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