root/drivers/usb/class/cdc-wdm.c

DEFINITIONS

1. wdm_find_device
2. wdm_find_device_by_minor
3. wdm_out_callback
4. wdm_in_callback
5. wdm_int_callback
6. kill_urbs
7. free_urbs
8. cleanup
9. service_outstanding_interrupt
10. wdm_flush
11. wdm_poll
12. wdm_open
13. wdm_release
14. wdm_ioctl
15. wdm_rxwork
16. service_interrupt_work
17. wdm_create
18. wdm_manage_power
19. wdm_probe
20. usb_cdc_wdm_register
21. wdm_disconnect
22. wdm_suspend
23. recover_from_urb_loss
24. wdm_resume
25. wdm_pre_reset
26. wdm_post_reset

   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,
 591                         /*
 592                          * needs both flags. We cannot do with one
 593                          * because resetting it would cause a race
 594                          * with write() yet we need to signal
 595                          * a disconnect
 596                          */
 597                         !test_bit(WDM_IN_USE, &desc->flags) ||
 598                         test_bit(WDM_DISCONNECTING, &desc->flags));
 599 
 600         /* cannot dereference desc->intf if WDM_DISCONNECTING */
 601         if (test_bit(WDM_DISCONNECTING, &desc->flags))
 602                 return -ENODEV;
 603         if (desc->werr < 0)
 604                 dev_err(&desc->intf->dev, "Error in flush path: %d\n",
 605                         desc->werr);
 606 
 607         return usb_translate_errors(desc->werr);
 608 }
 609 
 610 static __poll_t wdm_poll(struct file *file, struct poll_table_struct *wait)
 611 {
 612         struct wdm_device *desc = file->private_data;
 613         unsigned long flags;
 614         __poll_t mask = 0;
 615 
 616         spin_lock_irqsave(&desc->iuspin, flags);
 617         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 618                 mask = EPOLLHUP | EPOLLERR;
 619                 spin_unlock_irqrestore(&desc->iuspin, flags);
 620                 goto desc_out;
 621         }
 622         if (test_bit(WDM_READ, &desc->flags))
 623                 mask = EPOLLIN | EPOLLRDNORM;
 624         if (desc->rerr || desc->werr)
 625                 mask |= EPOLLERR;
 626         if (!test_bit(WDM_IN_USE, &desc->flags))
 627                 mask |= EPOLLOUT | EPOLLWRNORM;
 628         spin_unlock_irqrestore(&desc->iuspin, flags);
 629 
 630         poll_wait(file, &desc->wait, wait);
 631 
 632 desc_out:
 633         return mask;
 634 }
 635 
 636 static int wdm_open(struct inode *inode, struct file *file)
 637 {
 638         int minor = iminor(inode);
 639         int rv = -ENODEV;
 640         struct usb_interface *intf;
 641         struct wdm_device *desc;
 642 
 643         mutex_lock(&wdm_mutex);
 644         desc = wdm_find_device_by_minor(minor);
 645         if (!desc)
 646                 goto out;
 647 
 648         intf = desc->intf;
 649         if (test_bit(WDM_DISCONNECTING, &desc->flags))
 650                 goto out;
 651         file->private_data = desc;
 652 
 653         rv = usb_autopm_get_interface(desc->intf);
 654         if (rv < 0) {
 655                 dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
 656                 goto out;
 657         }
 658 
 659         /* using write lock to protect desc->count */
 660         mutex_lock(&desc->wlock);
 661         if (!desc->count++) {
 662                 desc->werr = 0;
 663                 desc->rerr = 0;
 664                 rv = usb_submit_urb(desc->validity, GFP_KERNEL);
 665                 if (rv < 0) {
 666                         desc->count--;
 667                         dev_err(&desc->intf->dev,
 668                                 "Error submitting int urb - %d\n", rv);
 669                         rv = usb_translate_errors(rv);
 670                 }
 671         } else {
 672                 rv = 0;
 673         }
 674         mutex_unlock(&desc->wlock);
 675         if (desc->count == 1)
 676                 desc->manage_power(intf, 1);
 677         usb_autopm_put_interface(desc->intf);
 678 out:
 679         mutex_unlock(&wdm_mutex);
 680         return rv;
 681 }
 682 
 683 static int wdm_release(struct inode *inode, struct file *file)
 684 {
 685         struct wdm_device *desc = file->private_data;
 686 
 687         mutex_lock(&wdm_mutex);
 688 
 689         /* using write lock to protect desc->count */
 690         mutex_lock(&desc->wlock);
 691         desc->count--;
 692         mutex_unlock(&desc->wlock);
 693 
 694         if (!desc->count) {
 695                 if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
 696                         dev_dbg(&desc->intf->dev, "wdm_release: cleanup\n");
 697                         kill_urbs(desc);
 698                         spin_lock_irq(&desc->iuspin);
 699                         desc->resp_count = 0;
 700                         spin_unlock_irq(&desc->iuspin);
 701                         desc->manage_power(desc->intf, 0);
 702                 } else {
 703                         /* must avoid dev_printk here as desc->intf is invalid */
 704                         pr_debug(KBUILD_MODNAME " %s: device gone - cleaning up\n", __func__);
 705                         cleanup(desc);
 706                 }
 707         }
 708         mutex_unlock(&wdm_mutex);
 709         return 0;
 710 }
 711 
 712 static long wdm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 713 {
 714         struct wdm_device *desc = file->private_data;
 715         int rv = 0;
 716 
 717         switch (cmd) {
 718         case IOCTL_WDM_MAX_COMMAND:
 719                 if (copy_to_user((void __user *)arg, &desc->wMaxCommand, sizeof(desc->wMaxCommand)))
 720                         rv = -EFAULT;
 721                 break;
 722         default:
 723                 rv = -ENOTTY;
 724         }
 725         return rv;
 726 }
 727 
 728 static const struct file_operations wdm_fops = {
 729         .owner =        THIS_MODULE,
 730         .read =         wdm_read,
 731         .write =        wdm_write,
 732         .open =         wdm_open,
 733         .flush =        wdm_flush,
 734         .release =      wdm_release,
 735         .poll =         wdm_poll,
 736         .unlocked_ioctl = wdm_ioctl,
 737         .compat_ioctl = wdm_ioctl,
 738         .llseek =       noop_llseek,
 739 };
 740 
 741 static struct usb_class_driver wdm_class = {
 742         .name =         "cdc-wdm%d",
 743         .fops =         &wdm_fops,
 744         .minor_base =   WDM_MINOR_BASE,
 745 };
 746 
 747 /* --- error handling --- */
 748 static void wdm_rxwork(struct work_struct *work)
 749 {
 750         struct wdm_device *desc = container_of(work, struct wdm_device, rxwork);
 751         unsigned long flags;
 752         int rv = 0;
 753         int responding;
 754 
 755         spin_lock_irqsave(&desc->iuspin, flags);
 756         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 757                 spin_unlock_irqrestore(&desc->iuspin, flags);
 758         } else {
 759                 responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
 760                 spin_unlock_irqrestore(&desc->iuspin, flags);
 761                 if (!responding)
 762                         rv = usb_submit_urb(desc->response, GFP_KERNEL);
 763                 if (rv < 0 && rv != -EPERM) {
 764                         spin_lock_irqsave(&desc->iuspin, flags);
 765                         clear_bit(WDM_RESPONDING, &desc->flags);
 766                         if (!test_bit(WDM_DISCONNECTING, &desc->flags))
 767                                 schedule_work(&desc->rxwork);
 768                         spin_unlock_irqrestore(&desc->iuspin, flags);
 769                 }
 770         }
 771 }
 772 
 773 static void service_interrupt_work(struct work_struct *work)
 774 {
 775         struct wdm_device *desc;
 776 
 777         desc = container_of(work, struct wdm_device, service_outs_intr);
 778 
 779         spin_lock_irq(&desc->iuspin);
 780         service_outstanding_interrupt(desc);
 781         if (!desc->resp_count) {
 782                 set_bit(WDM_READ, &desc->flags);
 783                 wake_up(&desc->wait);
 784         }
 785         spin_unlock_irq(&desc->iuspin);
 786 }
 787 
 788 /* --- hotplug --- */
 789 
 790 static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
 791                 u16 bufsize, int (*manage_power)(struct usb_interface *, int))
 792 {
 793         int rv = -ENOMEM;
 794         struct wdm_device *desc;
 795 
 796         desc = kzalloc(sizeof(struct wdm_device), GFP_KERNEL);
 797         if (!desc)
 798                 goto out;
 799         INIT_LIST_HEAD(&desc->device_list);
 800         mutex_init(&desc->rlock);
 801         mutex_init(&desc->wlock);
 802         spin_lock_init(&desc->iuspin);
 803         init_waitqueue_head(&desc->wait);
 804         desc->wMaxCommand = bufsize;
 805         /* this will be expanded and needed in hardware endianness */
 806         desc->inum = cpu_to_le16((u16)intf->cur_altsetting->desc.bInterfaceNumber);
 807         desc->intf = intf;
 808         INIT_WORK(&desc->rxwork, wdm_rxwork);
 809         INIT_WORK(&desc->service_outs_intr, service_interrupt_work);
 810 
 811         rv = -EINVAL;
 812         if (!usb_endpoint_is_int_in(ep))
 813                 goto err;
 814 
 815         desc->wMaxPacketSize = usb_endpoint_maxp(ep);
 816 
 817         desc->orq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
 818         if (!desc->orq)
 819                 goto err;
 820         desc->irq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
 821         if (!desc->irq)
 822                 goto err;
 823 
 824         desc->validity = usb_alloc_urb(0, GFP_KERNEL);
 825         if (!desc->validity)
 826                 goto err;
 827 
 828         desc->response = usb_alloc_urb(0, GFP_KERNEL);
 829         if (!desc->response)
 830                 goto err;
 831 
 832         desc->command = usb_alloc_urb(0, GFP_KERNEL);
 833         if (!desc->command)
 834                 goto err;
 835 
 836         desc->ubuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
 837         if (!desc->ubuf)
 838                 goto err;
 839 
 840         desc->sbuf = kmalloc(desc->wMaxPacketSize, GFP_KERNEL);
 841         if (!desc->sbuf)
 842                 goto err;
 843 
 844         desc->inbuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
 845         if (!desc->inbuf)
 846                 goto err;
 847 
 848         usb_fill_int_urb(
 849                 desc->validity,
 850                 interface_to_usbdev(intf),
 851                 usb_rcvintpipe(interface_to_usbdev(intf), ep->bEndpointAddress),
 852                 desc->sbuf,
 853                 desc->wMaxPacketSize,
 854                 wdm_int_callback,
 855                 desc,
 856                 ep->bInterval
 857         );
 858 
 859         desc->irq->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
 860         desc->irq->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
 861         desc->irq->wValue = 0;
 862         desc->irq->wIndex = desc->inum; /* already converted */
 863         desc->irq->wLength = cpu_to_le16(desc->wMaxCommand);
 864 
 865         usb_fill_control_urb(
 866                 desc->response,
 867                 interface_to_usbdev(intf),
 868                 /* using common endpoint 0 */
 869                 usb_rcvctrlpipe(interface_to_usbdev(desc->intf), 0),
 870                 (unsigned char *)desc->irq,
 871                 desc->inbuf,
 872                 desc->wMaxCommand,
 873                 wdm_in_callback,
 874                 desc
 875         );
 876 
 877         desc->manage_power = manage_power;
 878 
 879         spin_lock(&wdm_device_list_lock);
 880         list_add(&desc->device_list, &wdm_device_list);
 881         spin_unlock(&wdm_device_list_lock);
 882 
 883         rv = usb_register_dev(intf, &wdm_class);
 884         if (rv < 0)
 885                 goto err;
 886         else
 887                 dev_info(&intf->dev, "%s: USB WDM device\n", dev_name(intf->usb_dev));
 888 out:
 889         return rv;
 890 err:
 891         spin_lock(&wdm_device_list_lock);
 892         list_del(&desc->device_list);
 893         spin_unlock(&wdm_device_list_lock);
 894         cleanup(desc);
 895         return rv;
 896 }
 897 
 898 static int wdm_manage_power(struct usb_interface *intf, int on)
 899 {
 900         /* need autopm_get/put here to ensure the usbcore sees the new value */
 901         int rv = usb_autopm_get_interface(intf);
 902 
 903         intf->needs_remote_wakeup = on;
 904         if (!rv)
 905                 usb_autopm_put_interface(intf);
 906         return 0;
 907 }
 908 
 909 static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id)
 910 {
 911         int rv = -EINVAL;
 912         struct usb_host_interface *iface;
 913         struct usb_endpoint_descriptor *ep;
 914         struct usb_cdc_parsed_header hdr;
 915         u8 *buffer = intf->altsetting->extra;
 916         int buflen = intf->altsetting->extralen;
 917         u16 maxcom = WDM_DEFAULT_BUFSIZE;
 918 
 919         if (!buffer)
 920                 goto err;
 921 
 922         cdc_parse_cdc_header(&hdr, intf, buffer, buflen);
 923 
 924         if (hdr.usb_cdc_dmm_desc)
 925                 maxcom = le16_to_cpu(hdr.usb_cdc_dmm_desc->wMaxCommand);
 926 
 927         iface = intf->cur_altsetting;
 928         if (iface->desc.bNumEndpoints != 1)
 929                 goto err;
 930         ep = &iface->endpoint[0].desc;
 931 
 932         rv = wdm_create(intf, ep, maxcom, &wdm_manage_power);
 933 
 934 err:
 935         return rv;
 936 }
 937 
 938 /**
 939  * usb_cdc_wdm_register - register a WDM subdriver
 940  * @intf: usb interface the subdriver will associate with
 941  * @ep: interrupt endpoint to monitor for notifications
 942  * @bufsize: maximum message size to support for read/write
 943  *
 944  * Create WDM usb class character device and associate it with intf
 945  * without binding, allowing another driver to manage the interface.
 946  *
 947  * The subdriver will manage the given interrupt endpoint exclusively
 948  * and will issue control requests referring to the given intf. It
 949  * will otherwise avoid interferring, and in particular not do
 950  * usb_set_intfdata/usb_get_intfdata on intf.
 951  *
 952  * The return value is a pointer to the subdriver's struct usb_driver.
 953  * The registering driver is responsible for calling this subdriver's
 954  * disconnect, suspend, resume, pre_reset and post_reset methods from
 955  * its own.
 956  */
 957 struct usb_driver *usb_cdc_wdm_register(struct usb_interface *intf,
 958                                         struct usb_endpoint_descriptor *ep,
 959                                         int bufsize,
 960                                         int (*manage_power)(struct usb_interface *, int))
 961 {
 962         int rv;
 963 
 964         rv = wdm_create(intf, ep, bufsize, manage_power);
 965         if (rv < 0)
 966                 goto err;
 967 
 968         return &wdm_driver;
 969 err:
 970         return ERR_PTR(rv);
 971 }
 972 EXPORT_SYMBOL(usb_cdc_wdm_register);
 973 
 974 static void wdm_disconnect(struct usb_interface *intf)
 975 {
 976         struct wdm_device *desc;
 977         unsigned long flags;
 978 
 979         usb_deregister_dev(intf, &wdm_class);
 980         desc = wdm_find_device(intf);
 981         mutex_lock(&wdm_mutex);
 982 
 983         /* the spinlock makes sure no new urbs are generated in the callbacks */
 984         spin_lock_irqsave(&desc->iuspin, flags);
 985         set_bit(WDM_DISCONNECTING, &desc->flags);
 986         set_bit(WDM_READ, &desc->flags);
 987         spin_unlock_irqrestore(&desc->iuspin, flags);
 988         wake_up_all(&desc->wait);
 989         mutex_lock(&desc->rlock);
 990         mutex_lock(&desc->wlock);
 991         kill_urbs(desc);
 992         cancel_work_sync(&desc->rxwork);
 993         cancel_work_sync(&desc->service_outs_intr);
 994         mutex_unlock(&desc->wlock);
 995         mutex_unlock(&desc->rlock);
 996 
 997         /* the desc->intf pointer used as list key is now invalid */
 998         spin_lock(&wdm_device_list_lock);
 999         list_del(&desc->device_list);
1000         spin_unlock(&wdm_device_list_lock);
1001 
1002         if (!desc->count)
1003                 cleanup(desc);
1004         else
1005                 dev_dbg(&intf->dev, "%d open files - postponing cleanup\n", desc->count);
1006         mutex_unlock(&wdm_mutex);
1007 }
1008 
1009 #ifdef CONFIG_PM
1010 static int wdm_suspend(struct usb_interface *intf, pm_message_t message)
1011 {
1012         struct wdm_device *desc = wdm_find_device(intf);
1013         int rv = 0;
1014 
1015         dev_dbg(&desc->intf->dev, "wdm%d_suspend\n", intf->minor);
1016 
1017         /* if this is an autosuspend the caller does the locking */
1018         if (!PMSG_IS_AUTO(message)) {
1019                 mutex_lock(&desc->rlock);
1020                 mutex_lock(&desc->wlock);
1021         }
1022         spin_lock_irq(&desc->iuspin);
1023 
1024         if (PMSG_IS_AUTO(message) &&
1025                         (test_bit(WDM_IN_USE, &desc->flags)
1026                         || test_bit(WDM_RESPONDING, &desc->flags))) {
1027                 spin_unlock_irq(&desc->iuspin);
1028                 rv = -EBUSY;
1029         } else {
1030 
1031                 set_bit(WDM_SUSPENDING, &desc->flags);
1032                 spin_unlock_irq(&desc->iuspin);
1033                 /* callback submits work - order is essential */
1034                 kill_urbs(desc);
1035                 cancel_work_sync(&desc->rxwork);
1036                 cancel_work_sync(&desc->service_outs_intr);
1037         }
1038         if (!PMSG_IS_AUTO(message)) {
1039                 mutex_unlock(&desc->wlock);
1040                 mutex_unlock(&desc->rlock);
1041         }
1042 
1043         return rv;
1044 }
1045 #endif
1046 
1047 static int recover_from_urb_loss(struct wdm_device *desc)
1048 {
1049         int rv = 0;
1050 
1051         if (desc->count) {
1052                 rv = usb_submit_urb(desc->validity, GFP_NOIO);
1053                 if (rv < 0)
1054                         dev_err(&desc->intf->dev,
1055                                 "Error resume submitting int urb - %d\n", rv);
1056         }
1057         return rv;
1058 }
1059 
1060 #ifdef CONFIG_PM
1061 static int wdm_resume(struct usb_interface *intf)
1062 {
1063         struct wdm_device *desc = wdm_find_device(intf);
1064         int rv;
1065 
1066         dev_dbg(&desc->intf->dev, "wdm%d_resume\n", intf->minor);
1067 
1068         clear_bit(WDM_SUSPENDING, &desc->flags);
1069         rv = recover_from_urb_loss(desc);
1070 
1071         return rv;
1072 }
1073 #endif
1074 
1075 static int wdm_pre_reset(struct usb_interface *intf)
1076 {
1077         struct wdm_device *desc = wdm_find_device(intf);
1078 
1079         /*
1080          * we notify everybody using poll of
1081          * an exceptional situation
1082          * must be done before recovery lest a spontaneous
1083          * message from the device is lost
1084          */
1085         spin_lock_irq(&desc->iuspin);
1086         set_bit(WDM_RESETTING, &desc->flags);   /* inform read/write */
1087         set_bit(WDM_READ, &desc->flags);        /* unblock read */
1088         clear_bit(WDM_IN_USE, &desc->flags);    /* unblock write */
1089         desc->rerr = -EINTR;
1090         spin_unlock_irq(&desc->iuspin);
1091         wake_up_all(&desc->wait);
1092         mutex_lock(&desc->rlock);
1093         mutex_lock(&desc->wlock);
1094         kill_urbs(desc);
1095         cancel_work_sync(&desc->rxwork);
1096         cancel_work_sync(&desc->service_outs_intr);
1097         return 0;
1098 }
1099 
1100 static int wdm_post_reset(struct usb_interface *intf)
1101 {
1102         struct wdm_device *desc = wdm_find_device(intf);
1103         int rv;
1104 
1105         clear_bit(WDM_OVERFLOW, &desc->flags);
1106         clear_bit(WDM_RESETTING, &desc->flags);
1107         rv = recover_from_urb_loss(desc);
1108         mutex_unlock(&desc->wlock);
1109         mutex_unlock(&desc->rlock);
1110         return rv;
1111 }
1112 
1113 static struct usb_driver wdm_driver = {
1114         .name =         "cdc_wdm",
1115         .probe =        wdm_probe,
1116         .disconnect =   wdm_disconnect,
1117 #ifdef CONFIG_PM
1118         .suspend =      wdm_suspend,
1119         .resume =       wdm_resume,
1120         .reset_resume = wdm_resume,
1121 #endif
1122         .pre_reset =    wdm_pre_reset,
1123         .post_reset =   wdm_post_reset,
1124         .id_table =     wdm_ids,
1125         .supports_autosuspend = 1,
1126         .disable_hub_initiated_lpm = 1,
1127 };
1128 
1129 module_usb_driver(wdm_driver);
1130 
1131 MODULE_AUTHOR(DRIVER_AUTHOR);
1132 MODULE_DESCRIPTION(DRIVER_DESC);
1133 MODULE_LICENSE("GPL");