xref: /linux/drivers/net/usb/rndis_host.c (revision 2d87650a3bf1b80f7d0d150ee1af3f8a89e5b7aa)
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/init.h>
20 #include <linux/netdevice.h>
21 #include <linux/etherdevice.h>
22 #include <linux/ethtool.h>
23 #include <linux/workqueue.h>
24 #include <linux/slab.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 	netdev_dbg(dev->net, "rndis status urb, len %d stat %d\n",
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 		u32 status = le32_to_cpu(msg->status);
80 
81 		switch (status) {
82 		case RNDIS_STATUS_MEDIA_CONNECT:
83 			dev_info(udev, "rndis media connect\n");
84 			break;
85 		case RNDIS_STATUS_MEDIA_DISCONNECT:
86 			dev_info(udev, "rndis media disconnect\n");
87 			break;
88 		default:
89 			dev_info(udev, "rndis indication: 0x%08x\n", 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 	u32			xid = 0, msg_len, request_id, msg_type, rsp,
113 				status;
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 	msg_type = le32_to_cpu(buf->msg_type);
120 
121 	/* Issue the request; xid is unique, don't bother byteswapping it */
122 	if (likely(msg_type != RNDIS_MSG_HALT && msg_type != RNDIS_MSG_RESET)) {
123 		xid = dev->xid++;
124 		if (!xid)
125 			xid = dev->xid++;
126 		buf->request_id = (__force __le32) xid;
127 	}
128 	master_ifnum = info->control->cur_altsetting->desc.bInterfaceNumber;
129 	retval = usb_control_msg(dev->udev,
130 		usb_sndctrlpipe(dev->udev, 0),
131 		USB_CDC_SEND_ENCAPSULATED_COMMAND,
132 		USB_TYPE_CLASS | USB_RECIP_INTERFACE,
133 		0, master_ifnum,
134 		buf, le32_to_cpu(buf->msg_len),
135 		RNDIS_CONTROL_TIMEOUT_MS);
136 	if (unlikely(retval < 0 || xid == 0))
137 		return retval;
138 
139 	/* Some devices don't respond on the control channel until
140 	 * polled on the status channel, so do that first. */
141 	if (dev->driver_info->data & RNDIS_DRIVER_DATA_POLL_STATUS) {
142 		retval = usb_interrupt_msg(
143 			dev->udev,
144 			usb_rcvintpipe(dev->udev,
145 				       dev->status->desc.bEndpointAddress),
146 			&notification, sizeof(notification), &partial,
147 			RNDIS_CONTROL_TIMEOUT_MS);
148 		if (unlikely(retval < 0))
149 			return retval;
150 	}
151 
152 	/* Poll the control channel; the request probably completed immediately */
153 	rsp = le32_to_cpu(buf->msg_type) | RNDIS_MSG_COMPLETION;
154 	for (count = 0; count < 10; count++) {
155 		memset(buf, 0, CONTROL_BUFFER_SIZE);
156 		retval = usb_control_msg(dev->udev,
157 			usb_rcvctrlpipe(dev->udev, 0),
158 			USB_CDC_GET_ENCAPSULATED_RESPONSE,
159 			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
160 			0, master_ifnum,
161 			buf, buflen,
162 			RNDIS_CONTROL_TIMEOUT_MS);
163 		if (likely(retval >= 8)) {
164 			msg_type = le32_to_cpu(buf->msg_type);
165 			msg_len = le32_to_cpu(buf->msg_len);
166 			status = le32_to_cpu(buf->status);
167 			request_id = (__force u32) buf->request_id;
168 			if (likely(msg_type == rsp)) {
169 				if (likely(request_id == xid)) {
170 					if (unlikely(rsp == RNDIS_MSG_RESET_C))
171 						return 0;
172 					if (likely(RNDIS_STATUS_SUCCESS ==
173 							status))
174 						return 0;
175 					dev_dbg(&info->control->dev,
176 						"rndis reply status %08x\n",
177 						status);
178 					return -EL3RST;
179 				}
180 				dev_dbg(&info->control->dev,
181 					"rndis reply id %d expected %d\n",
182 					request_id, xid);
183 				/* then likely retry */
184 			} else switch (msg_type) {
185 			case RNDIS_MSG_INDICATE: /* fault/event */
186 				rndis_msg_indicate(dev, (void *)buf, buflen);
187 				break;
188 			case RNDIS_MSG_KEEPALIVE: { /* ping */
189 				struct rndis_keepalive_c *msg = (void *)buf;
190 
191 				msg->msg_type = cpu_to_le32(RNDIS_MSG_KEEPALIVE_C);
192 				msg->msg_len = cpu_to_le32(sizeof *msg);
193 				msg->status = cpu_to_le32(RNDIS_STATUS_SUCCESS);
194 				retval = usb_control_msg(dev->udev,
195 					usb_sndctrlpipe(dev->udev, 0),
196 					USB_CDC_SEND_ENCAPSULATED_COMMAND,
197 					USB_TYPE_CLASS | USB_RECIP_INTERFACE,
198 					0, master_ifnum,
199 					msg, sizeof *msg,
200 					RNDIS_CONTROL_TIMEOUT_MS);
201 				if (unlikely(retval < 0))
202 					dev_dbg(&info->control->dev,
203 						"rndis keepalive err %d\n",
204 						retval);
205 				}
206 				break;
207 			default:
208 				dev_dbg(&info->control->dev,
209 					"unexpected rndis msg %08x len %d\n",
210 					le32_to_cpu(buf->msg_type), msg_len);
211 			}
212 		} else {
213 			/* device probably issued a protocol stall; ignore */
214 			dev_dbg(&info->control->dev,
215 				"rndis response error, code %d\n", retval);
216 		}
217 		msleep(20);
218 	}
219 	dev_dbg(&info->control->dev, "rndis response timeout\n");
220 	return -ETIMEDOUT;
221 }
222 EXPORT_SYMBOL_GPL(rndis_command);
223 
224 /*
225  * rndis_query:
226  *
227  * Performs a query for @oid along with 0 or more bytes of payload as
228  * specified by @in_len. If @reply_len is not set to -1 then the reply
229  * length is checked against this value, resulting in an error if it
230  * doesn't match.
231  *
232  * NOTE: Adding a payload exactly or greater than the size of the expected
233  * response payload is an evident requirement MSFT added for ActiveSync.
234  *
235  * The only exception is for OIDs that return a variably sized response,
236  * in which case no payload should be added.  This undocumented (and
237  * nonsensical!) issue was found by sniffing protocol requests from the
238  * ActiveSync 4.1 Windows driver.
239  */
240 static int rndis_query(struct usbnet *dev, struct usb_interface *intf,
241 		void *buf, u32 oid, u32 in_len,
242 		void **reply, int *reply_len)
243 {
244 	int retval;
245 	union {
246 		void			*buf;
247 		struct rndis_msg_hdr	*header;
248 		struct rndis_query	*get;
249 		struct rndis_query_c	*get_c;
250 	} u;
251 	u32 off, len;
252 
253 	u.buf = buf;
254 
255 	memset(u.get, 0, sizeof *u.get + in_len);
256 	u.get->msg_type = cpu_to_le32(RNDIS_MSG_QUERY);
257 	u.get->msg_len = cpu_to_le32(sizeof *u.get + in_len);
258 	u.get->oid = cpu_to_le32(oid);
259 	u.get->len = cpu_to_le32(in_len);
260 	u.get->offset = cpu_to_le32(20);
261 
262 	retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
263 	if (unlikely(retval < 0)) {
264 		dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) failed, %d\n",
265 				oid, retval);
266 		return retval;
267 	}
268 
269 	off = le32_to_cpu(u.get_c->offset);
270 	len = le32_to_cpu(u.get_c->len);
271 	if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))
272 		goto response_error;
273 
274 	if (*reply_len != -1 && len != *reply_len)
275 		goto response_error;
276 
277 	*reply = (unsigned char *) &u.get_c->request_id + off;
278 	*reply_len = len;
279 
280 	return retval;
281 
282 response_error:
283 	dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) "
284 			"invalid response - off %d len %d\n",
285 		oid, off, len);
286 	return -EDOM;
287 }
288 
289 /* same as usbnet_netdev_ops but MTU change not allowed */
290 static const struct net_device_ops rndis_netdev_ops = {
291 	.ndo_open		= usbnet_open,
292 	.ndo_stop		= usbnet_stop,
293 	.ndo_start_xmit		= usbnet_start_xmit,
294 	.ndo_tx_timeout		= usbnet_tx_timeout,
295 	.ndo_set_mac_address 	= eth_mac_addr,
296 	.ndo_validate_addr	= eth_validate_addr,
297 };
298 
299 int
300 generic_rndis_bind(struct usbnet *dev, struct usb_interface *intf, int flags)
301 {
302 	int			retval;
303 	struct net_device	*net = dev->net;
304 	struct cdc_state	*info = (void *) &dev->data;
305 	union {
306 		void			*buf;
307 		struct rndis_msg_hdr	*header;
308 		struct rndis_init	*init;
309 		struct rndis_init_c	*init_c;
310 		struct rndis_query	*get;
311 		struct rndis_query_c	*get_c;
312 		struct rndis_set	*set;
313 		struct rndis_set_c	*set_c;
314 		struct rndis_halt	*halt;
315 	} u;
316 	u32			tmp;
317 	__le32			phym_unspec, *phym;
318 	int			reply_len;
319 	unsigned char		*bp;
320 
321 	/* we can't rely on i/o from stack working, or stack allocation */
322 	u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
323 	if (!u.buf)
324 		return -ENOMEM;
325 	retval = usbnet_generic_cdc_bind(dev, intf);
326 	if (retval < 0)
327 		goto fail;
328 
329 	u.init->msg_type = cpu_to_le32(RNDIS_MSG_INIT);
330 	u.init->msg_len = cpu_to_le32(sizeof *u.init);
331 	u.init->major_version = cpu_to_le32(1);
332 	u.init->minor_version = cpu_to_le32(0);
333 
334 	/* max transfer (in spec) is 0x4000 at full speed, but for
335 	 * TX we'll stick to one Ethernet packet plus RNDIS framing.
336 	 * For RX we handle drivers that zero-pad to end-of-packet.
337 	 * Don't let userspace change these settings.
338 	 *
339 	 * NOTE: there still seems to be wierdness here, as if we need
340 	 * to do some more things to make sure WinCE targets accept this.
341 	 * They default to jumbograms of 8KB or 16KB, which is absurd
342 	 * for such low data rates and which is also more than Linux
343 	 * can usually expect to allocate for SKB data...
344 	 */
345 	net->hard_header_len += sizeof (struct rndis_data_hdr);
346 	dev->hard_mtu = net->mtu + net->hard_header_len;
347 
348 	dev->maxpacket = usb_maxpacket(dev->udev, dev->out, 1);
349 	if (dev->maxpacket == 0) {
350 		netif_dbg(dev, probe, dev->net,
351 			  "dev->maxpacket can't be 0\n");
352 		retval = -EINVAL;
353 		goto fail_and_release;
354 	}
355 
356 	dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
357 	dev->rx_urb_size &= ~(dev->maxpacket - 1);
358 	u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);
359 
360 	net->netdev_ops = &rndis_netdev_ops;
361 
362 	retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
363 	if (unlikely(retval < 0)) {
364 		/* it might not even be an RNDIS device!! */
365 		dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
366 		goto fail_and_release;
367 	}
368 	tmp = le32_to_cpu(u.init_c->max_transfer_size);
369 	if (tmp < dev->hard_mtu) {
370 		if (tmp <= net->hard_header_len) {
371 			dev_err(&intf->dev,
372 				"dev can't take %u byte packets (max %u)\n",
373 				dev->hard_mtu, tmp);
374 			retval = -EINVAL;
375 			goto halt_fail_and_release;
376 		}
377 		dev_warn(&intf->dev,
378 			 "dev can't take %u byte packets (max %u), "
379 			 "adjusting MTU to %u\n",
380 			 dev->hard_mtu, tmp, tmp - net->hard_header_len);
381 		dev->hard_mtu = tmp;
382 		net->mtu = dev->hard_mtu - net->hard_header_len;
383 	}
384 
385 	/* REVISIT:  peripheral "alignment" request is ignored ... */
386 	dev_dbg(&intf->dev,
387 		"hard mtu %u (%u from dev), rx buflen %Zu, align %d\n",
388 		dev->hard_mtu, tmp, dev->rx_urb_size,
389 		1 << le32_to_cpu(u.init_c->packet_alignment));
390 
391 	/* module has some device initialization code needs to be done right
392 	 * after RNDIS_INIT */
393 	if (dev->driver_info->early_init &&
394 			dev->driver_info->early_init(dev) != 0)
395 		goto halt_fail_and_release;
396 
397 	/* Check physical medium */
398 	phym = NULL;
399 	reply_len = sizeof *phym;
400 	retval = rndis_query(dev, intf, u.buf,
401 			     RNDIS_OID_GEN_PHYSICAL_MEDIUM,
402 			     0, (void **) &phym, &reply_len);
403 	if (retval != 0 || !phym) {
404 		/* OID is optional so don't fail here. */
405 		phym_unspec = cpu_to_le32(RNDIS_PHYSICAL_MEDIUM_UNSPECIFIED);
406 		phym = &phym_unspec;
407 	}
408 	if ((flags & FLAG_RNDIS_PHYM_WIRELESS) &&
409 	    le32_to_cpup(phym) != RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
410 		netif_dbg(dev, probe, dev->net,
411 			  "driver requires wireless physical medium, but device is not\n");
412 		retval = -ENODEV;
413 		goto halt_fail_and_release;
414 	}
415 	if ((flags & FLAG_RNDIS_PHYM_NOT_WIRELESS) &&
416 	    le32_to_cpup(phym) == RNDIS_PHYSICAL_MEDIUM_WIRELESS_LAN) {
417 		netif_dbg(dev, probe, dev->net,
418 			  "driver requires non-wireless physical medium, but device is wireless.\n");
419 		retval = -ENODEV;
420 		goto halt_fail_and_release;
421 	}
422 
423 	/* Get designated host ethernet address */
424 	reply_len = ETH_ALEN;
425 	retval = rndis_query(dev, intf, u.buf,
426 			     RNDIS_OID_802_3_PERMANENT_ADDRESS,
427 			     48, (void **) &bp, &reply_len);
428 	if (unlikely(retval< 0)) {
429 		dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
430 		goto halt_fail_and_release;
431 	}
432 	memcpy(net->dev_addr, bp, ETH_ALEN);
433 
434 	/* set a nonzero filter to enable data transfers */
435 	memset(u.set, 0, sizeof *u.set);
436 	u.set->msg_type = cpu_to_le32(RNDIS_MSG_SET);
437 	u.set->msg_len = cpu_to_le32(4 + sizeof *u.set);
438 	u.set->oid = cpu_to_le32(RNDIS_OID_GEN_CURRENT_PACKET_FILTER);
439 	u.set->len = cpu_to_le32(4);
440 	u.set->offset = cpu_to_le32((sizeof *u.set) - 8);
441 	*(__le32 *)(u.buf + sizeof *u.set) = cpu_to_le32(RNDIS_DEFAULT_FILTER);
442 
443 	retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
444 	if (unlikely(retval < 0)) {
445 		dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
446 		goto halt_fail_and_release;
447 	}
448 
449 	retval = 0;
450 
451 	kfree(u.buf);
452 	return retval;
453 
454 halt_fail_and_release:
455 	memset(u.halt, 0, sizeof *u.halt);
456 	u.halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
457 	u.halt->msg_len = cpu_to_le32(sizeof *u.halt);
458 	(void) rndis_command(dev, (void *)u.halt, CONTROL_BUFFER_SIZE);
459 fail_and_release:
460 	usb_set_intfdata(info->data, NULL);
461 	usb_driver_release_interface(driver_of(intf), info->data);
462 	info->data = NULL;
463 fail:
464 	kfree(u.buf);
465 	return retval;
466 }
467 EXPORT_SYMBOL_GPL(generic_rndis_bind);
468 
469 static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
470 {
471 	return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
472 }
473 
474 void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
475 {
476 	struct rndis_halt	*halt;
477 
478 	/* try to clear any rndis state/activity (no i/o from stack!) */
479 	halt = kzalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
480 	if (halt) {
481 		halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
482 		halt->msg_len = cpu_to_le32(sizeof *halt);
483 		(void) rndis_command(dev, (void *)halt, CONTROL_BUFFER_SIZE);
484 		kfree(halt);
485 	}
486 
487 	usbnet_cdc_unbind(dev, intf);
488 }
489 EXPORT_SYMBOL_GPL(rndis_unbind);
490 
491 /*
492  * DATA -- host must not write zlps
493  */
494 int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
495 {
496 	/* peripheral may have batched packets to us... */
497 	while (likely(skb->len)) {
498 		struct rndis_data_hdr	*hdr = (void *)skb->data;
499 		struct sk_buff		*skb2;
500 		u32			msg_type, msg_len, data_offset, data_len;
501 
502 		msg_type = le32_to_cpu(hdr->msg_type);
503 		msg_len = le32_to_cpu(hdr->msg_len);
504 		data_offset = le32_to_cpu(hdr->data_offset);
505 		data_len = le32_to_cpu(hdr->data_len);
506 
507 		/* don't choke if we see oob, per-packet data, etc */
508 		if (unlikely(msg_type != RNDIS_MSG_PACKET || skb->len < msg_len
509 				|| (data_offset + data_len + 8) > msg_len)) {
510 			dev->net->stats.rx_frame_errors++;
511 			netdev_dbg(dev->net, "bad rndis message %d/%d/%d/%d, len %d\n",
512 				   le32_to_cpu(hdr->msg_type),
513 				   msg_len, data_offset, data_len, skb->len);
514 			return 0;
515 		}
516 		skb_pull(skb, 8 + data_offset);
517 
518 		/* at most one packet left? */
519 		if (likely((data_len - skb->len) <= sizeof *hdr)) {
520 			skb_trim(skb, data_len);
521 			break;
522 		}
523 
524 		/* try to return all the packets in the batch */
525 		skb2 = skb_clone(skb, GFP_ATOMIC);
526 		if (unlikely(!skb2))
527 			break;
528 		skb_pull(skb, msg_len - sizeof *hdr);
529 		skb_trim(skb2, data_len);
530 		usbnet_skb_return(dev, skb2);
531 	}
532 
533 	/* caller will usbnet_skb_return the remaining packet */
534 	return 1;
535 }
536 EXPORT_SYMBOL_GPL(rndis_rx_fixup);
537 
538 struct sk_buff *
539 rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
540 {
541 	struct rndis_data_hdr	*hdr;
542 	struct sk_buff		*skb2;
543 	unsigned		len = skb->len;
544 
545 	if (likely(!skb_cloned(skb))) {
546 		int	room = skb_headroom(skb);
547 
548 		/* enough head room as-is? */
549 		if (unlikely((sizeof *hdr) <= room))
550 			goto fill;
551 
552 		/* enough room, but needs to be readjusted? */
553 		room += skb_tailroom(skb);
554 		if (likely((sizeof *hdr) <= room)) {
555 			skb->data = memmove(skb->head + sizeof *hdr,
556 					    skb->data, len);
557 			skb_set_tail_pointer(skb, len);
558 			goto fill;
559 		}
560 	}
561 
562 	/* create a new skb, with the correct size (and tailpad) */
563 	skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
564 	dev_kfree_skb_any(skb);
565 	if (unlikely(!skb2))
566 		return skb2;
567 	skb = skb2;
568 
569 	/* fill out the RNDIS header.  we won't bother trying to batch
570 	 * packets; Linux minimizes wasted bandwidth through tx queues.
571 	 */
572 fill:
573 	hdr = (void *) __skb_push(skb, sizeof *hdr);
574 	memset(hdr, 0, sizeof *hdr);
575 	hdr->msg_type = cpu_to_le32(RNDIS_MSG_PACKET);
576 	hdr->msg_len = cpu_to_le32(skb->len);
577 	hdr->data_offset = cpu_to_le32(sizeof(*hdr) - 8);
578 	hdr->data_len = cpu_to_le32(len);
579 
580 	/* FIXME make the last packet always be short ... */
581 	return skb;
582 }
583 EXPORT_SYMBOL_GPL(rndis_tx_fixup);
584 
585 
586 static const struct driver_info	rndis_info = {
587 	.description =	"RNDIS device",
588 	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
589 	.bind =		rndis_bind,
590 	.unbind =	rndis_unbind,
591 	.status =	rndis_status,
592 	.rx_fixup =	rndis_rx_fixup,
593 	.tx_fixup =	rndis_tx_fixup,
594 };
595 
596 static const struct driver_info	rndis_poll_status_info = {
597 	.description =	"RNDIS device (poll status before control)",
598 	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
599 	.data =		RNDIS_DRIVER_DATA_POLL_STATUS,
600 	.bind =		rndis_bind,
601 	.unbind =	rndis_unbind,
602 	.status =	rndis_status,
603 	.rx_fixup =	rndis_rx_fixup,
604 	.tx_fixup =	rndis_tx_fixup,
605 };
606 
607 /*-------------------------------------------------------------------------*/
608 
609 static const struct usb_device_id	products [] = {
610 {
611 	/* 2Wire HomePortal 1000SW */
612 	USB_DEVICE_AND_INTERFACE_INFO(0x1630, 0x0042,
613 				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
614 	.driver_info = (unsigned long) &rndis_poll_status_info,
615 }, {
616 	/* RNDIS is MSFT's un-official variant of CDC ACM */
617 	USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
618 	.driver_info = (unsigned long) &rndis_info,
619 }, {
620 	/* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
621 	USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
622 	.driver_info = (unsigned long) &rndis_poll_status_info,
623 }, {
624 	/* RNDIS for tethering */
625 	USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
626 	.driver_info = (unsigned long) &rndis_info,
627 },
628 	{ },		// END
629 };
630 MODULE_DEVICE_TABLE(usb, products);
631 
632 static struct usb_driver rndis_driver = {
633 	.name =		"rndis_host",
634 	.id_table =	products,
635 	.probe =	usbnet_probe,
636 	.disconnect =	usbnet_disconnect,
637 	.suspend =	usbnet_suspend,
638 	.resume =	usbnet_resume,
639 	.disable_hub_initiated_lpm = 1,
640 };
641 
642 module_usb_driver(rndis_driver);
643 
644 MODULE_AUTHOR("David Brownell");
645 MODULE_DESCRIPTION("USB Host side RNDIS driver");
646 MODULE_LICENSE("GPL");
647