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