1 ===============================
2 Linux USB Printer Gadget Driver
3 ===============================
4
5 06/04/2007
6
7 Copyright (C) 2007 Craig W. Nadler <craig@nadler.us>
8
9
10
11 General
12 =======
13
14 This driver may be used if you are writing printer firmware using Linux as
15 the embedded OS. This driver has nothing to do with using a printer with
16 your Linux host system.
17
18 You will need a USB device controller and a Linux driver for it that accepts
19 a gadget / "device class" driver using the Linux USB Gadget API. After the
20 USB device controller driver is loaded then load the printer gadget driver.
21 This will present a printer interface to the USB Host that your USB Device
22 port is connected to.
23
24 This driver is structured for printer firmware that runs in user mode. The
25 user mode printer firmware will read and write data from the kernel mode
26 printer gadget driver using a device file. The printer returns a printer status
27 byte when the USB HOST sends a device request to get the printer status. The
28 user space firmware can read or write this status byte using a device file
29 /dev/g_printer . Both blocking and non-blocking read/write calls are supported.
30
31
32
33
34 Howto Use This Driver
35 =====================
36
37 To load the USB device controller driver and the printer gadget driver. The
38 following example uses the Netchip 2280 USB device controller driver::
39
40 modprobe net2280
41 modprobe g_printer
42
43
44 The follow command line parameter can be used when loading the printer gadget
45 (ex: modprobe g_printer idVendor=0x0525 idProduct=0xa4a8 ):
46
47 idVendor
48 This is the Vendor ID used in the device descriptor. The default is
49 the Netchip vendor id 0x0525. YOU MUST CHANGE TO YOUR OWN VENDOR ID
50 BEFORE RELEASING A PRODUCT. If you plan to release a product and don't
51 already have a Vendor ID please see www.usb.org for details on how to
52 get one.
53
54 idProduct
55 This is the Product ID used in the device descriptor. The default
56 is 0xa4a8, you should change this to an ID that's not used by any of
57 your other USB products if you have any. It would be a good idea to
58 start numbering your products starting with say 0x0001.
59
60 bcdDevice
61 This is the version number of your product. It would be a good idea
62 to put your firmware version here.
63
64 iManufacturer
65 A string containing the name of the Vendor.
66
67 iProduct
68 A string containing the Product Name.
69
70 iSerialNum
71 A string containing the Serial Number. This should be changed for
72 each unit of your product.
73
74 iPNPstring
75 The PNP ID string used for this printer. You will want to set
76 either on the command line or hard code the PNP ID string used for
77 your printer product.
78
79 qlen
80 The number of 8k buffers to use per endpoint. The default is 10, you
81 should tune this for your product. You may also want to tune the
82 size of each buffer for your product.
83
84
85
86
87 Using The Example Code
88 ======================
89
90 This example code talks to stdout, instead of a print engine.
91
92 To compile the test code below:
93
94 1) save it to a file called prn_example.c
95 2) compile the code with the follow command::
96
97 gcc prn_example.c -o prn_example
98
99
100
101 To read printer data from the host to stdout::
102
103 # prn_example -read_data
104
105
106 To write printer data from a file (data_file) to the host::
107
108 # cat data_file | prn_example -write_data
109
110
111 To get the current printer status for the gadget driver:::
112
113 # prn_example -get_status
114
115 Printer status is:
116 Printer is NOT Selected
117 Paper is Out
118 Printer OK
119
120
121 To set printer to Selected/On-line::
122
123 # prn_example -selected
124
125
126 To set printer to Not Selected/Off-line::
127
128 # prn_example -not_selected
129
130
131 To set paper status to paper out::
132
133 # prn_example -paper_out
134
135
136 To set paper status to paper loaded::
137
138 # prn_example -paper_loaded
139
140
141 To set error status to printer OK::
142
143 # prn_example -no_error
144
145
146 To set error status to ERROR::
147
148 # prn_example -error
149
150
151
152
153 Example Code
154 ============
155
156 ::
157
158
159 #include <stdio.h>
160 #include <stdlib.h>
161 #include <fcntl.h>
162 #include <linux/poll.h>
163 #include <sys/ioctl.h>
164 #include <linux/usb/g_printer.h>
165
166 #define PRINTER_FILE "/dev/g_printer"
167 #define BUF_SIZE 512
168
169
170 /*
171 * 'usage()' - Show program usage.
172 */
173
174 static void
175 usage(const char *option) /* I - Option string or NULL */
176 {
177 if (option) {
178 fprintf(stderr,"prn_example: Unknown option \"%s\"!\n",
179 option);
180 }
181
182 fputs("\n", stderr);
183 fputs("Usage: prn_example -[options]\n", stderr);
184 fputs("Options:\n", stderr);
185 fputs("\n", stderr);
186 fputs("-get_status Get the current printer status.\n", stderr);
187 fputs("-selected Set the selected status to selected.\n", stderr);
188 fputs("-not_selected Set the selected status to NOT selected.\n",
189 stderr);
190 fputs("-error Set the error status to error.\n", stderr);
191 fputs("-no_error Set the error status to NO error.\n", stderr);
192 fputs("-paper_out Set the paper status to paper out.\n", stderr);
193 fputs("-paper_loaded Set the paper status to paper loaded.\n",
194 stderr);
195 fputs("-read_data Read printer data from driver.\n", stderr);
196 fputs("-write_data Write printer sata to driver.\n", stderr);
197 fputs("-NB_read_data (Non-Blocking) Read printer data from driver.\n",
198 stderr);
199 fputs("\n\n", stderr);
200
201 exit(1);
202 }
203
204
205 static int
206 read_printer_data()
207 {
208 struct pollfd fd[1];
209
210 /* Open device file for printer gadget. */
211 fd[0].fd = open(PRINTER_FILE, O_RDWR);
212 if (fd[0].fd < 0) {
213 printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
214 close(fd[0].fd);
215 return(-1);
216 }
217
218 fd[0].events = POLLIN | POLLRDNORM;
219
220 while (1) {
221 static char buf[BUF_SIZE];
222 int bytes_read;
223 int retval;
224
225 /* Wait for up to 1 second for data. */
226 retval = poll(fd, 1, 1000);
227
228 if (retval && (fd[0].revents & POLLRDNORM)) {
229
230 /* Read data from printer gadget driver. */
231 bytes_read = read(fd[0].fd, buf, BUF_SIZE);
232
233 if (bytes_read < 0) {
234 printf("Error %d reading from %s\n",
235 fd[0].fd, PRINTER_FILE);
236 close(fd[0].fd);
237 return(-1);
238 } else if (bytes_read > 0) {
239 /* Write data to standard OUTPUT (stdout). */
240 fwrite(buf, 1, bytes_read, stdout);
241 fflush(stdout);
242 }
243
244 }
245
246 }
247
248 /* Close the device file. */
249 close(fd[0].fd);
250
251 return 0;
252 }
253
254
255 static int
256 write_printer_data()
257 {
258 struct pollfd fd[1];
259
260 /* Open device file for printer gadget. */
261 fd[0].fd = open (PRINTER_FILE, O_RDWR);
262 if (fd[0].fd < 0) {
263 printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
264 close(fd[0].fd);
265 return(-1);
266 }
267
268 fd[0].events = POLLOUT | POLLWRNORM;
269
270 while (1) {
271 int retval;
272 static char buf[BUF_SIZE];
273 /* Read data from standard INPUT (stdin). */
274 int bytes_read = fread(buf, 1, BUF_SIZE, stdin);
275
276 if (!bytes_read) {
277 break;
278 }
279
280 while (bytes_read) {
281
282 /* Wait for up to 1 second to sent data. */
283 retval = poll(fd, 1, 1000);
284
285 /* Write data to printer gadget driver. */
286 if (retval && (fd[0].revents & POLLWRNORM)) {
287 retval = write(fd[0].fd, buf, bytes_read);
288 if (retval < 0) {
289 printf("Error %d writing to %s\n",
290 fd[0].fd,
291 PRINTER_FILE);
292 close(fd[0].fd);
293 return(-1);
294 } else {
295 bytes_read -= retval;
296 }
297
298 }
299
300 }
301
302 }
303
304 /* Wait until the data has been sent. */
305 fsync(fd[0].fd);
306
307 /* Close the device file. */
308 close(fd[0].fd);
309
310 return 0;
311 }
312
313
314 static int
315 read_NB_printer_data()
316 {
317 int fd;
318 static char buf[BUF_SIZE];
319 int bytes_read;
320
321 /* Open device file for printer gadget. */
322 fd = open(PRINTER_FILE, O_RDWR|O_NONBLOCK);
323 if (fd < 0) {
324 printf("Error %d opening %s\n", fd, PRINTER_FILE);
325 close(fd);
326 return(-1);
327 }
328
329 while (1) {
330 /* Read data from printer gadget driver. */
331 bytes_read = read(fd, buf, BUF_SIZE);
332 if (bytes_read <= 0) {
333 break;
334 }
335
336 /* Write data to standard OUTPUT (stdout). */
337 fwrite(buf, 1, bytes_read, stdout);
338 fflush(stdout);
339 }
340
341 /* Close the device file. */
342 close(fd);
343
344 return 0;
345 }
346
347
348 static int
349 get_printer_status()
350 {
351 int retval;
352 int fd;
353
354 /* Open device file for printer gadget. */
355 fd = open(PRINTER_FILE, O_RDWR);
356 if (fd < 0) {
357 printf("Error %d opening %s\n", fd, PRINTER_FILE);
358 close(fd);
359 return(-1);
360 }
361
362 /* Make the IOCTL call. */
363 retval = ioctl(fd, GADGET_GET_PRINTER_STATUS);
364 if (retval < 0) {
365 fprintf(stderr, "ERROR: Failed to set printer status\n");
366 return(-1);
367 }
368
369 /* Close the device file. */
370 close(fd);
371
372 return(retval);
373 }
374
375
376 static int
377 set_printer_status(unsigned char buf, int clear_printer_status_bit)
378 {
379 int retval;
380 int fd;
381
382 retval = get_printer_status();
383 if (retval < 0) {
384 fprintf(stderr, "ERROR: Failed to get printer status\n");
385 return(-1);
386 }
387
388 /* Open device file for printer gadget. */
389 fd = open(PRINTER_FILE, O_RDWR);
390
391 if (fd < 0) {
392 printf("Error %d opening %s\n", fd, PRINTER_FILE);
393 close(fd);
394 return(-1);
395 }
396
397 if (clear_printer_status_bit) {
398 retval &= ~buf;
399 } else {
400 retval |= buf;
401 }
402
403 /* Make the IOCTL call. */
404 if (ioctl(fd, GADGET_SET_PRINTER_STATUS, (unsigned char)retval)) {
405 fprintf(stderr, "ERROR: Failed to set printer status\n");
406 return(-1);
407 }
408
409 /* Close the device file. */
410 close(fd);
411
412 return 0;
413 }
414
415
416 static int
417 display_printer_status()
418 {
419 char printer_status;
420
421 printer_status = get_printer_status();
422 if (printer_status < 0) {
423 fprintf(stderr, "ERROR: Failed to get printer status\n");
424 return(-1);
425 }
426
427 printf("Printer status is:\n");
428 if (printer_status & PRINTER_SELECTED) {
429 printf(" Printer is Selected\n");
430 } else {
431 printf(" Printer is NOT Selected\n");
432 }
433 if (printer_status & PRINTER_PAPER_EMPTY) {
434 printf(" Paper is Out\n");
435 } else {
436 printf(" Paper is Loaded\n");
437 }
438 if (printer_status & PRINTER_NOT_ERROR) {
439 printf(" Printer OK\n");
440 } else {
441 printf(" Printer ERROR\n");
442 }
443
444 return(0);
445 }
446
447
448 int
449 main(int argc, char *argv[])
450 {
451 int i; /* Looping var */
452 int retval = 0;
453
454 /* No Args */
455 if (argc == 1) {
456 usage(0);
457 exit(0);
458 }
459
460 for (i = 1; i < argc && !retval; i ++) {
461
462 if (argv[i][0] != '-') {
463 continue;
464 }
465
466 if (!strcmp(argv[i], "-get_status")) {
467 if (display_printer_status()) {
468 retval = 1;
469 }
470
471 } else if (!strcmp(argv[i], "-paper_loaded")) {
472 if (set_printer_status(PRINTER_PAPER_EMPTY, 1)) {
473 retval = 1;
474 }
475
476 } else if (!strcmp(argv[i], "-paper_out")) {
477 if (set_printer_status(PRINTER_PAPER_EMPTY, 0)) {
478 retval = 1;
479 }
480
481 } else if (!strcmp(argv[i], "-selected")) {
482 if (set_printer_status(PRINTER_SELECTED, 0)) {
483 retval = 1;
484 }
485
486 } else if (!strcmp(argv[i], "-not_selected")) {
487 if (set_printer_status(PRINTER_SELECTED, 1)) {
488 retval = 1;
489 }
490
491 } else if (!strcmp(argv[i], "-error")) {
492 if (set_printer_status(PRINTER_NOT_ERROR, 1)) {
493 retval = 1;
494 }
495
496 } else if (!strcmp(argv[i], "-no_error")) {
497 if (set_printer_status(PRINTER_NOT_ERROR, 0)) {
498 retval = 1;
499 }
500
501 } else if (!strcmp(argv[i], "-read_data")) {
502 if (read_printer_data()) {
503 retval = 1;
504 }
505
506 } else if (!strcmp(argv[i], "-write_data")) {
507 if (write_printer_data()) {
508 retval = 1;
509 }
510
511 } else if (!strcmp(argv[i], "-NB_read_data")) {
512 if (read_NB_printer_data()) {
513 retval = 1;
514 }
515
516 } else {
517 usage(argv[i]);
518 retval = 1;
519 }
520 }
521
522 exit(retval);
523 }
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.