drivers/net/usb/cdc_ether.c

   1 /*
   2  * CDC Ethernet based networking peripherals
   3  * Copyright (C) 2003-2005 by David Brownell
   4  * Copyright (C) 2006 by Ole Andre Vadla Ravnas (ActiveSync)
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 // #define      DEBUG                   // error path messages, extra info
  22 // #define      VERBOSE                 // more; success messages
  23
  24 #include <linux/module.h>
  25 #include <linux/init.h>
  26 #include <linux/netdevice.h>
  27 #include <linux/etherdevice.h>
  28 #include <linux/ethtool.h>
  29 #include <linux/workqueue.h>
  30 #include <linux/mii.h>
  31 #include <linux/usb.h>
  32 #include <linux/usb/cdc.h>
  33 #include <linux/usb/usbnet.h>
  34
  35
  36 #if defined(CONFIG_USB_NET_RNDIS_HOST) || defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
  37
  38 static int is_rndis(struct usb_interface_descriptor *desc)
  39 {
  40         return desc->bInterfaceClass == USB_CLASS_COMM
  41                 && desc->bInterfaceSubClass == 2
  42                 && desc->bInterfaceProtocol == 0xff;
  43 }
  44
  45 static int is_activesync(struct usb_interface_descriptor *desc)
  46 {
  47         return desc->bInterfaceClass == USB_CLASS_MISC
  48                 && desc->bInterfaceSubClass == 1
  49                 && desc->bInterfaceProtocol == 1;
  50 }
  51
  52 static int is_wireless_rndis(struct usb_interface_descriptor *desc)
  53 {
  54         return desc->bInterfaceClass == USB_CLASS_WIRELESS_CONTROLLER
  55                 && desc->bInterfaceSubClass == 1
  56                 && desc->bInterfaceProtocol == 3;
  57 }
  58
  59 #else
  60
  61 #define is_rndis(desc)          0
  62 #define is_activesync(desc)     0
  63 #define is_wireless_rndis(desc) 0
  64
  65 #endif
  66
  67 /*
  68  * probes control interface, claims data interface, collects the bulk
  69  * endpoints, activates data interface (if needed), maybe sets MTU.
  70  * all pure cdc, except for certain firmware workarounds, and knowing
  71  * that rndis uses one different rule.
  72  */
  73 int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
  74 {
  75         u8                              *buf = intf->cur_altsetting->extra;
  76         int                             len = intf->cur_altsetting->extralen;
  77         struct usb_interface_descriptor *d;
  78         struct cdc_state                *info = (void *) &dev->data;
  79         int                             status;
  80         int                             rndis;
  81         struct usb_driver               *driver = driver_of(intf);
  82
  83         if (sizeof dev->data < sizeof *info)
  84                 return -EDOM;
  85
  86         /* expect strict spec conformance for the descriptors, but
  87          * cope with firmware which stores them in the wrong place
  88          */
  89         if (len == 0 && dev->udev->actconfig->extralen) {
  90                 /* Motorola SB4100 (and others: Brad Hards says it's
  91                  * from a Broadcom design) put CDC descriptors here
  92                  */
  93                 buf = dev->udev->actconfig->extra;
  94                 len = dev->udev->actconfig->extralen;
  95                 if (len)
  96                         dev_dbg(&intf->dev,
  97                                 "CDC descriptors on config\n");
  98         }
  99
 100         /* Maybe CDC descriptors are after the endpoint?  This bug has
 101          * been seen on some 2Wire Inc RNDIS-ish products.
 102          */
 103         if (len == 0) {
 104                 struct usb_host_endpoint        *hep;
 105
 106                 hep = intf->cur_altsetting->endpoint;
 107                 if (hep) {
 108                         buf = hep->extra;
 109                         len = hep->extralen;
 110                 }
 111                 if (len)
 112                         dev_dbg(&intf->dev,
 113                                 "CDC descriptors on endpoint\n");
 114         }
 115
 116         /* this assumes that if there's a non-RNDIS vendor variant
 117          * of cdc-acm, it'll fail RNDIS requests cleanly.
 118          */
 119         rndis = is_rndis(&intf->cur_altsetting->desc)
 120                 || is_activesync(&intf->cur_altsetting->desc)
 121                 || is_wireless_rndis(&intf->cur_altsetting->desc);
 122
 123         memset(info, 0, sizeof *info);
 124         info->control = intf;
 125         while (len > 3) {
 126                 if (buf [1] != USB_DT_CS_INTERFACE)
 127                         goto next_desc;
 128
 129                 /* use bDescriptorSubType to identify the CDC descriptors.
 130                  * We expect devices with CDC header and union descriptors.
 131                  * For CDC Ethernet we need the ethernet descriptor.
 132                  * For RNDIS, ignore two (pointless) CDC modem descriptors
 133                  * in favor of a complicated OID-based RPC scheme doing what
 134                  * CDC Ethernet achieves with a simple descriptor.
 135                  */
 136                 switch (buf [2]) {
 137                 case USB_CDC_HEADER_TYPE:
 138                         if (info->header) {
 139                                 dev_dbg(&intf->dev, "extra CDC header\n");
 140                                 goto bad_desc;
 141                         }
 142                         info->header = (void *) buf;
 143                         if (info->header->bLength != sizeof *info->header) {
 144                                 dev_dbg(&intf->dev, "CDC header len %u\n",
 145                                         info->header->bLength);
 146                                 goto bad_desc;
 147                         }
 148                         break;
 149                 case USB_CDC_ACM_TYPE:
 150                         /* paranoia:  disambiguate a "real" vendor-specific
 151                          * modem interface from an RNDIS non-modem.
 152                          */
 153                         if (rndis) {
 154                                 struct usb_cdc_acm_descriptor *acm;
 155
 156                                 acm = (void *) buf;
 157                                 if (acm->bmCapabilities) {
 158                                         dev_dbg(&intf->dev,
 159                                                 "ACM capabilities %02x, "
 160                                                 "not really RNDIS?\n",
 161                                                 acm->bmCapabilities);
 162                                         goto bad_desc;
 163                                 }
 164                         }
 165                         break;
 166                 case USB_CDC_UNION_TYPE:
 167                         if (info->u) {
 168                                 dev_dbg(&intf->dev, "extra CDC union\n");
 169                                 goto bad_desc;
 170                         }
 171                         info->u = (void *) buf;
 172                         if (info->u->bLength != sizeof *info->u) {
 173                                 dev_dbg(&intf->dev, "CDC union len %u\n",
 174                                         info->u->bLength);
 175                                 goto bad_desc;
 176                         }
 177
 178                         /* we need a master/control interface (what we're
 179                          * probed with) and a slave/data interface; union
 180                          * descriptors sort this all out.
 181                          */
 182                         info->control = usb_ifnum_to_if(dev->udev,
 183                                                 info->u->bMasterInterface0);
 184                         info->data = usb_ifnum_to_if(dev->udev,
 185                                                 info->u->bSlaveInterface0);
 186                         if (!info->control || !info->data) {
 187                                 dev_dbg(&intf->dev,
 188                                         "master #%u/%p slave #%u/%p\n",
 189                                         info->u->bMasterInterface0,
 190                                         info->control,
 191                                         info->u->bSlaveInterface0,
 192                                         info->data);
 193                                 goto bad_desc;
 194                         }
 195                         if (info->control != intf) {
 196                                 dev_dbg(&intf->dev, "bogus CDC Union\n");
 197                                 /* Ambit USB Cable Modem (and maybe others)
 198                                  * interchanges master and slave interface.
 199                                  */
 200                                 if (info->data == intf) {
 201                                         info->data = info->control;
 202                                         info->control = intf;
 203                                 } else
 204                                         goto bad_desc;
 205                         }
 206
 207                         /* a data interface altsetting does the real i/o */
 208                         d = &info->data->cur_altsetting->desc;
 209                         if (d->bInterfaceClass != USB_CLASS_CDC_DATA) {
 210                                 dev_dbg(&intf->dev, "slave class %u\n",
 211                                         d->bInterfaceClass);
 212                                 goto bad_desc;
 213                         }
 214                         break;
 215                 case USB_CDC_ETHERNET_TYPE:
 216                         if (info->ether) {
 217                                 dev_dbg(&intf->dev, "extra CDC ether\n");
 218                                 goto bad_desc;
 219                         }
 220                         info->ether = (void *) buf;
 221                         if (info->ether->bLength != sizeof *info->ether) {
 222                                 dev_dbg(&intf->dev, "CDC ether len %u\n",
 223                                         info->ether->bLength);
 224                                 goto bad_desc;
 225                         }
 226                         dev->hard_mtu = le16_to_cpu(
 227                                                 info->ether->wMaxSegmentSize);
 228                         /* because of Zaurus, we may be ignoring the host
 229                          * side link address we were given.
 230                          */
 231                         break;
 232                 }
 233 next_desc:
 234                 len -= buf [0]; /* bLength */
 235                 buf += buf [0];
 236         }
 237
 238         /* Microsoft ActiveSync based and some regular RNDIS devices lack the
 239          * CDC descriptors, so we'll hard-wire the interfaces and not check
 240          * for descriptors.
 241          */
 242         if (rndis && !info->u) {
 243                 info->control = usb_ifnum_to_if(dev->udev, 0);
 244                 info->data = usb_ifnum_to_if(dev->udev, 1);
 245                 if (!info->control || !info->data) {
 246                         dev_dbg(&intf->dev,
 247                                 "rndis: master #0/%p slave #1/%p\n",
 248                                 info->control,
 249                                 info->data);
 250                         goto bad_desc;
 251                 }
 252
 253         } else if (!info->header || !info->u || (!rndis && !info->ether)) {
 254                 dev_dbg(&intf->dev, "missing cdc %s%s%sdescriptor\n",
 255                         info->header ? "" : "header ",
 256                         info->u ? "" : "union ",
 257                         info->ether ? "" : "ether ");
 258                 goto bad_desc;
 259         }
 260
 261         /* claim data interface and set it up ... with side effects.
 262          * network traffic can't flow until an altsetting is enabled.
 263          */
 264         status = usb_driver_claim_interface(driver, info->data, dev);
 265         if (status < 0)
 266                 return status;
 267         status = usbnet_get_endpoints(dev, info->data);
 268         if (status < 0) {
 269                 /* ensure immediate exit from usbnet_disconnect */
 270                 usb_set_intfdata(info->data, NULL);
 271                 usb_driver_release_interface(driver, info->data);
 272                 return status;
 273         }
 274
 275         /* status endpoint: optional for CDC Ethernet, not RNDIS (or ACM) */
 276         dev->status = NULL;
 277         if (info->control->cur_altsetting->desc.bNumEndpoints == 1) {
 278                 struct usb_endpoint_descriptor  *desc;
 279
 280                 dev->status = &info->control->cur_altsetting->endpoint [0];
 281                 desc = &dev->status->desc;
 282                 if (!usb_endpoint_is_int_in(desc)
 283                                 || (le16_to_cpu(desc->wMaxPacketSize)
 284                                         < sizeof(struct usb_cdc_notification))
 285                                 || !desc->bInterval) {
 286                         dev_dbg(&intf->dev, "bad notification endpoint\n");
 287                         dev->status = NULL;
 288                 }
 289         }
 290         if (rndis && !dev->status) {
 291                 dev_dbg(&intf->dev, "missing RNDIS status endpoint\n");
 292                 usb_set_intfdata(info->data, NULL);
 293                 usb_driver_release_interface(driver, info->data);
 294                 return -ENODEV;
 295         }
 296         return 0;
 297
 298 bad_desc:
 299         dev_info(&dev->udev->dev, "bad CDC descriptors\n");
 300         return -ENODEV;
 301 }
 302 EXPORT_SYMBOL_GPL(usbnet_generic_cdc_bind);
 303
 304 void usbnet_cdc_unbind(struct usbnet *dev, struct usb_interface *intf)
 305 {
 306         struct cdc_state                *info = (void *) &dev->data;
 307         struct usb_driver               *driver = driver_of(intf);
 308
 309         /* disconnect master --> disconnect slave */
 310         if (intf == info->control && info->data) {
 311                 /* ensure immediate exit from usbnet_disconnect */
 312                 usb_set_intfdata(info->data, NULL);
 313                 usb_driver_release_interface(driver, info->data);
 314                 info->data = NULL;
 315         }
 316
 317         /* and vice versa (just in case) */
 318         else if (intf == info->data && info->control) {
 319                 /* ensure immediate exit from usbnet_disconnect */
 320                 usb_set_intfdata(info->control, NULL);
 321                 usb_driver_release_interface(driver, info->control);
 322                 info->control = NULL;
 323         }
 324 }
 325 EXPORT_SYMBOL_GPL(usbnet_cdc_unbind);
 326
 327 /*-------------------------------------------------------------------------
 328  *
 329  * Communications Device Class, Ethernet Control model
 330  *
 331  * Takes two interfaces.  The DATA interface is inactive till an altsetting
 332  * is selected.  Configuration data includes class descriptors.  There's
 333  * an optional status endpoint on the control interface.
 334  *
 335  * This should interop with whatever the 2.4 "CDCEther.c" driver
 336  * (by Brad Hards) talked with, with more functionality.
 337  *
 338  *-------------------------------------------------------------------------*/
 339
 340 static void dumpspeed(struct usbnet *dev, __le32 *speeds)
 341 {
 342         if (netif_msg_timer(dev))
 343                 devinfo(dev, "link speeds: %u kbps up, %u kbps down",
 344                         __le32_to_cpu(speeds[0]) / 1000,
 345                 __le32_to_cpu(speeds[1]) / 1000);
 346 }
 347
 348 static void cdc_status(struct usbnet *dev, struct urb *urb)
 349 {
 350         struct usb_cdc_notification     *event;
 351
 352         if (urb->actual_length < sizeof *event)
 353                 return;
 354
 355         /* SPEED_CHANGE can get split into two 8-byte packets */
 356         if (test_and_clear_bit(EVENT_STS_SPLIT, &dev->flags)) {
 357                 dumpspeed(dev, (__le32 *) urb->transfer_buffer);
 358                 return;
 359         }
 360
 361         event = urb->transfer_buffer;
 362         switch (event->bNotificationType) {
 363         case USB_CDC_NOTIFY_NETWORK_CONNECTION:
 364                 if (netif_msg_timer(dev))
 365                         devdbg(dev, "CDC: carrier %s",
 366                                         event->wValue ? "on" : "off");
 367                 if (event->wValue)
 368                         netif_carrier_on(dev->net);
 369                 else
 370                         netif_carrier_off(dev->net);
 371                 break;
 372         case USB_CDC_NOTIFY_SPEED_CHANGE:       /* tx/rx rates */
 373                 if (netif_msg_timer(dev))
 374                         devdbg(dev, "CDC: speed change (len %d)",
 375                                         urb->actual_length);
 376                 if (urb->actual_length != (sizeof *event + 8))
 377                         set_bit(EVENT_STS_SPLIT, &dev->flags);
 378                 else
 379                         dumpspeed(dev, (__le32 *) &event[1]);
 380                 break;
 381         /* USB_CDC_NOTIFY_RESPONSE_AVAILABLE can happen too (e.g. RNDIS),
 382          * but there are no standard formats for the response data.
 383          */
 384         default:
 385                 deverr(dev, "CDC: unexpected notification %02x!",
 386                                  event->bNotificationType);
 387                 break;
 388         }
 389 }
 390
 391 static int cdc_bind(struct usbnet *dev, struct usb_interface *intf)
 392 {
 393         int                             status;
 394         struct cdc_state                *info = (void *) &dev->data;
 395
 396         status = usbnet_generic_cdc_bind(dev, intf);
 397         if (status < 0)
 398                 return status;
 399
 400         status = usbnet_get_ethernet_addr(dev, info->ether->iMACAddress);
 401         if (status < 0) {
 402                 usb_set_intfdata(info->data, NULL);
 403                 usb_driver_release_interface(driver_of(intf), info->data);
 404                 return status;
 405         }
 406
 407         /* FIXME cdc-ether has some multicast code too, though it complains
 408          * in routine cases.  info->ether describes the multicast support.
 409          * Implement that here, manipulating the cdc filter as needed.
 410          */
 411         return 0;
 412 }
 413
 414 static const struct driver_info cdc_info = {
 415         .description =  "CDC Ethernet Device",
 416         .flags =        FLAG_ETHER,
 417         // .check_connect = cdc_check_connect,
 418         .bind =         cdc_bind,
 419         .unbind =       usbnet_cdc_unbind,
 420         .status =       cdc_status,
 421 };
 422
 423 /*-------------------------------------------------------------------------*/
 424
 425
 426 static const struct usb_device_id       products [] = {
 427 /*
 428  * BLACKLIST !!
 429  *
 430  * First blacklist any products that are egregiously nonconformant
 431  * with the CDC Ethernet specs.  Minor braindamage we cope with; when
 432  * they're not even trying, needing a separate driver is only the first
 433  * of the differences to show up.
 434  */
 435
 436 #define ZAURUS_MASTER_INTERFACE \
 437         .bInterfaceClass        = USB_CLASS_COMM, \
 438         .bInterfaceSubClass     = USB_CDC_SUBCLASS_ETHERNET, \
 439         .bInterfaceProtocol     = USB_CDC_PROTO_NONE
 440
 441 /* SA-1100 based Sharp Zaurus ("collie"), or compatible;
 442  * wire-incompatible with true CDC Ethernet implementations.
 443  * (And, it seems, needlessly so...)
 444  */
 445 {
 446         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 447                           | USB_DEVICE_ID_MATCH_DEVICE,
 448         .idVendor               = 0x04DD,
 449         .idProduct              = 0x8004,
 450         ZAURUS_MASTER_INTERFACE,
 451         .driver_info            = 0,
 452 },
 453
 454 /* PXA-25x based Sharp Zaurii.  Note that it seems some of these
 455  * (later models especially) may have shipped only with firmware
 456  * advertising false "CDC MDLM" compatibility ... but we're not
 457  * clear which models did that, so for now let's assume the worst.
 458  */
 459 {
 460         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 461                           | USB_DEVICE_ID_MATCH_DEVICE,
 462         .idVendor               = 0x04DD,
 463         .idProduct              = 0x8005,       /* A-300 */
 464         ZAURUS_MASTER_INTERFACE,
 465         .driver_info            = 0,
 466 }, {
 467         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 468                           | USB_DEVICE_ID_MATCH_DEVICE,
 469         .idVendor               = 0x04DD,
 470         .idProduct              = 0x8006,       /* B-500/SL-5600 */
 471         ZAURUS_MASTER_INTERFACE,
 472         .driver_info            = 0,
 473 }, {
 474         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 475                   | USB_DEVICE_ID_MATCH_DEVICE,
 476         .idVendor               = 0x04DD,
 477         .idProduct              = 0x8007,       /* C-700 */
 478         ZAURUS_MASTER_INTERFACE,
 479         .driver_info            = 0,
 480 }, {
 481         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 482                  | USB_DEVICE_ID_MATCH_DEVICE,
 483         .idVendor               = 0x04DD,
 484         .idProduct              = 0x9031,       /* C-750 C-760 */
 485         ZAURUS_MASTER_INTERFACE,
 486         .driver_info            = 0,
 487 }, {
 488         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 489                  | USB_DEVICE_ID_MATCH_DEVICE,
 490         .idVendor               = 0x04DD,
 491         .idProduct              = 0x9032,       /* SL-6000 */
 492         ZAURUS_MASTER_INTERFACE,
 493         .driver_info            = 0,
 494 }, {
 495         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 496                  | USB_DEVICE_ID_MATCH_DEVICE,
 497         .idVendor               = 0x04DD,
 498         /* reported with some C860 units */
 499         .idProduct              = 0x9050,       /* C-860 */
 500         ZAURUS_MASTER_INTERFACE,
 501         .driver_info            = 0,
 502 },
 503
 504 /* Olympus has some models with a Zaurus-compatible option.
 505  * R-1000 uses a FreeScale i.MXL cpu (ARMv4T)
 506  */
 507 {
 508         .match_flags    =   USB_DEVICE_ID_MATCH_INT_INFO
 509                  | USB_DEVICE_ID_MATCH_DEVICE,
 510         .idVendor               = 0x07B4,
 511         .idProduct              = 0x0F02,       /* R-1000 */
 512         ZAURUS_MASTER_INTERFACE,
 513         .driver_info            = 0,
 514 },
 515
 516 /*
 517  * WHITELIST!!!
 518  *
 519  * CDC Ether uses two interfaces, not necessarily consecutive.
 520  * We match the main interface, ignoring the optional device
 521  * class so we could handle devices that aren't exclusively
 522  * CDC ether.
 523  *
 524  * NOTE:  this match must come AFTER entries blacklisting devices
 525  * because of bugs/quirks in a given product (like Zaurus, above).
 526  */
 527 {
 528         USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ETHERNET,
 529                         USB_CDC_PROTO_NONE),
 530         .driver_info = (unsigned long) &cdc_info,
 531 }, {
 532         /* Ericsson F3507g */
 533         USB_DEVICE_AND_INTERFACE_INFO(0x0bdb, 0x1900, USB_CLASS_COMM,
 534                         USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
 535         .driver_info = (unsigned long) &cdc_info,
 536 }, {
 537         /* Ericsson F3507g ver. 2 */
 538         USB_DEVICE_AND_INTERFACE_INFO(0x0bdb, 0x1902, USB_CLASS_COMM,
 539                         USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
 540         .driver_info = (unsigned long) &cdc_info,
 541 }, {
 542         /* Ericsson F3607gw */
 543         USB_DEVICE_AND_INTERFACE_INFO(0x0bdb, 0x1904, USB_CLASS_COMM,
 544                         USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
 545         .driver_info = (unsigned long) &cdc_info,
 546 }, {
 547         /* Ericsson F3307 */
 548         USB_DEVICE_AND_INTERFACE_INFO(0x0bdb, 0x1906, USB_CLASS_COMM,
 549                         USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
 550         .driver_info = (unsigned long) &cdc_info,
 551 }, {
 552         /* Toshiba F3507g */
 553         USB_DEVICE_AND_INTERFACE_INFO(0x0930, 0x130b, USB_CLASS_COMM,
 554                         USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
 555         .driver_info = (unsigned long) &cdc_info,
 556 }, {
 557         /* Dell F3507g */
 558         USB_DEVICE_AND_INTERFACE_INFO(0x413c, 0x8147, USB_CLASS_COMM,
 559                         USB_CDC_SUBCLASS_MDLM, USB_CDC_PROTO_NONE),
 560         .driver_info = (unsigned long) &cdc_info,
 561 },
 562         { },            // END
 563 };
 564 MODULE_DEVICE_TABLE(usb, products);
 565
 566 static struct usb_driver cdc_driver = {
 567         .name =         "cdc_ether",
 568         .id_table =     products,
 569         .probe =        usbnet_probe,
 570         .disconnect =   usbnet_disconnect,
 571         .suspend =      usbnet_suspend,
 572         .resume =       usbnet_resume,
 573 };
 574
 575
 576 static int __init cdc_init(void)
 577 {
 578         BUILD_BUG_ON((sizeof(((struct usbnet *)0)->data)
 579                         < sizeof(struct cdc_state)));
 580
 581         return usb_register(&cdc_driver);
 582 }
 583 module_init(cdc_init);
 584
 585 static void __exit cdc_exit(void)
 586 {
 587         usb_deregister(&cdc_driver);
 588 }
 589 module_exit(cdc_exit);
 590
 591 MODULE_AUTHOR("David Brownell");
 592 MODULE_DESCRIPTION("USB CDC Ethernet devices");
 593 MODULE_LICENSE("GPL");