drivers/usb/class/cdc-wdm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * cdc-wdm.c
   4  *
   5  * This driver supports USB CDC WCM Device Management.
   6  *
   7  * Copyright (c) 2007-2009 Oliver Neukum
   8  *
   9  * Some code taken from cdc-acm.c
  10  *
  11  * Released under the GPLv2.
  12  *
  13  * Many thanks to Carl Nordbeck
  14  */
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/ioctl.h>
  18 #include <linux/slab.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/bitops.h>
  23 #include <linux/poll.h>
  24 #include <linux/usb.h>
  25 #include <linux/usb/cdc.h>
  26 #include <asm/byteorder.h>
  27 #include <asm/unaligned.h>
  28 #include <linux/usb/cdc-wdm.h>
  29
  30 #define DRIVER_AUTHOR "Oliver Neukum"
  31 #define DRIVER_DESC "USB Abstract Control Model driver for USB WCM Device Management"
  32
  33 static const struct usb_device_id wdm_ids[] = {
  34         {
  35                 .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS |
  36                                  USB_DEVICE_ID_MATCH_INT_SUBCLASS,
  37                 .bInterfaceClass = USB_CLASS_COMM,
  38                 .bInterfaceSubClass = USB_CDC_SUBCLASS_DMM
  39         },
  40         { }
  41 };
  42
  43 MODULE_DEVICE_TABLE (usb, wdm_ids);
  44
  45 #define WDM_MINOR_BASE  176
  46
  47
  48 #define WDM_IN_USE              1
  49 #define WDM_DISCONNECTING       2
  50 #define WDM_RESULT              3
  51 #define WDM_READ                4
  52 #define WDM_INT_STALL           5
  53 #define WDM_POLL_RUNNING        6
  54 #define WDM_RESPONDING          7
  55 #define WDM_SUSPENDING          8
  56 #define WDM_RESETTING           9
  57 #define WDM_OVERFLOW            10
  58
  59 #define WDM_MAX                 16
  60
  61 /* CDC-WMC r1.1 requires wMaxCommand to be "at least 256 decimal (0x100)" */
  62 #define WDM_DEFAULT_BUFSIZE     256
  63
  64 static DEFINE_MUTEX(wdm_mutex);
  65 static DEFINE_SPINLOCK(wdm_device_list_lock);
  66 static LIST_HEAD(wdm_device_list);
  67
  68 /* --- method tables --- */
  69
  70 struct wdm_device {
  71         u8                      *inbuf; /* buffer for response */
  72         u8                      *outbuf; /* buffer for command */
  73         u8                      *sbuf; /* buffer for status */
  74         u8                      *ubuf; /* buffer for copy to user space */
  75
  76         struct urb              *command;
  77         struct urb              *response;
  78         struct urb              *validity;
  79         struct usb_interface    *intf;
  80         struct usb_ctrlrequest  *orq;
  81         struct usb_ctrlrequest  *irq;
  82         spinlock_t              iuspin;
  83
  84         unsigned long           flags;
  85         u16                     bufsize;
  86         u16                     wMaxCommand;
  87         u16                     wMaxPacketSize;
  88         __le16                  inum;
  89         int                     reslength;
  90         int                     length;
  91         int                     read;
  92         int                     count;
  93         dma_addr_t              shandle;
  94         dma_addr_t              ihandle;
  95         struct mutex            wlock;
  96         struct mutex            rlock;
  97         wait_queue_head_t       wait;
  98         struct work_struct      rxwork;
  99         struct work_struct      service_outs_intr;
 100         int                     werr;
 101         int                     rerr;
 102         int                     resp_count;
 103
 104         struct list_head        device_list;
 105         int                     (*manage_power)(struct usb_interface *, int);
 106 };
 107
 108 static struct usb_driver wdm_driver;
 109
 110 /* return intfdata if we own the interface, else look up intf in the list */
 111 static struct wdm_device *wdm_find_device(struct usb_interface *intf)
 112 {
 113         struct wdm_device *desc;
 114
 115         spin_lock(&wdm_device_list_lock);
 116         list_for_each_entry(desc, &wdm_device_list, device_list)
 117                 if (desc->intf == intf)
 118                         goto found;
 119         desc = NULL;
 120 found:
 121         spin_unlock(&wdm_device_list_lock);
 122
 123         return desc;
 124 }
 125
 126 static struct wdm_device *wdm_find_device_by_minor(int minor)
 127 {
 128         struct wdm_device *desc;
 129
 130         spin_lock(&wdm_device_list_lock);
 131         list_for_each_entry(desc, &wdm_device_list, device_list)
 132                 if (desc->intf->minor == minor)
 133                         goto found;
 134         desc = NULL;
 135 found:
 136         spin_unlock(&wdm_device_list_lock);
 137
 138         return desc;
 139 }
 140
 141 /* --- callbacks --- */
 142 static void wdm_out_callback(struct urb *urb)
 143 {
 144         struct wdm_device *desc;
 145         unsigned long flags;
 146
 147         desc = urb->context;
 148         spin_lock_irqsave(&desc->iuspin, flags);
 149         desc->werr = urb->status;
 150         spin_unlock_irqrestore(&desc->iuspin, flags);
 151         kfree(desc->outbuf);
 152         desc->outbuf = NULL;
 153         clear_bit(WDM_IN_USE, &desc->flags);
 154         wake_up(&desc->wait);
 155 }
 156
 157 static void wdm_in_callback(struct urb *urb)
 158 {
 159         unsigned long flags;
 160         struct wdm_device *desc = urb->context;
 161         int status = urb->status;
 162         int length = urb->actual_length;
 163
 164         spin_lock_irqsave(&desc->iuspin, flags);
 165         clear_bit(WDM_RESPONDING, &desc->flags);
 166
 167         if (status) {
 168                 switch (status) {
 169                 case -ENOENT:
 170                         dev_dbg(&desc->intf->dev,
 171                                 "nonzero urb status received: -ENOENT\n");
 172                         goto skip_error;
 173                 case -ECONNRESET:
 174                         dev_dbg(&desc->intf->dev,
 175                                 "nonzero urb status received: -ECONNRESET\n");
 176                         goto skip_error;
 177                 case -ESHUTDOWN:
 178                         dev_dbg(&desc->intf->dev,
 179                                 "nonzero urb status received: -ESHUTDOWN\n");
 180                         goto skip_error;
 181                 case -EPIPE:
 182                         dev_err(&desc->intf->dev,
 183                                 "nonzero urb status received: -EPIPE\n");
 184                         break;
 185                 default:
 186                         dev_err(&desc->intf->dev,
 187                                 "Unexpected error %d\n", status);
 188                         break;
 189                 }
 190         }
 191
 192         /*
 193          * only set a new error if there is no previous error.
 194          * Errors are only cleared during read/open
 195          * Avoid propagating -EPIPE (stall) to userspace since it is
 196          * better handled as an empty read
 197          */
 198         if (desc->rerr == 0 && status != -EPIPE)
 199                 desc->rerr = status;
 200
 201         if (length + desc->length > desc->wMaxCommand) {
 202                 /* The buffer would overflow */
 203                 set_bit(WDM_OVERFLOW, &desc->flags);
 204         } else {
 205                 /* we may already be in overflow */
 206                 if (!test_bit(WDM_OVERFLOW, &desc->flags)) {
 207                         memmove(desc->ubuf + desc->length, desc->inbuf, length);
 208                         desc->length += length;
 209                         desc->reslength = length;
 210                 }
 211         }
 212 skip_error:
 213
 214         if (desc->rerr) {
 215                 /*
 216                  * Since there was an error, userspace may decide to not read
 217                  * any data after poll'ing.
 218                  * We should respond to further attempts from the device to send
 219                  * data, so that we can get unstuck.
 220                  */
 221                 schedule_work(&desc->service_outs_intr);
 222         } else {
 223                 set_bit(WDM_READ, &desc->flags);
 224                 wake_up(&desc->wait);
 225         }
 226         spin_unlock_irqrestore(&desc->iuspin, flags);
 227 }
 228
 229 static void wdm_int_callback(struct urb *urb)
 230 {
 231         unsigned long flags;
 232         int rv = 0;
 233         int responding;
 234         int status = urb->status;
 235         struct wdm_device *desc;
 236         struct usb_cdc_notification *dr;
 237
 238         desc = urb->context;
 239         dr = (struct usb_cdc_notification *)desc->sbuf;
 240
 241         if (status) {
 242                 switch (status) {
 243                 case -ESHUTDOWN:
 244                 case -ENOENT:
 245                 case -ECONNRESET:
 246                         return; /* unplug */
 247                 case -EPIPE:
 248                         set_bit(WDM_INT_STALL, &desc->flags);
 249                         dev_err(&desc->intf->dev, "Stall on int endpoint\n");
 250                         goto sw; /* halt is cleared in work */
 251                 default:
 252                         dev_err(&desc->intf->dev,
 253                                 "nonzero urb status received: %d\n", status);
 254                         break;
 255                 }
 256         }
 257
 258         if (urb->actual_length < sizeof(struct usb_cdc_notification)) {
 259                 dev_err(&desc->intf->dev, "wdm_int_callback - %d bytes\n",
 260                         urb->actual_length);
 261                 goto exit;
 262         }
 263
 264         switch (dr->bNotificationType) {
 265         case USB_CDC_NOTIFY_RESPONSE_AVAILABLE:
 266                 dev_dbg(&desc->intf->dev,
 267                         "NOTIFY_RESPONSE_AVAILABLE received: index %d len %d\n",
 268                         le16_to_cpu(dr->wIndex), le16_to_cpu(dr->wLength));
 269                 break;
 270
 271         case USB_CDC_NOTIFY_NETWORK_CONNECTION:
 272
 273                 dev_dbg(&desc->intf->dev,
 274                         "NOTIFY_NETWORK_CONNECTION %s network\n",
 275                         dr->wValue ? "connected to" : "disconnected from");
 276                 goto exit;
 277         case USB_CDC_NOTIFY_SPEED_CHANGE:
 278                 dev_dbg(&desc->intf->dev, "SPEED_CHANGE received (len %u)\n",
 279                         urb->actual_length);
 280                 goto exit;
 281         default:
 282                 clear_bit(WDM_POLL_RUNNING, &desc->flags);
 283                 dev_err(&desc->intf->dev,
 284                         "unknown notification %d received: index %d len %d\n",
 285                         dr->bNotificationType,
 286                         le16_to_cpu(dr->wIndex),
 287                         le16_to_cpu(dr->wLength));
 288                 goto exit;
 289         }
 290
 291         spin_lock_irqsave(&desc->iuspin, flags);
 292         responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
 293         if (!desc->resp_count++ && !responding
 294                 && !test_bit(WDM_DISCONNECTING, &desc->flags)
 295                 && !test_bit(WDM_SUSPENDING, &desc->flags)) {
 296                 rv = usb_submit_urb(desc->response, GFP_ATOMIC);
 297                 dev_dbg(&desc->intf->dev, "submit response URB %d\n", rv);
 298         }
 299         spin_unlock_irqrestore(&desc->iuspin, flags);
 300         if (rv < 0) {
 301                 clear_bit(WDM_RESPONDING, &desc->flags);
 302                 if (rv == -EPERM)
 303                         return;
 304                 if (rv == -ENOMEM) {
 305 sw:
 306                         rv = schedule_work(&desc->rxwork);
 307                         if (rv)
 308                                 dev_err(&desc->intf->dev,
 309                                         "Cannot schedule work\n");
 310                 }
 311         }
 312 exit:
 313         rv = usb_submit_urb(urb, GFP_ATOMIC);
 314         if (rv)
 315                 dev_err(&desc->intf->dev,
 316                         "%s - usb_submit_urb failed with result %d\n",
 317                         __func__, rv);
 318
 319 }
 320
 321 static void kill_urbs(struct wdm_device *desc)
 322 {
 323         /* the order here is essential */
 324         usb_kill_urb(desc->command);
 325         usb_kill_urb(desc->validity);
 326         usb_kill_urb(desc->response);
 327 }
 328
 329 static void free_urbs(struct wdm_device *desc)
 330 {
 331         usb_free_urb(desc->validity);
 332         usb_free_urb(desc->response);
 333         usb_free_urb(desc->command);
 334 }
 335
 336 static void cleanup(struct wdm_device *desc)
 337 {
 338         kfree(desc->sbuf);
 339         kfree(desc->inbuf);
 340         kfree(desc->orq);
 341         kfree(desc->irq);
 342         kfree(desc->ubuf);
 343         free_urbs(desc);
 344         kfree(desc);
 345 }
 346
 347 static ssize_t wdm_write
 348 (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 349 {
 350         u8 *buf;
 351         int rv = -EMSGSIZE, r, we;
 352         struct wdm_device *desc = file->private_data;
 353         struct usb_ctrlrequest *req;
 354
 355         if (count > desc->wMaxCommand)
 356                 count = desc->wMaxCommand;
 357
 358         spin_lock_irq(&desc->iuspin);
 359         we = desc->werr;
 360         desc->werr = 0;
 361         spin_unlock_irq(&desc->iuspin);
 362         if (we < 0)
 363                 return usb_translate_errors(we);
 364
 365         buf = memdup_user(buffer, count);
 366         if (IS_ERR(buf))
 367                 return PTR_ERR(buf);
 368
 369         /* concurrent writes and disconnect */
 370         r = mutex_lock_interruptible(&desc->wlock);
 371         rv = -ERESTARTSYS;
 372         if (r)
 373                 goto out_free_mem;
 374
 375         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 376                 rv = -ENODEV;
 377                 goto out_free_mem_lock;
 378         }
 379
 380         r = usb_autopm_get_interface(desc->intf);
 381         if (r < 0) {
 382                 rv = usb_translate_errors(r);
 383                 goto out_free_mem_lock;
 384         }
 385
 386         if (!(file->f_flags & O_NONBLOCK))
 387                 r = wait_event_interruptible(desc->wait, !test_bit(WDM_IN_USE,
 388                                                                 &desc->flags));
 389         else
 390                 if (test_bit(WDM_IN_USE, &desc->flags))
 391                         r = -EAGAIN;
 392
 393         if (test_bit(WDM_RESETTING, &desc->flags))
 394                 r = -EIO;
 395
 396         if (r < 0) {
 397                 rv = r;
 398                 goto out_free_mem_pm;
 399         }
 400
 401         req = desc->orq;
 402         usb_fill_control_urb(
 403                 desc->command,
 404                 interface_to_usbdev(desc->intf),
 405                 /* using common endpoint 0 */
 406                 usb_sndctrlpipe(interface_to_usbdev(desc->intf), 0),
 407                 (unsigned char *)req,
 408                 buf,
 409                 count,
 410                 wdm_out_callback,
 411                 desc
 412         );
 413
 414         req->bRequestType = (USB_DIR_OUT | USB_TYPE_CLASS |
 415                              USB_RECIP_INTERFACE);
 416         req->bRequest = USB_CDC_SEND_ENCAPSULATED_COMMAND;
 417         req->wValue = 0;
 418         req->wIndex = desc->inum; /* already converted */
 419         req->wLength = cpu_to_le16(count);
 420         set_bit(WDM_IN_USE, &desc->flags);
 421         desc->outbuf = buf;
 422
 423         rv = usb_submit_urb(desc->command, GFP_KERNEL);
 424         if (rv < 0) {
 425                 desc->outbuf = NULL;
 426                 clear_bit(WDM_IN_USE, &desc->flags);
 427                 dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv);
 428                 rv = usb_translate_errors(rv);
 429                 goto out_free_mem_pm;
 430         } else {
 431                 dev_dbg(&desc->intf->dev, "Tx URB has been submitted index=%d\n",
 432                         le16_to_cpu(req->wIndex));
 433         }
 434
 435         usb_autopm_put_interface(desc->intf);
 436         mutex_unlock(&desc->wlock);
 437         return count;
 438
 439 out_free_mem_pm:
 440         usb_autopm_put_interface(desc->intf);
 441 out_free_mem_lock:
 442         mutex_unlock(&desc->wlock);
 443 out_free_mem:
 444         kfree(buf);
 445         return rv;
 446 }
 447
 448 /*
 449  * Submit the read urb if resp_count is non-zero.
 450  *
 451  * Called with desc->iuspin locked
 452  */
 453 static int service_outstanding_interrupt(struct wdm_device *desc)
 454 {
 455         int rv = 0;
 456
 457         /* submit read urb only if the device is waiting for it */
 458         if (!desc->resp_count || !--desc->resp_count)
 459                 goto out;
 460
 461         set_bit(WDM_RESPONDING, &desc->flags);
 462         spin_unlock_irq(&desc->iuspin);
 463         rv = usb_submit_urb(desc->response, GFP_KERNEL);
 464         spin_lock_irq(&desc->iuspin);
 465         if (rv) {
 466                 dev_err(&desc->intf->dev,
 467                         "usb_submit_urb failed with result %d\n", rv);
 468
 469                 /* make sure the next notification trigger a submit */
 470                 clear_bit(WDM_RESPONDING, &desc->flags);
 471                 desc->resp_count = 0;
 472         }
 473 out:
 474         return rv;
 475 }
 476
 477 static ssize_t wdm_read
 478 (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 479 {
 480         int rv, cntr;
 481         int i = 0;
 482         struct wdm_device *desc = file->private_data;
 483
 484
 485         rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */
 486         if (rv < 0)
 487                 return -ERESTARTSYS;
 488
 489         cntr = READ_ONCE(desc->length);
 490         if (cntr == 0) {
 491                 desc->read = 0;
 492 retry:
 493                 if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 494                         rv = -ENODEV;
 495                         goto err;
 496                 }
 497                 if (test_bit(WDM_OVERFLOW, &desc->flags)) {
 498                         clear_bit(WDM_OVERFLOW, &desc->flags);
 499                         rv = -ENOBUFS;
 500                         goto err;
 501                 }
 502                 i++;
 503                 if (file->f_flags & O_NONBLOCK) {
 504                         if (!test_bit(WDM_READ, &desc->flags)) {
 505                                 rv = -EAGAIN;
 506                                 goto err;
 507                         }
 508                         rv = 0;
 509                 } else {
 510                         rv = wait_event_interruptible(desc->wait,
 511                                 test_bit(WDM_READ, &desc->flags));
 512                 }
 513
 514                 /* may have happened while we slept */
 515                 if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 516                         rv = -ENODEV;
 517                         goto err;
 518                 }
 519                 if (test_bit(WDM_RESETTING, &desc->flags)) {
 520                         rv = -EIO;
 521                         goto err;
 522                 }
 523                 usb_mark_last_busy(interface_to_usbdev(desc->intf));
 524                 if (rv < 0) {
 525                         rv = -ERESTARTSYS;
 526                         goto err;
 527                 }
 528
 529                 spin_lock_irq(&desc->iuspin);
 530
 531                 if (desc->rerr) { /* read completed, error happened */
 532                         rv = usb_translate_errors(desc->rerr);
 533                         desc->rerr = 0;
 534                         spin_unlock_irq(&desc->iuspin);
 535                         goto err;
 536                 }
 537                 /*
 538                  * recheck whether we've lost the race
 539                  * against the completion handler
 540                  */
 541                 if (!test_bit(WDM_READ, &desc->flags)) { /* lost race */
 542                         spin_unlock_irq(&desc->iuspin);
 543                         goto retry;
 544                 }
 545
 546                 if (!desc->reslength) { /* zero length read */
 547                         dev_dbg(&desc->intf->dev, "zero length - clearing WDM_READ\n");
 548                         clear_bit(WDM_READ, &desc->flags);
 549                         rv = service_outstanding_interrupt(desc);
 550                         spin_unlock_irq(&desc->iuspin);
 551                         if (rv < 0)
 552                                 goto err;
 553                         goto retry;
 554                 }
 555                 cntr = desc->length;
 556                 spin_unlock_irq(&desc->iuspin);
 557         }
 558
 559         if (cntr > count)
 560                 cntr = count;
 561         rv = copy_to_user(buffer, desc->ubuf, cntr);
 562         if (rv > 0) {
 563                 rv = -EFAULT;
 564                 goto err;
 565         }
 566
 567         spin_lock_irq(&desc->iuspin);
 568
 569         for (i = 0; i < desc->length - cntr; i++)
 570                 desc->ubuf[i] = desc->ubuf[i + cntr];
 571
 572         desc->length -= cntr;
 573         /* in case we had outstanding data */
 574         if (!desc->length) {
 575                 clear_bit(WDM_READ, &desc->flags);
 576                 service_outstanding_interrupt(desc);
 577         }
 578         spin_unlock_irq(&desc->iuspin);
 579         rv = cntr;
 580
 581 err:
 582         mutex_unlock(&desc->rlock);
 583         return rv;
 584 }
 585
 586 static int wdm_flush(struct file *file, fl_owner_t id)
 587 {
 588         struct wdm_device *desc = file->private_data;
 589
 590         wait_event(desc->wait, !test_bit(WDM_IN_USE, &desc->flags));
 591
 592         /* cannot dereference desc->intf if WDM_DISCONNECTING */
 593         if (desc->werr < 0 && !test_bit(WDM_DISCONNECTING, &desc->flags))
 594                 dev_err(&desc->intf->dev, "Error in flush path: %d\n",
 595                         desc->werr);
 596
 597         return usb_translate_errors(desc->werr);
 598 }
 599
 600 static __poll_t wdm_poll(struct file *file, struct poll_table_struct *wait)
 601 {
 602         struct wdm_device *desc = file->private_data;
 603         unsigned long flags;
 604         __poll_t mask = 0;
 605
 606         spin_lock_irqsave(&desc->iuspin, flags);
 607         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 608                 mask = EPOLLHUP | EPOLLERR;
 609                 spin_unlock_irqrestore(&desc->iuspin, flags);
 610                 goto desc_out;
 611         }
 612         if (test_bit(WDM_READ, &desc->flags))
 613                 mask = EPOLLIN | EPOLLRDNORM;
 614         if (desc->rerr || desc->werr)
 615                 mask |= EPOLLERR;
 616         if (!test_bit(WDM_IN_USE, &desc->flags))
 617                 mask |= EPOLLOUT | EPOLLWRNORM;
 618         spin_unlock_irqrestore(&desc->iuspin, flags);
 619
 620         poll_wait(file, &desc->wait, wait);
 621
 622 desc_out:
 623         return mask;
 624 }
 625
 626 static int wdm_open(struct inode *inode, struct file *file)
 627 {
 628         int minor = iminor(inode);
 629         int rv = -ENODEV;
 630         struct usb_interface *intf;
 631         struct wdm_device *desc;
 632
 633         mutex_lock(&wdm_mutex);
 634         desc = wdm_find_device_by_minor(minor);
 635         if (!desc)
 636                 goto out;
 637
 638         intf = desc->intf;
 639         if (test_bit(WDM_DISCONNECTING, &desc->flags))
 640                 goto out;
 641         file->private_data = desc;
 642
 643         rv = usb_autopm_get_interface(desc->intf);
 644         if (rv < 0) {
 645                 dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
 646                 goto out;
 647         }
 648
 649         /* using write lock to protect desc->count */
 650         mutex_lock(&desc->wlock);
 651         if (!desc->count++) {
 652                 desc->werr = 0;
 653                 desc->rerr = 0;
 654                 rv = usb_submit_urb(desc->validity, GFP_KERNEL);
 655                 if (rv < 0) {
 656                         desc->count--;
 657                         dev_err(&desc->intf->dev,
 658                                 "Error submitting int urb - %d\n", rv);
 659                         rv = usb_translate_errors(rv);
 660                 }
 661         } else {
 662                 rv = 0;
 663         }
 664         mutex_unlock(&desc->wlock);
 665         if (desc->count == 1)
 666                 desc->manage_power(intf, 1);
 667         usb_autopm_put_interface(desc->intf);
 668 out:
 669         mutex_unlock(&wdm_mutex);
 670         return rv;
 671 }
 672
 673 static int wdm_release(struct inode *inode, struct file *file)
 674 {
 675         struct wdm_device *desc = file->private_data;
 676
 677         mutex_lock(&wdm_mutex);
 678
 679         /* using write lock to protect desc->count */
 680         mutex_lock(&desc->wlock);
 681         desc->count--;
 682         mutex_unlock(&desc->wlock);
 683
 684         if (!desc->count) {
 685                 if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
 686                         dev_dbg(&desc->intf->dev, "wdm_release: cleanup\n");
 687                         kill_urbs(desc);
 688                         spin_lock_irq(&desc->iuspin);
 689                         desc->resp_count = 0;
 690                         spin_unlock_irq(&desc->iuspin);
 691                         desc->manage_power(desc->intf, 0);
 692                 } else {
 693                         /* must avoid dev_printk here as desc->intf is invalid */
 694                         pr_debug(KBUILD_MODNAME " %s: device gone - cleaning up\n", __func__);
 695                         cleanup(desc);
 696                 }
 697         }
 698         mutex_unlock(&wdm_mutex);
 699         return 0;
 700 }
 701
 702 static long wdm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 703 {
 704         struct wdm_device *desc = file->private_data;
 705         int rv = 0;
 706
 707         switch (cmd) {
 708         case IOCTL_WDM_MAX_COMMAND:
 709                 if (copy_to_user((void __user *)arg, &desc->wMaxCommand, sizeof(desc->wMaxCommand)))
 710                         rv = -EFAULT;
 711                 break;
 712         default:
 713                 rv = -ENOTTY;
 714         }
 715         return rv;
 716 }
 717
 718 static const struct file_operations wdm_fops = {
 719         .owner =        THIS_MODULE,
 720         .read =         wdm_read,
 721         .write =        wdm_write,
 722         .open =         wdm_open,
 723         .flush =        wdm_flush,
 724         .release =      wdm_release,
 725         .poll =         wdm_poll,
 726         .unlocked_ioctl = wdm_ioctl,
 727         .compat_ioctl = wdm_ioctl,
 728         .llseek =       noop_llseek,
 729 };
 730
 731 static struct usb_class_driver wdm_class = {
 732         .name =         "cdc-wdm%d",
 733         .fops =         &wdm_fops,
 734         .minor_base =   WDM_MINOR_BASE,
 735 };
 736
 737 /* --- error handling --- */
 738 static void wdm_rxwork(struct work_struct *work)
 739 {
 740         struct wdm_device *desc = container_of(work, struct wdm_device, rxwork);
 741         unsigned long flags;
 742         int rv = 0;
 743         int responding;
 744
 745         spin_lock_irqsave(&desc->iuspin, flags);
 746         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 747                 spin_unlock_irqrestore(&desc->iuspin, flags);
 748         } else {
 749                 responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
 750                 spin_unlock_irqrestore(&desc->iuspin, flags);
 751                 if (!responding)
 752                         rv = usb_submit_urb(desc->response, GFP_KERNEL);
 753                 if (rv < 0 && rv != -EPERM) {
 754                         spin_lock_irqsave(&desc->iuspin, flags);
 755                         clear_bit(WDM_RESPONDING, &desc->flags);
 756                         if (!test_bit(WDM_DISCONNECTING, &desc->flags))
 757                                 schedule_work(&desc->rxwork);
 758                         spin_unlock_irqrestore(&desc->iuspin, flags);
 759                 }
 760         }
 761 }
 762
 763 static void service_interrupt_work(struct work_struct *work)
 764 {
 765         struct wdm_device *desc;
 766
 767         desc = container_of(work, struct wdm_device, service_outs_intr);
 768
 769         spin_lock_irq(&desc->iuspin);
 770         service_outstanding_interrupt(desc);
 771         if (!desc->resp_count) {
 772                 set_bit(WDM_READ, &desc->flags);
 773                 wake_up(&desc->wait);
 774         }
 775         spin_unlock_irq(&desc->iuspin);
 776 }
 777
 778 /* --- hotplug --- */
 779
 780 static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
 781                 u16 bufsize, int (*manage_power)(struct usb_interface *, int))
 782 {
 783         int rv = -ENOMEM;
 784         struct wdm_device *desc;
 785
 786         desc = kzalloc(sizeof(struct wdm_device), GFP_KERNEL);
 787         if (!desc)
 788                 goto out;
 789         INIT_LIST_HEAD(&desc->device_list);
 790         mutex_init(&desc->rlock);
 791         mutex_init(&desc->wlock);
 792         spin_lock_init(&desc->iuspin);
 793         init_waitqueue_head(&desc->wait);
 794         desc->wMaxCommand = bufsize;
 795         /* this will be expanded and needed in hardware endianness */
 796         desc->inum = cpu_to_le16((u16)intf->cur_altsetting->desc.bInterfaceNumber);
 797         desc->intf = intf;
 798         INIT_WORK(&desc->rxwork, wdm_rxwork);
 799         INIT_WORK(&desc->service_outs_intr, service_interrupt_work);
 800
 801         rv = -EINVAL;
 802         if (!usb_endpoint_is_int_in(ep))
 803                 goto err;
 804
 805         desc->wMaxPacketSize = usb_endpoint_maxp(ep);
 806
 807         desc->orq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
 808         if (!desc->orq)
 809                 goto err;
 810         desc->irq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
 811         if (!desc->irq)
 812                 goto err;
 813
 814         desc->validity = usb_alloc_urb(0, GFP_KERNEL);
 815         if (!desc->validity)
 816                 goto err;
 817
 818         desc->response = usb_alloc_urb(0, GFP_KERNEL);
 819         if (!desc->response)
 820                 goto err;
 821
 822         desc->command = usb_alloc_urb(0, GFP_KERNEL);
 823         if (!desc->command)
 824                 goto err;
 825
 826         desc->ubuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
 827         if (!desc->ubuf)
 828                 goto err;
 829
 830         desc->sbuf = kmalloc(desc->wMaxPacketSize, GFP_KERNEL);
 831         if (!desc->sbuf)
 832                 goto err;
 833
 834         desc->inbuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
 835         if (!desc->inbuf)
 836                 goto err;
 837
 838         usb_fill_int_urb(
 839                 desc->validity,
 840                 interface_to_usbdev(intf),
 841                 usb_rcvintpipe(interface_to_usbdev(intf), ep->bEndpointAddress),
 842                 desc->sbuf,
 843                 desc->wMaxPacketSize,
 844                 wdm_int_callback,
 845                 desc,
 846                 ep->bInterval
 847         );
 848
 849         desc->irq->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
 850         desc->irq->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
 851         desc->irq->wValue = 0;
 852         desc->irq->wIndex = desc->inum; /* already converted */
 853         desc->irq->wLength = cpu_to_le16(desc->wMaxCommand);
 854
 855         usb_fill_control_urb(
 856                 desc->response,
 857                 interface_to_usbdev(intf),
 858                 /* using common endpoint 0 */
 859                 usb_rcvctrlpipe(interface_to_usbdev(desc->intf), 0),
 860                 (unsigned char *)desc->irq,
 861                 desc->inbuf,
 862                 desc->wMaxCommand,
 863                 wdm_in_callback,
 864                 desc
 865         );
 866
 867         desc->manage_power = manage_power;
 868
 869         spin_lock(&wdm_device_list_lock);
 870         list_add(&desc->device_list, &wdm_device_list);
 871         spin_unlock(&wdm_device_list_lock);
 872
 873         rv = usb_register_dev(intf, &wdm_class);
 874         if (rv < 0)
 875                 goto err;
 876         else
 877                 dev_info(&intf->dev, "%s: USB WDM device\n", dev_name(intf->usb_dev));
 878 out:
 879         return rv;
 880 err:
 881         spin_lock(&wdm_device_list_lock);
 882         list_del(&desc->device_list);
 883         spin_unlock(&wdm_device_list_lock);
 884         cleanup(desc);
 885         return rv;
 886 }
 887
 888 static int wdm_manage_power(struct usb_interface *intf, int on)
 889 {
 890         /* need autopm_get/put here to ensure the usbcore sees the new value */
 891         int rv = usb_autopm_get_interface(intf);
 892
 893         intf->needs_remote_wakeup = on;
 894         if (!rv)
 895                 usb_autopm_put_interface(intf);
 896         return 0;
 897 }
 898
 899 static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id)
 900 {
 901         int rv = -EINVAL;
 902         struct usb_host_interface *iface;
 903         struct usb_endpoint_descriptor *ep;
 904         struct usb_cdc_parsed_header hdr;
 905         u8 *buffer = intf->altsetting->extra;
 906         int buflen = intf->altsetting->extralen;
 907         u16 maxcom = WDM_DEFAULT_BUFSIZE;
 908
 909         if (!buffer)
 910                 goto err;
 911
 912         cdc_parse_cdc_header(&hdr, intf, buffer, buflen);
 913
 914         if (hdr.usb_cdc_dmm_desc)
 915                 maxcom = le16_to_cpu(hdr.usb_cdc_dmm_desc->wMaxCommand);
 916
 917         iface = intf->cur_altsetting;
 918         if (iface->desc.bNumEndpoints != 1)
 919                 goto err;
 920         ep = &iface->endpoint[0].desc;
 921
 922         rv = wdm_create(intf, ep, maxcom, &wdm_manage_power);
 923
 924 err:
 925         return rv;
 926 }
 927
 928 /**
 929  * usb_cdc_wdm_register - register a WDM subdriver
 930  * @intf: usb interface the subdriver will associate with
 931  * @ep: interrupt endpoint to monitor for notifications
 932  * @bufsize: maximum message size to support for read/write
 933  *
 934  * Create WDM usb class character device and associate it with intf
 935  * without binding, allowing another driver to manage the interface.
 936  *
 937  * The subdriver will manage the given interrupt endpoint exclusively
 938  * and will issue control requests referring to the given intf. It
 939  * will otherwise avoid interferring, and in particular not do
 940  * usb_set_intfdata/usb_get_intfdata on intf.
 941  *
 942  * The return value is a pointer to the subdriver's struct usb_driver.
 943  * The registering driver is responsible for calling this subdriver's
 944  * disconnect, suspend, resume, pre_reset and post_reset methods from
 945  * its own.
 946  */
 947 struct usb_driver *usb_cdc_wdm_register(struct usb_interface *intf,
 948                                         struct usb_endpoint_descriptor *ep,
 949                                         int bufsize,
 950                                         int (*manage_power)(struct usb_interface *, int))
 951 {
 952         int rv = -EINVAL;
 953
 954         rv = wdm_create(intf, ep, bufsize, manage_power);
 955         if (rv < 0)
 956                 goto err;
 957
 958         return &wdm_driver;
 959 err:
 960         return ERR_PTR(rv);
 961 }
 962 EXPORT_SYMBOL(usb_cdc_wdm_register);
 963
 964 static void wdm_disconnect(struct usb_interface *intf)
 965 {
 966         struct wdm_device *desc;
 967         unsigned long flags;
 968
 969         usb_deregister_dev(intf, &wdm_class);
 970         desc = wdm_find_device(intf);
 971         mutex_lock(&wdm_mutex);
 972
 973         /* the spinlock makes sure no new urbs are generated in the callbacks */
 974         spin_lock_irqsave(&desc->iuspin, flags);
 975         set_bit(WDM_DISCONNECTING, &desc->flags);
 976         set_bit(WDM_READ, &desc->flags);
 977         /* to terminate pending flushes */
 978         clear_bit(WDM_IN_USE, &desc->flags);
 979         spin_unlock_irqrestore(&desc->iuspin, flags);
 980         wake_up_all(&desc->wait);
 981         mutex_lock(&desc->rlock);
 982         mutex_lock(&desc->wlock);
 983         kill_urbs(desc);
 984         cancel_work_sync(&desc->rxwork);
 985         cancel_work_sync(&desc->service_outs_intr);
 986         mutex_unlock(&desc->wlock);
 987         mutex_unlock(&desc->rlock);
 988
 989         /* the desc->intf pointer used as list key is now invalid */
 990         spin_lock(&wdm_device_list_lock);
 991         list_del(&desc->device_list);
 992         spin_unlock(&wdm_device_list_lock);
 993
 994         if (!desc->count)
 995                 cleanup(desc);
 996         else
 997                 dev_dbg(&intf->dev, "%d open files - postponing cleanup\n", desc->count);
 998         mutex_unlock(&wdm_mutex);
 999 }
1000
1001 #ifdef CONFIG_PM
1002 static int wdm_suspend(struct usb_interface *intf, pm_message_t message)
1003 {
1004         struct wdm_device *desc = wdm_find_device(intf);
1005         int rv = 0;
1006
1007         dev_dbg(&desc->intf->dev, "wdm%d_suspend\n", intf->minor);
1008
1009         /* if this is an autosuspend the caller does the locking */
1010         if (!PMSG_IS_AUTO(message)) {
1011                 mutex_lock(&desc->rlock);
1012                 mutex_lock(&desc->wlock);
1013         }
1014         spin_lock_irq(&desc->iuspin);
1015
1016         if (PMSG_IS_AUTO(message) &&
1017                         (test_bit(WDM_IN_USE, &desc->flags)
1018                         || test_bit(WDM_RESPONDING, &desc->flags))) {
1019                 spin_unlock_irq(&desc->iuspin);
1020                 rv = -EBUSY;
1021         } else {
1022
1023                 set_bit(WDM_SUSPENDING, &desc->flags);
1024                 spin_unlock_irq(&desc->iuspin);
1025                 /* callback submits work - order is essential */
1026                 kill_urbs(desc);
1027                 cancel_work_sync(&desc->rxwork);
1028                 cancel_work_sync(&desc->service_outs_intr);
1029         }
1030         if (!PMSG_IS_AUTO(message)) {
1031                 mutex_unlock(&desc->wlock);
1032                 mutex_unlock(&desc->rlock);
1033         }
1034
1035         return rv;
1036 }
1037 #endif
1038
1039 static int recover_from_urb_loss(struct wdm_device *desc)
1040 {
1041         int rv = 0;
1042
1043         if (desc->count) {
1044                 rv = usb_submit_urb(desc->validity, GFP_NOIO);
1045                 if (rv < 0)
1046                         dev_err(&desc->intf->dev,
1047                                 "Error resume submitting int urb - %d\n", rv);
1048         }
1049         return rv;
1050 }
1051
1052 #ifdef CONFIG_PM
1053 static int wdm_resume(struct usb_interface *intf)
1054 {
1055         struct wdm_device *desc = wdm_find_device(intf);
1056         int rv;
1057
1058         dev_dbg(&desc->intf->dev, "wdm%d_resume\n", intf->minor);
1059
1060         clear_bit(WDM_SUSPENDING, &desc->flags);
1061         rv = recover_from_urb_loss(desc);
1062
1063         return rv;
1064 }
1065 #endif
1066
1067 static int wdm_pre_reset(struct usb_interface *intf)
1068 {
1069         struct wdm_device *desc = wdm_find_device(intf);
1070
1071         /*
1072          * we notify everybody using poll of
1073          * an exceptional situation
1074          * must be done before recovery lest a spontaneous
1075          * message from the device is lost
1076          */
1077         spin_lock_irq(&desc->iuspin);
1078         set_bit(WDM_RESETTING, &desc->flags);   /* inform read/write */
1079         set_bit(WDM_READ, &desc->flags);        /* unblock read */
1080         clear_bit(WDM_IN_USE, &desc->flags);    /* unblock write */
1081         desc->rerr = -EINTR;
1082         spin_unlock_irq(&desc->iuspin);
1083         wake_up_all(&desc->wait);
1084         mutex_lock(&desc->rlock);
1085         mutex_lock(&desc->wlock);
1086         kill_urbs(desc);
1087         cancel_work_sync(&desc->rxwork);
1088         cancel_work_sync(&desc->service_outs_intr);
1089         return 0;
1090 }
1091
1092 static int wdm_post_reset(struct usb_interface *intf)
1093 {
1094         struct wdm_device *desc = wdm_find_device(intf);
1095         int rv;
1096
1097         clear_bit(WDM_OVERFLOW, &desc->flags);
1098         clear_bit(WDM_RESETTING, &desc->flags);
1099         rv = recover_from_urb_loss(desc);
1100         mutex_unlock(&desc->wlock);
1101         mutex_unlock(&desc->rlock);
1102         return rv;
1103 }
1104
1105 static struct usb_driver wdm_driver = {
1106         .name =         "cdc_wdm",
1107         .probe =        wdm_probe,
1108         .disconnect =   wdm_disconnect,
1109 #ifdef CONFIG_PM
1110         .suspend =      wdm_suspend,
1111         .resume =       wdm_resume,
1112         .reset_resume = wdm_resume,
1113 #endif
1114         .pre_reset =    wdm_pre_reset,
1115         .post_reset =   wdm_post_reset,
1116         .id_table =     wdm_ids,
1117         .supports_autosuspend = 1,
1118         .disable_hub_initiated_lpm = 1,
1119 };
1120
1121 module_usb_driver(wdm_driver);
1122
1123 MODULE_AUTHOR(DRIVER_AUTHOR);
1124 MODULE_DESCRIPTION(DRIVER_DESC);
1125 MODULE_LICENSE("GPL");