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/slab.h>
  18 #include <linux/module.h>
  19 #include <linux/kref.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/usb.h>
  22 #include <linux/mutex.h>
  23
  24
  25 /* Define these values to match your devices */
  26 #define USB_SKEL_VENDOR_ID      0xfff0
  27 #define USB_SKEL_PRODUCT_ID     0xfff0
  28
  29 /* table of devices that work with this driver */
  30 static const struct usb_device_id skel_table[] = {
  31         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
  32         { }                                     /* Terminating entry */
  33 };
  34 MODULE_DEVICE_TABLE(usb, skel_table);
  35
  36
  37 /* Get a minor range for your devices from the usb maintainer */
  38 #define USB_SKEL_MINOR_BASE     192
  39
  40 /* our private defines. if this grows any larger, use your own .h file */
  41 #define MAX_TRANSFER            (PAGE_SIZE - 512)
  42 /* MAX_TRANSFER is chosen so that the VM is not stressed by
  43    allocations > PAGE_SIZE and the number of packets in a page
  44    is an integer 512 is the largest possible packet on EHCI */
  45 #define WRITES_IN_FLIGHT        8
  46 /* arbitrarily chosen */
  47
  48 /* Structure to hold all of our device specific stuff */
  49 struct usb_skel {
  50         struct usb_device       *udev;                  /* the usb device for this device */
  51         struct usb_interface    *interface;             /* the interface for this device */
  52         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
  53         struct usb_anchor       submitted;              /* in case we need to retract our submissions */
  54         struct urb              *bulk_in_urb;           /* the urb to read data with */
  55         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
  56         size_t                  bulk_in_size;           /* the size of the receive buffer */
  57         size_t                  bulk_in_filled;         /* number of bytes in the buffer */
  58         size_t                  bulk_in_copied;         /* already copied to user space */
  59         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  60         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  61         int                     errors;                 /* the last request tanked */
  62         bool                    ongoing_read;           /* a read is going on */
  63         spinlock_t              err_lock;               /* lock for errors */
  64         struct kref             kref;
  65         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
  66         unsigned long           disconnected:1;
  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_intf(dev->interface);
  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         usb_autopm_put_interface(dev->interface);
 132
 133         /* decrement the count on our device */
 134         kref_put(&dev->kref, skel_delete);
 135         return 0;
 136 }
 137
 138 static int skel_flush(struct file *file, fl_owner_t id)
 139 {
 140         struct usb_skel *dev;
 141         int res;
 142
 143         dev = file->private_data;
 144         if (dev == NULL)
 145                 return -ENODEV;
 146
 147         /* wait for io to stop */
 148         mutex_lock(&dev->io_mutex);
 149         skel_draw_down(dev);
 150
 151         /* read out errors, leave subsequent opens a clean slate */
 152         spin_lock_irq(&dev->err_lock);
 153         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
 154         dev->errors = 0;
 155         spin_unlock_irq(&dev->err_lock);
 156
 157         mutex_unlock(&dev->io_mutex);
 158
 159         return res;
 160 }
 161
 162 static void skel_read_bulk_callback(struct urb *urb)
 163 {
 164         struct usb_skel *dev;
 165
 166         dev = urb->context;
 167
 168         spin_lock(&dev->err_lock);
 169         /* sync/async unlink faults aren't errors */
 170         if (urb->status) {
 171                 if (!(urb->status == -ENOENT ||
 172                     urb->status == -ECONNRESET ||
 173                     urb->status == -ESHUTDOWN))
 174                         dev_err(&dev->interface->dev,
 175                                 "%s - nonzero write bulk status received: %d\n",
 176                                 __func__, urb->status);
 177
 178                 dev->errors = urb->status;
 179         } else {
 180                 dev->bulk_in_filled = urb->actual_length;
 181         }
 182         dev->ongoing_read = 0;
 183         spin_unlock(&dev->err_lock);
 184
 185         wake_up_interruptible(&dev->bulk_in_wait);
 186 }
 187
 188 static int skel_do_read_io(struct usb_skel *dev, size_t count)
 189 {
 190         int rv;
 191
 192         /* prepare a read */
 193         usb_fill_bulk_urb(dev->bulk_in_urb,
 194                         dev->udev,
 195                         usb_rcvbulkpipe(dev->udev,
 196                                 dev->bulk_in_endpointAddr),
 197                         dev->bulk_in_buffer,
 198                         min(dev->bulk_in_size, count),
 199                         skel_read_bulk_callback,
 200                         dev);
 201         /* tell everybody to leave the URB alone */
 202         spin_lock_irq(&dev->err_lock);
 203         dev->ongoing_read = 1;
 204         spin_unlock_irq(&dev->err_lock);
 205
 206         /* submit bulk in urb, which means no data to deliver */
 207         dev->bulk_in_filled = 0;
 208         dev->bulk_in_copied = 0;
 209
 210         /* do it */
 211         rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
 212         if (rv < 0) {
 213                 dev_err(&dev->interface->dev,
 214                         "%s - failed submitting read urb, error %d\n",
 215                         __func__, rv);
 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->disconnected) {                /* 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_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read));
 265                 if (rv < 0)
 266                         goto exit;
 267         }
 268
 269         /* errors must be reported */
 270         rv = dev->errors;
 271         if (rv < 0) {
 272                 /* any error is reported once */
 273                 dev->errors = 0;
 274                 /* to preserve notifications about reset */
 275                 rv = (rv == -EPIPE) ? rv : -EIO;
 276                 /* report it */
 277                 goto exit;
 278         }
 279
 280         /*
 281          * if the buffer is filled we may satisfy the read
 282          * else we need to start IO
 283          */
 284
 285         if (dev->bulk_in_filled) {
 286                 /* we had read data */
 287                 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
 288                 size_t chunk = min(available, count);
 289
 290                 if (!available) {
 291                         /*
 292                          * all data has been used
 293                          * actual IO needs to be done
 294                          */
 295                         rv = skel_do_read_io(dev, count);
 296                         if (rv < 0)
 297                                 goto exit;
 298                         else
 299                                 goto retry;
 300                 }
 301                 /*
 302                  * data is available
 303                  * chunk tells us how much shall be copied
 304                  */
 305
 306                 if (copy_to_user(buffer,
 307                                  dev->bulk_in_buffer + dev->bulk_in_copied,
 308                                  chunk))
 309                         rv = -EFAULT;
 310                 else
 311                         rv = chunk;
 312
 313                 dev->bulk_in_copied += chunk;
 314
 315                 /*
 316                  * if we are asked for more than we have,
 317                  * we start IO but don't wait
 318                  */
 319                 if (available < count)
 320                         skel_do_read_io(dev, count - chunk);
 321         } else {
 322                 /* no data in the buffer */
 323                 rv = skel_do_read_io(dev, count);
 324                 if (rv < 0)
 325                         goto exit;
 326                 else
 327                         goto retry;
 328         }
 329 exit:
 330         mutex_unlock(&dev->io_mutex);
 331         return rv;
 332 }
 333
 334 static void skel_write_bulk_callback(struct urb *urb)
 335 {
 336         struct usb_skel *dev;
 337
 338         dev = urb->context;
 339
 340         /* sync/async unlink faults aren't errors */
 341         if (urb->status) {
 342                 if (!(urb->status == -ENOENT ||
 343                     urb->status == -ECONNRESET ||
 344                     urb->status == -ESHUTDOWN))
 345                         dev_err(&dev->interface->dev,
 346                                 "%s - nonzero write bulk status received: %d\n",
 347                                 __func__, urb->status);
 348
 349                 spin_lock(&dev->err_lock);
 350                 dev->errors = urb->status;
 351                 spin_unlock(&dev->err_lock);
 352         }
 353
 354         /* free up our allocated buffer */
 355         usb_free_coherent(urb->dev, urb->transfer_buffer_length,
 356                           urb->transfer_buffer, urb->transfer_dma);
 357         up(&dev->limit_sem);
 358 }
 359
 360 static ssize_t skel_write(struct file *file, const char *user_buffer,
 361                           size_t count, loff_t *ppos)
 362 {
 363         struct usb_skel *dev;
 364         int retval = 0;
 365         struct urb *urb = NULL;
 366         char *buf = NULL;
 367         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 368
 369         dev = file->private_data;
 370
 371         /* verify that we actually have some data to write */
 372         if (count == 0)
 373                 goto exit;
 374
 375         /*
 376          * limit the number of URBs in flight to stop a user from using up all
 377          * RAM
 378          */
 379         if (!(file->f_flags & O_NONBLOCK)) {
 380                 if (down_interruptible(&dev->limit_sem)) {
 381                         retval = -ERESTARTSYS;
 382                         goto exit;
 383                 }
 384         } else {
 385                 if (down_trylock(&dev->limit_sem)) {
 386                         retval = -EAGAIN;
 387                         goto exit;
 388                 }
 389         }
 390
 391         spin_lock_irq(&dev->err_lock);
 392         retval = dev->errors;
 393         if (retval < 0) {
 394                 /* any error is reported once */
 395                 dev->errors = 0;
 396                 /* to preserve notifications about reset */
 397                 retval = (retval == -EPIPE) ? retval : -EIO;
 398         }
 399         spin_unlock_irq(&dev->err_lock);
 400         if (retval < 0)
 401                 goto error;
 402
 403         /* create a urb, and a buffer for it, and copy the data to the urb */
 404         urb = usb_alloc_urb(0, GFP_KERNEL);
 405         if (!urb) {
 406                 retval = -ENOMEM;
 407                 goto error;
 408         }
 409
 410         buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
 411                                  &urb->transfer_dma);
 412         if (!buf) {
 413                 retval = -ENOMEM;
 414                 goto error;
 415         }
 416
 417         if (copy_from_user(buf, user_buffer, writesize)) {
 418                 retval = -EFAULT;
 419                 goto error;
 420         }
 421
 422         /* this lock makes sure we don't submit URBs to gone devices */
 423         mutex_lock(&dev->io_mutex);
 424         if (dev->disconnected) {                /* disconnect() was called */
 425                 mutex_unlock(&dev->io_mutex);
 426                 retval = -ENODEV;
 427                 goto error;
 428         }
 429
 430         /* initialize the urb properly */
 431         usb_fill_bulk_urb(urb, dev->udev,
 432                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 433                           buf, writesize, skel_write_bulk_callback, dev);
 434         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 435         usb_anchor_urb(urb, &dev->submitted);
 436
 437         /* send the data out the bulk port */
 438         retval = usb_submit_urb(urb, GFP_KERNEL);
 439         mutex_unlock(&dev->io_mutex);
 440         if (retval) {
 441                 dev_err(&dev->interface->dev,
 442                         "%s - failed submitting write urb, error %d\n",
 443                         __func__, retval);
 444                 goto error_unanchor;
 445         }
 446
 447         /*
 448          * release our reference to this urb, the USB core will eventually free
 449          * it entirely
 450          */
 451         usb_free_urb(urb);
 452
 453
 454         return writesize;
 455
 456 error_unanchor:
 457         usb_unanchor_urb(urb);
 458 error:
 459         if (urb) {
 460                 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
 461                 usb_free_urb(urb);
 462         }
 463         up(&dev->limit_sem);
 464
 465 exit:
 466         return retval;
 467 }
 468
 469 static const struct file_operations skel_fops = {
 470         .owner =        THIS_MODULE,
 471         .read =         skel_read,
 472         .write =        skel_write,
 473         .open =         skel_open,
 474         .release =      skel_release,
 475         .flush =        skel_flush,
 476         .llseek =       noop_llseek,
 477 };
 478
 479 /*
 480  * usb class driver info in order to get a minor number from the usb core,
 481  * and to have the device registered with the driver core
 482  */
 483 static struct usb_class_driver skel_class = {
 484         .name =         "skel%d",
 485         .fops =         &skel_fops,
 486         .minor_base =   USB_SKEL_MINOR_BASE,
 487 };
 488
 489 static int skel_probe(struct usb_interface *interface,
 490                       const struct usb_device_id *id)
 491 {
 492         struct usb_skel *dev;
 493         struct usb_endpoint_descriptor *bulk_in, *bulk_out;
 494         int retval;
 495
 496         /* allocate memory for our device state and initialize it */
 497         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 498         if (!dev)
 499                 return -ENOMEM;
 500
 501         kref_init(&dev->kref);
 502         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 503         mutex_init(&dev->io_mutex);
 504         spin_lock_init(&dev->err_lock);
 505         init_usb_anchor(&dev->submitted);
 506         init_waitqueue_head(&dev->bulk_in_wait);
 507
 508         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 509         dev->interface = usb_get_intf(interface);
 510
 511         /* set up the endpoint information */
 512         /* use only the first bulk-in and bulk-out endpoints */
 513         retval = usb_find_common_endpoints(interface->cur_altsetting,
 514                         &bulk_in, &bulk_out, NULL, NULL);
 515         if (retval) {
 516                 dev_err(&interface->dev,
 517                         "Could not find both bulk-in and bulk-out endpoints\n");
 518                 goto error;
 519         }
 520
 521         dev->bulk_in_size = usb_endpoint_maxp(bulk_in);
 522         dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress;
 523         dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL);
 524         if (!dev->bulk_in_buffer) {
 525                 retval = -ENOMEM;
 526                 goto error;
 527         }
 528         dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 529         if (!dev->bulk_in_urb) {
 530                 retval = -ENOMEM;
 531                 goto error;
 532         }
 533
 534         dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress;
 535
 536         /* save our data pointer in this interface device */
 537         usb_set_intfdata(interface, dev);
 538
 539         /* we can register the device now, as it is ready */
 540         retval = usb_register_dev(interface, &skel_class);
 541         if (retval) {
 542                 /* something prevented us from registering this driver */
 543                 dev_err(&interface->dev,
 544                         "Not able to get a minor for this device.\n");
 545                 usb_set_intfdata(interface, NULL);
 546                 goto error;
 547         }
 548
 549         /* let the user know what node this device is now attached to */
 550         dev_info(&interface->dev,
 551                  "USB Skeleton device now attached to USBSkel-%d",
 552                  interface->minor);
 553         return 0;
 554
 555 error:
 556         /* this frees allocated memory */
 557         kref_put(&dev->kref, skel_delete);
 558
 559         return retval;
 560 }
 561
 562 static void skel_disconnect(struct usb_interface *interface)
 563 {
 564         struct usb_skel *dev;
 565         int minor = interface->minor;
 566
 567         dev = usb_get_intfdata(interface);
 568         usb_set_intfdata(interface, NULL);
 569
 570         /* give back our minor */
 571         usb_deregister_dev(interface, &skel_class);
 572
 573         /* prevent more I/O from starting */
 574         mutex_lock(&dev->io_mutex);
 575         dev->disconnected = 1;
 576         mutex_unlock(&dev->io_mutex);
 577
 578         usb_kill_anchored_urbs(&dev->submitted);
 579
 580         /* decrement our usage count */
 581         kref_put(&dev->kref, skel_delete);
 582
 583         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
 584 }
 585
 586 static void skel_draw_down(struct usb_skel *dev)
 587 {
 588         int time;
 589
 590         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
 591         if (!time)
 592                 usb_kill_anchored_urbs(&dev->submitted);
 593         usb_kill_urb(dev->bulk_in_urb);
 594 }
 595
 596 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
 597 {
 598         struct usb_skel *dev = usb_get_intfdata(intf);
 599
 600         if (!dev)
 601                 return 0;
 602         skel_draw_down(dev);
 603         return 0;
 604 }
 605
 606 static int skel_resume(struct usb_interface *intf)
 607 {
 608         return 0;
 609 }
 610
 611 static int skel_pre_reset(struct usb_interface *intf)
 612 {
 613         struct usb_skel *dev = usb_get_intfdata(intf);
 614
 615         mutex_lock(&dev->io_mutex);
 616         skel_draw_down(dev);
 617
 618         return 0;
 619 }
 620
 621 static int skel_post_reset(struct usb_interface *intf)
 622 {
 623         struct usb_skel *dev = usb_get_intfdata(intf);
 624
 625         /* we are sure no URBs are active - no locking needed */
 626         dev->errors = -EPIPE;
 627         mutex_unlock(&dev->io_mutex);
 628
 629         return 0;
 630 }
 631
 632 static struct usb_driver skel_driver = {
 633         .name =         "skeleton",
 634         .probe =        skel_probe,
 635         .disconnect =   skel_disconnect,
 636         .suspend =      skel_suspend,
 637         .resume =       skel_resume,
 638         .pre_reset =    skel_pre_reset,
 639         .post_reset =   skel_post_reset,
 640         .id_table =     skel_table,
 641         .supports_autosuspend = 1,
 642 };
 643
 644 module_usb_driver(skel_driver);
 645
 646 MODULE_LICENSE("GPL");