aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/net/usb/rndis_host.c
blob: cd991a0f75bb3ef919d8ba9f513b982eba884163 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
/*
 * Host Side support for RNDIS Networking Links
 * Copyright (C) 2005 by David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

// #define	DEBUG			// error path messages, extra info
// #define	VERBOSE			// more; success messages

#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/workqueue.h>
#include <linux/mii.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>

#include "usbnet.h"


/*
 * RNDIS is NDIS remoted over USB.  It's a MSFT variant of CDC ACM ... of
 * course ACM was intended for modems, not Ethernet links!  USB's standard
 * for Ethernet links is "CDC Ethernet", which is significantly simpler.
 *
 * NOTE that Microsoft's "RNDIS 1.0" specification is incomplete.  Issues
 * include:
 *    - Power management in particular relies on information that's scattered
 *	through other documentation, and which is incomplete or incorrect even
 *	there.
 *    - There are various undocumented protocol requirements, such as the
 *	need to send unused garbage in control-OUT messages.
 *    - In some cases, MS-Windows will emit undocumented requests; this
 *	matters more to peripheral implementations than host ones.
 *
 * Moreover there's a no-open-specs variant of RNDIS called "ActiveSync".
 *
 * For these reasons and others, ** USE OF RNDIS IS STRONGLY DISCOURAGED ** in
 * favor of such non-proprietary alternatives as CDC Ethernet or the newer (and
 * currently rare) "Ethernet Emulation Model" (EEM).
 */

/*
 * CONTROL uses CDC "encapsulated commands" with funky notifications.
 *  - control-out:  SEND_ENCAPSULATED
 *  - interrupt-in:  RESPONSE_AVAILABLE
 *  - control-in:  GET_ENCAPSULATED
 *
 * We'll try to ignore the RESPONSE_AVAILABLE notifications.
 *
 * REVISIT some RNDIS implementations seem to have curious issues still
 * to be resolved.
 */
struct rndis_msg_hdr {
	__le32	msg_type;			/* RNDIS_MSG_* */
	__le32	msg_len;
	// followed by data that varies between messages
	__le32	request_id;
	__le32	status;
	// ... and more
} __attribute__ ((packed));

/* MS-Windows uses this strange size, but RNDIS spec says 1024 minimum */
#define	CONTROL_BUFFER_SIZE		1025

/* RNDIS defines an (absurdly huge) 10 second control timeout,
 * but ActiveSync seems to use a more usual 5 second timeout
 * (which matches the USB 2.0 spec).
 */
#define	RNDIS_CONTROL_TIMEOUT_MS	(5 * 1000)


#define ccpu2 __constant_cpu_to_le32

#define RNDIS_MSG_COMPLETION	ccpu2(0x80000000)

/* codes for "msg_type" field of rndis messages;
 * only the data channel uses packet messages (maybe batched);
 * everything else goes on the control channel.
 */
#define RNDIS_MSG_PACKET	ccpu2(0x00000001)	/* 1-N packets */
#define RNDIS_MSG_INIT		ccpu2(0x00000002)
#define RNDIS_MSG_INIT_C	(RNDIS_MSG_INIT|RNDIS_MSG_COMPLETION)
#define RNDIS_MSG_HALT		ccpu2(0x00000003)
#define RNDIS_MSG_QUERY		ccpu2(0x00000004)
#define RNDIS_MSG_QUERY_C	(RNDIS_MSG_QUERY|RNDIS_MSG_COMPLETION)
#define RNDIS_MSG_SET		ccpu2(0x00000005)
#define RNDIS_MSG_SET_C		(RNDIS_MSG_SET|RNDIS_MSG_COMPLETION)
#define RNDIS_MSG_RESET		ccpu2(0x00000006)
#define RNDIS_MSG_RESET_C	(RNDIS_MSG_RESET|RNDIS_MSG_COMPLETION)
#define RNDIS_MSG_INDICATE	ccpu2(0x00000007)
#define RNDIS_MSG_KEEPALIVE	ccpu2(0x00000008)
#define RNDIS_MSG_KEEPALIVE_C	(RNDIS_MSG_KEEPALIVE|RNDIS_MSG_COMPLETION)

/* codes for "status" field of completion messages */
#define	RNDIS_STATUS_SUCCESS		ccpu2(0x00000000)
#define	RNDIS_STATUS_FAILURE		ccpu2(0xc0000001)
#define	RNDIS_STATUS_INVALID_DATA	ccpu2(0xc0010015)
#define	RNDIS_STATUS_NOT_SUPPORTED	ccpu2(0xc00000bb)
#define	RNDIS_STATUS_MEDIA_CONNECT	ccpu2(0x4001000b)
#define	RNDIS_STATUS_MEDIA_DISCONNECT	ccpu2(0x4001000c)


struct rndis_data_hdr {
	__le32	msg_type;		/* RNDIS_MSG_PACKET */
	__le32	msg_len;		// rndis_data_hdr + data_len + pad
	__le32	data_offset;		// 36 -- right after header
	__le32	data_len;		// ... real packet size

	__le32	oob_data_offset;	// zero
	__le32	oob_data_len;		// zero
	__le32	num_oob;		// zero
	__le32	packet_data_offset;	// zero

	__le32	packet_data_len;	// zero
	__le32	vc_handle;		// zero
	__le32	reserved;		// zero
} __attribute__ ((packed));

struct rndis_init {		/* OUT */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_INIT */
	__le32	msg_len;			// 24
	__le32	request_id;
	__le32	major_version;			// of rndis (1.0)
	__le32	minor_version;
	__le32	max_transfer_size;
} __attribute__ ((packed));

struct rndis_init_c {		/* IN */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_INIT_C */
	__le32	msg_len;
	__le32	request_id;
	__le32	status;
	__le32	major_version;			// of rndis (1.0)
	__le32	minor_version;
	__le32	device_flags;
	__le32	medium;				// zero == 802.3
	__le32	max_packets_per_message;
	__le32	max_transfer_size;
	__le32	packet_alignment;		// max 7; (1<<n) bytes
	__le32	af_list_offset;			// zero
	__le32	af_list_size;			// zero
} __attribute__ ((packed));

struct rndis_halt {		/* OUT (no reply) */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_HALT */
	__le32	msg_len;
	__le32	request_id;
} __attribute__ ((packed));

struct rndis_query {		/* OUT */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_QUERY */
	__le32	msg_len;
	__le32	request_id;
	__le32	oid;
	__le32	len;
	__le32	offset;
/*?*/	__le32	handle;				// zero
} __attribute__ ((packed));

struct rndis_query_c {		/* IN */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_QUERY_C */
	__le32	msg_len;
	__le32	request_id;
	__le32	status;
	__le32	len;
	__le32	offset;
} __attribute__ ((packed));

struct rndis_set {		/* OUT */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_SET */
	__le32	msg_len;
	__le32	request_id;
	__le32	oid;
	__le32	len;
	__le32	offset;
/*?*/	__le32	handle;				// zero
} __attribute__ ((packed));

struct rndis_set_c {		/* IN */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_SET_C */
	__le32	msg_len;
	__le32	request_id;
	__le32	status;
} __attribute__ ((packed));

struct rndis_reset {		/* IN */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_RESET */
	__le32	msg_len;
	__le32	reserved;
} __attribute__ ((packed));

struct rndis_reset_c {		/* OUT */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_RESET_C */
	__le32	msg_len;
	__le32	status;
	__le32	addressing_lost;
} __attribute__ ((packed));

struct rndis_indicate {		/* IN (unrequested) */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_INDICATE */
	__le32	msg_len;
	__le32	status;
	__le32	length;
	__le32	offset;
/**/	__le32	diag_status;
	__le32	error_offset;
/**/	__le32	message;
} __attribute__ ((packed));

struct rndis_keepalive {	/* OUT (optionally IN) */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_KEEPALIVE */
	__le32	msg_len;
	__le32	request_id;
} __attribute__ ((packed));

struct rndis_keepalive_c {	/* IN (optionally OUT) */
	// header and:
	__le32	msg_type;			/* RNDIS_MSG_KEEPALIVE_C */
	__le32	msg_len;
	__le32	request_id;
	__le32	status;
} __attribute__ ((packed));

/* NOTE:  about 30 OIDs are "mandatory" for peripherals to support ... and
 * there are gobs more that may optionally be supported.  We'll avoid as much
 * of that mess as possible.
 */
#define OID_802_3_PERMANENT_ADDRESS	ccpu2(0x01010101)
#define OID_GEN_MAXIMUM_FRAME_SIZE	ccpu2(0x00010106)
#define OID_GEN_CURRENT_PACKET_FILTER	ccpu2(0x0001010e)

/*
 * RNDIS notifications from device: command completion; "reverse"
 * keepalives; etc
 */
static void rndis_status(struct usbnet *dev, struct urb *urb)
{
	devdbg(dev, "rndis status urb, len %d stat %d",
		urb->actual_length, urb->status);
	// FIXME for keepalives, respond immediately (asynchronously)
	// if not an RNDIS status, do like cdc_status(dev,urb) does
}

/*
 * RPC done RNDIS-style.  Caller guarantees:
 * - message is properly byteswapped
 * - there's no other request pending
 * - buf can hold up to 1KB response (required by RNDIS spec)
 * On return, the first few entries are already byteswapped.
 *
 * Call context is likely probe(), before interface name is known,
 * which is why we won't try to use it in the diagnostics.
 */
static int rndis_command(struct usbnet *dev, struct rndis_msg_hdr *buf)
{
	struct cdc_state	*info = (void *) &dev->data;
	int			master_ifnum;
	int			retval;
	unsigned		count;
	__le32			rsp;
	u32			xid = 0, msg_len, request_id;

	/* REVISIT when this gets called from contexts other than probe() or
	 * disconnect(): either serialize, or dispatch responses on xid
	 */

	/* Issue the request; xid is unique, don't bother byteswapping it */
	if (likely(buf->msg_type != RNDIS_MSG_HALT
			&& buf->msg_type != RNDIS_MSG_RESET)) {
		xid = dev->xid++;
		if (!xid)
			xid = dev->xid++;
		buf->request_id = (__force __le32) xid;
	}
	master_ifnum = info->control->cur_altsetting->desc.bInterfaceNumber;
	retval = usb_control_msg(dev->udev,
		usb_sndctrlpipe(dev->udev, 0),
		USB_CDC_SEND_ENCAPSULATED_COMMAND,
		USB_TYPE_CLASS | USB_RECIP_INTERFACE,
		0, master_ifnum,
		buf, le32_to_cpu(buf->msg_len),
		RNDIS_CONTROL_TIMEOUT_MS);
	if (unlikely(retval < 0 || xid == 0))
		return retval;

	// FIXME Seems like some devices discard responses when
	// we time out and cancel our "get response" requests...
	// so, this is fragile.  Probably need to poll for status.

	/* ignore status endpoint, just poll the control channel;
	 * the request probably completed immediately
	 */
	rsp = buf->msg_type | RNDIS_MSG_COMPLETION;
	for (count = 0; count < 10; count++) {
		memset(buf, 0, CONTROL_BUFFER_SIZE);
		retval = usb_control_msg(dev->udev,
			usb_rcvctrlpipe(dev->udev, 0),
			USB_CDC_GET_ENCAPSULATED_RESPONSE,
			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
			0, master_ifnum,
			buf, CONTROL_BUFFER_SIZE,
			RNDIS_CONTROL_TIMEOUT_MS);
		if (likely(retval >= 8)) {
			msg_len = le32_to_cpu(buf->msg_len);
			request_id = (__force u32) buf->request_id;
			if (likely(buf->msg_type == rsp)) {
				if (likely(request_id == xid)) {
					if (unlikely(rsp == RNDIS_MSG_RESET_C))
						return 0;
					if (likely(RNDIS_STATUS_SUCCESS
							== buf->status))
						return 0;
					dev_dbg(&info->control->dev,
						"rndis reply status %08x\n",
						le32_to_cpu(buf->status));
					return -EL3RST;
				}
				dev_dbg(&info->control->dev,
					"rndis reply id %d expected %d\n",
					request_id, xid);
				/* then likely retry */
			} else switch (buf->msg_type) {
			case RNDIS_MSG_INDICATE: {	/* fault */
				// struct rndis_indicate *msg = (void *)buf;
				dev_info(&info->control->dev,
					"rndis fault indication\n");
				}
				break;
			case RNDIS_MSG_KEEPALIVE: {	/* ping */
				struct rndis_keepalive_c *msg = (void *)buf;

				msg->msg_type = RNDIS_MSG_KEEPALIVE_C;
				msg->msg_len = ccpu2(sizeof *msg);
				msg->status = RNDIS_STATUS_SUCCESS;
				retval = usb_control_msg(dev->udev,
					usb_sndctrlpipe(dev->udev, 0),
					USB_CDC_SEND_ENCAPSULATED_COMMAND,
					USB_TYPE_CLASS | USB_RECIP_INTERFACE,
					0, master_ifnum,
					msg, sizeof *msg,
					RNDIS_CONTROL_TIMEOUT_MS);
				if (unlikely(retval < 0))
					dev_dbg(&info->control->dev,
						"rndis keepalive err %d\n",
						retval);
				}
				break;
			default:
				dev_dbg(&info->control->dev,
					"unexpected rndis msg %08x len %d\n",
					le32_to_cpu(buf->msg_type), msg_len);
			}
		} else {
			/* device probably issued a protocol stall; ignore */
			dev_dbg(&info->control->dev,
				"rndis response error, code %d\n", retval);
		}
		msleep(2);
	}
	dev_dbg(&info->control->dev, "rndis response timeout\n");
	return -ETIMEDOUT;
}

/*
 * rndis_query:
 *
 * Performs a query for @oid along with 0 or more bytes of payload as
 * specified by @in_len. If @reply_len is not set to -1 then the reply
 * length is checked against this value, resulting in an error if it
 * doesn't match.
 *
 * NOTE: Adding a payload exactly or greater than the size of the expected
 * response payload is an evident requirement MSFT added for ActiveSync.
 *
 * The only exception is for OIDs that return a variably sized response,
 * in which case no payload should be added.  This undocumented (and
 * nonsensical!) issue was found by sniffing protocol requests from the
 * ActiveSync 4.1 Windows driver.
 */
static int rndis_query(struct usbnet *dev, struct usb_interface *intf,
		void *buf, u32 oid, u32 in_len,
		void **reply, int *reply_len)
{
	int retval;
	union {
		void			*buf;
		struct rndis_msg_hdr	*header;
		struct rndis_query	*get;
		struct rndis_query_c	*get_c;
	} u;
	u32 off, len;

	u.buf = buf;

	memset(u.get, 0, sizeof *u.get + in_len);
	u.get->msg_type = RNDIS_MSG_QUERY;
	u.get->msg_len = cpu_to_le32(sizeof *u.get + in_len);
	u.get->oid = oid;
	u.get->len = cpu_to_le32(in_len);
	u.get->offset = ccpu2(20);

	retval = rndis_command(dev, u.header);
	if (unlikely(retval < 0)) {
		dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) failed, %d\n",
				oid, retval);
		return retval;
	}

	off = le32_to_cpu(u.get_c->offset);
	len = le32_to_cpu(u.get_c->len);
	if (unlikely((8 + off + len) > CONTROL_BUFFER_SIZE))
		goto response_error;

	if (*reply_len != -1 && len != *reply_len)
		goto response_error;

	*reply = (unsigned char *) &u.get_c->request_id + off;
	*reply_len = len;

	return retval;

response_error:
	dev_err(&intf->dev, "RNDIS_MSG_QUERY(0x%08x) "
			"invalid response - off %d len %d\n",
		oid, off, len);
	return -EDOM;
}

static int rndis_bind(struct usbnet *dev, struct usb_interface *intf)
{
	int			retval;
	struct net_device	*net = dev->net;
	struct cdc_state	*info = (void *) &dev->data;
	union {
		void			*buf;
		struct rndis_msg_hdr	*header;
		struct rndis_init	*init;
		struct rndis_init_c	*init_c;
		struct rndis_query	*get;
		struct rndis_query_c	*get_c;
		struct rndis_set	*set;
		struct rndis_set_c	*set_c;
	} u;
	u32			tmp;
	int			reply_len;
	unsigned char		*bp;

	/* we can't rely on i/o from stack working, or stack allocation */
	u.buf = kmalloc(CONTROL_BUFFER_SIZE, GFP_KERNEL);
	if (!u.buf)
		return -ENOMEM;
	retval = usbnet_generic_cdc_bind(dev, intf);
	if (retval < 0)
		goto fail;

	u.init->msg_type = RNDIS_MSG_INIT;
	u.init->msg_len = ccpu2(sizeof *u.init);
	u.init->major_version = ccpu2(1);
	u.init->minor_version = ccpu2(0);

	/* max transfer (in spec) is 0x4000 at full speed, but for
	 * TX we'll stick to one Ethernet packet plus RNDIS framing.
	 * For RX we handle drivers that zero-pad to end-of-packet.
	 * Don't let userspace change these settings.
	 *
	 * NOTE: there still seems to be wierdness here, as if we need
	 * to do some more things to make sure WinCE targets accept this.
	 * They default to jumbograms of 8KB or 16KB, which is absurd
	 * for such low data rates and which is also more than Linux
	 * can usually expect to allocate for SKB data...
	 */
	net->hard_header_len += sizeof (struct rndis_data_hdr);
	dev->hard_mtu = net->mtu + net->hard_header_len;

	dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
	dev->rx_urb_size &= ~(dev->maxpacket - 1);
	u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);

	net->change_mtu = NULL;
	retval = rndis_command(dev, u.header);
	if (unlikely(retval < 0)) {
		/* it might not even be an RNDIS device!! */
		dev_err(&intf->dev, "RNDIS init failed, %d\n", retval);
		goto fail_and_release;
	}
	tmp = le32_to_cpu(u.init_c->max_transfer_size);
	if (tmp < dev->hard_mtu) {
		dev_err(&intf->dev,
			"dev can't take %u byte packets (max %u)\n",
			dev->hard_mtu, tmp);
		retval = -EINVAL;
		goto fail_and_release;
	}

	/* REVISIT:  peripheral "alignment" request is ignored ... */
	dev_dbg(&intf->dev,
		"hard mtu %u (%u from dev), rx buflen %Zu, align %d\n",
		dev->hard_mtu, tmp, dev->rx_urb_size,
		1 << le32_to_cpu(u.init_c->packet_alignment));

	/* Get designated host ethernet address */
	reply_len = ETH_ALEN;
	retval = rndis_query(dev, intf, u.buf, OID_802_3_PERMANENT_ADDRESS,
			48, (void **) &bp, &reply_len);
	if (unlikely(retval< 0)) {
		dev_err(&intf->dev, "rndis get ethaddr, %d\n", retval);
		goto fail_and_release;
	}
	memcpy(net->dev_addr, bp, ETH_ALEN);

	/* set a nonzero filter to enable data transfers */
	memset(u.set, 0, sizeof *u.set);
	u.set->msg_type = RNDIS_MSG_SET;
	u.set->msg_len = ccpu2(4 + sizeof *u.set);
	u.set->oid = OID_GEN_CURRENT_PACKET_FILTER;
	u.set->len = ccpu2(4);
	u.set->offset = ccpu2((sizeof *u.set) - 8);
	*(__le32 *)(u.buf + sizeof *u.set) = ccpu2(DEFAULT_FILTER);

	retval = rndis_command(dev, u.header);
	if (unlikely(retval < 0)) {
		dev_err(&intf->dev, "rndis set packet filter, %d\n", retval);
		goto fail_and_release;
	}

	retval = 0;

	kfree(u.buf);
	return retval;

fail_and_release:
	usb_set_intfdata(info->data, NULL);
	usb_driver_release_interface(driver_of(intf), info->data);
	info->data = NULL;
fail:
	kfree(u.buf);
	return retval;
}

static void rndis_unbind(struct usbnet *dev, struct usb_interface *intf)
{
	struct rndis_halt	*halt;

	/* try to clear any rndis state/activity (no i/o from stack!) */
	halt = kzalloc(sizeof *halt, GFP_KERNEL);
	if (halt) {
		halt->msg_type = RNDIS_MSG_HALT;
		halt->msg_len = ccpu2(sizeof *halt);
		(void) rndis_command(dev, (void *)halt);
		kfree(halt);
	}

	return usbnet_cdc_unbind(dev, intf);
}

/*
 * DATA -- host must not write zlps
 */
static int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
{
	/* peripheral may have batched packets to us... */
	while (likely(skb->len)) {
		struct rndis_data_hdr	*hdr = (void *)skb->data;
		struct sk_buff		*skb2;
		u32			msg_len, data_offset, data_len;

		msg_len = le32_to_cpu(hdr->msg_len);
		data_offset = le32_to_cpu(hdr->data_offset);
		data_len = le32_to_cpu(hdr->data_len);

		/* don't choke if we see oob, per-packet data, etc */
		if (unlikely(hdr->msg_type != RNDIS_MSG_PACKET
				|| skb->len < msg_len
				|| (data_offset + data_len + 8) > msg_len)) {
			dev->stats.rx_frame_errors++;
			devdbg(dev, "bad rndis message %d/%d/%d/%d, len %d",
				le32_to_cpu(hdr->msg_type),
				msg_len, data_offset, data_len, skb->len);
			return 0;
		}
		skb_pull(skb, 8 + data_offset);

		/* at most one packet left? */
		if (likely((data_len - skb->len) <= sizeof *hdr)) {
			skb_trim(skb, data_len);
			break;
		}

		/* try to return all the packets in the batch */
		skb2 = skb_clone(skb, GFP_ATOMIC);
		if (unlikely(!skb2))
			break;
		skb_pull(skb, msg_len - sizeof *hdr);
		skb_trim(skb2, data_len);
		usbnet_skb_return(dev, skb2);
	}

	/* caller will usbnet_skb_return the remaining packet */
	return 1;
}

static struct sk_buff *
rndis_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
{
	struct rndis_data_hdr	*hdr;
	struct sk_buff		*skb2;
	unsigned		len = skb->len;

	if (likely(!skb_cloned(skb))) {
		int	room = skb_headroom(skb);

		/* enough head room as-is? */
		if (unlikely((sizeof *hdr) <= room))
			goto fill;

		/* enough room, but needs to be readjusted? */
		room += skb_tailroom(skb);
		if (likely((sizeof *hdr) <= room)) {
			skb->data = memmove(skb->head + sizeof *hdr,
					    skb->data, len);
			skb_set_tail_pointer(skb, len);
			goto fill;
		}
	}

	/* create a new skb, with the correct size (and tailpad) */
	skb2 = skb_copy_expand(skb, sizeof *hdr, 1, flags);
	dev_kfree_skb_any(skb);
	if (unlikely(!skb2))
		return skb2;
	skb = skb2;

	/* fill out the RNDIS header.  we won't bother trying to batch
	 * packets; Linux minimizes wasted bandwidth through tx queues.
	 */
fill:
	hdr = (void *) __skb_push(skb, sizeof *hdr);
	memset(hdr, 0, sizeof *hdr);
	hdr->msg_type = RNDIS_MSG_PACKET;
	hdr->msg_len = cpu_to_le32(skb->len);
	hdr->data_offset = ccpu2(sizeof(*hdr) - 8);
	hdr->data_len = cpu_to_le32(len);

	/* FIXME make the last packet always be short ... */
	return skb;
}


static const struct driver_info	rndis_info = {
	.description =	"RNDIS device",
	.flags =	FLAG_ETHER | FLAG_FRAMING_RN | FLAG_NO_SETINT,
	.bind =		rndis_bind,
	.unbind =	rndis_unbind,
	.status =	rndis_status,
	.rx_fixup =	rndis_rx_fixup,
	.tx_fixup =	rndis_tx_fixup,
};

#undef ccpu2


/*-------------------------------------------------------------------------*/

static const struct usb_device_id	products [] = {
{
	/* RNDIS is MSFT's un-official variant of CDC ACM */
	USB_INTERFACE_INFO(USB_CLASS_COMM, 2 /* ACM */, 0x0ff),
	.driver_info = (unsigned long) &rndis_info,
}, {
	/* "ActiveSync" is an undocumented variant of RNDIS, used in WM5 */
	USB_INTERFACE_INFO(USB_CLASS_MISC, 1, 1),
	.driver_info = (unsigned long) &rndis_info,
},
	{ },		// END
};
MODULE_DEVICE_TABLE(usb, products);

static struct usb_driver rndis_driver = {
	.name =		"rndis_host",
	.id_table =	products,
	.probe =	usbnet_probe,
	.disconnect =	usbnet_disconnect,
	.suspend =	usbnet_suspend,
	.resume =	usbnet_resume,
};

static int __init rndis_init(void)
{
	return usb_register(&rndis_driver);
}
module_init(rndis_init);

static void __exit rndis_exit(void)
{
	usb_deregister(&rndis_driver);
}
module_exit(rndis_exit);

MODULE_AUTHOR("David Brownell");
MODULE_DESCRIPTION("USB Host side RNDIS driver");
MODULE_LICENSE("GPL");