC_SETREGS\fR ioctl has no affect
318 on this register. Valid bit values for dsr are: \fBECPP_nERR\fR,
319 \fBECPP_SLCT\fR, \fBECPP_PE\fR, \fBECPP_nACK\fR, \fBECPP_nBUSY\fR. All other
320 bits are reserved and always return \fB1\fR.
321 .sp
322 The control register is read/write. Valid bit values for dcr are:
323 \fBECPP_STB\fR, \fBECPP_AFX\fR, \fBECPP_nINIT\fR, \fBECPP_SLCTIN\fR. All other
324 bits are reserved. Reading reserved bits always return 1. An attempt to write
325 0s into these bits results in \fBEINVAL\fR.
326 .RE
327
328 .SH DEVICE SPECIAL FILES
329 .ne 2
330 .na
331 \fB\fB/dev/lp\fIN\fR\fR\fR
332 .ad
333 .RS 19n
334 x86 only. (Backwards compatibility with former \fBlp\fR(7D) devices.)
335 .RE
336
337 .sp
338 .ne 2
339 .na
340 \fB\fB/dev/printers/\fIN\fR\fR\fR
341 .ad
342 .RS 19n
343 1284 compliant parallel port device special files appears in both namespaces.
344 .RE
345
346 .SH FILES
347 .ne 2
348 .na
349 \fB/kernel/drv/sparcv9/ecpp\fR
350 .ad
351 .sp .6
352 .RS 4n
353 Device driver (SPARC)
354 .RE
355
356 .sp
357 .ne 2
358 .na
359 \fB/kernel/drv/amd64/ecpp\fR
360 .ad
361 .sp .6
362 .RS 4n
363 Device driver (x86)
364 .RE
365
366 .sp
367 .ne 2
368 .na
369 \fB/kernel/drv/ecpp.conf\fR
370 .ad
371 .sp .6
372 .RS 4n
373 Driver configuration file
374 .RE
375
376 .SH ERRORS
377 .ne 2
378 .na
379 \fB\fBEBADF\fR\fR
380 .ad
381 .RS 10n
382 The device is opened for write-only access and a read is attempted, or the
383 device is opened for read-only access and a write is attempted.
384 .RE
385
386 .sp
387 .ne 2
388 .na
389 \fB\fBEBUSY\fR\fR
390 .ad
391 .RS 10n
392 The device has been opened and another open is attempted. An attempt has been
393 made to unload the driver while one of the units is open.
394 .RE
395
396 .sp
397 .ne 2
398 .na
399 \fB\fBEINVAL\fR\fR
400 .ad
401 .RS 10n
402 A \fBECPPIOC_SETPARMS\fR \fBioctl()\fR is attempted with an out-of-range value
403 in the \fBecpp_transfer_parms\fR structure. A \fBECPPIOC_SETREGS\fR
404 \fBioctl()\fR is attempted with an invalid value in the \fBecpp_regs\fR
405 structure. An \fBioctl()\fR is attempted with an invalid value in the command
406 argument.An invalid command argument is received during \fBmodload\fR(1M) or
407 \fBmodunload\fR(1M).
408 .RE
409
410 .sp
411 .ne 2
412 .na
413 \fB\fBEIO\fR\fR
414 .ad
415 .RS 10n
416 The driver encountered a bus error when attempting an access. A read or write
417 did not complete properly, due to a peripheral error or a transfer timeout.
418 .RE
419
420 .sp
421 .ne 2
422 .na
423 \fB\fBENXIO\fR\fR
424 .ad
425 .RS 10n
426 The driver has received an open request for a unit for which the attach failed.
427 The driver has received a write request for a unit which has an active
428 peripheral error.
429 .RE
430
431 .SH ATTRIBUTES
432 See \fBattributes\fR(5) for descriptions of the following attributes:
433 .sp
434
435 .sp
436 .TS
437 box;
438 c | c
439 l | l .
440 ATTRIBUTE TYPE ATTRIBUTE VALUE
441 _
442 Architecture PCI-based systems
443 _
444 ISA-based systems (x86)
445 _
446 Interface stability Evolving
447 .TE
448
449 .SH SEE ALSO
450 \fBmodload\fR(1M), \fBmodunload\fR(1M), \fBupdate_drv\fR(1M), \fBioctl\fR(2),
451 \fBopen\fR(2), \fBread\fR(2), \fBwrite\fR(2), \fBattributes\fR(5),
452 \fBusbprn\fR(7D), \fBprnio\fR(7I), \fBstreamio\fR(7I)
453 .sp
454 .LP
455 \fIIEEE Std 1284-1994\fR
456 .SH DIAGNOSTICS
457 .ne 2
458 .na
459 \fBParallel port controller not supported\fR
460 .ad
461 .sp .6
462 .RS 4n
463 Driver does not support parallel port controller on the given host. Attach
464 failed.
465 .RE