1===============================
2Linux USB Printer Gadget Driver
3===============================
4
506/04/2007
6
7Copyright (C) 2007 Craig W. Nadler <craig@nadler.us>
8
9
10
11General
12=======
13
14This driver may be used if you are writing printer firmware using Linux as
15the embedded OS. This driver has nothing to do with using a printer with
16your Linux host system.
17
18You will need a USB device controller and a Linux driver for it that accepts
19a gadget / "device class" driver using the Linux USB Gadget API. After the
20USB device controller driver is loaded then load the printer gadget driver.
21This will present a printer interface to the USB Host that your USB Device
22port is connected to.
23
24This driver is structured for printer firmware that runs in user mode. The
25user mode printer firmware will read and write data from the kernel mode
26printer gadget driver using a device file. The printer returns a printer status
27byte when the USB HOST sends a device request to get the printer status.  The
28user 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
34Howto Use This Driver
35=====================
36
37To load the USB device controller driver and the printer gadget driver. The
38following example uses the Netchip 2280 USB device controller driver::
39
40	modprobe net2280
41	modprobe g_printer
42
43
44The follow command line parameter can be used when loading the printer gadget
45(ex: modprobe g_printer idVendor=0x0525 idProduct=0xa4a8 ):
46
47idVendor
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
54idProduct
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
60bcdDevice
61	This is the version number of your product. It would be a good idea
62	to put your firmware version here.
63
64iManufacturer
65	A string containing the name of the Vendor.
66
67iProduct
68	A string containing the Product Name.
69
70iSerialNum
71	A string containing the Serial Number. This should be changed for
72	each unit of your product.
73
74iPNPstring
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
79qlen
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
87Using The Example Code
88======================
89
90This example code talks to stdout, instead of a print engine.
91
92To compile the test code below:
93
941) save it to a file called prn_example.c
952) compile the code with the follow command::
96
97	 gcc prn_example.c -o prn_example
98
99
100
101To read printer data from the host to stdout::
102
103	# prn_example -read_data
104
105
106To write printer data from a file (data_file) to the host::
107
108	# cat data_file | prn_example -write_data
109
110
111To 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
121To set printer to Selected/On-line::
122
123	# prn_example -selected
124
125
126To set printer to Not Selected/Off-line::
127
128	# prn_example -not_selected
129
130
131To set paper status to paper out::
132
133	# prn_example -paper_out
134
135
136To set paper status to paper loaded::
137
138	# prn_example -paper_loaded
139
140
141To set error status to printer OK::
142
143	# prn_example -no_error
144
145
146To set error status to ERROR::
147
148	# prn_example -error
149
150
151
152
153Example 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  }
524