drivers/usb/usb-skeleton.c

   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");