aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/usb/gadget_printer.txt
blob: ad995bf0db4176153ff3b37769a8c47e6e445438 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510

                       Linux USB Printer Gadget Driver
                                 06/04/2007

              Copyright (C) 2007 Craig W. Nadler <craig@nadler.us>



GENERAL
=======

This driver may be used if you are writing printer firmware using Linux as
the embedded OS. This driver has nothing to do with using a printer with
your Linux host system.

You will need a USB device controller and a Linux driver for it that accepts
a gadget / "device class" driver using the Linux USB Gadget API. After the
USB device controller driver is loaded then load the printer gadget driver.
This will present a printer interface to the USB Host that your USB Device
port is connected to.

This driver is structured for printer firmware that runs in user mode. The
user mode printer firmware will read and write data from the kernel mode
printer gadget driver using a device file. The printer returns a printer status
byte when the USB HOST sends a device request to get the printer status.  The
user space firmware can read or write this status byte using a device file
/dev/g_printer . Both blocking and non-blocking read/write calls are supported.




HOWTO USE THIS DRIVER
=====================

To load the USB device controller driver and the printer gadget driver. The
following example uses the Netchip 2280 USB device controller driver:

modprobe net2280
modprobe g_printer


The follow command line parameter can be used when loading the printer gadget
(ex: modprobe g_printer idVendor=0x0525 idProduct=0xa4a8 ):

idVendor - This is the Vendor ID used in the device descriptor. The default is
	the Netchip vendor id 0x0525. YOU MUST CHANGE TO YOUR OWN VENDOR ID
	BEFORE RELEASING A PRODUCT. If you plan to release a product and don't
	already have a Vendor ID please see www.usb.org for details on how to
	get one.

idProduct - This is the Product ID used in the device descriptor. The default
	is 0xa4a8, you should change this to an ID that's not used by any of
	your other USB products if you have any. It would be a good idea to
	start numbering your products starting with say 0x0001.

bcdDevice - This is the version number of your product. It would be a good idea
	to put your firmware version here.

iManufacturer - A string containing the name of the Vendor.

iProduct - A string containing the Product Name.

iSerialNum - A string containing the Serial Number. This should be changed for
	each unit of your product.

iPNPstring -  The PNP ID string used for this printer. You will want to set
	either on the command line or hard code the PNP ID string used for
	your printer product.

qlen - The number of 8k buffers to use per endpoint. The default is 10, you
	should tune this for your product. You may also want to tune the
	size of each buffer for your product.




USING THE EXAMPLE CODE
======================

This example code talks to stdout, instead of a print engine.

To compile the test code below:

1) save it to a file called prn_example.c
2) compile the code with the follow command:
	 gcc prn_example.c -o prn_example



To read printer data from the host to stdout:

	# prn_example -read_data


To write printer data from a file (data_file) to the host:

	# cat data_file | prn_example -write_data


To get the current printer status for the gadget driver:

	# prn_example -get_status

	Printer status is:
	     Printer is NOT Selected
	     Paper is Out
	     Printer OK


To set printer to Selected/On-line:

	# prn_example -selected


To set printer to Not Selected/Off-line:

	# prn_example -not_selected


To set paper status to paper out:

	# prn_example -paper_out


To set paper status to paper loaded:

	# prn_example -paper_loaded


To set error status to printer OK:

	# prn_example -no_error


To set error status to ERROR:

	# prn_example -error




EXAMPLE CODE
============


#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/poll.h>
#include <sys/ioctl.h>
#include <linux/usb/g_printer.h>

#define PRINTER_FILE			"/dev/g_printer"
#define BUF_SIZE			512


/*
 * 'usage()' - Show program usage.
 */

static void
usage(const char *option)		/* I - Option string or NULL */
{
	if (option) {
		fprintf(stderr,"prn_example: Unknown option \"%s\"!\n",
				option);
	}

	fputs("\n", stderr);
	fputs("Usage: prn_example -[options]\n", stderr);
	fputs("Options:\n", stderr);
	fputs("\n", stderr);
	fputs("-get_status    Get the current printer status.\n", stderr);
	fputs("-selected      Set the selected status to selected.\n", stderr);
	fputs("-not_selected  Set the selected status to NOT selected.\n",
			stderr);
	fputs("-error         Set the error status to error.\n", stderr);
	fputs("-no_error      Set the error status to NO error.\n", stderr);
	fputs("-paper_out     Set the paper status to paper out.\n", stderr);
	fputs("-paper_loaded  Set the paper status to paper loaded.\n",
			stderr);
	fputs("-read_data     Read printer data from driver.\n", stderr);
	fputs("-write_data    Write printer sata to driver.\n", stderr);
	fputs("-NB_read_data  (Non-Blocking) Read printer data from driver.\n",
			stderr);
	fputs("\n\n", stderr);

	exit(1);
}


static int
read_printer_data()
{
	struct pollfd	fd[1];

	/* Open device file for printer gadget. */
	fd[0].fd = open(PRINTER_FILE, O_RDWR);
	if (fd[0].fd < 0) {
		printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
		close(fd[0].fd);
		return(-1);
	}

	fd[0].events = POLLIN | POLLRDNORM;

	while (1) {
		static char buf[BUF_SIZE];
		int bytes_read;
		int retval;

		/* Wait for up to 1 second for data. */
		retval = poll(fd, 1, 1000);

		if (retval && (fd[0].revents & POLLRDNORM)) {

			/* Read data from printer gadget driver. */
			bytes_read = read(fd[0].fd, buf, BUF_SIZE);

			if (bytes_read < 0) {
				printf("Error %d reading from %s\n",
						fd[0].fd, PRINTER_FILE);
				close(fd[0].fd);
				return(-1);
			} else if (bytes_read > 0) {
				/* Write data to standard OUTPUT (stdout). */
				fwrite(buf, 1, bytes_read, stdout);
				fflush(stdout);
			}

		}

	}

	/* Close the device file. */
	close(fd[0].fd);

	return 0;
}


static int
write_printer_data()
{
	struct pollfd	fd[1];

	/* Open device file for printer gadget. */
	fd[0].fd = open (PRINTER_FILE, O_RDWR);
	if (fd[0].fd < 0) {
		printf("Error %d opening %s\n", fd[0].fd, PRINTER_FILE);
		close(fd[0].fd);
		return(-1);
	}

	fd[0].events = POLLOUT | POLLWRNORM;

	while (1) {
		int retval;
		static char buf[BUF_SIZE];
		/* Read data from standard INPUT (stdin). */
		int bytes_read = fread(buf, 1, BUF_SIZE, stdin);

		if (!bytes_read) {
			break;
		}

		while (bytes_read) {

			/* Wait for up to 1 second to sent data. */
			retval = poll(fd, 1, 1000);

			/* Write data to printer gadget driver. */
			if (retval && (fd[0].revents & POLLWRNORM)) {
				retval = write(fd[0].fd, buf, bytes_read);
				if (retval < 0) {
					printf("Error %d writing to %s\n",
							fd[0].fd,
							PRINTER_FILE);
					close(fd[0].fd);
					return(-1);
				} else {
					bytes_read -= retval;
				}

			}

		}

	}

	/* Wait until the data has been sent. */
	fsync(fd[0].fd);

	/* Close the device file. */
	close(fd[0].fd);

	return 0;
}


static int
read_NB_printer_data()
{
	int		fd;
	static char	buf[BUF_SIZE];
	int		bytes_read;

	/* Open device file for printer gadget. */
	fd = open(PRINTER_FILE, O_RDWR|O_NONBLOCK);
	if (fd < 0) {
		printf("Error %d opening %s\n", fd, PRINTER_FILE);
		close(fd);
		return(-1);
	}

	while (1) {
		/* Read data from printer gadget driver. */
		bytes_read = read(fd, buf, BUF_SIZE);
		if (bytes_read <= 0) {
			break;
		}

		/* Write data to standard OUTPUT (stdout). */
		fwrite(buf, 1, bytes_read, stdout);
		fflush(stdout);
	}

	/* Close the device file. */
	close(fd);

	return 0;
}


static int
get_printer_status()
{
	int	retval;
	int	fd;

	/* Open device file for printer gadget. */
	fd = open(PRINTER_FILE, O_RDWR);
	if (fd < 0) {
		printf("Error %d opening %s\n", fd, PRINTER_FILE);
		close(fd);
		return(-1);
	}

	/* Make the IOCTL call. */
	retval = ioctl(fd, GADGET_GET_PRINTER_STATUS);
	if (retval < 0) {
		fprintf(stderr, "ERROR: Failed to set printer status\n");
		return(-1);
	}

	/* Close the device file. */
	close(fd);

	return(retval);
}


static int
set_printer_status(unsigned char buf, int clear_printer_status_bit)
{
	int	retval;
	int	fd;

	retval = get_printer_status();
	if (retval < 0) {
		fprintf(stderr, "ERROR: Failed to get printer status\n");
		return(-1);
	}

	/* Open device file for printer gadget. */
	fd = open(PRINTER_FILE, O_RDWR);

	if (fd < 0) {
		printf("Error %d opening %s\n", fd, PRINTER_FILE);
		close(fd);
		return(-1);
	}

	if (clear_printer_status_bit) {
		retval &= ~buf;
	} else {
		retval |= buf;
	}

	/* Make the IOCTL call. */
	if (ioctl(fd, GADGET_SET_PRINTER_STATUS, (unsigned char)retval)) {
		fprintf(stderr, "ERROR: Failed to set printer status\n");
		return(-1);
	}

	/* Close the device file. */
	close(fd);

	return 0;
}


static int
display_printer_status()
{
	char	printer_status;

	printer_status = get_printer_status();
	if (printer_status < 0) {
		fprintf(stderr, "ERROR: Failed to get printer status\n");
		return(-1);
	}

	printf("Printer status is:\n");
	if (printer_status & PRINTER_SELECTED) {
		printf("     Printer is Selected\n");
	} else {
		printf("     Printer is NOT Selected\n");
	}
	if (printer_status & PRINTER_PAPER_EMPTY) {
		printf("     Paper is Out\n");
	} else {
		printf("     Paper is Loaded\n");
	}
	if (printer_status & PRINTER_NOT_ERROR) {
		printf("     Printer OK\n");
	} else {
		printf("     Printer ERROR\n");
	}

	return(0);
}


int
main(int  argc, char *argv[])
{
	int	i;		/* Looping var */
	int	retval = 0;

	/* No Args */
	if (argc == 1) {
		usage(0);
		exit(0);
	}

	for (i = 1; i < argc && !retval; i ++) {

		if (argv[i][0] != '-') {
			continue;
		}

		if (!strcmp(argv[i], "-get_status")) {
			if (display_printer_status()) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-paper_loaded")) {
			if (set_printer_status(PRINTER_PAPER_EMPTY, 1)) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-paper_out")) {
			if (set_printer_status(PRINTER_PAPER_EMPTY, 0)) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-selected")) {
			if (set_printer_status(PRINTER_SELECTED, 0)) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-not_selected")) {
			if (set_printer_status(PRINTER_SELECTED, 1)) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-error")) {
			if (set_printer_status(PRINTER_NOT_ERROR, 1)) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-no_error")) {
			if (set_printer_status(PRINTER_NOT_ERROR, 0)) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-read_data")) {
			if (read_printer_data()) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-write_data")) {
			if (write_printer_data()) {
				retval = 1;
			}

		} else if (!strcmp(argv[i], "-NB_read_data")) {
			if (read_NB_printer_data()) {
				retval = 1;
			}

		} else {
			usage(argv[i]);
			retval = 1;
		}
	}

	exit(retval);
}