drivers/net/usb/rndis_host.c

   1 /*
   2  * Host Side support for RNDIS Networking Links
   3  * Copyright (C) 2005 by David Brownell
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/etherdevice.h>
  23 #include <linux/ethtool.h>
  24 #include <linux/workqueue.h>
  25 #include <linux/slab.h>
  26 #include <linux/mii.h>
  27 #include <linux/usb.h>
  28 #include <linux/usb/cdc.h>
  29 #include <linux/usb/usbnet.h>
  30 #include <linux/usb/rndis_host.h>
  31
  32
  33 /*
  34  * RNDIS is NDIS remoted over USB.  It's a MSFT variant of CDC ACM ... of
  35  * course ACM was intended for modems, not Ethernet links!  USB's standard
  36  * for Ethernet links is "CDC Ethernet", which is significantly simpler.
  37  *
  38  * NOTE that Microsoft's "RNDIS 1.0" specification is incomplete.  Issues
  39  * include:
  40  *    - Power management in particular relies on information that's scattered
  41  *      through other documentation, and which is incomplete or incorrect even
  42  *      there.
  43  *    - There are various undocumented protocol requirements, such as the
  44  *      need to send unused garbage in control-OUT messages.
  45  *    - In some cases, MS-Windows will emit undocumented requests; this
  46  *      matters more to peripheral implementations than host ones.
  47  *
  48  * Moreover there's a no-open-specs variant of RNDIS called "ActiveSync".
  49  *
  50  * For these reasons and others, ** USE OF RNDIS IS STRONGLY DISCOURAGED ** in
  51  * favor of such non-proprietary alternatives as CDC Ethernet or the newer (and
  52  * currently rare) "Ethernet Emulation Model" (EEM).
  53  */
  54
  55 /*
  56  * RNDIS notifications from device: command completion; "reverse"
  57  * keepalives; etc
  58  */
  59 void rndis_status(struct usbnet *dev, struct urb *urb)
  60 {
  61         netdev_dbg(dev->net, "rndis status urb, len %d stat %d\n",
  62                    urb->actual_length, urb->status);
  63         // FIXME for keepalives, respond immediately (asynchronously)
  64         // if not an RNDIS status, do like cdc_status(dev,urb) does
  65 }
  66 EXPORT_SYMBOL_GPL(rndis_status);
  67
  68 /*
  69  * RNDIS indicate messages.
  70  */
  71 static void rndis_msg_indicate(struct usbnet *dev, struct rndis_indicate *msg,
  72                                 int buflen)
  73 {
  74         struct cdc_state *info = (void *)&dev->data;
  75         struct device *udev = &info->control->dev;
  76
  77         if (dev->driver_info->indication) {
  78                 dev->driver_info->indication(dev, msg, buflen);
  79         } else {
  80                 switch (msg->status) {
  81                 case RNDIS_STATUS_MEDIA_CONNECT:
  82                         dev_info(udev, "rndis media connect\n");
  83                         break;
  84                 case RNDIS_STATUS_MEDIA_DISCONNECT:
  85                         dev_info(udev, "rndis media disconnect\n");
  86                         break;
  87                 default:
  88                         dev_info(udev, "rndis indication: 0x%08x\n",
  89                                         le32_to_cpu(msg->status));
  90                 }
  91         }
  92 }
  93
  94 /*
  95  * RPC done RNDIS-style.  Caller guarantees:
  96  * - message is properly byteswapped
  97  * - there's no other request pending
  98  * - buf can hold up to 1KB response (required by RNDIS spec)
  99  * On return, the first few entries are already byteswapped.
 100  *
 101  * Call context is likely probe(), before interface name is known,
 102  * which is why we won't try to use it in the diagnostics.
 103  */
 104 int rndis_command(struct usbnet *dev, struct rndis_msg_hdr *buf, int buflen)
 105 {
 106         struct cdc_state        *info = (void *) &dev->data;
 107         struct usb_cdc_notification notification;
 108         int                     master_ifnum;
 109         int                     retval;
 110         int                     partial;
 111         unsigned                count;
 112         __le32                  rsp;
 113         u32                     xid = 0, msg_len, request_id;
 114
 115         /* REVISIT when this gets called from contexts other than probe() or
 116          * disconnect(): either serialize, or dispatch responses on xid
 117          */
 118
 119         /* Issue the request; xid is unique, don't bother byteswapping it */
 120         if (likely(buf->msg_type != RNDIS_MSG_HALT &&
 121                    buf->msg_type != RNDIS_MSG_RESET)) {
 122                 xid = dev->xid++;
 123                 if (!xid)
 124                         xid = dev->xid++;
 125                 buf->request_id = (__force __le32) xid;
 126         }
 127         master_ifnum = info->control->cur_altsetting->desc.bInterfaceNumber;
 128         retval = usb_control_msg(dev->udev,
 129                 usb_sndctrlpipe(dev->udev, 0),
 130                 USB_CDC_SEND_ENCAPSULATED_COMMAND,
 131                 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 132                 0, master_ifnum,
 133                 buf, le32_to_cpu(buf->msg_len),
 134                 RNDIS_CONTROL_TIMEOUT_MS);
 135         if (unlikely(retval < 0 || xid == 0))
 136                 return retval;
 137
 138         /* Some devices don't respond on the control channel until
 139          * polled on the status channel, so do that first. */
 140         retval = usb_interrupt_msg(
 141                 dev->udev,
 142                 usb_rcvintpipe(dev->udev, dev->status->desc.bEndpointAddress),
 143                 &notification, sizeof(notification), &partial,
 144                 RNDIS_CONTROL_TIMEOUT_MS);
 145         if (unlikely(retval < 0))
 146                 return retval;
 147
 148         /* Poll the control channel; the request probably completed immediately */
 149         rsp = buf->msg_type | RNDIS_MSG_COMPLETION;
 150         for (count = 0; count < 10; count++) {
 151                 memset(buf, 0, CONTROL_BUFFER_SIZE);
 152                 retval = usb_control_msg(dev->udev,
 153                         usb_rcvctrlpipe(dev->udev, 0),
 154                         USB_CDC_GET_ENCAPSULATED_RESPONSE,
 155                         USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 156                         0, master_ifnum,
 157                         buf, buflen,
 158                         RNDIS_CONTROL_TIMEOUT_MS);
 159                 if (likely(retval >= 8)) {
 160                         msg_len = le32_to_cpu(buf->msg_len);
 161                         request_id = (__force u32) buf->request_id;
 162                         if (likely(buf->msg_type == rsp)) {
 163                                 if (likely(request_id == xid)) {
 164                                         if (unlikely(rsp == RNDIS_MSG_RESET_C))
 165                                                 return 0;
 166                                         if (likely(RNDIS_STATUS_SUCCESS
 167                                                         == buf->status))
 168                                                 return 0;
 169                                         dev_dbg(&info->control->dev,
 170                                                 "rndis reply status %08x\n",
 171                                                 le32_to_cpu(buf->status));
 172                                         return -EL3RST;
 173                                 }
 174                                 dev_dbg(&info->control->dev,
 175                                         "rndis reply id %d expected %d\n",
 176                                         request_id, xid);
 177                                 /* then likely retry */
 178                         } else switch (buf->msg_type) {
 179                         case RNDIS_MSG_INDICATE:        /* fault/event */
 180                                 rndis_msg_indicate(dev, (void *)buf, buflen);
 181
 182                                 break;
 183                         case RNDIS_MSG_KEEPALIVE: {     /* ping */
 184                                 struct rndis_keepalive_c *msg = (void *)buf;
 185
 186                                 msg->msg_type = RNDIS_MSG_KEEPALIVE_C;
 187                                 msg->msg_len = cpu_to_le32(sizeof *msg);
 188                                 msg->status = RNDIS_STATUS_SUCCESS;
 189                                 retval = usb_control_msg(dev->udev,
 190                                         usb_sndctrlpipe(dev->udev, 0),
 191                                         USB_CDC_SEND_ENCAPSULATED_COMMAND,
 192                                         USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 193                                         0, master_ifnum,
 194                                         msg, sizeof *msg,
 195                                         RNDIS_CONTROL_TIMEOUT_MS);
 196                                 if (unlikely(retval < 0))
 197                                         dev_dbg(&info->control->dev,
 198                                                 "rndis keepalive err %d\n",
 199                                                 retval);
 200                                 }
 201                                 break;
 202                         default:
 203                                 dev_dbg(&info->control->dev,
 204                                         "unexpected rndis msg %08x len %d\n",
 205                                         le32_to_cpu(buf->msg_type), msg_len);
 206                         }
 207                 } else {
 208                         /* device probably issued a protocol stall; ignore */
 209                         dev_dbg(&info->control->dev,
 210                                 "rndis response error, code %d\n", retval);
 211                 }
 212                 msleep(20);
 213         }
 214         dev_dbg(&info->control->dev, "rndis response timeout\n");
 215         return -ETIMEDOUT;
 216 }
 217 EXPORT_SYMBOL_GPL(rndis_command);
 218
 219 /*
 220  * rndis_query:
 221  *
 222  * Performs a query for @oid along with 0 or more bytes of payload as
 223  * specified by @in_len. If @reply_len is not set to -1 then the reply
 224  * length is checked against this value, resulting in an error if it
 225  * doesn't match.
 226  *
 227  * NOTE: Adding a payload exactly or greater than the size of the expected
 228  * response payload is an evident requirement MSFT added for ActiveSync.
 229  *
 230  * The only exception is for OIDs that return a variably sized response,
 231  * in which case no payload should be added.  This undocumented (and
 232  * nonsensical!) issue was found by sniffing protocol requests from the
 233  * ActiveSync 4.1 Windows driver.
 234  */
 235 static int rndis_query(struct usbnet *dev, struct usb_interface *intf,
 236                 void *buf, __le32 oid, u32 in_len,
 237                 void **reply, int *reply_len)
 238 {
 239         int retval;
 240         union {
 241                 void                    *buf;
 242                 struct rndis_msg_hdr    *header;
 243                 struct rndis_query      *get;
 244                 struct rndis_query_c    *get_c;
 245         } u;
 246         u32 off, len;
 247
 248         u.buf = buf;
 249
 250         memset(u.get, 0, sizeof *u.get + in_len);
 251         u.get->msg_type = RNDIS_MSG_QUERY;
 252         u.get->msg_len = cpu_to_le32(sizeof *u.get + in_len);
 253         u.get->oid = oid;
 254         u.get->len = cpu_to_le32(in_len);
 255         u.get->offset = cpu_to_le32(20);
 256
 257         retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
 258         if (unlikely(retval < 0)) {
 259                 dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) failed, %d\n",
 260                                 oid, retval);
 261                 return retval;
 262         }
 263
 264         off = le32_to_cpu(u.get_c->offset);
 265         len = le32_to_cpu(u.get_c->len);
 266         if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))
 267                 goto response_error;
 268
 269         if (*reply_len != -1 && len != *reply_len)
 270                 goto response_error;
 271
 272         *reply = (unsigned char *) &u.get_c->request_id + off;
 273         *reply_len = len;
 274
 275         return retval;
 276
 277 response_error:
 278         dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) "
 279                         "invalid response - off %d len %d\n",
 280                 oid, off, len);
 281         return -EDOM;
 282 }
 283
 284 /* same as usbnet_netdev_ops but MTU change not allowed */
 285 static const struct net_device_ops rndis_netdev_ops = {
 286         .ndo_open               = usbnet_open,
 287         .ndo_stop               = usbnet_stop,
 288         .ndo_start_xmit         = usbnet_start_xmit,
 289         .ndo_tx_timeout         = usbnet_tx_timeout,
 290         .ndo_set_mac_address    = eth_mac_addr,
 291         .ndo_validate_addr      = eth_validate_addr,
 292 };
 293
 294 int
 295 generic_rndis_bind(struct usbnet *dev, struct usb_interface *intf, int flags)
 296 {
 297         int                     retval;
 298         struct net_device       *net = dev->net;
 299         struct cdc_state        *info = (void *) &dev->data;
 300         union {
 301                 void                    *buf;
 302                 struct rndis_msg_hdr    *header;
 303                 struct rndis_init       *init;
 304                 struct rndis_init_c     *init_c;
 305                 struct rndis_query      *get;
 306                 struct rndis_query_c    *get_c;
 307                 struct rndis_set        *set;
 308                 struct rndis_set_c      *set_c;
 309                 struct rndis_halt       *halt;
 310         } u;
 311         u32                     tmp;
 312         __le32                  phym_unspec, *phym;
 313         int                     reply_len;
 314         unsigned char           *bp;
 315
 316         /* we can't rely on i/o from stack working, or stack allocation */
 317         u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
 318         if (!u.buf)
 319                 return -ENOMEM;
 320         retval = usbnet_generic_cdc_bind(dev, intf);
 321         if (retval < 0)
 322                 goto fail;
 323
 324         u.init->msg_type = RNDIS_MSG_INIT;
 325         u.init->msg_len = cpu_to_le32(sizeof *u.init);
 326         u.init->major_version = cpu_to_le32(1);
 327         u.init->minor_version = cpu_to_le32(0);
 328
 329         /* max transfer (in spec) is 0x4000 at full speed, but for
 330          * TX we'll stick to one Ethernet packet plus RNDIS framing.
 331          * For RX we handle drivers that zero-pad to end-of-packet.
 332          * Don't let userspace change these settings.
 333          *
 334          * NOTE: there still seems to be wierdness here, as if we need
 335          * to do some more things to make sure WinCE targets accept this.
 336          * They default to jumbograms of 8KB or 16KB, which is absurd
 337          * for such low data rates and which is also more than Linux
 338          * can usually expect to allocate for SKB data...
 339          */
 340         net->hard_header_len += sizeof (struct rndis_data_hdr);
 341         dev->hard_mtu = net->mtu + net->hard_header_len;
 342
 343         dev->maxpacket = usb_maxpacket(dev->udev, dev->out, 1);
 344         if (dev->maxpacket == 0) {
 345                 netif_dbg(dev, probe, dev->net,
 346                           "dev->maxpacket can't be 0\n");
 347                 retval = -EINVAL;
 348                 goto fail_and_release;
 349         }
 350
 351         dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
 352         dev->rx_urb_size &= ~(dev->maxpacket - 1);
 353         u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);
 354
 355         net->netdev_ops = &rndis_netdev_ops;
 356
 357         retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
 358         if (unlikely(retval < 0)) {
 359                 /* it might not even be an RNDIS device!! */
 360                 dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
 361                 goto fail_and_release;
 362         }
 363         tmp = le32_to_cpu(u.init_c->max_transfer_size);
 364         if (tmp < dev->hard_mtu) {
 365                 if (tmp <= net->hard_header_len) {
 366                         dev_err(&intf->dev,
 367                                 "dev can't take %u byte packets (max %u)\n",
 368                                 dev->hard_mtu, tmp);
 369                         retval = -EINVAL;
 370                         goto halt_fail_and_release;
 371                 }
 372                 dev_warn(&intf->dev,
 373                          "dev can't take %u byte packets (max %u), "
 374                          "adjusting MTU to %u\n",
 375                          dev->hard_mtu, tmp, tmp - net->hard_header_len);
 376                 dev->hard_mtu = tmp;
 377                 net->mtu = dev->hard_mtu - net->hard_header_len;
 378         }
 379
 380         /* REVISIT:  peripheral "alignment" request is ignored ... */
 381         dev_dbg(&intf->dev,
 382                 "hard mtu %u (%u from dev), rx buflen %Zu, align %d\n",
 383                 dev->hard_mtu, tmp, dev->rx_urb_size,
 384                 1 << le32_to_cpu(u.init_c->packet_alignment));
 385
 386         /* module has some device initialization code needs to be done right
 387          * after RNDIS_INIT */
 388         if (dev->driver_info->early_init &&
 389                         dev->driver_info->early_init(dev) != 0)
 390                 goto halt_fail_and_release;
 391
 392         /* Check physical medium */
 393         phym = NULL;
 394         reply_len = sizeof *phym;
 395         retval = rndis_query(dev, intf, u.buf, OID_GEN_PHYSICAL_MEDIUM,
 396                         0, (void **) &phym, &reply_len);
 397         if (retval != 0 || !phym) {
 398                 /* OID is optional so don't fail here. */
 399                 phym_unspec = RNDIS_PHYSICAL_MEDIUM_UNSPECIFIED;
 400                 phym = &phym_unspec;
 401         }
 402         if ((flags & FLAG_RNDIS_PHYM_WIRELESS) &&
 403                         *phym != RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
 404                 netif_dbg(dev, probe, dev->net,
 405                           "driver requires wireless physical medium, but device is not\n");
 406                 retval = -ENODEV;
 407                 goto halt_fail_and_release;
 408         }
 409         if ((flags & FLAG_RNDIS_PHYM_NOT_WIRELESS) &&
 410                         *phym == RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
 411                 netif_dbg(dev, probe, dev->net,
 412                           "driver requires non-wireless physical medium, but device is wireless.\n");
 413                 retval = -ENODEV;
 414                 goto halt_fail_and_release;
 415         }
 416
 417         /* Get designated host ethernet address */
 418         reply_len = ETH_ALEN;
 419         retval = rndis_query(dev, intf, u.buf, OID_802_3_PERMANENT_ADDRESS,
 420                         48, (void **) &bp, &reply_len);
 421         if (unlikely(retval< 0)) {
 422                 dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
 423                 goto halt_fail_and_release;
 424         }
 425         memcpy(net->dev_addr, bp, ETH_ALEN);
 426         memcpy(net->perm_addr, bp, ETH_ALEN);
 427
 428         /* set a nonzero filter to enable data transfers */
 429         memset(u.set, 0, sizeof *u.set);
 430         u.set->msg_type = RNDIS_MSG_SET;
 431         u.set->msg_len = cpu_to_le32(4 + sizeof *u.set);
 432         u.set->oid = OID_GEN_CURRENT_PACKET_FILTER;
 433         u.set->len = cpu_to_le32(4);
 434         u.set->offset = cpu_to_le32((sizeof *u.set) - 8);
 435         *(__le32 *)(u.buf + sizeof *u.set) = RNDIS_DEFAULT_FILTER;
 436
 437         retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
 438         if (unlikely(retval < 0)) {
 439                 dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
 440                 goto halt_fail_and_release;
 441         }
 442
 443         retval = 0;
 444
 445         kfree(u.buf);
 446         return retval;
 447
 448 halt_fail_and_release:
 449         memset(u.halt, 0, sizeof *u.halt);
 450         u.halt->msg_type = RNDIS_MSG_HALT;
 451         u.halt->msg_len = cpu_to_le32(sizeof *u.halt);
 452         (void) rndis_command(dev, (void *)u.halt, CONTROL_BUFFER_SIZE);
 453 fail_and_release:
 454         usb_set_intfdata(info->data, NULL);
 455         usb_driver_release_interface(driver_of(intf), info->data);
 456         info->data = NULL;
 457 fail:
 458         kfree(u.buf);
 459         return retval;
 460 }
 461 EXPORT_SYMBOL_GPL(generic_rndis_bind);
 462
 463 static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
 464 {
 465         return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
 466 }
 467
 468 void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
 469 {
 470         struct rndis_halt       *halt;
 471
 472         /* try to clear any rndis state/activity (no i/o from stack!) */
 473         halt = kzalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
 474         if (halt) {
 475                 halt->msg_type = RNDIS_MSG_HALT;
 476                 halt->msg_len = cpu_to_le32(sizeof *halt);
 477                 (void) rndis_command(dev, (void *)halt, CONTROL_BUFFER_SIZE);
 478                 kfree(halt);
 479         }
 480
 481         usbnet_cdc_unbind(dev, intf);
 482 }
 483 EXPORT_SYMBOL_GPL(rndis_unbind);
 484
 485 /*
 486  * DATA -- host must not write zlps
 487  */
 488 int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 489 {
 490         /* peripheral may have batched packets to us... */
 491         while (likely(skb->len)) {
 492                 struct rndis_data_hdr   *hdr = (void *)skb->data;
 493                 struct sk_buff          *skb2;
 494                 u32                     msg_len, data_offset, data_len;
 495
 496                 msg_len = le32_to_cpu(hdr->msg_len);
 497                 data_offset = le32_to_cpu(hdr->data_offset);
 498                 data_len = le32_to_cpu(hdr->data_len);
 499
 500                 /* don't choke if we see oob, per-packet data, etc */
 501                 if (unlikely(hdr->msg_type != RNDIS_MSG_PACKET ||
 502                              skb->len < msg_len ||
 503                              (data_offset + data_len + 8) > msg_len)) {
 504                         dev->net->stats.rx_frame_errors++;
 505                         netdev_dbg(dev->net, "bad rndis message %d/%d/%d/%d, len %d\n",
 506                                    le32_to_cpu(hdr->msg_type),
 507                                    msg_len, data_offset, data_len, skb->len);
 508                         return 0;
 509                 }
 510                 skb_pull(skb, 8 + data_offset);
 511
 512                 /* at most one packet left? */
 513                 if (likely((data_len - skb->len) <= sizeof *hdr)) {
 514                         skb_trim(skb, data_len);
 515                         break;
 516                 }
 517
 518                 /* try to return all the packets in the batch */
 519                 skb2 = skb_clone(skb, GFP_ATOMIC);
 520                 if (unlikely(!skb2))
 521                         break;
 522                 skb_pull(skb, msg_len - sizeof *hdr);
 523                 skb_trim(skb2, data_len);
 524                 usbnet_skb_return(dev, skb2);
 525         }
 526
 527         /* caller will usbnet_skb_return the remaining packet */
 528         return 1;
 529 }
 530 EXPORT_SYMBOL_GPL(rndis_rx_fixup);
 531
 532 struct sk_buff *
 533 rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
 534 {
 535         struct rndis_data_hdr   *hdr;
 536         struct sk_buff          *skb2;
 537         unsigned                len = skb->len;
 538
 539         if (likely(!skb_cloned(skb))) {
 540                 int     room = skb_headroom(skb);
 541
 542                 /* enough head room as-is? */
 543                 if (unlikely((sizeof *hdr) <= room))
 544                         goto fill;
 545
 546                 /* enough room, but needs to be readjusted? */
 547                 room += skb_tailroom(skb);
 548                 if (likely((sizeof *hdr) <= room)) {
 549                         skb->data = memmove(skb->head + sizeof *hdr,
 550                                             skb->data, len);
 551                         skb_set_tail_pointer(skb, len);
 552                         goto fill;
 553                 }
 554         }
 555
 556         /* create a new skb, with the correct size (and tailpad) */
 557         skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
 558         dev_kfree_skb_any(skb);
 559         if (unlikely(!skb2))
 560                 return skb2;
 561         skb = skb2;
 562
 563         /* fill out the RNDIS header.  we won't bother trying to batch
 564          * packets; Linux minimizes wasted bandwidth through tx queues.
 565          */
 566 fill:
 567         hdr = (void *) __skb_push(skb, sizeof *hdr);
 568         memset(hdr, 0, sizeof *hdr);
 569         hdr->msg_type = RNDIS_MSG_PACKET;
 570         hdr->msg_len = cpu_to_le32(skb->len);
 571         hdr->data_offset = cpu_to_le32(sizeof(*hdr) - 8);
 572         hdr->data_len = cpu_to_le32(len);
 573
 574         /* FIXME make the last packet always be short ... */
 575         return skb;
 576 }
 577 EXPORT_SYMBOL_GPL(rndis_tx_fixup);
 578
 579
 580 static const struct driver_info rndis_info = {
 581         .description =  "RNDIS device",
 582         .flags =        FLAG_ETHER | FLAG_FRAMING_RN | FLAG_NO_SETINT,
 583         .bind =         rndis_bind,
 584         .unbind =       rndis_unbind,
 585         .status =       rndis_status,
 586         .rx_fixup =     rndis_rx_fixup,
 587         .tx_fixup =     rndis_tx_fixup,
 588 };
 589
 590 /*-------------------------------------------------------------------------*/
 591
 592 static const struct usb_device_id       products [] = {
 593 {
 594         /* RNDIS is MSFT's un-official variant of CDC ACM */
 595         USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
 596         .driver_info = (unsigned long) &rndis_info,
 597 }, {
 598         /* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
 599         USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
 600         .driver_info = (unsigned long) &rndis_info,
 601 }, {
 602         /* RNDIS for tethering */
 603         USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
 604         .driver_info = (unsigned long) &rndis_info,
 605 },
 606         { },            // END
 607 };
 608 MODULE_DEVICE_TABLE(usb, products);
 609
 610 static struct usb_driver rndis_driver = {
 611         .name =         "rndis_host",
 612         .id_table =     products,
 613         .probe =        usbnet_probe,
 614         .disconnect =   usbnet_disconnect,
 615         .suspend =      usbnet_suspend,
 616         .resume =       usbnet_resume,
 617 };
 618
 619 static int __init rndis_init(void)
 620 {
 621         return usb_register(&rndis_driver);
 622 }
 623 module_init(rndis_init);
 624
 625 static void __exit rndis_exit(void)
 626 {
 627         usb_deregister(&rndis_driver);
 628 }
 629 module_exit(rndis_exit);
 630
 631 MODULE_AUTHOR("David Brownell");
 632 MODULE_DESCRIPTION("USB Host side RNDIS driver");
 633 MODULE_LICENSE("GPL");