1 /* 2 * USB Skeleton driver - 2.2 3 * 4 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation, version 2. 9 * 10 * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c 11 * but has been rewritten to be easier to read and use. 12 * 13 */ 14 15 #include <linux/kernel.h> 16 #include <linux/errno.h> 17 #include <linux/init.h> 18 #include <linux/slab.h> 19 #include <linux/module.h> 20 #include <linux/kref.h> 21 #include <linux/uaccess.h> 22 #include <linux/usb.h> 23 #include <linux/mutex.h> 24 25 26 /* Define these values to match your devices */ 27 #define USB_SKEL_VENDOR_ID 0xfff0 28 #define USB_SKEL_PRODUCT_ID 0xfff0 29 30 /* table of devices that work with this driver */ 31 static const struct usb_device_id skel_table[] = { 32 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) }, 33 { } /* Terminating entry */ 34 }; 35 MODULE_DEVICE_TABLE(usb, skel_table); 36 37 38 /* Get a minor range for your devices from the usb maintainer */ 39 #define USB_SKEL_MINOR_BASE 192 40 41 /* our private defines. if this grows any larger, use your own .h file */ 42 #define MAX_TRANSFER (PAGE_SIZE - 512) 43 /* MAX_TRANSFER is chosen so that the VM is not stressed by 44 allocations > PAGE_SIZE and the number of packets in a page 45 is an integer 512 is the largest possible packet on EHCI */ 46 #define WRITES_IN_FLIGHT 8 47 /* arbitrarily chosen */ 48 49 /* Structure to hold all of our device specific stuff */ 50 struct usb_skel { 51 struct usb_device *udev; /* the usb device for this device */ 52 struct usb_interface *interface; /* the interface for this device */ 53 struct semaphore limit_sem; /* limiting the number of writes in progress */ 54 struct usb_anchor submitted; /* in case we need to retract our submissions */ 55 struct urb *bulk_in_urb; /* the urb to read data with */ 56 unsigned char *bulk_in_buffer; /* the buffer to receive data */ 57 size_t bulk_in_size; /* the size of the receive buffer */ 58 size_t bulk_in_filled; /* number of bytes in the buffer */ 59 size_t bulk_in_copied; /* already copied to user space */ 60 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */ 61 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */ 62 int errors; /* the last request tanked */ 63 bool ongoing_read; /* a read is going on */ 64 bool processed_urb; /* indicates we haven't processed the urb */ 65 spinlock_t err_lock; /* lock for errors */ 66 struct kref kref; 67 struct mutex io_mutex; /* synchronize I/O with disconnect */ 68 struct completion bulk_in_completion; /* to wait for an ongoing read */ 69 }; 70 #define to_skel_dev(d) container_of(d, struct usb_skel, kref) 71 72 static struct usb_driver skel_driver; 73 static void skel_draw_down(struct usb_skel *dev); 74 75 static void skel_delete(struct kref *kref) 76 { 77 struct usb_skel *dev = to_skel_dev(kref); 78 79 usb_free_urb(dev->bulk_in_urb); 80 usb_put_dev(dev->udev); 81 kfree(dev->bulk_in_buffer); 82 kfree(dev); 83 } 84 85 static int skel_open(struct inode *inode, struct file *file) 86 { 87 struct usb_skel *dev; 88 struct usb_interface *interface; 89 int subminor; 90 int retval = 0; 91 92 subminor = iminor(inode); 93 94 interface = usb_find_interface(&skel_driver, subminor); 95 if (!interface) { 96 pr_err("%s - error, can't find device for minor %d\n", 97 __func__, subminor); 98 retval = -ENODEV; 99 goto exit; 100 } 101 102 dev = usb_get_intfdata(interface); 103 if (!dev) { 104 retval = -ENODEV; 105 goto exit; 106 } 107 108 retval = usb_autopm_get_interface(interface); 109 if (retval) 110 goto exit; 111 112 /* increment our usage count for the device */ 113 kref_get(&dev->kref); 114 115 /* save our object in the file's private structure */ 116 file->private_data = dev; 117 118 exit: 119 return retval; 120 } 121 122 static int skel_release(struct inode *inode, struct file *file) 123 { 124 struct usb_skel *dev; 125 126 dev = file->private_data; 127 if (dev == NULL) 128 return -ENODEV; 129 130 /* allow the device to be autosuspended */ 131 mutex_lock(&dev->io_mutex); 132 if (dev->interface) 133 usb_autopm_put_interface(dev->interface); 134 mutex_unlock(&dev->io_mutex); 135 136 /* decrement the count on our device */ 137 kref_put(&dev->kref, skel_delete); 138 return 0; 139 } 140 141 static int skel_flush(struct file *file, fl_owner_t id) 142 { 143 struct usb_skel *dev; 144 int res; 145 146 dev = file->private_data; 147 if (dev == NULL) 148 return -ENODEV; 149 150 /* wait for io to stop */ 151 mutex_lock(&dev->io_mutex); 152 skel_draw_down(dev); 153 154 /* read out errors, leave subsequent opens a clean slate */ 155 spin_lock_irq(&dev->err_lock); 156 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0; 157 dev->errors = 0; 158 spin_unlock_irq(&dev->err_lock); 159 160 mutex_unlock(&dev->io_mutex); 161 162 return res; 163 } 164 165 static void skel_read_bulk_callback(struct urb *urb) 166 { 167 struct usb_skel *dev; 168 169 dev = urb->context; 170 171 spin_lock(&dev->err_lock); 172 /* sync/async unlink faults aren't errors */ 173 if (urb->status) { 174 if (!(urb->status == -ENOENT || 175 urb->status == -ECONNRESET || 176 urb->status == -ESHUTDOWN)) 177 dev_err(&dev->interface->dev, 178 "%s - nonzero write bulk status received: %d\n", 179 __func__, urb->status); 180 181 dev->errors = urb->status; 182 } else { 183 dev->bulk_in_filled = urb->actual_length; 184 } 185 dev->ongoing_read = 0; 186 spin_unlock(&dev->err_lock); 187 188 complete(&dev->bulk_in_completion); 189 } 190 191 static int skel_do_read_io(struct usb_skel *dev, size_t count) 192 { 193 int rv; 194 195 /* prepare a read */ 196 usb_fill_bulk_urb(dev->bulk_in_urb, 197 dev->udev, 198 usb_rcvbulkpipe(dev->udev, 199 dev->bulk_in_endpointAddr), 200 dev->bulk_in_buffer, 201 min(dev->bulk_in_size, count), 202 skel_read_bulk_callback, 203 dev); 204 /* tell everybody to leave the URB alone */ 205 spin_lock_irq(&dev->err_lock); 206 dev->ongoing_read = 1; 207 spin_unlock_irq(&dev->err_lock); 208 209 /* do it */ 210 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL); 211 if (rv < 0) { 212 dev_err(&dev->interface->dev, 213 "%s - failed submitting read urb, error %d\n", 214 __func__, rv); 215 dev->bulk_in_filled = 0; 216 rv = (rv == -ENOMEM) ? rv : -EIO; 217 spin_lock_irq(&dev->err_lock); 218 dev->ongoing_read = 0; 219 spin_unlock_irq(&dev->err_lock); 220 } 221 222 return rv; 223 } 224 225 static ssize_t skel_read(struct file *file, char *buffer, size_t count, 226 loff_t *ppos) 227 { 228 struct usb_skel *dev; 229 int rv; 230 bool ongoing_io; 231 232 dev = file->private_data; 233 234 /* if we cannot read at all, return EOF */ 235 if (!dev->bulk_in_urb || !count) 236 return 0; 237 238 /* no concurrent readers */ 239 rv = mutex_lock_interruptible(&dev->io_mutex); 240 if (rv < 0) 241 return rv; 242 243 if (!dev->interface) { /* disconnect() was called */ 244 rv = -ENODEV; 245 goto exit; 246 } 247 248 /* if IO is under way, we must not touch things */ 249 retry: 250 spin_lock_irq(&dev->err_lock); 251 ongoing_io = dev->ongoing_read; 252 spin_unlock_irq(&dev->err_lock); 253 254 if (ongoing_io) { 255 /* nonblocking IO shall not wait */ 256 if (file->f_flags & O_NONBLOCK) { 257 rv = -EAGAIN; 258 goto exit; 259 } 260 /* 261 * IO may take forever 262 * hence wait in an interruptible state 263 */ 264 rv = wait_for_completion_interruptible(&dev->bulk_in_completion); 265 if (rv < 0) 266 goto exit; 267 /* 268 * by waiting we also semiprocessed the urb 269 * we must finish now 270 */ 271 dev->bulk_in_copied = 0; 272 dev->processed_urb = 1; 273 } 274 275 if (!dev->processed_urb) { 276 /* 277 * the URB hasn't been processed 278 * do it now 279 */ 280 wait_for_completion(&dev->bulk_in_completion); 281 dev->bulk_in_copied = 0; 282 dev->processed_urb = 1; 283 } 284 285 /* errors must be reported */ 286 rv = dev->errors; 287 if (rv < 0) { 288 /* any error is reported once */ 289 dev->errors = 0; 290 /* to preserve notifications about reset */ 291 rv = (rv == -EPIPE) ? rv : -EIO; 292 /* no data to deliver */ 293 dev->bulk_in_filled = 0; 294 /* report it */ 295 goto exit; 296 } 297 298 /* 299 * if the buffer is filled we may satisfy the read 300 * else we need to start IO 301 */ 302 303 if (dev->bulk_in_filled) { 304 /* we had read data */ 305 size_t available = dev->bulk_in_filled - dev->bulk_in_copied; 306 size_t chunk = min(available, count); 307 308 if (!available) { 309 /* 310 * all data has been used 311 * actual IO needs to be done 312 */ 313 rv = skel_do_read_io(dev, count); 314 if (rv < 0) 315 goto exit; 316 else 317 goto retry; 318 } 319 /* 320 * data is available 321 * chunk tells us how much shall be copied 322 */ 323 324 if (copy_to_user(buffer, 325 dev->bulk_in_buffer + dev->bulk_in_copied, 326 chunk)) 327 rv = -EFAULT; 328 else 329 rv = chunk; 330 331 dev->bulk_in_copied += chunk; 332 333 /* 334 * if we are asked for more than we have, 335 * we start IO but don't wait 336 */ 337 if (available < count) 338 skel_do_read_io(dev, count - chunk); 339 } else { 340 /* no data in the buffer */ 341 rv = skel_do_read_io(dev, count); 342 if (rv < 0) 343 goto exit; 344 else if (!(file->f_flags & O_NONBLOCK)) 345 goto retry; 346 rv = -EAGAIN; 347 } 348 exit: 349 mutex_unlock(&dev->io_mutex); 350 return rv; 351 } 352 353 static void skel_write_bulk_callback(struct urb *urb) 354 { 355 struct usb_skel *dev; 356 357 dev = urb->context; 358 359 /* sync/async unlink faults aren't errors */ 360 if (urb->status) { 361 if (!(urb->status == -ENOENT || 362 urb->status == -ECONNRESET || 363 urb->status == -ESHUTDOWN)) 364 dev_err(&dev->interface->dev, 365 "%s - nonzero write bulk status received: %d\n", 366 __func__, urb->status); 367 368 spin_lock(&dev->err_lock); 369 dev->errors = urb->status; 370 spin_unlock(&dev->err_lock); 371 } 372 373 /* free up our allocated buffer */ 374 usb_free_coherent(urb->dev, urb->transfer_buffer_length, 375 urb->transfer_buffer, urb->transfer_dma); 376 up(&dev->limit_sem); 377 } 378 379 static ssize_t skel_write(struct file *file, const char *user_buffer, 380 size_t count, loff_t *ppos) 381 { 382 struct usb_skel *dev; 383 int retval = 0; 384 struct urb *urb = NULL; 385 char *buf = NULL; 386 size_t writesize = min(count, (size_t)MAX_TRANSFER); 387 388 dev = file->private_data; 389 390 /* verify that we actually have some data to write */ 391 if (count == 0) 392 goto exit; 393 394 /* 395 * limit the number of URBs in flight to stop a user from using up all 396 * RAM 397 */ 398 if (!(file->f_flags & O_NONBLOCK)) { 399 if (down_interruptible(&dev->limit_sem)) { 400 retval = -ERESTARTSYS; 401 goto exit; 402 } 403 } else { 404 if (down_trylock(&dev->limit_sem)) { 405 retval = -EAGAIN; 406 goto exit; 407 } 408 } 409 410 spin_lock_irq(&dev->err_lock); 411 retval = dev->errors; 412 if (retval < 0) { 413 /* any error is reported once */ 414 dev->errors = 0; 415 /* to preserve notifications about reset */ 416 retval = (retval == -EPIPE) ? retval : -EIO; 417 } 418 spin_unlock_irq(&dev->err_lock); 419 if (retval < 0) 420 goto error; 421 422 /* create a urb, and a buffer for it, and copy the data to the urb */ 423 urb = usb_alloc_urb(0, GFP_KERNEL); 424 if (!urb) { 425 retval = -ENOMEM; 426 goto error; 427 } 428 429 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL, 430 &urb->transfer_dma); 431 if (!buf) { 432 retval = -ENOMEM; 433 goto error; 434 } 435 436 if (copy_from_user(buf, user_buffer, writesize)) { 437 retval = -EFAULT; 438 goto error; 439 } 440 441 /* this lock makes sure we don't submit URBs to gone devices */ 442 mutex_lock(&dev->io_mutex); 443 if (!dev->interface) { /* disconnect() was called */ 444 mutex_unlock(&dev->io_mutex); 445 retval = -ENODEV; 446 goto error; 447 } 448 449 /* initialize the urb properly */ 450 usb_fill_bulk_urb(urb, dev->udev, 451 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), 452 buf, writesize, skel_write_bulk_callback, dev); 453 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; 454 usb_anchor_urb(urb, &dev->submitted); 455 456 /* send the data out the bulk port */ 457 retval = usb_submit_urb(urb, GFP_KERNEL); 458 mutex_unlock(&dev->io_mutex); 459 if (retval) { 460 dev_err(&dev->interface->dev, 461 "%s - failed submitting write urb, error %d\n", 462 __func__, retval); 463 goto error_unanchor; 464 } 465 466 /* 467 * release our reference to this urb, the USB core will eventually free 468 * it entirely 469 */ 470 usb_free_urb(urb); 471 472 473 return writesize; 474 475 error_unanchor: 476 usb_unanchor_urb(urb); 477 error: 478 if (urb) { 479 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma); 480 usb_free_urb(urb); 481 } 482 up(&dev->limit_sem); 483 484 exit: 485 return retval; 486 } 487 488 static const struct file_operations skel_fops = { 489 .owner = THIS_MODULE, 490 .read = skel_read, 491 .write = skel_write, 492 .open = skel_open, 493 .release = skel_release, 494 .flush = skel_flush, 495 .llseek = noop_llseek, 496 }; 497 498 /* 499 * usb class driver info in order to get a minor number from the usb core, 500 * and to have the device registered with the driver core 501 */ 502 static struct usb_class_driver skel_class = { 503 .name = "skel%d", 504 .fops = &skel_fops, 505 .minor_base = USB_SKEL_MINOR_BASE, 506 }; 507 508 static int skel_probe(struct usb_interface *interface, 509 const struct usb_device_id *id) 510 { 511 struct usb_skel *dev; 512 struct usb_host_interface *iface_desc; 513 struct usb_endpoint_descriptor *endpoint; 514 size_t buffer_size; 515 int i; 516 int retval = -ENOMEM; 517 518 /* allocate memory for our device state and initialize it */ 519 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 520 if (!dev) { 521 dev_err(&interface->dev, "Out of memory\n"); 522 goto error; 523 } 524 kref_init(&dev->kref); 525 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); 526 mutex_init(&dev->io_mutex); 527 spin_lock_init(&dev->err_lock); 528 init_usb_anchor(&dev->submitted); 529 init_completion(&dev->bulk_in_completion); 530 531 dev->udev = usb_get_dev(interface_to_usbdev(interface)); 532 dev->interface = interface; 533 534 /* set up the endpoint information */ 535 /* use only the first bulk-in and bulk-out endpoints */ 536 iface_desc = interface->cur_altsetting; 537 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) { 538 endpoint = &iface_desc->endpoint[i].desc; 539 540 if (!dev->bulk_in_endpointAddr && 541 usb_endpoint_is_bulk_in(endpoint)) { 542 /* we found a bulk in endpoint */ 543 buffer_size = usb_endpoint_maxp(endpoint); 544 dev->bulk_in_size = buffer_size; 545 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress; 546 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL); 547 if (!dev->bulk_in_buffer) { 548 dev_err(&interface->dev, 549 "Could not allocate bulk_in_buffer\n"); 550 goto error; 551 } 552 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL); 553 if (!dev->bulk_in_urb) { 554 dev_err(&interface->dev, 555 "Could not allocate bulk_in_urb\n"); 556 goto error; 557 } 558 } 559 560 if (!dev->bulk_out_endpointAddr && 561 usb_endpoint_is_bulk_out(endpoint)) { 562 /* we found a bulk out endpoint */ 563 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress; 564 } 565 } 566 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) { 567 dev_err(&interface->dev, 568 "Could not find both bulk-in and bulk-out endpoints\n"); 569 goto error; 570 } 571 572 /* save our data pointer in this interface device */ 573 usb_set_intfdata(interface, dev); 574 575 /* we can register the device now, as it is ready */ 576 retval = usb_register_dev(interface, &skel_class); 577 if (retval) { 578 /* something prevented us from registering this driver */ 579 dev_err(&interface->dev, 580 "Not able to get a minor for this device.\n"); 581 usb_set_intfdata(interface, NULL); 582 goto error; 583 } 584 585 /* let the user know what node this device is now attached to */ 586 dev_info(&interface->dev, 587 "USB Skeleton device now attached to USBSkel-%d", 588 interface->minor); 589 return 0; 590 591 error: 592 if (dev) 593 /* this frees allocated memory */ 594 kref_put(&dev->kref, skel_delete); 595 return retval; 596 } 597 598 static void skel_disconnect(struct usb_interface *interface) 599 { 600 struct usb_skel *dev; 601 int minor = interface->minor; 602 603 dev = usb_get_intfdata(interface); 604 usb_set_intfdata(interface, NULL); 605 606 /* give back our minor */ 607 usb_deregister_dev(interface, &skel_class); 608 609 /* prevent more I/O from starting */ 610 mutex_lock(&dev->io_mutex); 611 dev->interface = NULL; 612 mutex_unlock(&dev->io_mutex); 613 614 usb_kill_anchored_urbs(&dev->submitted); 615 616 /* decrement our usage count */ 617 kref_put(&dev->kref, skel_delete); 618 619 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor); 620 } 621 622 static void skel_draw_down(struct usb_skel *dev) 623 { 624 int time; 625 626 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000); 627 if (!time) 628 usb_kill_anchored_urbs(&dev->submitted); 629 usb_kill_urb(dev->bulk_in_urb); 630 } 631 632 static int skel_suspend(struct usb_interface *intf, pm_message_t message) 633 { 634 struct usb_skel *dev = usb_get_intfdata(intf); 635 636 if (!dev) 637 return 0; 638 skel_draw_down(dev); 639 return 0; 640 } 641 642 static int skel_resume(struct usb_interface *intf) 643 { 644 return 0; 645 } 646 647 static int skel_pre_reset(struct usb_interface *intf) 648 { 649 struct usb_skel *dev = usb_get_intfdata(intf); 650 651 mutex_lock(&dev->io_mutex); 652 skel_draw_down(dev); 653 654 return 0; 655 } 656 657 static int skel_post_reset(struct usb_interface *intf) 658 { 659 struct usb_skel *dev = usb_get_intfdata(intf); 660 661 /* we are sure no URBs are active - no locking needed */ 662 dev->errors = -EPIPE; 663 mutex_unlock(&dev->io_mutex); 664 665 return 0; 666 } 667 668 static struct usb_driver skel_driver = { 669 .name = "skeleton", 670 .probe = skel_probe, 671 .disconnect = skel_disconnect, 672 .suspend = skel_suspend, 673 .resume = skel_resume, 674 .pre_reset = skel_pre_reset, 675 .post_reset = skel_post_reset, 676 .id_table = skel_table, 677 .supports_autosuspend = 1, 678 }; 679 680 module_usb_driver(skel_driver); 681 682 MODULE_LICENSE("GPL"); 683