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                 pr_err("%s - error, can't find device for minor %d\n",
  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         retval = usb_autopm_get_interface(interface);
 109         if (retval)
 110                 goto exit;
 111
 112         /* increment our usage count for the device */
 113         kref_get(&dev->kref);
 114
 115         /* save our object in the file's private structure */
 116         file->private_data = dev;
 117
 118 exit:
 119         return retval;
 120 }
 121
 122 static int skel_release(struct inode *inode, struct file *file)
 123 {
 124         struct usb_skel *dev;
 125
 126         dev = file->private_data;
 127         if (dev == NULL)
 128                 return -ENODEV;
 129
 130         /* allow the device to be autosuspended */
 131         mutex_lock(&dev->io_mutex);
 132         if (dev->interface)
 133                 usb_autopm_put_interface(dev->interface);
 134         mutex_unlock(&dev->io_mutex);
 135
 136         /* decrement the count on our device */
 137         kref_put(&dev->kref, skel_delete);
 138         return 0;
 139 }
 140
 141 static int skel_flush(struct file *file, fl_owner_t id)
 142 {
 143         struct usb_skel *dev;
 144         int res;
 145
 146         dev = file->private_data;
 147         if (dev == NULL)
 148                 return -ENODEV;
 149
 150         /* wait for io to stop */
 151         mutex_lock(&dev->io_mutex);
 152         skel_draw_down(dev);
 153
 154         /* read out errors, leave subsequent opens a clean slate */
 155         spin_lock_irq(&dev->err_lock);
 156         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
 157         dev->errors = 0;
 158         spin_unlock_irq(&dev->err_lock);
 159
 160         mutex_unlock(&dev->io_mutex);
 161
 162         return res;
 163 }
 164
 165 static void skel_read_bulk_callback(struct urb *urb)
 166 {
 167         struct usb_skel *dev;
 168
 169         dev = urb->context;
 170
 171         spin_lock(&dev->err_lock);
 172         /* sync/async unlink faults aren't errors */
 173         if (urb->status) {
 174                 if (!(urb->status == -ENOENT ||
 175                     urb->status == -ECONNRESET ||
 176                     urb->status == -ESHUTDOWN))
 177                         dev_err(&dev->interface->dev,
 178                                 "%s - nonzero write bulk status received: %d\n",
 179                                 __func__, urb->status);
 180
 181                 dev->errors = urb->status;
 182         } else {
 183                 dev->bulk_in_filled = urb->actual_length;
 184         }
 185         dev->ongoing_read = 0;
 186         spin_unlock(&dev->err_lock);
 187
 188         complete(&dev->bulk_in_completion);
 189 }
 190
 191 static int skel_do_read_io(struct usb_skel *dev, size_t count)
 192 {
 193         int rv;
 194
 195         /* prepare a read */
 196         usb_fill_bulk_urb(dev->bulk_in_urb,
 197                         dev->udev,
 198                         usb_rcvbulkpipe(dev->udev,
 199                                 dev->bulk_in_endpointAddr),
 200                         dev->bulk_in_buffer,
 201                         min(dev->bulk_in_size, count),
 202                         skel_read_bulk_callback,
 203                         dev);
 204         /* tell everybody to leave the URB alone */
 205         spin_lock_irq(&dev->err_lock);
 206         dev->ongoing_read = 1;
 207         spin_unlock_irq(&dev->err_lock);
 208
 209         /* do it */
 210         rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
 211         if (rv < 0) {
 212                 dev_err(&dev->interface->dev,
 213                         "%s - failed submitting read urb, error %d\n",
 214                         __func__, rv);
 215                 dev->bulk_in_filled = 0;
 216                 rv = (rv == -ENOMEM) ? rv : -EIO;
 217                 spin_lock_irq(&dev->err_lock);
 218                 dev->ongoing_read = 0;
 219                 spin_unlock_irq(&dev->err_lock);
 220         }
 221
 222         return rv;
 223 }
 224
 225 static ssize_t skel_read(struct file *file, char *buffer, size_t count,
 226                          loff_t *ppos)
 227 {
 228         struct usb_skel *dev;
 229         int rv;
 230         bool ongoing_io;
 231
 232         dev = file->private_data;
 233
 234         /* if we cannot read at all, return EOF */
 235         if (!dev->bulk_in_urb || !count)
 236                 return 0;
 237
 238         /* no concurrent readers */
 239         rv = mutex_lock_interruptible(&dev->io_mutex);
 240         if (rv < 0)
 241                 return rv;
 242
 243         if (!dev->interface) {          /* disconnect() was called */
 244                 rv = -ENODEV;
 245                 goto exit;
 246         }
 247
 248         /* if IO is under way, we must not touch things */
 249 retry:
 250         spin_lock_irq(&dev->err_lock);
 251         ongoing_io = dev->ongoing_read;
 252         spin_unlock_irq(&dev->err_lock);
 253
 254         if (ongoing_io) {
 255                 /* nonblocking IO shall not wait */
 256                 if (file->f_flags & O_NONBLOCK) {
 257                         rv = -EAGAIN;
 258                         goto exit;
 259                 }
 260                 /*
 261                  * IO may take forever
 262                  * hence wait in an interruptible state
 263                  */
 264                 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
 265                 if (rv < 0)
 266                         goto exit;
 267                 /*
 268                  * by waiting we also semiprocessed the urb
 269                  * we must finish now
 270                  */
 271                 dev->bulk_in_copied = 0;
 272                 dev->processed_urb = 1;
 273         }
 274
 275         if (!dev->processed_urb) {
 276                 /*
 277                  * the URB hasn't been processed
 278                  * do it now
 279                  */
 280                 wait_for_completion(&dev->bulk_in_completion);
 281                 dev->bulk_in_copied = 0;
 282                 dev->processed_urb = 1;
 283         }
 284
 285         /* errors must be reported */
 286         rv = dev->errors;
 287         if (rv < 0) {
 288                 /* any error is reported once */
 289                 dev->errors = 0;
 290                 /* to preserve notifications about reset */
 291                 rv = (rv == -EPIPE) ? rv : -EIO;
 292                 /* no data to deliver */
 293                 dev->bulk_in_filled = 0;
 294                 /* report it */
 295                 goto exit;
 296         }
 297
 298         /*
 299          * if the buffer is filled we may satisfy the read
 300          * else we need to start IO
 301          */
 302
 303         if (dev->bulk_in_filled) {
 304                 /* we had read data */
 305                 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
 306                 size_t chunk = min(available, count);
 307
 308                 if (!available) {
 309                         /*
 310                          * all data has been used
 311                          * actual IO needs to be done
 312                          */
 313                         rv = skel_do_read_io(dev, count);
 314                         if (rv < 0)
 315                                 goto exit;
 316                         else
 317                                 goto retry;
 318                 }
 319                 /*
 320                  * data is available
 321                  * chunk tells us how much shall be copied
 322                  */
 323
 324                 if (copy_to_user(buffer,
 325                                  dev->bulk_in_buffer + dev->bulk_in_copied,
 326                                  chunk))
 327                         rv = -EFAULT;
 328                 else
 329                         rv = chunk;
 330
 331                 dev->bulk_in_copied += chunk;
 332
 333                 /*
 334                  * if we are asked for more than we have,
 335                  * we start IO but don't wait
 336                  */
 337                 if (available < count)
 338                         skel_do_read_io(dev, count - chunk);
 339         } else {
 340                 /* no data in the buffer */
 341                 rv = skel_do_read_io(dev, count);
 342                 if (rv < 0)
 343                         goto exit;
 344                 else if (!(file->f_flags & O_NONBLOCK))
 345                         goto retry;
 346                 rv = -EAGAIN;
 347         }
 348 exit:
 349         mutex_unlock(&dev->io_mutex);
 350         return rv;
 351 }
 352
 353 static void skel_write_bulk_callback(struct urb *urb)
 354 {
 355         struct usb_skel *dev;
 356
 357         dev = urb->context;
 358
 359         /* sync/async unlink faults aren't errors */
 360         if (urb->status) {
 361                 if (!(urb->status == -ENOENT ||
 362                     urb->status == -ECONNRESET ||
 363                     urb->status == -ESHUTDOWN))
 364                         dev_err(&dev->interface->dev,
 365                                 "%s - nonzero write bulk status received: %d\n",
 366                                 __func__, urb->status);
 367
 368                 spin_lock(&dev->err_lock);
 369                 dev->errors = urb->status;
 370                 spin_unlock(&dev->err_lock);
 371         }
 372
 373         /* free up our allocated buffer */
 374         usb_free_coherent(urb->dev, urb->transfer_buffer_length,
 375                           urb->transfer_buffer, urb->transfer_dma);
 376         up(&dev->limit_sem);
 377 }
 378
 379 static ssize_t skel_write(struct file *file, const char *user_buffer,
 380                           size_t count, loff_t *ppos)
 381 {
 382         struct usb_skel *dev;
 383         int retval = 0;
 384         struct urb *urb = NULL;
 385         char *buf = NULL;
 386         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 387
 388         dev = file->private_data;
 389
 390         /* verify that we actually have some data to write */
 391         if (count == 0)
 392                 goto exit;
 393
 394         /*
 395          * limit the number of URBs in flight to stop a user from using up all
 396          * RAM
 397          */
 398         if (!(file->f_flags & O_NONBLOCK)) {
 399                 if (down_interruptible(&dev->limit_sem)) {
 400                         retval = -ERESTARTSYS;
 401                         goto exit;
 402                 }
 403         } else {
 404                 if (down_trylock(&dev->limit_sem)) {
 405                         retval = -EAGAIN;
 406                         goto exit;
 407                 }
 408         }
 409
 410         spin_lock_irq(&dev->err_lock);
 411         retval = dev->errors;
 412         if (retval < 0) {
 413                 /* any error is reported once */
 414                 dev->errors = 0;
 415                 /* to preserve notifications about reset */
 416                 retval = (retval == -EPIPE) ? retval : -EIO;
 417         }
 418         spin_unlock_irq(&dev->err_lock);
 419         if (retval < 0)
 420                 goto error;
 421
 422         /* create a urb, and a buffer for it, and copy the data to the urb */
 423         urb = usb_alloc_urb(0, GFP_KERNEL);
 424         if (!urb) {
 425                 retval = -ENOMEM;
 426                 goto error;
 427         }
 428
 429         buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
 430                                  &urb->transfer_dma);
 431         if (!buf) {
 432                 retval = -ENOMEM;
 433                 goto error;
 434         }
 435
 436         if (copy_from_user(buf, user_buffer, writesize)) {
 437                 retval = -EFAULT;
 438                 goto error;
 439         }
 440
 441         /* this lock makes sure we don't submit URBs to gone devices */
 442         mutex_lock(&dev->io_mutex);
 443         if (!dev->interface) {          /* disconnect() was called */
 444                 mutex_unlock(&dev->io_mutex);
 445                 retval = -ENODEV;
 446                 goto error;
 447         }
 448
 449         /* initialize the urb properly */
 450         usb_fill_bulk_urb(urb, dev->udev,
 451                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 452                           buf, writesize, skel_write_bulk_callback, dev);
 453         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 454         usb_anchor_urb(urb, &dev->submitted);
 455
 456         /* send the data out the bulk port */
 457         retval = usb_submit_urb(urb, GFP_KERNEL);
 458         mutex_unlock(&dev->io_mutex);
 459         if (retval) {
 460                 dev_err(&dev->interface->dev,
 461                         "%s - failed submitting write urb, error %d\n",
 462                         __func__, retval);
 463                 goto error_unanchor;
 464         }
 465
 466         /*
 467          * release our reference to this urb, the USB core will eventually free
 468          * it entirely
 469          */
 470         usb_free_urb(urb);
 471
 472
 473         return writesize;
 474
 475 error_unanchor:
 476         usb_unanchor_urb(urb);
 477 error:
 478         if (urb) {
 479                 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
 480                 usb_free_urb(urb);
 481         }
 482         up(&dev->limit_sem);
 483
 484 exit:
 485         return retval;
 486 }
 487
 488 static const struct file_operations skel_fops = {
 489         .owner =        THIS_MODULE,
 490         .read =         skel_read,
 491         .write =        skel_write,
 492         .open =         skel_open,
 493         .release =      skel_release,
 494         .flush =        skel_flush,
 495         .llseek =       noop_llseek,
 496 };
 497
 498 /*
 499  * usb class driver info in order to get a minor number from the usb core,
 500  * and to have the device registered with the driver core
 501  */
 502 static struct usb_class_driver skel_class = {
 503         .name =         "skel%d",
 504         .fops =         &skel_fops,
 505         .minor_base =   USB_SKEL_MINOR_BASE,
 506 };
 507
 508 static int skel_probe(struct usb_interface *interface,
 509                       const struct usb_device_id *id)
 510 {
 511         struct usb_skel *dev;
 512         struct usb_host_interface *iface_desc;
 513         struct usb_endpoint_descriptor *endpoint;
 514         size_t buffer_size;
 515         int i;
 516         int retval = -ENOMEM;
 517
 518         /* allocate memory for our device state and initialize it */
 519         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 520         if (!dev) {
 521                 dev_err(&interface->dev, "Out of memory\n");
 522                 goto error;
 523         }
 524         kref_init(&dev->kref);
 525         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 526         mutex_init(&dev->io_mutex);
 527         spin_lock_init(&dev->err_lock);
 528         init_usb_anchor(&dev->submitted);
 529         init_completion(&dev->bulk_in_completion);
 530
 531         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 532         dev->interface = interface;
 533
 534         /* set up the endpoint information */
 535         /* use only the first bulk-in and bulk-out endpoints */
 536         iface_desc = interface->cur_altsetting;
 537         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 538                 endpoint = &iface_desc->endpoint[i].desc;
 539
 540                 if (!dev->bulk_in_endpointAddr &&
 541                     usb_endpoint_is_bulk_in(endpoint)) {
 542                         /* we found a bulk in endpoint */
 543                         buffer_size = usb_endpoint_maxp(endpoint);
 544                         dev->bulk_in_size = buffer_size;
 545                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 546                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 547                         if (!dev->bulk_in_buffer) {
 548                                 dev_err(&interface->dev,
 549                                         "Could not allocate bulk_in_buffer\n");
 550                                 goto error;
 551                         }
 552                         dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 553                         if (!dev->bulk_in_urb) {
 554                                 dev_err(&interface->dev,
 555                                         "Could not allocate bulk_in_urb\n");
 556                                 goto error;
 557                         }
 558                 }
 559
 560                 if (!dev->bulk_out_endpointAddr &&
 561                     usb_endpoint_is_bulk_out(endpoint)) {
 562                         /* we found a bulk out endpoint */
 563                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 564                 }
 565         }
 566         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 567                 dev_err(&interface->dev,
 568                         "Could not find both bulk-in and bulk-out endpoints\n");
 569                 goto error;
 570         }
 571
 572         /* save our data pointer in this interface device */
 573         usb_set_intfdata(interface, dev);
 574
 575         /* we can register the device now, as it is ready */
 576         retval = usb_register_dev(interface, &skel_class);
 577         if (retval) {
 578                 /* something prevented us from registering this driver */
 579                 dev_err(&interface->dev,
 580                         "Not able to get a minor for this device.\n");
 581                 usb_set_intfdata(interface, NULL);
 582                 goto error;
 583         }
 584
 585         /* let the user know what node this device is now attached to */
 586         dev_info(&interface->dev,
 587                  "USB Skeleton device now attached to USBSkel-%d",
 588                  interface->minor);
 589         return 0;
 590
 591 error:
 592         if (dev)
 593                 /* this frees allocated memory */
 594                 kref_put(&dev->kref, skel_delete);
 595         return retval;
 596 }
 597
 598 static void skel_disconnect(struct usb_interface *interface)
 599 {
 600         struct usb_skel *dev;
 601         int minor = interface->minor;
 602
 603         dev = usb_get_intfdata(interface);
 604         usb_set_intfdata(interface, NULL);
 605
 606         /* give back our minor */
 607         usb_deregister_dev(interface, &skel_class);
 608
 609         /* prevent more I/O from starting */
 610         mutex_lock(&dev->io_mutex);
 611         dev->interface = NULL;
 612         mutex_unlock(&dev->io_mutex);
 613
 614         usb_kill_anchored_urbs(&dev->submitted);
 615
 616         /* decrement our usage count */
 617         kref_put(&dev->kref, skel_delete);
 618
 619         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
 620 }
 621
 622 static void skel_draw_down(struct usb_skel *dev)
 623 {
 624         int time;
 625
 626         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
 627         if (!time)
 628                 usb_kill_anchored_urbs(&dev->submitted);
 629         usb_kill_urb(dev->bulk_in_urb);
 630 }
 631
 632 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
 633 {
 634         struct usb_skel *dev = usb_get_intfdata(intf);
 635
 636         if (!dev)
 637                 return 0;
 638         skel_draw_down(dev);
 639         return 0;
 640 }
 641
 642 static int skel_resume(struct usb_interface *intf)
 643 {
 644         return 0;
 645 }
 646
 647 static int skel_pre_reset(struct usb_interface *intf)
 648 {
 649         struct usb_skel *dev = usb_get_intfdata(intf);
 650
 651         mutex_lock(&dev->io_mutex);
 652         skel_draw_down(dev);
 653
 654         return 0;
 655 }
 656
 657 static int skel_post_reset(struct usb_interface *intf)
 658 {
 659         struct usb_skel *dev = usb_get_intfdata(intf);
 660
 661         /* we are sure no URBs are active - no locking needed */
 662         dev->errors = -EPIPE;
 663         mutex_unlock(&dev->io_mutex);
 664
 665         return 0;
 666 }
 667
 668 static struct usb_driver skel_driver = {
 669         .name =         "skeleton",
 670         .probe =        skel_probe,
 671         .disconnect =   skel_disconnect,
 672         .suspend =      skel_suspend,
 673         .resume =       skel_resume,
 674         .pre_reset =    skel_pre_reset,
 675         .post_reset =   skel_post_reset,
 676         .id_table =     skel_table,
 677         .supports_autosuspend = 1,
 678 };
 679
 680 module_usb_driver(skel_driver);
 681
 682 MODULE_LICENSE("GPL");