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