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, see <http://www.gnu.org/licenses/>.
  17  */
  18 #include <linux/module.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/etherdevice.h>
  21 #include <linux/ethtool.h>
  22 #include <linux/workqueue.h>
  23 #include <linux/slab.h>
  24 #include <linux/mii.h>
  25 #include <linux/usb.h>
  26 #include <linux/usb/cdc.h>
  27 #include <linux/usb/usbnet.h>
  28 #include <linux/usb/rndis_host.h>
  29
  30
  31 /*
  32  * RNDIS is NDIS remoted over USB.  It's a MSFT variant of CDC ACM ... of
  33  * course ACM was intended for modems, not Ethernet links!  USB's standard
  34  * for Ethernet links is "CDC Ethernet", which is significantly simpler.
  35  *
  36  * NOTE that Microsoft's "RNDIS 1.0" specification is incomplete.  Issues
  37  * include:
  38  *    - Power management in particular relies on information that's scattered
  39  *      through other documentation, and which is incomplete or incorrect even
  40  *      there.
  41  *    - There are various undocumented protocol requirements, such as the
  42  *      need to send unused garbage in control-OUT messages.
  43  *    - In some cases, MS-Windows will emit undocumented requests; this
  44  *      matters more to peripheral implementations than host ones.
  45  *
  46  * Moreover there's a no-open-specs variant of RNDIS called "ActiveSync".
  47  *
  48  * For these reasons and others, ** USE OF RNDIS IS STRONGLY DISCOURAGED ** in
  49  * favor of such non-proprietary alternatives as CDC Ethernet or the newer (and
  50  * currently rare) "Ethernet Emulation Model" (EEM).
  51  */
  52
  53 /*
  54  * RNDIS notifications from device: command completion; "reverse"
  55  * keepalives; etc
  56  */
  57 void rndis_status(struct usbnet *dev, struct urb *urb)
  58 {
  59         netdev_dbg(dev->net, "rndis status urb, len %d stat %d\n",
  60                    urb->actual_length, urb->status);
  61         // FIXME for keepalives, respond immediately (asynchronously)
  62         // if not an RNDIS status, do like cdc_status(dev,urb) does
  63 }
  64 EXPORT_SYMBOL_GPL(rndis_status);
  65
  66 /*
  67  * RNDIS indicate messages.
  68  */
  69 static void rndis_msg_indicate(struct usbnet *dev, struct rndis_indicate *msg,
  70                                 int buflen)
  71 {
  72         struct cdc_state *info = (void *)&dev->data;
  73         struct device *udev = &info->control->dev;
  74
  75         if (dev->driver_info->indication) {
  76                 dev->driver_info->indication(dev, msg, buflen);
  77         } else {
  78                 u32 status = le32_to_cpu(msg->status);
  79
  80                 switch (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", 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         struct usb_cdc_notification notification;
 107         int                     master_ifnum;
 108         int                     retval;
 109         int                     partial;
 110         unsigned                count;
 111         u32                     xid = 0, msg_len, request_id, msg_type, rsp,
 112                                 status;
 113
 114         /* REVISIT when this gets called from contexts other than probe() or
 115          * disconnect(): either serialize, or dispatch responses on xid
 116          */
 117
 118         msg_type = le32_to_cpu(buf->msg_type);
 119
 120         /* Issue the request; xid is unique, don't bother byteswapping it */
 121         if (likely(msg_type != RNDIS_MSG_HALT && 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         if (dev->driver_info->data & RNDIS_DRIVER_DATA_POLL_STATUS) {
 141                 retval = usb_interrupt_msg(
 142                         dev->udev,
 143                         usb_rcvintpipe(dev->udev,
 144                                        dev->status->desc.bEndpointAddress),
 145                         &notification, sizeof(notification), &partial,
 146                         RNDIS_CONTROL_TIMEOUT_MS);
 147                 if (unlikely(retval < 0))
 148                         return retval;
 149         }
 150
 151         /* Poll the control channel; the request probably completed immediately */
 152         rsp = le32_to_cpu(buf->msg_type) | RNDIS_MSG_COMPLETION;
 153         for (count = 0; count < 10; count++) {
 154                 memset(buf, 0, CONTROL_BUFFER_SIZE);
 155                 retval = usb_control_msg(dev->udev,
 156                         usb_rcvctrlpipe(dev->udev, 0),
 157                         USB_CDC_GET_ENCAPSULATED_RESPONSE,
 158                         USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 159                         0, master_ifnum,
 160                         buf, buflen,
 161                         RNDIS_CONTROL_TIMEOUT_MS);
 162                 if (likely(retval >= 8)) {
 163                         msg_type = le32_to_cpu(buf->msg_type);
 164                         msg_len = le32_to_cpu(buf->msg_len);
 165                         status = le32_to_cpu(buf->status);
 166                         request_id = (__force u32) buf->request_id;
 167                         if (likely(msg_type == rsp)) {
 168                                 if (likely(request_id == xid)) {
 169                                         if (unlikely(rsp == RNDIS_MSG_RESET_C))
 170                                                 return 0;
 171                                         if (likely(RNDIS_STATUS_SUCCESS ==
 172                                                         status))
 173                                                 return 0;
 174                                         dev_dbg(&info->control->dev,
 175                                                 "rndis reply status %08x\n",
 176                                                 status);
 177                                         return -EL3RST;
 178                                 }
 179                                 dev_dbg(&info->control->dev,
 180                                         "rndis reply id %d expected %d\n",
 181                                         request_id, xid);
 182                                 /* then likely retry */
 183                         } else switch (msg_type) {
 184                         case RNDIS_MSG_INDICATE: /* fault/event */
 185                                 rndis_msg_indicate(dev, (void *)buf, buflen);
 186                                 break;
 187                         case RNDIS_MSG_KEEPALIVE: { /* ping */
 188                                 struct rndis_keepalive_c *msg = (void *)buf;
 189
 190                                 msg->msg_type = cpu_to_le32(RNDIS_MSG_KEEPALIVE_C);
 191                                 msg->msg_len = cpu_to_le32(sizeof *msg);
 192                                 msg->status = cpu_to_le32(RNDIS_STATUS_SUCCESS);
 193                                 retval = usb_control_msg(dev->udev,
 194                                         usb_sndctrlpipe(dev->udev, 0),
 195                                         USB_CDC_SEND_ENCAPSULATED_COMMAND,
 196                                         USB_TYPE_CLASS | USB_RECIP_INTERFACE,
 197                                         0, master_ifnum,
 198                                         msg, sizeof *msg,
 199                                         RNDIS_CONTROL_TIMEOUT_MS);
 200                                 if (unlikely(retval < 0))
 201                                         dev_dbg(&info->control->dev,
 202                                                 "rndis keepalive err %d\n",
 203                                                 retval);
 204                                 }
 205                                 break;
 206                         default:
 207                                 dev_dbg(&info->control->dev,
 208                                         "unexpected rndis msg %08x len %d\n",
 209                                         le32_to_cpu(buf->msg_type), msg_len);
 210                         }
 211                 } else {
 212                         /* device probably issued a protocol stall; ignore */
 213                         dev_dbg(&info->control->dev,
 214                                 "rndis response error, code %d\n", retval);
 215                 }
 216                 msleep(20);
 217         }
 218         dev_dbg(&info->control->dev, "rndis response timeout\n");
 219         return -ETIMEDOUT;
 220 }
 221 EXPORT_SYMBOL_GPL(rndis_command);
 222
 223 /*
 224  * rndis_query:
 225  *
 226  * Performs a query for @oid along with 0 or more bytes of payload as
 227  * specified by @in_len. If @reply_len is not set to -1 then the reply
 228  * length is checked against this value, resulting in an error if it
 229  * doesn't match.
 230  *
 231  * NOTE: Adding a payload exactly or greater than the size of the expected
 232  * response payload is an evident requirement MSFT added for ActiveSync.
 233  *
 234  * The only exception is for OIDs that return a variably sized response,
 235  * in which case no payload should be added.  This undocumented (and
 236  * nonsensical!) issue was found by sniffing protocol requests from the
 237  * ActiveSync 4.1 Windows driver.
 238  */
 239 static int rndis_query(struct usbnet *dev, struct usb_interface *intf,
 240                 void *buf, u32 oid, u32 in_len,
 241                 void **reply, int *reply_len)
 242 {
 243         int retval;
 244         union {
 245                 void                    *buf;
 246                 struct rndis_msg_hdr    *header;
 247                 struct rndis_query      *get;
 248                 struct rndis_query_c    *get_c;
 249         } u;
 250         u32 off, len;
 251
 252         u.buf = buf;
 253
 254         memset(u.get, 0, sizeof *u.get + in_len);
 255         u.get->msg_type = cpu_to_le32(RNDIS_MSG_QUERY);
 256         u.get->msg_len = cpu_to_le32(sizeof *u.get + in_len);
 257         u.get->oid = cpu_to_le32(oid);
 258         u.get->len = cpu_to_le32(in_len);
 259         u.get->offset = cpu_to_le32(20);
 260
 261         retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
 262         if (unlikely(retval < 0)) {
 263                 dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) failed, %d\n",
 264                                 oid, retval);
 265                 return retval;
 266         }
 267
 268         off = le32_to_cpu(u.get_c->offset);
 269         len = le32_to_cpu(u.get_c->len);
 270         if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))
 271                 goto response_error;
 272
 273         if (*reply_len != -1 && len != *reply_len)
 274                 goto response_error;
 275
 276         *reply = (unsigned char *) &u.get_c->request_id + off;
 277         *reply_len = len;
 278
 279         return retval;
 280
 281 response_error:
 282         dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) "
 283                         "invalid response - off %d len %d\n",
 284                 oid, off, len);
 285         return -EDOM;
 286 }
 287
 288 /* same as usbnet_netdev_ops but MTU change not allowed */
 289 static const struct net_device_ops rndis_netdev_ops = {
 290         .ndo_open               = usbnet_open,
 291         .ndo_stop               = usbnet_stop,
 292         .ndo_start_xmit         = usbnet_start_xmit,
 293         .ndo_tx_timeout         = usbnet_tx_timeout,
 294         .ndo_set_mac_address    = eth_mac_addr,
 295         .ndo_validate_addr      = eth_validate_addr,
 296 };
 297
 298 int
 299 generic_rndis_bind(struct usbnet *dev, struct usb_interface *intf, int flags)
 300 {
 301         int                     retval;
 302         struct net_device       *net = dev->net;
 303         struct cdc_state        *info = (void *) &dev->data;
 304         union {
 305                 void                    *buf;
 306                 struct rndis_msg_hdr    *header;
 307                 struct rndis_init       *init;
 308                 struct rndis_init_c     *init_c;
 309                 struct rndis_query      *get;
 310                 struct rndis_query_c    *get_c;
 311                 struct rndis_set        *set;
 312                 struct rndis_set_c      *set_c;
 313                 struct rndis_halt       *halt;
 314         } u;
 315         u32                     tmp;
 316         __le32                  phym_unspec, *phym;
 317         int                     reply_len;
 318         unsigned char           *bp;
 319
 320         /* we can't rely on i/o from stack working, or stack allocation */
 321         u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
 322         if (!u.buf)
 323                 return -ENOMEM;
 324         retval = usbnet_generic_cdc_bind(dev, intf);
 325         if (retval < 0)
 326                 goto fail;
 327
 328         u.init->msg_type = cpu_to_le32(RNDIS_MSG_INIT);
 329         u.init->msg_len = cpu_to_le32(sizeof *u.init);
 330         u.init->major_version = cpu_to_le32(1);
 331         u.init->minor_version = cpu_to_le32(0);
 332
 333         /* max transfer (in spec) is 0x4000 at full speed, but for
 334          * TX we'll stick to one Ethernet packet plus RNDIS framing.
 335          * For RX we handle drivers that zero-pad to end-of-packet.
 336          * Don't let userspace change these settings.
 337          *
 338          * NOTE: there still seems to be wierdness here, as if we need
 339          * to do some more things to make sure WinCE targets accept this.
 340          * They default to jumbograms of 8KB or 16KB, which is absurd
 341          * for such low data rates and which is also more than Linux
 342          * can usually expect to allocate for SKB data...
 343          */
 344         net->hard_header_len += sizeof (struct rndis_data_hdr);
 345         dev->hard_mtu = net->mtu + net->hard_header_len;
 346
 347         dev->maxpacket = usb_maxpacket(dev->udev, dev->out, 1);
 348         if (dev->maxpacket == 0) {
 349                 netif_dbg(dev, probe, dev->net,
 350                           "dev->maxpacket can't be 0\n");
 351                 retval = -EINVAL;
 352                 goto fail_and_release;
 353         }
 354
 355         dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
 356         dev->rx_urb_size &= ~(dev->maxpacket - 1);
 357         u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);
 358
 359         net->netdev_ops = &rndis_netdev_ops;
 360
 361         retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
 362         if (unlikely(retval < 0)) {
 363                 /* it might not even be an RNDIS device!! */
 364                 dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
 365                 goto fail_and_release;
 366         }
 367         tmp = le32_to_cpu(u.init_c->max_transfer_size);
 368         if (tmp < dev->hard_mtu) {
 369                 if (tmp <= net->hard_header_len) {
 370                         dev_err(&intf->dev,
 371                                 "dev can't take %u byte packets (max %u)\n",
 372                                 dev->hard_mtu, tmp);
 373                         retval = -EINVAL;
 374                         goto halt_fail_and_release;
 375                 }
 376                 dev_warn(&intf->dev,
 377                          "dev can't take %u byte packets (max %u), "
 378                          "adjusting MTU to %u\n",
 379                          dev->hard_mtu, tmp, tmp - net->hard_header_len);
 380                 dev->hard_mtu = tmp;
 381                 net->mtu = dev->hard_mtu - net->hard_header_len;
 382         }
 383
 384         /* REVISIT:  peripheral "alignment" request is ignored ... */
 385         dev_dbg(&intf->dev,
 386                 "hard mtu %u (%u from dev), rx buflen %Zu, align %d\n",
 387                 dev->hard_mtu, tmp, dev->rx_urb_size,
 388                 1 << le32_to_cpu(u.init_c->packet_alignment));
 389
 390         /* module has some device initialization code needs to be done right
 391          * after RNDIS_INIT */
 392         if (dev->driver_info->early_init &&
 393                         dev->driver_info->early_init(dev) != 0)
 394                 goto halt_fail_and_release;
 395
 396         /* Check physical medium */
 397         phym = NULL;
 398         reply_len = sizeof *phym;
 399         retval = rndis_query(dev, intf, u.buf,
 400                              RNDIS_OID_GEN_PHYSICAL_MEDIUM,
 401                              0, (void **) &phym, &reply_len);
 402         if (retval != 0 || !phym) {
 403                 /* OID is optional so don't fail here. */
 404                 phym_unspec = cpu_to_le32(RNDIS_PHYSICAL_MEDIUM_UNSPECIFIED);
 405                 phym = &phym_unspec;
 406         }
 407         if ((flags & FLAG_RNDIS_PHYM_WIRELESS) &&
 408             le32_to_cpup(phym) != RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
 409                 netif_dbg(dev, probe, dev->net,
 410                           "driver requires wireless physical medium, but device is not\n");
 411                 retval = -ENODEV;
 412                 goto halt_fail_and_release;
 413         }
 414         if ((flags & FLAG_RNDIS_PHYM_NOT_WIRELESS) &&
 415             le32_to_cpup(phym) == RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
 416                 netif_dbg(dev, probe, dev->net,
 417                           "driver requires non-wireless physical medium, but device is wireless.\n");
 418                 retval = -ENODEV;
 419                 goto halt_fail_and_release;
 420         }
 421
 422         /* Get designated host ethernet address */
 423         reply_len = ETH_ALEN;
 424         retval = rndis_query(dev, intf, u.buf,
 425                              RNDIS_OID_802_3_PERMANENT_ADDRESS,
 426                              48, (void **) &bp, &reply_len);
 427         if (unlikely(retval< 0)) {
 428                 dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
 429                 goto halt_fail_and_release;
 430         }
 431         memcpy(net->dev_addr, bp, ETH_ALEN);
 432
 433         /* set a nonzero filter to enable data transfers */
 434         memset(u.set, 0, sizeof *u.set);
 435         u.set->msg_type = cpu_to_le32(RNDIS_MSG_SET);
 436         u.set->msg_len = cpu_to_le32(4 + sizeof *u.set);
 437         u.set->oid = cpu_to_le32(RNDIS_OID_GEN_CURRENT_PACKET_FILTER);
 438         u.set->len = cpu_to_le32(4);
 439         u.set->offset = cpu_to_le32((sizeof *u.set) - 8);
 440         *(__le32 *)(u.buf + sizeof *u.set) = cpu_to_le32(RNDIS_DEFAULT_FILTER);
 441
 442         retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
 443         if (unlikely(retval < 0)) {
 444                 dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
 445                 goto halt_fail_and_release;
 446         }
 447
 448         retval = 0;
 449
 450         kfree(u.buf);
 451         return retval;
 452
 453 halt_fail_and_release:
 454         memset(u.halt, 0, sizeof *u.halt);
 455         u.halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
 456         u.halt->msg_len = cpu_to_le32(sizeof *u.halt);
 457         (void) rndis_command(dev, (void *)u.halt, CONTROL_BUFFER_SIZE);
 458 fail_and_release:
 459         usb_set_intfdata(info->data, NULL);
 460         usb_driver_release_interface(driver_of(intf), info->data);
 461         info->data = NULL;
 462 fail:
 463         kfree(u.buf);
 464         return retval;
 465 }
 466 EXPORT_SYMBOL_GPL(generic_rndis_bind);
 467
 468 static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
 469 {
 470         return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
 471 }
 472
 473 void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
 474 {
 475         struct rndis_halt       *halt;
 476
 477         /* try to clear any rndis state/activity (no i/o from stack!) */
 478         halt = kzalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
 479         if (halt) {
 480                 halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
 481                 halt->msg_len = cpu_to_le32(sizeof *halt);
 482                 (void) rndis_command(dev, (void *)halt, CONTROL_BUFFER_SIZE);
 483                 kfree(halt);
 484         }
 485
 486         usbnet_cdc_unbind(dev, intf);
 487 }
 488 EXPORT_SYMBOL_GPL(rndis_unbind);
 489
 490 /*
 491  * DATA -- host must not write zlps
 492  */
 493 int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 494 {
 495         /* This check is no longer done by usbnet */
 496         if (skb->len < dev->net->hard_header_len)
 497                 return 0;
 498
 499         /* peripheral may have batched packets to us... */
 500         while (likely(skb->len)) {
 501                 struct rndis_data_hdr   *hdr = (void *)skb->data;
 502                 struct sk_buff          *skb2;
 503                 u32                     msg_type, msg_len, data_offset, data_len;
 504
 505                 msg_type = le32_to_cpu(hdr->msg_type);
 506                 msg_len = le32_to_cpu(hdr->msg_len);
 507                 data_offset = le32_to_cpu(hdr->data_offset);
 508                 data_len = le32_to_cpu(hdr->data_len);
 509
 510                 /* don't choke if we see oob, per-packet data, etc */
 511                 if (unlikely(msg_type != RNDIS_MSG_PACKET || skb->len < msg_len
 512                                 || (data_offset + data_len + 8) > msg_len)) {
 513                         dev->net->stats.rx_frame_errors++;
 514                         netdev_dbg(dev->net, "bad rndis message %d/%d/%d/%d, len %d\n",
 515                                    le32_to_cpu(hdr->msg_type),
 516                                    msg_len, data_offset, data_len, skb->len);
 517                         return 0;
 518                 }
 519                 skb_pull(skb, 8 + data_offset);
 520
 521                 /* at most one packet left? */
 522                 if (likely((data_len - skb->len) <= sizeof *hdr)) {
 523                         skb_trim(skb, data_len);
 524                         break;
 525                 }
 526
 527                 /* try to return all the packets in the batch */
 528                 skb2 = skb_clone(skb, GFP_ATOMIC);
 529                 if (unlikely(!skb2))
 530                         break;
 531                 skb_pull(skb, msg_len - sizeof *hdr);
 532                 skb_trim(skb2, data_len);
 533                 usbnet_skb_return(dev, skb2);
 534         }
 535
 536         /* caller will usbnet_skb_return the remaining packet */
 537         return 1;
 538 }
 539 EXPORT_SYMBOL_GPL(rndis_rx_fixup);
 540
 541 struct sk_buff *
 542 rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
 543 {
 544         struct rndis_data_hdr   *hdr;
 545         struct sk_buff          *skb2;
 546         unsigned                len = skb->len;
 547
 548         if (likely(!skb_cloned(skb))) {
 549                 int     room = skb_headroom(skb);
 550
 551                 /* enough head room as-is? */
 552                 if (unlikely((sizeof *hdr) <= room))
 553                         goto fill;
 554
 555                 /* enough room, but needs to be readjusted? */
 556                 room += skb_tailroom(skb);
 557                 if (likely((sizeof *hdr) <= room)) {
 558                         skb->data = memmove(skb->head + sizeof *hdr,
 559                                             skb->data, len);
 560                         skb_set_tail_pointer(skb, len);
 561                         goto fill;
 562                 }
 563         }
 564
 565         /* create a new skb, with the correct size (and tailpad) */
 566         skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
 567         dev_kfree_skb_any(skb);
 568         if (unlikely(!skb2))
 569                 return skb2;
 570         skb = skb2;
 571
 572         /* fill out the RNDIS header.  we won't bother trying to batch
 573          * packets; Linux minimizes wasted bandwidth through tx queues.
 574          */
 575 fill:
 576         hdr = (void *) __skb_push(skb, sizeof *hdr);
 577         memset(hdr, 0, sizeof *hdr);
 578         hdr->msg_type = cpu_to_le32(RNDIS_MSG_PACKET);
 579         hdr->msg_len = cpu_to_le32(skb->len);
 580         hdr->data_offset = cpu_to_le32(sizeof(*hdr) - 8);
 581         hdr->data_len = cpu_to_le32(len);
 582
 583         /* FIXME make the last packet always be short ... */
 584         return skb;
 585 }
 586 EXPORT_SYMBOL_GPL(rndis_tx_fixup);
 587
 588
 589 static const struct driver_info rndis_info = {
 590         .description =  "RNDIS device",
 591         .flags =        FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
 592         .bind =         rndis_bind,
 593         .unbind =       rndis_unbind,
 594         .status =       rndis_status,
 595         .rx_fixup =     rndis_rx_fixup,
 596         .tx_fixup =     rndis_tx_fixup,
 597 };
 598
 599 static const struct driver_info rndis_poll_status_info = {
 600         .description =  "RNDIS device (poll status before control)",
 601         .flags =        FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
 602         .data =         RNDIS_DRIVER_DATA_POLL_STATUS,
 603         .bind =         rndis_bind,
 604         .unbind =       rndis_unbind,
 605         .status =       rndis_status,
 606         .rx_fixup =     rndis_rx_fixup,
 607         .tx_fixup =     rndis_tx_fixup,
 608 };
 609
 610 /*-------------------------------------------------------------------------*/
 611
 612 static const struct usb_device_id       products [] = {
 613 {
 614         /* 2Wire HomePortal 1000SW */
 615         USB_DEVICE_AND_INTERFACE_INFO(0x1630, 0x0042,
 616                                       USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
 617         .driver_info = (unsigned long) &rndis_poll_status_info,
 618 }, {
 619         /* RNDIS is MSFT's un-official variant of CDC ACM */
 620         USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
 621         .driver_info = (unsigned long) &rndis_info,
 622 }, {
 623         /* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
 624         USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
 625         .driver_info = (unsigned long) &rndis_poll_status_info,
 626 }, {
 627         /* RNDIS for tethering */
 628         USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
 629         .driver_info = (unsigned long) &rndis_info,
 630 },
 631         { },            // END
 632 };
 633 MODULE_DEVICE_TABLE(usb, products);
 634
 635 static struct usb_driver rndis_driver = {
 636         .name =         "rndis_host",
 637         .id_table =     products,
 638         .probe =        usbnet_probe,
 639         .disconnect =   usbnet_disconnect,
 640         .suspend =      usbnet_suspend,
 641         .resume =       usbnet_resume,
 642         .disable_hub_initiated_lpm = 1,
 643 };
 644
 645 module_usb_driver(rndis_driver);
 646
 647 MODULE_AUTHOR("David Brownell");
 648 MODULE_DESCRIPTION("USB Host side RNDIS driver");
 649 MODULE_LICENSE("GPL");