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 */ 31static const struct usb_device_id skel_table[] = { 32 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) }, 33 { } /* Terminating entry */ 34}; 35MODULE_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 */ 50struct 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 int open_count; /* count the number of openers */ 64 bool ongoing_read; /* a read is going on */ 65 bool processed_urb; /* indicates we haven't processed the urb */ 66 spinlock_t err_lock; /* lock for errors */ 67 struct kref kref; 68 struct mutex io_mutex; /* synchronize I/O with disconnect */ 69 struct completion bulk_in_completion; /* to wait for an ongoing read */ 70}; 71#define to_skel_dev(d) container_of(d, struct usb_skel, kref) 72 73static struct usb_driver skel_driver; 74static void skel_draw_down(struct usb_skel *dev); 75 76static void skel_delete(struct kref *kref) 77{ 78 struct usb_skel *dev = to_skel_dev(kref); 79 80 usb_free_urb(dev->bulk_in_urb); 81 usb_put_dev(dev->udev); 82 kfree(dev->bulk_in_buffer); 83 kfree(dev); 84} 85 86static int skel_open(struct inode *inode, struct file *file) 87{ 88 struct usb_skel *dev; 89 struct usb_interface *interface; 90 int subminor; 91 int retval = 0; 92 93 subminor = iminor(inode); 94 95 interface = usb_find_interface(&skel_driver, subminor); 96 if (!interface) { 97 err("%s - error, can't find device for minor %d", 98 __func__, subminor); 99 retval = -ENODEV; 100 goto exit; 101 } 102 103 dev = usb_get_intfdata(interface); 104 if (!dev) { 105 retval = -ENODEV; 106 goto exit; 107 } 108 109 /* increment our usage count for the device */ 110 kref_get(&dev->kref); 111 112 /* lock the device to allow correctly handling errors 113 * in resumption */ 114 mutex_lock(&dev->io_mutex); 115 116 if (!dev->open_count++) { 117 retval = usb_autopm_get_interface(interface); 118 if (retval) { 119 dev->open_count--; 120 mutex_unlock(&dev->io_mutex); 121 kref_put(&dev->kref, skel_delete); 122 goto exit; 123 } 124 } /* else { //uncomment this block if you want exclusive open 125 retval = -EBUSY; 126 dev->open_count--; 127 mutex_unlock(&dev->io_mutex); 128 kref_put(&dev->kref, skel_delete); 129 goto exit; 130 } */ 131 /* prevent the device from being autosuspended */ 132 133 /* save our object in the file's private structure */ 134 file->private_data = dev; 135 mutex_unlock(&dev->io_mutex); 136 137exit: 138 return retval; 139} 140 141static int skel_release(struct inode *inode, struct file *file) 142{ 143 struct usb_skel *dev; 144 145 dev = file->private_data; 146 if (dev == NULL) 147 return -ENODEV; 148 149 /* allow the device to be autosuspended */ 150 mutex_lock(&dev->io_mutex); 151 if (!--dev->open_count && dev->interface) 152 usb_autopm_put_interface(dev->interface); 153 mutex_unlock(&dev->io_mutex); 154 155 /* decrement the count on our device */ 156 kref_put(&dev->kref, skel_delete); 157 return 0; 158} 159 160static int skel_flush(struct file *file, fl_owner_t id) 161{ 162 struct usb_skel *dev; 163 int res; 164 165 dev = file->private_data; 166 if (dev == NULL) 167 return -ENODEV; 168 169 /* wait for io to stop */ 170 mutex_lock(&dev->io_mutex); 171 skel_draw_down(dev); 172 173 /* read out errors, leave subsequent opens a clean slate */ 174 spin_lock_irq(&dev->err_lock); 175 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0; 176 dev->errors = 0; 177 spin_unlock_irq(&dev->err_lock); 178 179 mutex_unlock(&dev->io_mutex); 180 181 return res; 182} 183 184static void skel_read_bulk_callback(struct urb *urb) 185{ 186 struct usb_skel *dev; 187 188 dev = urb->context; 189 190 spin_lock(&dev->err_lock); 191 /* sync/async unlink faults aren't errors */ 192 if (urb->status) { 193 if (!(urb->status == -ENOENT || 194 urb->status == -ECONNRESET || 195 urb->status == -ESHUTDOWN)) 196 err("%s - nonzero write bulk status received: %d", 197 __func__, urb->status); 198 199 dev->errors = urb->status; 200 } else { 201 dev->bulk_in_filled = urb->actual_length; 202 } 203 dev->ongoing_read = 0; 204 spin_unlock(&dev->err_lock); 205 206 complete(&dev->bulk_in_completion); 207} 208 209static int skel_do_read_io(struct usb_skel *dev, size_t count) 210{ 211 int rv; 212 213 /* prepare a read */ 214 usb_fill_bulk_urb(dev->bulk_in_urb, 215 dev->udev, 216 usb_rcvbulkpipe(dev->udev, 217 dev->bulk_in_endpointAddr), 218 dev->bulk_in_buffer, 219 min(dev->bulk_in_size, count), 220 skel_read_bulk_callback, 221 dev); 222 /* tell everybody to leave the URB alone */ 223 spin_lock_irq(&dev->err_lock); 224 dev->ongoing_read = 1; 225 spin_unlock_irq(&dev->err_lock); 226 227 /* do it */ 228 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL); 229 if (rv < 0) { 230 err("%s - failed submitting read urb, error %d", 231 __func__, rv); 232 dev->bulk_in_filled = 0; 233 rv = (rv == -ENOMEM) ? rv : -EIO; 234 spin_lock_irq(&dev->err_lock); 235 dev->ongoing_read = 0; 236 spin_unlock_irq(&dev->err_lock); 237 } 238 239 return rv; 240} 241 242static ssize_t skel_read(struct file *file, char *buffer, size_t count, 243 loff_t *ppos) 244{ 245 struct usb_skel *dev; 246 int rv; 247 bool ongoing_io; 248 249 dev = file->private_data; 250 251 /* if we cannot read at all, return EOF */ 252 if (!dev->bulk_in_urb || !count) 253 return 0; 254 255 /* no concurrent readers */ 256 rv = mutex_lock_interruptible(&dev->io_mutex); 257 if (rv < 0) 258 return rv; 259 260 if (!dev->interface) { /* disconnect() was called */ 261 rv = -ENODEV; 262 goto exit; 263 } 264 265 /* if IO is under way, we must not touch things */ 266retry: 267 spin_lock_irq(&dev->err_lock); 268 ongoing_io = dev->ongoing_read; 269 spin_unlock_irq(&dev->err_lock); 270 271 if (ongoing_io) { 272 /* nonblocking IO shall not wait */ 273 if (file->f_flags & O_NONBLOCK) { 274 rv = -EAGAIN; 275 goto exit; 276 } 277 /* 278 * IO may take forever 279 * hence wait in an interruptible state 280 */ 281 rv = wait_for_completion_interruptible(&dev->bulk_in_completion); 282 if (rv < 0) 283 goto exit; 284 /* 285 * by waiting we also semiprocessed the urb 286 * we must finish now 287 */ 288 dev->bulk_in_copied = 0; 289 dev->processed_urb = 1; 290 } 291 292 if (!dev->processed_urb) { 293 /* 294 * the URB hasn't been processed 295 * do it now 296 */ 297 wait_for_completion(&dev->bulk_in_completion); 298 dev->bulk_in_copied = 0; 299 dev->processed_urb = 1; 300 } 301 302 /* errors must be reported */ 303 rv = dev->errors; 304 if (rv < 0) { 305 /* any error is reported once */ 306 dev->errors = 0; 307 /* to preserve notifications about reset */ 308 rv = (rv == -EPIPE) ? rv : -EIO; 309 /* no data to deliver */ 310 dev->bulk_in_filled = 0; 311 /* report it */ 312 goto exit; 313 } 314 315 /* 316 * if the buffer is filled we may satisfy the read 317 * else we need to start IO 318 */ 319 320 if (dev->bulk_in_filled) { 321 /* we had read data */ 322 size_t available = dev->bulk_in_filled - dev->bulk_in_copied; 323 size_t chunk = min(available, count); 324 325 if (!available) { 326 /* 327 * all data has been used 328 * actual IO needs to be done 329 */ 330 rv = skel_do_read_io(dev, count); 331 if (rv < 0) 332 goto exit; 333 else 334 goto retry; 335 } 336 /* 337 * data is available 338 * chunk tells us how much shall be copied 339 */ 340 341 if (copy_to_user(buffer, 342 dev->bulk_in_buffer + dev->bulk_in_copied, 343 chunk)) 344 rv = -EFAULT; 345 else 346 rv = chunk; 347 348 dev->bulk_in_copied += chunk; 349 350 /* 351 * if we are asked for more than we have, 352 * we start IO but don't wait 353 */ 354 if (available < count) 355 skel_do_read_io(dev, count - chunk); 356 } else { 357 /* no data in the buffer */ 358 rv = skel_do_read_io(dev, count); 359 if (rv < 0) 360 goto exit; 361 else if (!(file->f_flags & O_NONBLOCK)) 362 goto retry; 363 rv = -EAGAIN; 364 } 365exit: 366 mutex_unlock(&dev->io_mutex); 367 return rv; 368} 369 370static void skel_write_bulk_callback(struct urb *urb) 371{ 372 struct usb_skel *dev; 373 374 dev = urb->context; 375 376 /* sync/async unlink faults aren't errors */ 377 if (urb->status) { 378 if (!(urb->status == -ENOENT || 379 urb->status == -ECONNRESET || 380 urb->status == -ESHUTDOWN)) 381 err("%s - nonzero write bulk status received: %d", 382 __func__, urb->status); 383 384 spin_lock(&dev->err_lock); 385 dev->errors = urb->status; 386 spin_unlock(&dev->err_lock); 387 } 388 389 /* free up our allocated buffer */ 390 usb_free_coherent(urb->dev, urb->transfer_buffer_length, 391 urb->transfer_buffer, urb->transfer_dma); 392 up(&dev->limit_sem); 393} 394 395static ssize_t skel_write(struct file *file, const char *user_buffer, 396 size_t count, loff_t *ppos) 397{ 398 struct usb_skel *dev; 399 int retval = 0; 400 struct urb *urb = NULL; 401 char *buf = NULL; 402 size_t writesize = min(count, (size_t)MAX_TRANSFER); 403 404 dev = file->private_data; 405 406 /* verify that we actually have some data to write */ 407 if (count == 0) 408 goto exit; 409 410 /* 411 * limit the number of URBs in flight to stop a user from using up all 412 * RAM 413 */ 414 if (!(file->f_flags & O_NONBLOCK)) { 415 if (down_interruptible(&dev->limit_sem)) { 416 retval = -ERESTARTSYS; 417 goto exit; 418 } 419 } else { 420 if (down_trylock(&dev->limit_sem)) { 421 retval = -EAGAIN; 422 goto exit; 423 } 424 } 425 426 spin_lock_irq(&dev->err_lock); 427 retval = dev->errors; 428 if (retval < 0) { 429 /* any error is reported once */ 430 dev->errors = 0; 431 /* to preserve notifications about reset */ 432 retval = (retval == -EPIPE) ? retval : -EIO; 433 } 434 spin_unlock_irq(&dev->err_lock); 435 if (retval < 0) 436 goto error; 437 438 /* create a urb, and a buffer for it, and copy the data to the urb */ 439 urb = usb_alloc_urb(0, GFP_KERNEL); 440 if (!urb) { 441 retval = -ENOMEM; 442 goto error; 443 } 444 445 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL, 446 &urb->transfer_dma); 447 if (!buf) { 448 retval = -ENOMEM; 449 goto error; 450 } 451 452 if (copy_from_user(buf, user_buffer, writesize)) { 453 retval = -EFAULT; 454 goto error; 455 } 456 457 /* this lock makes sure we don't submit URBs to gone devices */ 458 mutex_lock(&dev->io_mutex); 459 if (!dev->interface) { /* disconnect() was called */ 460 mutex_unlock(&dev->io_mutex); 461 retval = -ENODEV; 462 goto error; 463 } 464 465 /* initialize the urb properly */ 466 usb_fill_bulk_urb(urb, dev->udev, 467 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), 468 buf, writesize, skel_write_bulk_callback, dev); 469 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; 470 usb_anchor_urb(urb, &dev->submitted); 471 472 /* send the data out the bulk port */ 473 retval = usb_submit_urb(urb, GFP_KERNEL); 474 mutex_unlock(&dev->io_mutex); 475 if (retval) { 476 err("%s - failed submitting write urb, error %d", __func__, 477 retval); 478 goto error_unanchor; 479 } 480 481 /* 482 * release our reference to this urb, the USB core will eventually free 483 * it entirely 484 */ 485 usb_free_urb(urb); 486 487 488 return writesize; 489 490error_unanchor: 491 usb_unanchor_urb(urb); 492error: 493 if (urb) { 494 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma); 495 usb_free_urb(urb); 496 } 497 up(&dev->limit_sem); 498 499exit: 500 return retval; 501} 502 503static const struct file_operations skel_fops = { 504 .owner = THIS_MODULE, 505 .read = skel_read, 506 .write = skel_write, 507 .open = skel_open, 508 .release = skel_release, 509 .flush = skel_flush, 510}; 511 512/* 513 * usb class driver info in order to get a minor number from the usb core, 514 * and to have the device registered with the driver core 515 */ 516static struct usb_class_driver skel_class = { 517 .name = "skel%d", 518 .fops = &skel_fops, 519 .minor_base = USB_SKEL_MINOR_BASE, 520}; 521 522static int skel_probe(struct usb_interface *interface, 523 const struct usb_device_id *id) 524{ 525 struct usb_skel *dev; 526 struct usb_host_interface *iface_desc; 527 struct usb_endpoint_descriptor *endpoint; 528 size_t buffer_size; 529 int i; 530 int retval = -ENOMEM; 531 532 /* allocate memory for our device state and initialize it */ 533 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 534 if (!dev) { 535 err("Out of memory"); 536 goto error; 537 } 538 kref_init(&dev->kref); 539 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); 540 mutex_init(&dev->io_mutex); 541 spin_lock_init(&dev->err_lock); 542 init_usb_anchor(&dev->submitted); 543 init_completion(&dev->bulk_in_completion); 544 545 dev->udev = usb_get_dev(interface_to_usbdev(interface)); 546 dev->interface = interface; 547 548 /* set up the endpoint information */ 549 /* use only the first bulk-in and bulk-out endpoints */ 550 iface_desc = interface->cur_altsetting; 551 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) { 552 endpoint = &iface_desc->endpoint[i].desc; 553 554 if (!dev->bulk_in_endpointAddr && 555 usb_endpoint_is_bulk_in(endpoint)) { 556 /* we found a bulk in endpoint */ 557 buffer_size = le16_to_cpu(endpoint->wMaxPacketSize); 558 dev->bulk_in_size = buffer_size; 559 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress; 560 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL); 561 if (!dev->bulk_in_buffer) { 562 err("Could not allocate bulk_in_buffer"); 563 goto error; 564 } 565 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL); 566 if (!dev->bulk_in_urb) { 567 err("Could not allocate bulk_in_urb"); 568 goto error; 569 } 570 } 571 572 if (!dev->bulk_out_endpointAddr && 573 usb_endpoint_is_bulk_out(endpoint)) { 574 /* we found a bulk out endpoint */ 575 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress; 576 } 577 } 578 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) { 579 err("Could not find both bulk-in and bulk-out endpoints"); 580 goto error; 581 } 582 583 /* save our data pointer in this interface device */ 584 usb_set_intfdata(interface, dev); 585 586 /* we can register the device now, as it is ready */ 587 retval = usb_register_dev(interface, &skel_class); 588 if (retval) { 589 /* something prevented us from registering this driver */ 590 err("Not able to get a minor for this device."); 591 usb_set_intfdata(interface, NULL); 592 goto error; 593 } 594 595 /* let the user know what node this device is now attached to */ 596 dev_info(&interface->dev, 597 "USB Skeleton device now attached to USBSkel-%d", 598 interface->minor); 599 return 0; 600 601error: 602 if (dev) 603 /* this frees allocated memory */ 604 kref_put(&dev->kref, skel_delete); 605 return retval; 606} 607 608static void skel_disconnect(struct usb_interface *interface) 609{ 610 struct usb_skel *dev; 611 int minor = interface->minor; 612 613 dev = usb_get_intfdata(interface); 614 usb_set_intfdata(interface, NULL); 615 616 /* give back our minor */ 617 usb_deregister_dev(interface, &skel_class); 618 619 /* prevent more I/O from starting */ 620 mutex_lock(&dev->io_mutex); 621 dev->interface = NULL; 622 mutex_unlock(&dev->io_mutex); 623 624 usb_kill_anchored_urbs(&dev->submitted); 625 626 /* decrement our usage count */ 627 kref_put(&dev->kref, skel_delete); 628 629 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor); 630} 631 632static void skel_draw_down(struct usb_skel *dev) 633{ 634 int time; 635 636 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000); 637 if (!time) 638 usb_kill_anchored_urbs(&dev->submitted); 639 usb_kill_urb(dev->bulk_in_urb); 640} 641 642static int skel_suspend(struct usb_interface *intf, pm_message_t message) 643{ 644 struct usb_skel *dev = usb_get_intfdata(intf); 645 646 if (!dev) 647 return 0; 648 skel_draw_down(dev); 649 return 0; 650} 651 652static int skel_resume(struct usb_interface *intf) 653{ 654 return 0; 655} 656 657static int skel_pre_reset(struct usb_interface *intf) 658{ 659 struct usb_skel *dev = usb_get_intfdata(intf); 660 661 mutex_lock(&dev->io_mutex); 662 skel_draw_down(dev); 663 664 return 0; 665} 666 667static int skel_post_reset(struct usb_interface *intf) 668{ 669 struct usb_skel *dev = usb_get_intfdata(intf); 670 671 /* we are sure no URBs are active - no locking needed */ 672 dev->errors = -EPIPE; 673 mutex_unlock(&dev->io_mutex); 674 675 return 0; 676} 677 678static struct usb_driver skel_driver = { 679 .name = "skeleton", 680 .probe = skel_probe, 681 .disconnect = skel_disconnect, 682 .suspend = skel_suspend, 683 .resume = skel_resume, 684 .pre_reset = skel_pre_reset, 685 .post_reset = skel_post_reset, 686 .id_table = skel_table, 687 .supports_autosuspend = 1, 688}; 689 690static int __init usb_skel_init(void) 691{ 692 int result; 693 694 /* register this driver with the USB subsystem */ 695 result = usb_register(&skel_driver); 696 if (result) 697 err("usb_register failed. Error number %d", result); 698 699 return result; 700} 701 702static void __exit usb_skel_exit(void) 703{ 704 /* deregister this driver with the USB subsystem */ 705 usb_deregister(&skel_driver); 706} 707 708module_init(usb_skel_init); 709module_exit(usb_skel_exit); 710 711MODULE_LICENSE("GPL"); 712