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 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");