xref: /linux/drivers/net/usb/rndis_host.c (revision b6ebbac51bedf9e98e837688bc838f400196da5e)
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 
432 	if (bp[0] & 0x02)
433 		eth_hw_addr_random(net);
434 	else
435 		ether_addr_copy(net->dev_addr, bp);
436 
437 	/* set a nonzero filter to enable data transfers */
438 	memset(u.set, 0, sizeof *u.set);
439 	u.set->msg_type = cpu_to_le32(RNDIS_MSG_SET);
440 	u.set->msg_len = cpu_to_le32(4 + sizeof *u.set);
441 	u.set->oid = cpu_to_le32(RNDIS_OID_GEN_CURRENT_PACKET_FILTER);
442 	u.set->len = cpu_to_le32(4);
443 	u.set->offset = cpu_to_le32((sizeof *u.set) - 8);
444 	*(__le32 *)(u.buf + sizeof *u.set) = cpu_to_le32(RNDIS_DEFAULT_FILTER);
445 
446 	retval = rndis_command(dev, u.header, CONTROL_BUFFER_SIZE);
447 	if (unlikely(retval < 0)) {
448 		dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
449 		goto halt_fail_and_release;
450 	}
451 
452 	retval = 0;
453 
454 	kfree(u.buf);
455 	return retval;
456 
457 halt_fail_and_release:
458 	memset(u.halt, 0, sizeof *u.halt);
459 	u.halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
460 	u.halt->msg_len = cpu_to_le32(sizeof *u.halt);
461 	(void) rndis_command(dev, (void *)u.halt, CONTROL_BUFFER_SIZE);
462 fail_and_release:
463 	usb_set_intfdata(info->data, NULL);
464 	usb_driver_release_interface(driver_of(intf), info->data);
465 	info->data = NULL;
466 fail:
467 	kfree(u.buf);
468 	return retval;
469 }
470 EXPORT_SYMBOL_GPL(generic_rndis_bind);
471 
472 static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
473 {
474 	return generic_rndis_bind(dev, intf, FLAG_RNDIS_PHYM_NOT_WIRELESS);
475 }
476 
477 void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
478 {
479 	struct rndis_halt	*halt;
480 
481 	/* try to clear any rndis state/activity (no i/o from stack!) */
482 	halt = kzalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
483 	if (halt) {
484 		halt->msg_type = cpu_to_le32(RNDIS_MSG_HALT);
485 		halt->msg_len = cpu_to_le32(sizeof *halt);
486 		(void) rndis_command(dev, (void *)halt, CONTROL_BUFFER_SIZE);
487 		kfree(halt);
488 	}
489 
490 	usbnet_cdc_unbind(dev, intf);
491 }
492 EXPORT_SYMBOL_GPL(rndis_unbind);
493 
494 /*
495  * DATA -- host must not write zlps
496  */
497 int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
498 {
499 	/* This check is no longer done by usbnet */
500 	if (skb->len < dev->net->hard_header_len)
501 		return 0;
502 
503 	/* peripheral may have batched packets to us... */
504 	while (likely(skb->len)) {
505 		struct rndis_data_hdr	*hdr = (void *)skb->data;
506 		struct sk_buff		*skb2;
507 		u32			msg_type, msg_len, data_offset, data_len;
508 
509 		msg_type = le32_to_cpu(hdr->msg_type);
510 		msg_len = le32_to_cpu(hdr->msg_len);
511 		data_offset = le32_to_cpu(hdr->data_offset);
512 		data_len = le32_to_cpu(hdr->data_len);
513 
514 		/* don't choke if we see oob, per-packet data, etc */
515 		if (unlikely(msg_type != RNDIS_MSG_PACKET || skb->len < msg_len
516 				|| (data_offset + data_len + 8) > msg_len)) {
517 			dev->net->stats.rx_frame_errors++;
518 			netdev_dbg(dev->net, "bad rndis message %d/%d/%d/%d, len %d\n",
519 				   le32_to_cpu(hdr->msg_type),
520 				   msg_len, data_offset, data_len, skb->len);
521 			return 0;
522 		}
523 		skb_pull(skb, 8 + data_offset);
524 
525 		/* at most one packet left? */
526 		if (likely((data_len - skb->len) <= sizeof *hdr)) {
527 			skb_trim(skb, data_len);
528 			break;
529 		}
530 
531 		/* try to return all the packets in the batch */
532 		skb2 = skb_clone(skb, GFP_ATOMIC);
533 		if (unlikely(!skb2))
534 			break;
535 		skb_pull(skb, msg_len - sizeof *hdr);
536 		skb_trim(skb2, data_len);
537 		usbnet_skb_return(dev, skb2);
538 	}
539 
540 	/* caller will usbnet_skb_return the remaining packet */
541 	return 1;
542 }
543 EXPORT_SYMBOL_GPL(rndis_rx_fixup);
544 
545 struct sk_buff *
546 rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
547 {
548 	struct rndis_data_hdr	*hdr;
549 	struct sk_buff		*skb2;
550 	unsigned		len = skb->len;
551 
552 	if (likely(!skb_cloned(skb))) {
553 		int	room = skb_headroom(skb);
554 
555 		/* enough head room as-is? */
556 		if (unlikely((sizeof *hdr) <= room))
557 			goto fill;
558 
559 		/* enough room, but needs to be readjusted? */
560 		room += skb_tailroom(skb);
561 		if (likely((sizeof *hdr) <= room)) {
562 			skb->data = memmove(skb->head + sizeof *hdr,
563 					    skb->data, len);
564 			skb_set_tail_pointer(skb, len);
565 			goto fill;
566 		}
567 	}
568 
569 	/* create a new skb, with the correct size (and tailpad) */
570 	skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
571 	dev_kfree_skb_any(skb);
572 	if (unlikely(!skb2))
573 		return skb2;
574 	skb = skb2;
575 
576 	/* fill out the RNDIS header.  we won't bother trying to batch
577 	 * packets; Linux minimizes wasted bandwidth through tx queues.
578 	 */
579 fill:
580 	hdr = (void *) __skb_push(skb, sizeof *hdr);
581 	memset(hdr, 0, sizeof *hdr);
582 	hdr->msg_type = cpu_to_le32(RNDIS_MSG_PACKET);
583 	hdr->msg_len = cpu_to_le32(skb->len);
584 	hdr->data_offset = cpu_to_le32(sizeof(*hdr) - 8);
585 	hdr->data_len = cpu_to_le32(len);
586 
587 	/* FIXME make the last packet always be short ... */
588 	return skb;
589 }
590 EXPORT_SYMBOL_GPL(rndis_tx_fixup);
591 
592 
593 static const struct driver_info	rndis_info = {
594 	.description =	"RNDIS device",
595 	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
596 	.bind =		rndis_bind,
597 	.unbind =	rndis_unbind,
598 	.status =	rndis_status,
599 	.rx_fixup =	rndis_rx_fixup,
600 	.tx_fixup =	rndis_tx_fixup,
601 };
602 
603 static const struct driver_info	rndis_poll_status_info = {
604 	.description =	"RNDIS device (poll status before control)",
605 	.flags =	FLAG_ETHER | FLAG_POINTTOPOINT | FLAG_FRAMING_RN | FLAG_NO_SETINT,
606 	.data =		RNDIS_DRIVER_DATA_POLL_STATUS,
607 	.bind =		rndis_bind,
608 	.unbind =	rndis_unbind,
609 	.status =	rndis_status,
610 	.rx_fixup =	rndis_rx_fixup,
611 	.tx_fixup =	rndis_tx_fixup,
612 };
613 
614 /*-------------------------------------------------------------------------*/
615 
616 static const struct usb_device_id	products [] = {
617 {
618 	/* 2Wire HomePortal 1000SW */
619 	USB_DEVICE_AND_INTERFACE_INFO(0x1630, 0x0042,
620 				      USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
621 	.driver_info = (unsigned long) &rndis_poll_status_info,
622 }, {
623 	/* RNDIS is MSFT's un-official variant of CDC ACM */
624 	USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
625 	.driver_info = (unsigned long) &rndis_info,
626 }, {
627 	/* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
628 	USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
629 	.driver_info = (unsigned long) &rndis_poll_status_info,
630 }, {
631 	/* RNDIS for tethering */
632 	USB_INTERFACE_INFO(USB_CLASS_WIRELESS_CONTROLLER, 1, 3),
633 	.driver_info = (unsigned long) &rndis_info,
634 },
635 	{ },		// END
636 };
637 MODULE_DEVICE_TABLE(usb, products);
638 
639 static struct usb_driver rndis_driver = {
640 	.name =		"rndis_host",
641 	.id_table =	products,
642 	.probe =	usbnet_probe,
643 	.disconnect =	usbnet_disconnect,
644 	.suspend =	usbnet_suspend,
645 	.resume =	usbnet_resume,
646 	.disable_hub_initiated_lpm = 1,
647 };
648 
649 module_usb_driver(rndis_driver);
650 
651 MODULE_AUTHOR("David Brownell");
652 MODULE_DESCRIPTION("USB Host side RNDIS driver");
653 MODULE_LICENSE("GPL");
654