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