Documentation/usb/gadget_printer.rst

14 This driver may be used if you are writing printer firmware using Linux as
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
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.
62 	to put your firmware version here.
97 	 gcc prn_example.c -o prn_example
103 	# prn_example -read_data
108 	# cat data_file | prn_example -write_data
113 	# prn_example -get_status
121 To set printer to Selected/On-line::
123 	# prn_example -selected
126 To set printer to Not Selected/Off-line::
128 	# prn_example -not_selected
133 	# prn_example -paper_out
138 	# prn_example -paper_loaded
143 	# prn_example -no_error
148 	# prn_example -error
171    * 'usage()' - Show program usage.
175   usage(const char *option)		/* I - Option string or NULL */
183 	fputs("Usage: prn_example -[options]\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",
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",
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",
210 	/* Open device file for printer gadget. */
211 	fd[0].fd = open(PRINTER_FILE, O_RDWR);
215 		return(-1);
237 				return(-1);
260 	/* Open device file for printer gadget. */
261 	fd[0].fd = open (PRINTER_FILE, O_RDWR);
265 		return(-1);
293 					return(-1);
295 					bytes_read -= retval;
321 	/* Open device file for printer gadget. */
322 	fd = open(PRINTER_FILE, O_RDWR|O_NONBLOCK);
326 		return(-1);
354 	/* Open device file for printer gadget. */
355 	fd = open(PRINTER_FILE, O_RDWR);
359 		return(-1);
366 		return(-1);
385 		return(-1);
388 	/* Open device file for printer gadget. */
389 	fd = open(PRINTER_FILE, O_RDWR);
394 		return(-1);
406 		return(-1);
424 		return(-1);
462 		if (argv[i][0] != '-') {
466 		if (!strcmp(argv[i], "-get_status")) {
471 		} else if (!strcmp(argv[i], "-paper_loaded")) {
476 		} else if (!strcmp(argv[i], "-paper_out")) {
481 		} else if (!strcmp(argv[i], "-selected")) {
486 		} else if (!strcmp(argv[i], "-not_selected")) {
491 		} else if (!strcmp(argv[i], "-error")) {
496 		} else if (!strcmp(argv[i], "-no_error")) {
501 		} else if (!strcmp(argv[i], "-read_data")) {
506 		} else if (!strcmp(argv[i], "-write_data")) {
511 		} else if (!strcmp(argv[i], "-NB_read_data")) {