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