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 329 goto retry; 330 } 331 exit: 332 mutex_unlock(&dev->io_mutex); 333 return rv; 334 } 335 336 static void skel_write_bulk_callback(struct urb *urb) 337 { 338 struct usb_skel *dev; 339 340 dev = urb->context; 341 342 /* sync/async unlink faults aren't errors */ 343 if (urb->status) { 344 if (!(urb->status == -ENOENT || 345 urb->status == -ECONNRESET || 346 urb->status == -ESHUTDOWN)) 347 dev_err(&dev->interface->dev, 348 "%s - nonzero write bulk status received: %d\n", 349 __func__, urb->status); 350 351 spin_lock(&dev->err_lock); 352 dev->errors = urb->status; 353 spin_unlock(&dev->err_lock); 354 } 355 356 /* free up our allocated buffer */ 357 usb_free_coherent(urb->dev, urb->transfer_buffer_length, 358 urb->transfer_buffer, urb->transfer_dma); 359 up(&dev->limit_sem); 360 } 361 362 static ssize_t skel_write(struct file *file, const char *user_buffer, 363 size_t count, loff_t *ppos) 364 { 365 struct usb_skel *dev; 366 int retval = 0; 367 struct urb *urb = NULL; 368 char *buf = NULL; 369 size_t writesize = min(count, (size_t)MAX_TRANSFER); 370 371 dev = file->private_data; 372 373 /* verify that we actually have some data to write */ 374 if (count == 0) 375 goto exit; 376 377 /* 378 * limit the number of URBs in flight to stop a user from using up all 379 * RAM 380 */ 381 if (!(file->f_flags & O_NONBLOCK)) { 382 if (down_interruptible(&dev->limit_sem)) { 383 retval = -ERESTARTSYS; 384 goto exit; 385 } 386 } else { 387 if (down_trylock(&dev->limit_sem)) { 388 retval = -EAGAIN; 389 goto exit; 390 } 391 } 392 393 spin_lock_irq(&dev->err_lock); 394 retval = dev->errors; 395 if (retval < 0) { 396 /* any error is reported once */ 397 dev->errors = 0; 398 /* to preserve notifications about reset */ 399 retval = (retval == -EPIPE) ? retval : -EIO; 400 } 401 spin_unlock_irq(&dev->err_lock); 402 if (retval < 0) 403 goto error; 404 405 /* create a urb, and a buffer for it, and copy the data to the urb */ 406 urb = usb_alloc_urb(0, GFP_KERNEL); 407 if (!urb) { 408 retval = -ENOMEM; 409 goto error; 410 } 411 412 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL, 413 &urb->transfer_dma); 414 if (!buf) { 415 retval = -ENOMEM; 416 goto error; 417 } 418 419 if (copy_from_user(buf, user_buffer, writesize)) { 420 retval = -EFAULT; 421 goto error; 422 } 423 424 /* this lock makes sure we don't submit URBs to gone devices */ 425 mutex_lock(&dev->io_mutex); 426 if (!dev->interface) { /* disconnect() was called */ 427 mutex_unlock(&dev->io_mutex); 428 retval = -ENODEV; 429 goto error; 430 } 431 432 /* initialize the urb properly */ 433 usb_fill_bulk_urb(urb, dev->udev, 434 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), 435 buf, writesize, skel_write_bulk_callback, dev); 436 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; 437 usb_anchor_urb(urb, &dev->submitted); 438 439 /* send the data out the bulk port */ 440 retval = usb_submit_urb(urb, GFP_KERNEL); 441 mutex_unlock(&dev->io_mutex); 442 if (retval) { 443 dev_err(&dev->interface->dev, 444 "%s - failed submitting write urb, error %d\n", 445 __func__, retval); 446 goto error_unanchor; 447 } 448 449 /* 450 * release our reference to this urb, the USB core will eventually free 451 * it entirely 452 */ 453 usb_free_urb(urb); 454 455 456 return writesize; 457 458 error_unanchor: 459 usb_unanchor_urb(urb); 460 error: 461 if (urb) { 462 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma); 463 usb_free_urb(urb); 464 } 465 up(&dev->limit_sem); 466 467 exit: 468 return retval; 469 } 470 471 static const struct file_operations skel_fops = { 472 .owner = THIS_MODULE, 473 .read = skel_read, 474 .write = skel_write, 475 .open = skel_open, 476 .release = skel_release, 477 .flush = skel_flush, 478 .llseek = noop_llseek, 479 }; 480 481 /* 482 * usb class driver info in order to get a minor number from the usb core, 483 * and to have the device registered with the driver core 484 */ 485 static struct usb_class_driver skel_class = { 486 .name = "skel%d", 487 .fops = &skel_fops, 488 .minor_base = USB_SKEL_MINOR_BASE, 489 }; 490 491 static int skel_probe(struct usb_interface *interface, 492 const struct usb_device_id *id) 493 { 494 struct usb_skel *dev; 495 struct usb_host_interface *iface_desc; 496 struct usb_endpoint_descriptor *endpoint; 497 size_t buffer_size; 498 int i; 499 int retval = -ENOMEM; 500 501 /* allocate memory for our device state and initialize it */ 502 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 503 if (!dev) { 504 dev_err(&interface->dev, "Out of memory\n"); 505 goto error; 506 } 507 kref_init(&dev->kref); 508 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); 509 mutex_init(&dev->io_mutex); 510 spin_lock_init(&dev->err_lock); 511 init_usb_anchor(&dev->submitted); 512 init_waitqueue_head(&dev->bulk_in_wait); 513 514 dev->udev = usb_get_dev(interface_to_usbdev(interface)); 515 dev->interface = interface; 516 517 /* set up the endpoint information */ 518 /* use only the first bulk-in and bulk-out endpoints */ 519 iface_desc = interface->cur_altsetting; 520 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) { 521 endpoint = &iface_desc->endpoint[i].desc; 522 523 if (!dev->bulk_in_endpointAddr && 524 usb_endpoint_is_bulk_in(endpoint)) { 525 /* we found a bulk in endpoint */ 526 buffer_size = usb_endpoint_maxp(endpoint); 527 dev->bulk_in_size = buffer_size; 528 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress; 529 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL); 530 if (!dev->bulk_in_buffer) { 531 dev_err(&interface->dev, 532 "Could not allocate bulk_in_buffer\n"); 533 goto error; 534 } 535 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL); 536 if (!dev->bulk_in_urb) { 537 dev_err(&interface->dev, 538 "Could not allocate bulk_in_urb\n"); 539 goto error; 540 } 541 } 542 543 if (!dev->bulk_out_endpointAddr && 544 usb_endpoint_is_bulk_out(endpoint)) { 545 /* we found a bulk out endpoint */ 546 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress; 547 } 548 } 549 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) { 550 dev_err(&interface->dev, 551 "Could not find both bulk-in and bulk-out endpoints\n"); 552 goto error; 553 } 554 555 /* save our data pointer in this interface device */ 556 usb_set_intfdata(interface, dev); 557 558 /* we can register the device now, as it is ready */ 559 retval = usb_register_dev(interface, &skel_class); 560 if (retval) { 561 /* something prevented us from registering this driver */ 562 dev_err(&interface->dev, 563 "Not able to get a minor for this device.\n"); 564 usb_set_intfdata(interface, NULL); 565 goto error; 566 } 567 568 /* let the user know what node this device is now attached to */ 569 dev_info(&interface->dev, 570 "USB Skeleton device now attached to USBSkel-%d", 571 interface->minor); 572 return 0; 573 574 error: 575 if (dev) 576 /* this frees allocated memory */ 577 kref_put(&dev->kref, skel_delete); 578 return retval; 579 } 580 581 static void skel_disconnect(struct usb_interface *interface) 582 { 583 struct usb_skel *dev; 584 int minor = interface->minor; 585 586 dev = usb_get_intfdata(interface); 587 usb_set_intfdata(interface, NULL); 588 589 /* give back our minor */ 590 usb_deregister_dev(interface, &skel_class); 591 592 /* prevent more I/O from starting */ 593 mutex_lock(&dev->io_mutex); 594 dev->interface = NULL; 595 mutex_unlock(&dev->io_mutex); 596 597 usb_kill_anchored_urbs(&dev->submitted); 598 599 /* decrement our usage count */ 600 kref_put(&dev->kref, skel_delete); 601 602 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor); 603 } 604 605 static void skel_draw_down(struct usb_skel *dev) 606 { 607 int time; 608 609 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000); 610 if (!time) 611 usb_kill_anchored_urbs(&dev->submitted); 612 usb_kill_urb(dev->bulk_in_urb); 613 } 614 615 static int skel_suspend(struct usb_interface *intf, pm_message_t message) 616 { 617 struct usb_skel *dev = usb_get_intfdata(intf); 618 619 if (!dev) 620 return 0; 621 skel_draw_down(dev); 622 return 0; 623 } 624 625 static int skel_resume(struct usb_interface *intf) 626 { 627 return 0; 628 } 629 630 static int skel_pre_reset(struct usb_interface *intf) 631 { 632 struct usb_skel *dev = usb_get_intfdata(intf); 633 634 mutex_lock(&dev->io_mutex); 635 skel_draw_down(dev); 636 637 return 0; 638 } 639 640 static int skel_post_reset(struct usb_interface *intf) 641 { 642 struct usb_skel *dev = usb_get_intfdata(intf); 643 644 /* we are sure no URBs are active - no locking needed */ 645 dev->errors = -EPIPE; 646 mutex_unlock(&dev->io_mutex); 647 648 return 0; 649 } 650 651 static struct usb_driver skel_driver = { 652 .name = "skeleton", 653 .probe = skel_probe, 654 .disconnect = skel_disconnect, 655 .suspend = skel_suspend, 656 .resume = skel_resume, 657 .pre_reset = skel_pre_reset, 658 .post_reset = skel_post_reset, 659 .id_table = skel_table, 660 .supports_autosuspend = 1, 661 }; 662 663 module_usb_driver(skel_driver); 664 665 MODULE_LICENSE("GPL"); 666