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 /* we cannot wait forever at flush() */
  62 #define WDM_FLUSH_TIMEOUT       (30 * HZ)
  63
  64 /* CDC-WMC r1.1 requires wMaxCommand to be "at least 256 decimal (0x100)" */
  65 #define WDM_DEFAULT_BUFSIZE     256
  66
  67 static DEFINE_MUTEX(wdm_mutex);
  68 static DEFINE_SPINLOCK(wdm_device_list_lock);
  69 static LIST_HEAD(wdm_device_list);
  70
  71 /* --- method tables --- */
  72
  73 struct wdm_device {
  74         u8                      *inbuf; /* buffer for response */
  75         u8                      *outbuf; /* buffer for command */
  76         u8                      *sbuf; /* buffer for status */
  77         u8                      *ubuf; /* buffer for copy to user space */
  78
  79         struct urb              *command;
  80         struct urb              *response;
  81         struct urb              *validity;
  82         struct usb_interface    *intf;
  83         struct usb_ctrlrequest  *orq;
  84         struct usb_ctrlrequest  *irq;
  85         spinlock_t              iuspin;
  86
  87         unsigned long           flags;
  88         u16                     bufsize;
  89         u16                     wMaxCommand;
  90         u16                     wMaxPacketSize;
  91         __le16                  inum;
  92         int                     reslength;
  93         int                     length;
  94         int                     read;
  95         int                     count;
  96         dma_addr_t              shandle;
  97         dma_addr_t              ihandle;
  98         struct mutex            wlock;
  99         struct mutex            rlock;
 100         wait_queue_head_t       wait;
 101         struct work_struct      rxwork;
 102         struct work_struct      service_outs_intr;
 103         int                     werr;
 104         int                     rerr;
 105         int                     resp_count;
 106
 107         struct list_head        device_list;
 108         int                     (*manage_power)(struct usb_interface *, int);
 109 };
 110
 111 static struct usb_driver wdm_driver;
 112
 113 /* return intfdata if we own the interface, else look up intf in the list */
 114 static struct wdm_device *wdm_find_device(struct usb_interface *intf)
 115 {
 116         struct wdm_device *desc;
 117
 118         spin_lock(&wdm_device_list_lock);
 119         list_for_each_entry(desc, &wdm_device_list, device_list)
 120                 if (desc->intf == intf)
 121                         goto found;
 122         desc = NULL;
 123 found:
 124         spin_unlock(&wdm_device_list_lock);
 125
 126         return desc;
 127 }
 128
 129 static struct wdm_device *wdm_find_device_by_minor(int minor)
 130 {
 131         struct wdm_device *desc;
 132
 133         spin_lock(&wdm_device_list_lock);
 134         list_for_each_entry(desc, &wdm_device_list, device_list)
 135                 if (desc->intf->minor == minor)
 136                         goto found;
 137         desc = NULL;
 138 found:
 139         spin_unlock(&wdm_device_list_lock);
 140
 141         return desc;
 142 }
 143
 144 /* --- callbacks --- */
 145 static void wdm_out_callback(struct urb *urb)
 146 {
 147         struct wdm_device *desc;
 148         unsigned long flags;
 149
 150         desc = urb->context;
 151         spin_lock_irqsave(&desc->iuspin, flags);
 152         desc->werr = urb->status;
 153         spin_unlock_irqrestore(&desc->iuspin, flags);
 154         kfree(desc->outbuf);
 155         desc->outbuf = NULL;
 156         clear_bit(WDM_IN_USE, &desc->flags);
 157         wake_up_all(&desc->wait);
 158 }
 159
 160 static void wdm_in_callback(struct urb *urb)
 161 {
 162         unsigned long flags;
 163         struct wdm_device *desc = urb->context;
 164         int status = urb->status;
 165         int length = urb->actual_length;
 166
 167         spin_lock_irqsave(&desc->iuspin, flags);
 168         clear_bit(WDM_RESPONDING, &desc->flags);
 169
 170         if (status) {
 171                 switch (status) {
 172                 case -ENOENT:
 173                         dev_dbg(&desc->intf->dev,
 174                                 "nonzero urb status received: -ENOENT\n");
 175                         goto skip_error;
 176                 case -ECONNRESET:
 177                         dev_dbg(&desc->intf->dev,
 178                                 "nonzero urb status received: -ECONNRESET\n");
 179                         goto skip_error;
 180                 case -ESHUTDOWN:
 181                         dev_dbg(&desc->intf->dev,
 182                                 "nonzero urb status received: -ESHUTDOWN\n");
 183                         goto skip_error;
 184                 case -EPIPE:
 185                         dev_err(&desc->intf->dev,
 186                                 "nonzero urb status received: -EPIPE\n");
 187                         break;
 188                 default:
 189                         dev_err(&desc->intf->dev,
 190                                 "Unexpected error %d\n", status);
 191                         break;
 192                 }
 193         }
 194
 195         /*
 196          * only set a new error if there is no previous error.
 197          * Errors are only cleared during read/open
 198          * Avoid propagating -EPIPE (stall) to userspace since it is
 199          * better handled as an empty read
 200          */
 201         if (desc->rerr == 0 && status != -EPIPE)
 202                 desc->rerr = status;
 203
 204         if (length + desc->length > desc->wMaxCommand) {
 205                 /* The buffer would overflow */
 206                 set_bit(WDM_OVERFLOW, &desc->flags);
 207         } else {
 208                 /* we may already be in overflow */
 209                 if (!test_bit(WDM_OVERFLOW, &desc->flags)) {
 210                         memmove(desc->ubuf + desc->length, desc->inbuf, length);
 211                         desc->length += length;
 212                         desc->reslength = length;
 213                 }
 214         }
 215 skip_error:
 216
 217         if (desc->rerr) {
 218                 /*
 219                  * Since there was an error, userspace may decide to not read
 220                  * any data after poll'ing.
 221                  * We should respond to further attempts from the device to send
 222                  * data, so that we can get unstuck.
 223                  */
 224                 schedule_work(&desc->service_outs_intr);
 225         } else {
 226                 set_bit(WDM_READ, &desc->flags);
 227                 wake_up(&desc->wait);
 228         }
 229         spin_unlock_irqrestore(&desc->iuspin, flags);
 230 }
 231
 232 static void wdm_int_callback(struct urb *urb)
 233 {
 234         unsigned long flags;
 235         int rv = 0;
 236         int responding;
 237         int status = urb->status;
 238         struct wdm_device *desc;
 239         struct usb_cdc_notification *dr;
 240
 241         desc = urb->context;
 242         dr = (struct usb_cdc_notification *)desc->sbuf;
 243
 244         if (status) {
 245                 switch (status) {
 246                 case -ESHUTDOWN:
 247                 case -ENOENT:
 248                 case -ECONNRESET:
 249                         return; /* unplug */
 250                 case -EPIPE:
 251                         set_bit(WDM_INT_STALL, &desc->flags);
 252                         dev_err(&desc->intf->dev, "Stall on int endpoint\n");
 253                         goto sw; /* halt is cleared in work */
 254                 default:
 255                         dev_err(&desc->intf->dev,
 256                                 "nonzero urb status received: %d\n", status);
 257                         break;
 258                 }
 259         }
 260
 261         if (urb->actual_length < sizeof(struct usb_cdc_notification)) {
 262                 dev_err(&desc->intf->dev, "wdm_int_callback - %d bytes\n",
 263                         urb->actual_length);
 264                 goto exit;
 265         }
 266
 267         switch (dr->bNotificationType) {
 268         case USB_CDC_NOTIFY_RESPONSE_AVAILABLE:
 269                 dev_dbg(&desc->intf->dev,
 270                         "NOTIFY_RESPONSE_AVAILABLE received: index %d len %d\n",
 271                         le16_to_cpu(dr->wIndex), le16_to_cpu(dr->wLength));
 272                 break;
 273
 274         case USB_CDC_NOTIFY_NETWORK_CONNECTION:
 275
 276                 dev_dbg(&desc->intf->dev,
 277                         "NOTIFY_NETWORK_CONNECTION %s network\n",
 278                         dr->wValue ? "connected to" : "disconnected from");
 279                 goto exit;
 280         case USB_CDC_NOTIFY_SPEED_CHANGE:
 281                 dev_dbg(&desc->intf->dev, "SPEED_CHANGE received (len %u)\n",
 282                         urb->actual_length);
 283                 goto exit;
 284         default:
 285                 clear_bit(WDM_POLL_RUNNING, &desc->flags);
 286                 dev_err(&desc->intf->dev,
 287                         "unknown notification %d received: index %d len %d\n",
 288                         dr->bNotificationType,
 289                         le16_to_cpu(dr->wIndex),
 290                         le16_to_cpu(dr->wLength));
 291                 goto exit;
 292         }
 293
 294         spin_lock_irqsave(&desc->iuspin, flags);
 295         responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
 296         if (!desc->resp_count++ && !responding
 297                 && !test_bit(WDM_DISCONNECTING, &desc->flags)
 298                 && !test_bit(WDM_SUSPENDING, &desc->flags)) {
 299                 rv = usb_submit_urb(desc->response, GFP_ATOMIC);
 300                 dev_dbg(&desc->intf->dev, "submit response URB %d\n", rv);
 301         }
 302         spin_unlock_irqrestore(&desc->iuspin, flags);
 303         if (rv < 0) {
 304                 clear_bit(WDM_RESPONDING, &desc->flags);
 305                 if (rv == -EPERM)
 306                         return;
 307                 if (rv == -ENOMEM) {
 308 sw:
 309                         rv = schedule_work(&desc->rxwork);
 310                         if (rv)
 311                                 dev_err(&desc->intf->dev,
 312                                         "Cannot schedule work\n");
 313                 }
 314         }
 315 exit:
 316         rv = usb_submit_urb(urb, GFP_ATOMIC);
 317         if (rv)
 318                 dev_err(&desc->intf->dev,
 319                         "%s - usb_submit_urb failed with result %d\n",
 320                         __func__, rv);
 321
 322 }
 323
 324 static void kill_urbs(struct wdm_device *desc)
 325 {
 326         /* the order here is essential */
 327         usb_kill_urb(desc->command);
 328         usb_kill_urb(desc->validity);
 329         usb_kill_urb(desc->response);
 330 }
 331
 332 static void free_urbs(struct wdm_device *desc)
 333 {
 334         usb_free_urb(desc->validity);
 335         usb_free_urb(desc->response);
 336         usb_free_urb(desc->command);
 337 }
 338
 339 static void cleanup(struct wdm_device *desc)
 340 {
 341         kfree(desc->sbuf);
 342         kfree(desc->inbuf);
 343         kfree(desc->orq);
 344         kfree(desc->irq);
 345         kfree(desc->ubuf);
 346         free_urbs(desc);
 347         kfree(desc);
 348 }
 349
 350 static ssize_t wdm_write
 351 (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 352 {
 353         u8 *buf;
 354         int rv = -EMSGSIZE, r, we;
 355         struct wdm_device *desc = file->private_data;
 356         struct usb_ctrlrequest *req;
 357
 358         if (count > desc->wMaxCommand)
 359                 count = desc->wMaxCommand;
 360
 361         spin_lock_irq(&desc->iuspin);
 362         we = desc->werr;
 363         desc->werr = 0;
 364         spin_unlock_irq(&desc->iuspin);
 365         if (we < 0)
 366                 return usb_translate_errors(we);
 367
 368         buf = memdup_user(buffer, count);
 369         if (IS_ERR(buf))
 370                 return PTR_ERR(buf);
 371
 372         /* concurrent writes and disconnect */
 373         r = mutex_lock_interruptible(&desc->wlock);
 374         rv = -ERESTARTSYS;
 375         if (r)
 376                 goto out_free_mem;
 377
 378         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 379                 rv = -ENODEV;
 380                 goto out_free_mem_lock;
 381         }
 382
 383         r = usb_autopm_get_interface(desc->intf);
 384         if (r < 0) {
 385                 rv = usb_translate_errors(r);
 386                 goto out_free_mem_lock;
 387         }
 388
 389         if (!(file->f_flags & O_NONBLOCK))
 390                 r = wait_event_interruptible(desc->wait, !test_bit(WDM_IN_USE,
 391                                                                 &desc->flags));
 392         else
 393                 if (test_bit(WDM_IN_USE, &desc->flags))
 394                         r = -EAGAIN;
 395
 396         if (test_bit(WDM_RESETTING, &desc->flags))
 397                 r = -EIO;
 398
 399         if (test_bit(WDM_DISCONNECTING, &desc->flags))
 400                 r = -ENODEV;
 401
 402         if (r < 0) {
 403                 rv = r;
 404                 goto out_free_mem_pm;
 405         }
 406
 407         req = desc->orq;
 408         usb_fill_control_urb(
 409                 desc->command,
 410                 interface_to_usbdev(desc->intf),
 411                 /* using common endpoint 0 */
 412                 usb_sndctrlpipe(interface_to_usbdev(desc->intf), 0),
 413                 (unsigned char *)req,
 414                 buf,
 415                 count,
 416                 wdm_out_callback,
 417                 desc
 418         );
 419
 420         req->bRequestType = (USB_DIR_OUT | USB_TYPE_CLASS |
 421                              USB_RECIP_INTERFACE);
 422         req->bRequest = USB_CDC_SEND_ENCAPSULATED_COMMAND;
 423         req->wValue = 0;
 424         req->wIndex = desc->inum; /* already converted */
 425         req->wLength = cpu_to_le16(count);
 426         set_bit(WDM_IN_USE, &desc->flags);
 427         desc->outbuf = buf;
 428
 429         rv = usb_submit_urb(desc->command, GFP_KERNEL);
 430         if (rv < 0) {
 431                 desc->outbuf = NULL;
 432                 clear_bit(WDM_IN_USE, &desc->flags);
 433                 wake_up_all(&desc->wait); /* for wdm_wait_for_response() */
 434                 dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv);
 435                 rv = usb_translate_errors(rv);
 436                 goto out_free_mem_pm;
 437         } else {
 438                 dev_dbg(&desc->intf->dev, "Tx URB has been submitted index=%d\n",
 439                         le16_to_cpu(req->wIndex));
 440         }
 441
 442         usb_autopm_put_interface(desc->intf);
 443         mutex_unlock(&desc->wlock);
 444         return count;
 445
 446 out_free_mem_pm:
 447         usb_autopm_put_interface(desc->intf);
 448 out_free_mem_lock:
 449         mutex_unlock(&desc->wlock);
 450 out_free_mem:
 451         kfree(buf);
 452         return rv;
 453 }
 454
 455 /*
 456  * Submit the read urb if resp_count is non-zero.
 457  *
 458  * Called with desc->iuspin locked
 459  */
 460 static int service_outstanding_interrupt(struct wdm_device *desc)
 461 {
 462         int rv = 0;
 463
 464         /* submit read urb only if the device is waiting for it */
 465         if (!desc->resp_count || !--desc->resp_count)
 466                 goto out;
 467
 468         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 469                 rv = -ENODEV;
 470                 goto out;
 471         }
 472         if (test_bit(WDM_RESETTING, &desc->flags)) {
 473                 rv = -EIO;
 474                 goto out;
 475         }
 476
 477         set_bit(WDM_RESPONDING, &desc->flags);
 478         spin_unlock_irq(&desc->iuspin);
 479         rv = usb_submit_urb(desc->response, GFP_KERNEL);
 480         spin_lock_irq(&desc->iuspin);
 481         if (rv) {
 482                 if (!test_bit(WDM_DISCONNECTING, &desc->flags))
 483                         dev_err(&desc->intf->dev,
 484                                 "usb_submit_urb failed with result %d\n", rv);
 485
 486                 /* make sure the next notification trigger a submit */
 487                 clear_bit(WDM_RESPONDING, &desc->flags);
 488                 desc->resp_count = 0;
 489         }
 490 out:
 491         return rv;
 492 }
 493
 494 static ssize_t wdm_read
 495 (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 496 {
 497         int rv, cntr;
 498         int i = 0;
 499         struct wdm_device *desc = file->private_data;
 500
 501
 502         rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */
 503         if (rv < 0)
 504                 return -ERESTARTSYS;
 505
 506         cntr = READ_ONCE(desc->length);
 507         if (cntr == 0) {
 508                 desc->read = 0;
 509 retry:
 510                 if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 511                         rv = -ENODEV;
 512                         goto err;
 513                 }
 514                 if (test_bit(WDM_OVERFLOW, &desc->flags)) {
 515                         clear_bit(WDM_OVERFLOW, &desc->flags);
 516                         rv = -ENOBUFS;
 517                         goto err;
 518                 }
 519                 i++;
 520                 if (file->f_flags & O_NONBLOCK) {
 521                         if (!test_bit(WDM_READ, &desc->flags)) {
 522                                 rv = -EAGAIN;
 523                                 goto err;
 524                         }
 525                         rv = 0;
 526                 } else {
 527                         rv = wait_event_interruptible(desc->wait,
 528                                 test_bit(WDM_READ, &desc->flags));
 529                 }
 530
 531                 /* may have happened while we slept */
 532                 if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 533                         rv = -ENODEV;
 534                         goto err;
 535                 }
 536                 if (test_bit(WDM_RESETTING, &desc->flags)) {
 537                         rv = -EIO;
 538                         goto err;
 539                 }
 540                 usb_mark_last_busy(interface_to_usbdev(desc->intf));
 541                 if (rv < 0) {
 542                         rv = -ERESTARTSYS;
 543                         goto err;
 544                 }
 545
 546                 spin_lock_irq(&desc->iuspin);
 547
 548                 if (desc->rerr) { /* read completed, error happened */
 549                         rv = usb_translate_errors(desc->rerr);
 550                         desc->rerr = 0;
 551                         spin_unlock_irq(&desc->iuspin);
 552                         goto err;
 553                 }
 554                 /*
 555                  * recheck whether we've lost the race
 556                  * against the completion handler
 557                  */
 558                 if (!test_bit(WDM_READ, &desc->flags)) { /* lost race */
 559                         spin_unlock_irq(&desc->iuspin);
 560                         goto retry;
 561                 }
 562
 563                 if (!desc->reslength) { /* zero length read */
 564                         dev_dbg(&desc->intf->dev, "zero length - clearing WDM_READ\n");
 565                         clear_bit(WDM_READ, &desc->flags);
 566                         rv = service_outstanding_interrupt(desc);
 567                         spin_unlock_irq(&desc->iuspin);
 568                         if (rv < 0)
 569                                 goto err;
 570                         goto retry;
 571                 }
 572                 cntr = desc->length;
 573                 spin_unlock_irq(&desc->iuspin);
 574         }
 575
 576         if (cntr > count)
 577                 cntr = count;
 578         rv = copy_to_user(buffer, desc->ubuf, cntr);
 579         if (rv > 0) {
 580                 rv = -EFAULT;
 581                 goto err;
 582         }
 583
 584         spin_lock_irq(&desc->iuspin);
 585
 586         for (i = 0; i < desc->length - cntr; i++)
 587                 desc->ubuf[i] = desc->ubuf[i + cntr];
 588
 589         desc->length -= cntr;
 590         /* in case we had outstanding data */
 591         if (!desc->length) {
 592                 clear_bit(WDM_READ, &desc->flags);
 593                 service_outstanding_interrupt(desc);
 594         }
 595         spin_unlock_irq(&desc->iuspin);
 596         rv = cntr;
 597
 598 err:
 599         mutex_unlock(&desc->rlock);
 600         return rv;
 601 }
 602
 603 static int wdm_wait_for_response(struct file *file, long timeout)
 604 {
 605         struct wdm_device *desc = file->private_data;
 606         long rv; /* Use long here because (int) MAX_SCHEDULE_TIMEOUT < 0. */
 607
 608         /*
 609          * Needs both flags. We cannot do with one because resetting it would
 610          * cause a race with write() yet we need to signal a disconnect.
 611          */
 612         rv = wait_event_interruptible_timeout(desc->wait,
 613                               !test_bit(WDM_IN_USE, &desc->flags) ||
 614                               test_bit(WDM_DISCONNECTING, &desc->flags),
 615                               timeout);
 616
 617         /*
 618          * To report the correct error. This is best effort.
 619          * We are inevitably racing with the hardware.
 620          */
 621         if (test_bit(WDM_DISCONNECTING, &desc->flags))
 622                 return -ENODEV;
 623         if (!rv)
 624                 return -EIO;
 625         if (rv < 0)
 626                 return -EINTR;
 627
 628         spin_lock_irq(&desc->iuspin);
 629         rv = desc->werr;
 630         desc->werr = 0;
 631         spin_unlock_irq(&desc->iuspin);
 632
 633         return usb_translate_errors(rv);
 634
 635 }
 636
 637 /*
 638  * You need to send a signal when you react to malicious or defective hardware.
 639  * Also, don't abort when fsync() returned -EINVAL, for older kernels which do
 640  * not implement wdm_flush() will return -EINVAL.
 641  */
 642 static int wdm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 643 {
 644         return wdm_wait_for_response(file, MAX_SCHEDULE_TIMEOUT);
 645 }
 646
 647 /*
 648  * Same with wdm_fsync(), except it uses finite timeout in order to react to
 649  * malicious or defective hardware which ceased communication after close() was
 650  * implicitly called due to process termination.
 651  */
 652 static int wdm_flush(struct file *file, fl_owner_t id)
 653 {
 654         return wdm_wait_for_response(file, WDM_FLUSH_TIMEOUT);
 655 }
 656
 657 static __poll_t wdm_poll(struct file *file, struct poll_table_struct *wait)
 658 {
 659         struct wdm_device *desc = file->private_data;
 660         unsigned long flags;
 661         __poll_t mask = 0;
 662
 663         spin_lock_irqsave(&desc->iuspin, flags);
 664         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 665                 mask = EPOLLHUP | EPOLLERR;
 666                 spin_unlock_irqrestore(&desc->iuspin, flags);
 667                 goto desc_out;
 668         }
 669         if (test_bit(WDM_READ, &desc->flags))
 670                 mask = EPOLLIN | EPOLLRDNORM;
 671         if (desc->rerr || desc->werr)
 672                 mask |= EPOLLERR;
 673         if (!test_bit(WDM_IN_USE, &desc->flags))
 674                 mask |= EPOLLOUT | EPOLLWRNORM;
 675         spin_unlock_irqrestore(&desc->iuspin, flags);
 676
 677         poll_wait(file, &desc->wait, wait);
 678
 679 desc_out:
 680         return mask;
 681 }
 682
 683 static int wdm_open(struct inode *inode, struct file *file)
 684 {
 685         int minor = iminor(inode);
 686         int rv = -ENODEV;
 687         struct usb_interface *intf;
 688         struct wdm_device *desc;
 689
 690         mutex_lock(&wdm_mutex);
 691         desc = wdm_find_device_by_minor(minor);
 692         if (!desc)
 693                 goto out;
 694
 695         intf = desc->intf;
 696         if (test_bit(WDM_DISCONNECTING, &desc->flags))
 697                 goto out;
 698         file->private_data = desc;
 699
 700         rv = usb_autopm_get_interface(desc->intf);
 701         if (rv < 0) {
 702                 dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
 703                 goto out;
 704         }
 705
 706         /* using write lock to protect desc->count */
 707         mutex_lock(&desc->wlock);
 708         if (!desc->count++) {
 709                 desc->werr = 0;
 710                 desc->rerr = 0;
 711                 rv = usb_submit_urb(desc->validity, GFP_KERNEL);
 712                 if (rv < 0) {
 713                         desc->count--;
 714                         dev_err(&desc->intf->dev,
 715                                 "Error submitting int urb - %d\n", rv);
 716                         rv = usb_translate_errors(rv);
 717                 }
 718         } else {
 719                 rv = 0;
 720         }
 721         mutex_unlock(&desc->wlock);
 722         if (desc->count == 1)
 723                 desc->manage_power(intf, 1);
 724         usb_autopm_put_interface(desc->intf);
 725 out:
 726         mutex_unlock(&wdm_mutex);
 727         return rv;
 728 }
 729
 730 static int wdm_release(struct inode *inode, struct file *file)
 731 {
 732         struct wdm_device *desc = file->private_data;
 733
 734         mutex_lock(&wdm_mutex);
 735
 736         /* using write lock to protect desc->count */
 737         mutex_lock(&desc->wlock);
 738         desc->count--;
 739         mutex_unlock(&desc->wlock);
 740
 741         if (!desc->count) {
 742                 if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
 743                         dev_dbg(&desc->intf->dev, "wdm_release: cleanup\n");
 744                         kill_urbs(desc);
 745                         spin_lock_irq(&desc->iuspin);
 746                         desc->resp_count = 0;
 747                         spin_unlock_irq(&desc->iuspin);
 748                         desc->manage_power(desc->intf, 0);
 749                 } else {
 750                         /* must avoid dev_printk here as desc->intf is invalid */
 751                         pr_debug(KBUILD_MODNAME " %s: device gone - cleaning up\n", __func__);
 752                         cleanup(desc);
 753                 }
 754         }
 755         mutex_unlock(&wdm_mutex);
 756         return 0;
 757 }
 758
 759 static long wdm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 760 {
 761         struct wdm_device *desc = file->private_data;
 762         int rv = 0;
 763
 764         switch (cmd) {
 765         case IOCTL_WDM_MAX_COMMAND:
 766                 if (copy_to_user((void __user *)arg, &desc->wMaxCommand, sizeof(desc->wMaxCommand)))
 767                         rv = -EFAULT;
 768                 break;
 769         default:
 770                 rv = -ENOTTY;
 771         }
 772         return rv;
 773 }
 774
 775 static const struct file_operations wdm_fops = {
 776         .owner =        THIS_MODULE,
 777         .read =         wdm_read,
 778         .write =        wdm_write,
 779         .fsync =        wdm_fsync,
 780         .open =         wdm_open,
 781         .flush =        wdm_flush,
 782         .release =      wdm_release,
 783         .poll =         wdm_poll,
 784         .unlocked_ioctl = wdm_ioctl,
 785         .compat_ioctl = compat_ptr_ioctl,
 786         .llseek =       noop_llseek,
 787 };
 788
 789 static struct usb_class_driver wdm_class = {
 790         .name =         "cdc-wdm%d",
 791         .fops =         &wdm_fops,
 792         .minor_base =   WDM_MINOR_BASE,
 793 };
 794
 795 /* --- error handling --- */
 796 static void wdm_rxwork(struct work_struct *work)
 797 {
 798         struct wdm_device *desc = container_of(work, struct wdm_device, rxwork);
 799         unsigned long flags;
 800         int rv = 0;
 801         int responding;
 802
 803         spin_lock_irqsave(&desc->iuspin, flags);
 804         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
 805                 spin_unlock_irqrestore(&desc->iuspin, flags);
 806         } else {
 807                 responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
 808                 spin_unlock_irqrestore(&desc->iuspin, flags);
 809                 if (!responding)
 810                         rv = usb_submit_urb(desc->response, GFP_KERNEL);
 811                 if (rv < 0 && rv != -EPERM) {
 812                         spin_lock_irqsave(&desc->iuspin, flags);
 813                         clear_bit(WDM_RESPONDING, &desc->flags);
 814                         if (!test_bit(WDM_DISCONNECTING, &desc->flags))
 815                                 schedule_work(&desc->rxwork);
 816                         spin_unlock_irqrestore(&desc->iuspin, flags);
 817                 }
 818         }
 819 }
 820
 821 static void service_interrupt_work(struct work_struct *work)
 822 {
 823         struct wdm_device *desc;
 824
 825         desc = container_of(work, struct wdm_device, service_outs_intr);
 826
 827         spin_lock_irq(&desc->iuspin);
 828         service_outstanding_interrupt(desc);
 829         if (!desc->resp_count) {
 830                 set_bit(WDM_READ, &desc->flags);
 831                 wake_up(&desc->wait);
 832         }
 833         spin_unlock_irq(&desc->iuspin);
 834 }
 835
 836 /* --- hotplug --- */
 837
 838 static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
 839                 u16 bufsize, int (*manage_power)(struct usb_interface *, int))
 840 {
 841         int rv = -ENOMEM;
 842         struct wdm_device *desc;
 843
 844         desc = kzalloc(sizeof(struct wdm_device), GFP_KERNEL);
 845         if (!desc)
 846                 goto out;
 847         INIT_LIST_HEAD(&desc->device_list);
 848         mutex_init(&desc->rlock);
 849         mutex_init(&desc->wlock);
 850         spin_lock_init(&desc->iuspin);
 851         init_waitqueue_head(&desc->wait);
 852         desc->wMaxCommand = bufsize;
 853         /* this will be expanded and needed in hardware endianness */
 854         desc->inum = cpu_to_le16((u16)intf->cur_altsetting->desc.bInterfaceNumber);
 855         desc->intf = intf;
 856         INIT_WORK(&desc->rxwork, wdm_rxwork);
 857         INIT_WORK(&desc->service_outs_intr, service_interrupt_work);
 858
 859         rv = -EINVAL;
 860         if (!usb_endpoint_is_int_in(ep))
 861                 goto err;
 862
 863         desc->wMaxPacketSize = usb_endpoint_maxp(ep);
 864
 865         desc->orq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
 866         if (!desc->orq)
 867                 goto err;
 868         desc->irq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
 869         if (!desc->irq)
 870                 goto err;
 871
 872         desc->validity = usb_alloc_urb(0, GFP_KERNEL);
 873         if (!desc->validity)
 874                 goto err;
 875
 876         desc->response = usb_alloc_urb(0, GFP_KERNEL);
 877         if (!desc->response)
 878                 goto err;
 879
 880         desc->command = usb_alloc_urb(0, GFP_KERNEL);
 881         if (!desc->command)
 882                 goto err;
 883
 884         desc->ubuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
 885         if (!desc->ubuf)
 886                 goto err;
 887
 888         desc->sbuf = kmalloc(desc->wMaxPacketSize, GFP_KERNEL);
 889         if (!desc->sbuf)
 890                 goto err;
 891
 892         desc->inbuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
 893         if (!desc->inbuf)
 894                 goto err;
 895
 896         usb_fill_int_urb(
 897                 desc->validity,
 898                 interface_to_usbdev(intf),
 899                 usb_rcvintpipe(interface_to_usbdev(intf), ep->bEndpointAddress),
 900                 desc->sbuf,
 901                 desc->wMaxPacketSize,
 902                 wdm_int_callback,
 903                 desc,
 904                 ep->bInterval
 905         );
 906
 907         desc->irq->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
 908         desc->irq->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
 909         desc->irq->wValue = 0;
 910         desc->irq->wIndex = desc->inum; /* already converted */
 911         desc->irq->wLength = cpu_to_le16(desc->wMaxCommand);
 912
 913         usb_fill_control_urb(
 914                 desc->response,
 915                 interface_to_usbdev(intf),
 916                 /* using common endpoint 0 */
 917                 usb_rcvctrlpipe(interface_to_usbdev(desc->intf), 0),
 918                 (unsigned char *)desc->irq,
 919                 desc->inbuf,
 920                 desc->wMaxCommand,
 921                 wdm_in_callback,
 922                 desc
 923         );
 924
 925         desc->manage_power = manage_power;
 926
 927         spin_lock(&wdm_device_list_lock);
 928         list_add(&desc->device_list, &wdm_device_list);
 929         spin_unlock(&wdm_device_list_lock);
 930
 931         rv = usb_register_dev(intf, &wdm_class);
 932         if (rv < 0)
 933                 goto err;
 934         else
 935                 dev_info(&intf->dev, "%s: USB WDM device\n", dev_name(intf->usb_dev));
 936 out:
 937         return rv;
 938 err:
 939         spin_lock(&wdm_device_list_lock);
 940         list_del(&desc->device_list);
 941         spin_unlock(&wdm_device_list_lock);
 942         cleanup(desc);
 943         return rv;
 944 }
 945
 946 static int wdm_manage_power(struct usb_interface *intf, int on)
 947 {
 948         /* need autopm_get/put here to ensure the usbcore sees the new value */
 949         int rv = usb_autopm_get_interface(intf);
 950
 951         intf->needs_remote_wakeup = on;
 952         if (!rv)
 953                 usb_autopm_put_interface(intf);
 954         return 0;
 955 }
 956
 957 static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id)
 958 {
 959         int rv = -EINVAL;
 960         struct usb_host_interface *iface;
 961         struct usb_endpoint_descriptor *ep;
 962         struct usb_cdc_parsed_header hdr;
 963         u8 *buffer = intf->altsetting->extra;
 964         int buflen = intf->altsetting->extralen;
 965         u16 maxcom = WDM_DEFAULT_BUFSIZE;
 966
 967         if (!buffer)
 968                 goto err;
 969
 970         cdc_parse_cdc_header(&hdr, intf, buffer, buflen);
 971
 972         if (hdr.usb_cdc_dmm_desc)
 973                 maxcom = le16_to_cpu(hdr.usb_cdc_dmm_desc->wMaxCommand);
 974
 975         iface = intf->cur_altsetting;
 976         if (iface->desc.bNumEndpoints != 1)
 977                 goto err;
 978         ep = &iface->endpoint[0].desc;
 979
 980         rv = wdm_create(intf, ep, maxcom, &wdm_manage_power);
 981
 982 err:
 983         return rv;
 984 }
 985
 986 /**
 987  * usb_cdc_wdm_register - register a WDM subdriver
 988  * @intf: usb interface the subdriver will associate with
 989  * @ep: interrupt endpoint to monitor for notifications
 990  * @bufsize: maximum message size to support for read/write
 991  * @manage_power: call-back invoked during open and release to
 992  *                manage the device's power
 993  * Create WDM usb class character device and associate it with intf
 994  * without binding, allowing another driver to manage the interface.
 995  *
 996  * The subdriver will manage the given interrupt endpoint exclusively
 997  * and will issue control requests referring to the given intf. It
 998  * will otherwise avoid interferring, and in particular not do
 999  * usb_set_intfdata/usb_get_intfdata on intf.
1000  *
1001  * The return value is a pointer to the subdriver's struct usb_driver.
1002  * The registering driver is responsible for calling this subdriver's
1003  * disconnect, suspend, resume, pre_reset and post_reset methods from
1004  * its own.
1005  */
1006 struct usb_driver *usb_cdc_wdm_register(struct usb_interface *intf,
1007                                         struct usb_endpoint_descriptor *ep,
1008                                         int bufsize,
1009                                         int (*manage_power)(struct usb_interface *, int))
1010 {
1011         int rv;
1012
1013         rv = wdm_create(intf, ep, bufsize, manage_power);
1014         if (rv < 0)
1015                 goto err;
1016
1017         return &wdm_driver;
1018 err:
1019         return ERR_PTR(rv);
1020 }
1021 EXPORT_SYMBOL(usb_cdc_wdm_register);
1022
1023 static void wdm_disconnect(struct usb_interface *intf)
1024 {
1025         struct wdm_device *desc;
1026         unsigned long flags;
1027
1028         usb_deregister_dev(intf, &wdm_class);
1029         desc = wdm_find_device(intf);
1030         mutex_lock(&wdm_mutex);
1031
1032         /* the spinlock makes sure no new urbs are generated in the callbacks */
1033         spin_lock_irqsave(&desc->iuspin, flags);
1034         set_bit(WDM_DISCONNECTING, &desc->flags);
1035         set_bit(WDM_READ, &desc->flags);
1036         spin_unlock_irqrestore(&desc->iuspin, flags);
1037         wake_up_all(&desc->wait);
1038         mutex_lock(&desc->rlock);
1039         mutex_lock(&desc->wlock);
1040         cancel_work_sync(&desc->rxwork);
1041         cancel_work_sync(&desc->service_outs_intr);
1042         kill_urbs(desc);
1043         mutex_unlock(&desc->wlock);
1044         mutex_unlock(&desc->rlock);
1045
1046         /* the desc->intf pointer used as list key is now invalid */
1047         spin_lock(&wdm_device_list_lock);
1048         list_del(&desc->device_list);
1049         spin_unlock(&wdm_device_list_lock);
1050
1051         if (!desc->count)
1052                 cleanup(desc);
1053         else
1054                 dev_dbg(&intf->dev, "%d open files - postponing cleanup\n", desc->count);
1055         mutex_unlock(&wdm_mutex);
1056 }
1057
1058 #ifdef CONFIG_PM
1059 static int wdm_suspend(struct usb_interface *intf, pm_message_t message)
1060 {
1061         struct wdm_device *desc = wdm_find_device(intf);
1062         int rv = 0;
1063
1064         dev_dbg(&desc->intf->dev, "wdm%d_suspend\n", intf->minor);
1065
1066         /* if this is an autosuspend the caller does the locking */
1067         if (!PMSG_IS_AUTO(message)) {
1068                 mutex_lock(&desc->rlock);
1069                 mutex_lock(&desc->wlock);
1070         }
1071         spin_lock_irq(&desc->iuspin);
1072
1073         if (PMSG_IS_AUTO(message) &&
1074                         (test_bit(WDM_IN_USE, &desc->flags)
1075                         || test_bit(WDM_RESPONDING, &desc->flags))) {
1076                 spin_unlock_irq(&desc->iuspin);
1077                 rv = -EBUSY;
1078         } else {
1079
1080                 set_bit(WDM_SUSPENDING, &desc->flags);
1081                 spin_unlock_irq(&desc->iuspin);
1082                 /* callback submits work - order is essential */
1083                 kill_urbs(desc);
1084                 cancel_work_sync(&desc->rxwork);
1085                 cancel_work_sync(&desc->service_outs_intr);
1086         }
1087         if (!PMSG_IS_AUTO(message)) {
1088                 mutex_unlock(&desc->wlock);
1089                 mutex_unlock(&desc->rlock);
1090         }
1091
1092         return rv;
1093 }
1094 #endif
1095
1096 static int recover_from_urb_loss(struct wdm_device *desc)
1097 {
1098         int rv = 0;
1099
1100         if (desc->count) {
1101                 rv = usb_submit_urb(desc->validity, GFP_NOIO);
1102                 if (rv < 0)
1103                         dev_err(&desc->intf->dev,
1104                                 "Error resume submitting int urb - %d\n", rv);
1105         }
1106         return rv;
1107 }
1108
1109 #ifdef CONFIG_PM
1110 static int wdm_resume(struct usb_interface *intf)
1111 {
1112         struct wdm_device *desc = wdm_find_device(intf);
1113         int rv;
1114
1115         dev_dbg(&desc->intf->dev, "wdm%d_resume\n", intf->minor);
1116
1117         clear_bit(WDM_SUSPENDING, &desc->flags);
1118         rv = recover_from_urb_loss(desc);
1119
1120         return rv;
1121 }
1122 #endif
1123
1124 static int wdm_pre_reset(struct usb_interface *intf)
1125 {
1126         struct wdm_device *desc = wdm_find_device(intf);
1127
1128         /*
1129          * we notify everybody using poll of
1130          * an exceptional situation
1131          * must be done before recovery lest a spontaneous
1132          * message from the device is lost
1133          */
1134         spin_lock_irq(&desc->iuspin);
1135         set_bit(WDM_RESETTING, &desc->flags);   /* inform read/write */
1136         set_bit(WDM_READ, &desc->flags);        /* unblock read */
1137         clear_bit(WDM_IN_USE, &desc->flags);    /* unblock write */
1138         desc->rerr = -EINTR;
1139         spin_unlock_irq(&desc->iuspin);
1140         wake_up_all(&desc->wait);
1141         mutex_lock(&desc->rlock);
1142         mutex_lock(&desc->wlock);
1143         kill_urbs(desc);
1144         cancel_work_sync(&desc->rxwork);
1145         cancel_work_sync(&desc->service_outs_intr);
1146         return 0;
1147 }
1148
1149 static int wdm_post_reset(struct usb_interface *intf)
1150 {
1151         struct wdm_device *desc = wdm_find_device(intf);
1152         int rv;
1153
1154         clear_bit(WDM_OVERFLOW, &desc->flags);
1155         clear_bit(WDM_RESETTING, &desc->flags);
1156         rv = recover_from_urb_loss(desc);
1157         mutex_unlock(&desc->wlock);
1158         mutex_unlock(&desc->rlock);
1159         return rv;
1160 }
1161
1162 static struct usb_driver wdm_driver = {
1163         .name =         "cdc_wdm",
1164         .probe =        wdm_probe,
1165         .disconnect =   wdm_disconnect,
1166 #ifdef CONFIG_PM
1167         .suspend =      wdm_suspend,
1168         .resume =       wdm_resume,
1169         .reset_resume = wdm_resume,
1170 #endif
1171         .pre_reset =    wdm_pre_reset,
1172         .post_reset =   wdm_post_reset,
1173         .id_table =     wdm_ids,
1174         .supports_autosuspend = 1,
1175         .disable_hub_initiated_lpm = 1,
1176 };
1177
1178 module_usb_driver(wdm_driver);
1179
1180 MODULE_AUTHOR(DRIVER_AUTHOR);
1181 MODULE_DESCRIPTION(DRIVER_DESC);
1182 MODULE_LICENSE("GPL");