aboutsummaryrefslogtreecommitdiff
path: root/drivers/usb/wusbcore/cbaf.c
blob: c0c5665e60a917de8ca6680164bfd598b0d4f83c (plain)
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
/*
 * Wireless USB - Cable Based Association
 *
 *
 * Copyright (C) 2006 Intel Corporation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 * Copyright (C) 2008 Cambridge Silicon Radio Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 *
 * WUSB devices have to be paired (associated in WUSB lingo) so
 * that they can connect to the system.
 *
 * One way of pairing is using CBA-Cable Based Association. First
 * time you plug the device with a cable, association is done between
 * host and device and subsequent times, you can connect wirelessly
 * without having to associate again. That's the idea.
 *
 * This driver does nothing Earth shattering. It just provides an
 * interface to chat with the wire-connected device so we can get a
 * CDID (device ID) that might have been previously associated to a
 * CHID (host ID) and to set up a new <CHID,CDID,CK> triplet
 * (connection context), with the CK being the secret, or connection
 * key. This is the pairing data.
 *
 * When a device with the CBA capability connects, the probe routine
 * just creates a bunch of sysfs files that a user space enumeration
 * manager uses to allow it to connect wirelessly to the system or not.
 *
 * The process goes like this:
 *
 * 1. Device plugs, cbaf is loaded, notifications happen.
 *
 * 2. The connection manager (CM) sees a device with CBAF capability
 *    (the wusb_chid etc. files in /sys/devices/blah/OURDEVICE).
 *
 * 3. The CM writes the host name, supported band groups, and the CHID
 *    (host ID) into the wusb_host_name, wusb_host_band_groups and
 *    wusb_chid files. These get sent to the device and the CDID (if
 *    any) for this host is requested.
 *
 * 4. The CM can verify that the device's supported band groups
 *    (wusb_device_band_groups) are compatible with the host.
 *
 * 5. The CM reads the wusb_cdid file.
 *
 * 6. The CM looks up its database
 *
 * 6.1 If it has a matching CHID,CDID entry, the device has been
 *     authorized before (paired) and nothing further needs to be
 *     done.
 *
 * 6.2 If the CDID is zero (or the CM doesn't find a matching CDID in
 *     its database), the device is assumed to be not known.  The CM
 *     may associate the host with device by: writing a randomly
 *     generated CDID to wusb_cdid and then a random CK to wusb_ck
 *     (this uploads the new CC to the device).
 *
 *     CMD may choose to prompt the user before associating with a new
 *     device.
 *
 * 7. Device is unplugged.
 *
 * When the device tries to connect wirelessly, it will present its
 * CDID to the WUSB host controller.  The CM will query the
 * database. If the CHID/CDID pair found, it will (with a 4-way
 * handshake) challenge the device to demonstrate it has the CK secret
 * key (from our database) without actually exchanging it. Once
 * satisfied, crypto keys are derived from the CK, the device is
 * connected and all communication is encrypted.
 *
 * References:
 *   [WUSB-AM] Association Models Supplement to the Certified Wireless
 *             Universal Serial Bus Specification, version 1.0.
 */
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/usb.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/uwb.h>
#include <linux/usb/wusb.h>
#include <linux/usb/association.h>

#define CBA_NAME_LEN 0x40 /* [WUSB-AM] table 4-7 */

/* An instance of a Cable-Based-Association-Framework device */
struct cbaf {
	struct usb_device *usb_dev;
	struct usb_interface *usb_iface;
	void *buffer;
	size_t buffer_size;

	struct wusb_ckhdid chid;
	char host_name[CBA_NAME_LEN];
	u16 host_band_groups;

	struct wusb_ckhdid cdid;
	char device_name[CBA_NAME_LEN];
	u16 device_band_groups;

	struct wusb_ckhdid ck;
};

/*
 * Verify that a CBAF USB-interface has what we need
 *
 * According to [WUSB-AM], CBA devices should provide at least two
 * interfaces:
 *  - RETRIEVE_HOST_INFO
 *  - ASSOCIATE
 *
 * If the device doesn't provide these interfaces, we do not know how
 * to deal with it.
 */
static int cbaf_check(struct cbaf *cbaf)
{
	int result;
	struct device *dev = &cbaf->usb_iface->dev;
	struct wusb_cbaf_assoc_info *assoc_info;
	struct wusb_cbaf_assoc_request *assoc_request;
	size_t assoc_size;
	void *itr, *top;
	int ar_rhi = 0, ar_assoc = 0;

	result = usb_control_msg(
		cbaf->usb_dev, usb_rcvctrlpipe(cbaf->usb_dev, 0),
		CBAF_REQ_GET_ASSOCIATION_INFORMATION,
		USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
		0, cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
		cbaf->buffer, cbaf->buffer_size, 1000 /* FIXME: arbitrary */);
	if (result < 0) {
		dev_err(dev, "Cannot get available association types: %d\n",
			result);
		return result;
	}

	assoc_info = cbaf->buffer;
	if (result < sizeof(*assoc_info)) {
		dev_err(dev, "Not enough data to decode association info "
			"header (%zu vs %zu bytes required)\n",
			(size_t)result, sizeof(*assoc_info));
		return result;
	}

	assoc_size = le16_to_cpu(assoc_info->Length);
	if (result < assoc_size) {
		dev_err(dev, "Not enough data to decode association info "
			"(%zu vs %zu bytes required)\n",
			(size_t)assoc_size, sizeof(*assoc_info));
		return result;
	}
	/*
	 * From now on, we just verify, but won't error out unless we
	 * don't find the AR_TYPE_WUSB_{RETRIEVE_HOST_INFO,ASSOCIATE}
	 * types.
	 */
	itr = cbaf->buffer + sizeof(*assoc_info);
	top = cbaf->buffer + assoc_size;
	dev_dbg(dev, "Found %u association requests (%zu bytes)\n",
		 assoc_info->NumAssociationRequests, assoc_size);

	while (itr < top) {
		u16 ar_type, ar_subtype;
		u32 ar_size;
		const char *ar_name;

		assoc_request = itr;

		if (top - itr < sizeof(*assoc_request)) {
			dev_err(dev, "Not enough data to decode associaton "
				"request (%zu vs %zu bytes needed)\n",
				top - itr, sizeof(*assoc_request));
			break;
		}

		ar_type = le16_to_cpu(assoc_request->AssociationTypeId);
		ar_subtype = le16_to_cpu(assoc_request->AssociationSubTypeId);
		ar_size = le32_to_cpu(assoc_request->AssociationTypeInfoSize);
		ar_name = "unknown";

		switch (ar_type) {
		case AR_TYPE_WUSB:
			/* Verify we have what is mandated by [WUSB-AM]. */
			switch (ar_subtype) {
			case AR_TYPE_WUSB_RETRIEVE_HOST_INFO:
				ar_name = "RETRIEVE_HOST_INFO";
				ar_rhi = 1;
				break;
			case AR_TYPE_WUSB_ASSOCIATE:
				/* send assoc data */
				ar_name = "ASSOCIATE";
				ar_assoc = 1;
				break;
			};
			break;
		};

		dev_dbg(dev, "Association request #%02u: 0x%04x/%04x "
			 "(%zu bytes): %s\n",
			 assoc_request->AssociationDataIndex, ar_type,
			 ar_subtype, (size_t)ar_size, ar_name);

		itr += sizeof(*assoc_request);
	}

	if (!ar_rhi) {
		dev_err(dev, "Missing RETRIEVE_HOST_INFO association "
			"request\n");
		return -EINVAL;
	}
	if (!ar_assoc) {
		dev_err(dev, "Missing ASSOCIATE association request\n");
		return -EINVAL;
	}

	return 0;
}

static const struct wusb_cbaf_host_info cbaf_host_info_defaults = {
	.AssociationTypeId_hdr    = WUSB_AR_AssociationTypeId,
	.AssociationTypeId    	  = cpu_to_le16(AR_TYPE_WUSB),
	.AssociationSubTypeId_hdr = WUSB_AR_AssociationSubTypeId,
	.AssociationSubTypeId = cpu_to_le16(AR_TYPE_WUSB_RETRIEVE_HOST_INFO),
	.CHID_hdr                 = WUSB_AR_CHID,
	.LangID_hdr               = WUSB_AR_LangID,
	.HostFriendlyName_hdr     = WUSB_AR_HostFriendlyName,
};

/* Send WUSB host information (CHID and name) to a CBAF device */
static int cbaf_send_host_info(struct cbaf *cbaf)
{
	struct wusb_cbaf_host_info *hi;
	size_t name_len;
	size_t hi_size;

	hi = cbaf->buffer;
	memset(hi, 0, sizeof(*hi));
	*hi = cbaf_host_info_defaults;
	hi->CHID = cbaf->chid;
	hi->LangID = 0;	/* FIXME: I guess... */
	strlcpy(hi->HostFriendlyName, cbaf->host_name, CBA_NAME_LEN);
	name_len = strlen(cbaf->host_name);
	hi->HostFriendlyName_hdr.len = cpu_to_le16(name_len);
	hi_size = sizeof(*hi) + name_len;

	return usb_control_msg(cbaf->usb_dev, usb_sndctrlpipe(cbaf->usb_dev, 0),
			CBAF_REQ_SET_ASSOCIATION_RESPONSE,
			USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
			0x0101,
			cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
			hi, hi_size, 1000 /* FIXME: arbitrary */);
}

/*
 * Get device's information (CDID) associated to CHID
 *
 * The device will return it's information (CDID, name, bandgroups)
 * associated to the CHID we have set before, or 0 CDID and default
 * name and bandgroup if no CHID set or unknown.
 */
static int cbaf_cdid_get(struct cbaf *cbaf)
{
	int result;
	struct device *dev = &cbaf->usb_iface->dev;
	struct wusb_cbaf_device_info *di;
	size_t needed;

	di = cbaf->buffer;
	result = usb_control_msg(
		cbaf->usb_dev, usb_rcvctrlpipe(cbaf->usb_dev, 0),
		CBAF_REQ_GET_ASSOCIATION_REQUEST,
		USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
		0x0200, cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
		di, cbaf->buffer_size, 1000 /* FIXME: arbitrary */);
	if (result < 0) {
		dev_err(dev, "Cannot request device information: %d\n", result);
		return result;
	}

	needed = result < sizeof(*di) ? sizeof(*di) : le32_to_cpu(di->Length);
	if (result < needed) {
		dev_err(dev, "Not enough data in DEVICE_INFO reply (%zu vs "
			"%zu bytes needed)\n", (size_t)result, needed);
		return result;
	}

	strlcpy(cbaf->device_name, di->DeviceFriendlyName, CBA_NAME_LEN);
	cbaf->cdid = di->CDID;
	cbaf->device_band_groups = le16_to_cpu(di->BandGroups);

	return 0;
}

static ssize_t cbaf_wusb_chid_show(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);
	char pr_chid[WUSB_CKHDID_STRSIZE];

	ckhdid_printf(pr_chid, sizeof(pr_chid), &cbaf->chid);
	return scnprintf(buf, PAGE_SIZE, "%s\n", pr_chid);
}

static ssize_t cbaf_wusb_chid_store(struct device *dev,
					 struct device_attribute *attr,
					 const char *buf, size_t size)
{
	ssize_t result;
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);

	result = sscanf(buf,
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx",
			&cbaf->chid.data[0] , &cbaf->chid.data[1],
			&cbaf->chid.data[2] , &cbaf->chid.data[3],
			&cbaf->chid.data[4] , &cbaf->chid.data[5],
			&cbaf->chid.data[6] , &cbaf->chid.data[7],
			&cbaf->chid.data[8] , &cbaf->chid.data[9],
			&cbaf->chid.data[10], &cbaf->chid.data[11],
			&cbaf->chid.data[12], &cbaf->chid.data[13],
			&cbaf->chid.data[14], &cbaf->chid.data[15]);

	if (result != 16)
		return -EINVAL;

	result = cbaf_send_host_info(cbaf);
	if (result < 0)
		return result;
	result = cbaf_cdid_get(cbaf);
	if (result < 0)
		return -result;
	return size;
}
static DEVICE_ATTR(wusb_chid, 0600, cbaf_wusb_chid_show, cbaf_wusb_chid_store);

static ssize_t cbaf_wusb_host_name_show(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);

	return scnprintf(buf, PAGE_SIZE, "%s\n", cbaf->host_name);
}

static ssize_t cbaf_wusb_host_name_store(struct device *dev,
					 struct device_attribute *attr,
					 const char *buf, size_t size)
{
	ssize_t result;
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);

	result = sscanf(buf, "%63s", cbaf->host_name);
	if (result != 1)
		return -EINVAL;

	return size;
}
static DEVICE_ATTR(wusb_host_name, 0600, cbaf_wusb_host_name_show,
					 cbaf_wusb_host_name_store);

static ssize_t cbaf_wusb_host_band_groups_show(struct device *dev,
					       struct device_attribute *attr,
					       char *buf)
{
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);

	return scnprintf(buf, PAGE_SIZE, "0x%04x\n", cbaf->host_band_groups);
}

static ssize_t cbaf_wusb_host_band_groups_store(struct device *dev,
						struct device_attribute *attr,
						const char *buf, size_t size)
{
	ssize_t result;
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);
	u16 band_groups = 0;

	result = sscanf(buf, "%04hx", &band_groups);
	if (result != 1)
		return -EINVAL;

	cbaf->host_band_groups = band_groups;

	return size;
}

static DEVICE_ATTR(wusb_host_band_groups, 0600,
		   cbaf_wusb_host_band_groups_show,
		   cbaf_wusb_host_band_groups_store);

static const struct wusb_cbaf_device_info cbaf_device_info_defaults = {
	.Length_hdr               = WUSB_AR_Length,
	.CDID_hdr                 = WUSB_AR_CDID,
	.BandGroups_hdr           = WUSB_AR_BandGroups,
	.LangID_hdr               = WUSB_AR_LangID,
	.DeviceFriendlyName_hdr   = WUSB_AR_DeviceFriendlyName,
};

static ssize_t cbaf_wusb_cdid_show(struct device *dev,
				   struct device_attribute *attr, char *buf)
{
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);
	char pr_cdid[WUSB_CKHDID_STRSIZE];

	ckhdid_printf(pr_cdid, sizeof(pr_cdid), &cbaf->cdid);
	return scnprintf(buf, PAGE_SIZE, "%s\n", pr_cdid);
}

static ssize_t cbaf_wusb_cdid_store(struct device *dev,
				struct device_attribute *attr,
				const char *buf, size_t size)
{
	ssize_t result;
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);
	struct wusb_ckhdid cdid;

	result = sscanf(buf,
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx",
			&cdid.data[0] , &cdid.data[1],
			&cdid.data[2] , &cdid.data[3],
			&cdid.data[4] , &cdid.data[5],
			&cdid.data[6] , &cdid.data[7],
			&cdid.data[8] , &cdid.data[9],
			&cdid.data[10], &cdid.data[11],
			&cdid.data[12], &cdid.data[13],
			&cdid.data[14], &cdid.data[15]);
	if (result != 16)
		return -EINVAL;

	cbaf->cdid = cdid;

	return size;
}
static DEVICE_ATTR(wusb_cdid, 0600, cbaf_wusb_cdid_show, cbaf_wusb_cdid_store);

static ssize_t cbaf_wusb_device_band_groups_show(struct device *dev,
						 struct device_attribute *attr,
						 char *buf)
{
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);

	return scnprintf(buf, PAGE_SIZE, "0x%04x\n", cbaf->device_band_groups);
}

static DEVICE_ATTR(wusb_device_band_groups, 0600,
		   cbaf_wusb_device_band_groups_show,
		   NULL);

static ssize_t cbaf_wusb_device_name_show(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);

	return scnprintf(buf, PAGE_SIZE, "%s\n", cbaf->device_name);
}
static DEVICE_ATTR(wusb_device_name, 0600, cbaf_wusb_device_name_show, NULL);

static const struct wusb_cbaf_cc_data cbaf_cc_data_defaults = {
	.AssociationTypeId_hdr    = WUSB_AR_AssociationTypeId,
	.AssociationTypeId    	  = cpu_to_le16(AR_TYPE_WUSB),
	.AssociationSubTypeId_hdr = WUSB_AR_AssociationSubTypeId,
	.AssociationSubTypeId     = cpu_to_le16(AR_TYPE_WUSB_ASSOCIATE),
	.Length_hdr               = WUSB_AR_Length,
	.Length               	  = cpu_to_le32(sizeof(struct wusb_cbaf_cc_data)),
	.ConnectionContext_hdr    = WUSB_AR_ConnectionContext,
	.BandGroups_hdr           = WUSB_AR_BandGroups,
};

static const struct wusb_cbaf_cc_data_fail cbaf_cc_data_fail_defaults = {
	.AssociationTypeId_hdr    = WUSB_AR_AssociationTypeId,
	.AssociationSubTypeId_hdr = WUSB_AR_AssociationSubTypeId,
	.Length_hdr               = WUSB_AR_Length,
	.AssociationStatus_hdr    = WUSB_AR_AssociationStatus,
};

/*
 * Send a new CC to the device.
 */
static int cbaf_cc_upload(struct cbaf *cbaf)
{
	int result;
	struct device *dev = &cbaf->usb_iface->dev;
	struct wusb_cbaf_cc_data *ccd;
	char pr_cdid[WUSB_CKHDID_STRSIZE];

	ccd =  cbaf->buffer;
	*ccd = cbaf_cc_data_defaults;
	ccd->CHID = cbaf->chid;
	ccd->CDID = cbaf->cdid;
	ccd->CK = cbaf->ck;
	ccd->BandGroups = cpu_to_le16(cbaf->host_band_groups);

	dev_dbg(dev, "Trying to upload CC:\n");
	ckhdid_printf(pr_cdid, sizeof(pr_cdid), &ccd->CHID);
	dev_dbg(dev, "  CHID       %s\n", pr_cdid);
	ckhdid_printf(pr_cdid, sizeof(pr_cdid), &ccd->CDID);
	dev_dbg(dev, "  CDID       %s\n", pr_cdid);
	dev_dbg(dev, "  Bandgroups 0x%04x\n", cbaf->host_band_groups);

	result = usb_control_msg(
		cbaf->usb_dev, usb_sndctrlpipe(cbaf->usb_dev, 0),
		CBAF_REQ_SET_ASSOCIATION_RESPONSE,
		USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
		0x0201, cbaf->usb_iface->cur_altsetting->desc.bInterfaceNumber,
		ccd, sizeof(*ccd), 1000 /* FIXME: arbitrary */);

	return result;
}

static ssize_t cbaf_wusb_ck_store(struct device *dev,
				  struct device_attribute *attr,
				  const char *buf, size_t size)
{
	ssize_t result;
	struct usb_interface *iface = to_usb_interface(dev);
	struct cbaf *cbaf = usb_get_intfdata(iface);

	result = sscanf(buf,
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx "
			"%02hhx %02hhx %02hhx %02hhx",
			&cbaf->ck.data[0] , &cbaf->ck.data[1],
			&cbaf->ck.data[2] , &cbaf->ck.data[3],
			&cbaf->ck.data[4] , &cbaf->ck.data[5],
			&cbaf->ck.data[6] , &cbaf->ck.data[7],
			&cbaf->ck.data[8] , &cbaf->ck.data[9],
			&cbaf->ck.data[10], &cbaf->ck.data[11],
			&cbaf->ck.data[12], &cbaf->ck.data[13],
			&cbaf->ck.data[14], &cbaf->ck.data[15]);
	if (result != 16)
		return -EINVAL;

	result = cbaf_cc_upload(cbaf);
	if (result < 0)
		return result;

	return size;
}
static DEVICE_ATTR(wusb_ck, 0600, NULL, cbaf_wusb_ck_store);

static struct attribute *cbaf_dev_attrs[] = {
	&dev_attr_wusb_host_name.attr,
	&dev_attr_wusb_host_band_groups.attr,
	&dev_attr_wusb_chid.attr,
	&dev_attr_wusb_cdid.attr,
	&dev_attr_wusb_device_name.attr,
	&dev_attr_wusb_device_band_groups.attr,
	&dev_attr_wusb_ck.attr,
	NULL,
};

static struct attribute_group cbaf_dev_attr_group = {
	.name = NULL,	/* we want them in the same directory */
	.attrs = cbaf_dev_attrs,
};

static int cbaf_probe(struct usb_interface *iface,
		      const struct usb_device_id *id)
{
	struct cbaf *cbaf;
	struct device *dev = &iface->dev;
	int result = -ENOMEM;

	cbaf = kzalloc(sizeof(*cbaf), GFP_KERNEL);
	if (cbaf == NULL)
		goto error_kzalloc;
	cbaf->buffer = kmalloc(512, GFP_KERNEL);
	if (cbaf->buffer == NULL)
		goto error_kmalloc_buffer;

	cbaf->buffer_size = 512;
	cbaf->usb_dev = usb_get_dev(interface_to_usbdev(iface));
	cbaf->usb_iface = usb_get_intf(iface);
	result = cbaf_check(cbaf);
	if (result < 0) {
		dev_err(dev, "This device is not WUSB-CBAF compliant"
			"and is not supported yet.\n");
		goto error_check;
	}

	result = sysfs_create_group(&dev->kobj, &cbaf_dev_attr_group);
	if (result < 0) {
		dev_err(dev, "Can't register sysfs attr group: %d\n", result);
		goto error_create_group;
	}
	usb_set_intfdata(iface, cbaf);
	return 0;

error_create_group:
error_check:
	kfree(cbaf->buffer);
error_kmalloc_buffer:
	kfree(cbaf);
error_kzalloc:
	return result;
}

static void cbaf_disconnect(struct usb_interface *iface)
{
	struct cbaf *cbaf = usb_get_intfdata(iface);
	struct device *dev = &iface->dev;
	sysfs_remove_group(&dev->kobj, &cbaf_dev_attr_group);
	usb_set_intfdata(iface, NULL);
	usb_put_intf(iface);
	kfree(cbaf->buffer);
	/* paranoia: clean up crypto keys */
	kzfree(cbaf);
}

static const struct usb_device_id cbaf_id_table[] = {
	{ USB_INTERFACE_INFO(0xef, 0x03, 0x01), },
	{ },
};
MODULE_DEVICE_TABLE(usb, cbaf_id_table);

static struct usb_driver cbaf_driver = {
	.name =		"wusb-cbaf",
	.id_table =	cbaf_id_table,
	.probe =	cbaf_probe,
	.disconnect =	cbaf_disconnect,
};

static int __init cbaf_driver_init(void)
{
	return usb_register(&cbaf_driver);
}
module_init(cbaf_driver_init);

static void __exit cbaf_driver_exit(void)
{
	usb_deregister(&cbaf_driver);
}
module_exit(cbaf_driver_exit);

MODULE_AUTHOR("Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>");
MODULE_DESCRIPTION("Wireless USB Cable Based Association");
MODULE_LICENSE("GPL");