aboutsummaryrefslogtreecommitdiff
path: root/drivers/usb/core/usb.c
blob: 087af73a59dd70aa270694abde9e9233a51fe241 (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
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
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
/*
 * drivers/usb/usb.c
 *
 * (C) Copyright Linus Torvalds 1999
 * (C) Copyright Johannes Erdfelt 1999-2001
 * (C) Copyright Andreas Gal 1999
 * (C) Copyright Gregory P. Smith 1999
 * (C) Copyright Deti Fliegl 1999 (new USB architecture)
 * (C) Copyright Randy Dunlap 2000
 * (C) Copyright David Brownell 2000-2004
 * (C) Copyright Yggdrasil Computing, Inc. 2000
 *     (usb_device_id matching changes by Adam J. Richter)
 * (C) Copyright Greg Kroah-Hartman 2002-2003
 *
 * NOTE! This is not actually a driver at all, rather this is
 * just a collection of helper routines that implement the
 * generic USB things that the real drivers can use..
 *
 * Think of this as a "USB library" rather than anything else.
 * It should be considered a slave, with no callbacks. Callbacks
 * are evil.
 */

#include <linux/config.h>

#ifdef CONFIG_USB_DEBUG
	#define DEBUG
#else
	#undef DEBUG
#endif

#include <linux/module.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/interrupt.h>  /* for in_interrupt() */
#include <linux/kmod.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/smp_lock.h>
#include <linux/rwsem.h>
#include <linux/usb.h>

#include <asm/io.h>
#include <asm/scatterlist.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>

#include "hcd.h"
#include "usb.h"


const char *usbcore_name = "usbcore";

static int nousb;	/* Disable USB when built into kernel image */
			/* Not honored on modular build */

static DECLARE_RWSEM(usb_all_devices_rwsem);


static int generic_probe (struct device *dev)
{
	return 0;
}
static int generic_remove (struct device *dev)
{
	struct usb_device *udev = to_usb_device(dev);

	/* if this is only an unbind, not a physical disconnect, then
	 * unconfigure the device */
	if (udev->state == USB_STATE_CONFIGURED)
		usb_set_configuration(udev, 0);

	/* in case the call failed or the device was suspended */
	if (udev->state >= USB_STATE_CONFIGURED)
		usb_disable_device(udev, 0);
	return 0;
}

static struct device_driver usb_generic_driver = {
	.owner = THIS_MODULE,
	.name =	"usb",
	.bus = &usb_bus_type,
	.probe = generic_probe,
	.remove = generic_remove,
};

static int usb_generic_driver_data;

/* called from driver core with usb_bus_type.subsys writelock */
static int usb_probe_interface(struct device *dev)
{
	struct usb_interface * intf = to_usb_interface(dev);
	struct usb_driver * driver = to_usb_driver(dev->driver);
	const struct usb_device_id *id;
	int error = -ENODEV;

	dev_dbg(dev, "%s\n", __FUNCTION__);

	if (!driver->probe)
		return error;
	/* FIXME we'd much prefer to just resume it ... */
	if (interface_to_usbdev(intf)->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;

	id = usb_match_id (intf, driver->id_table);
	if (id) {
		dev_dbg (dev, "%s - got id\n", __FUNCTION__);
		intf->condition = USB_INTERFACE_BINDING;
		error = driver->probe (intf, id);
		intf->condition = error ? USB_INTERFACE_UNBOUND :
				USB_INTERFACE_BOUND;
	}

	return error;
}

/* called from driver core with usb_bus_type.subsys writelock */
static int usb_unbind_interface(struct device *dev)
{
	struct usb_interface *intf = to_usb_interface(dev);
	struct usb_driver *driver = to_usb_driver(intf->dev.driver);

	intf->condition = USB_INTERFACE_UNBINDING;

	/* release all urbs for this interface */
	usb_disable_interface(interface_to_usbdev(intf), intf);

	if (driver && driver->disconnect)
		driver->disconnect(intf);

	/* reset other interface state */
	usb_set_interface(interface_to_usbdev(intf),
			intf->altsetting[0].desc.bInterfaceNumber,
			0);
	usb_set_intfdata(intf, NULL);
	intf->condition = USB_INTERFACE_UNBOUND;

	return 0;
}

/**
 * usb_register - register a USB driver
 * @new_driver: USB operations for the driver
 *
 * Registers a USB driver with the USB core.  The list of unattached
 * interfaces will be rescanned whenever a new driver is added, allowing
 * the new driver to attach to any recognized devices.
 * Returns a negative error code on failure and 0 on success.
 * 
 * NOTE: if you want your driver to use the USB major number, you must call
 * usb_register_dev() to enable that functionality.  This function no longer
 * takes care of that.
 */
int usb_register(struct usb_driver *new_driver)
{
	int retval = 0;

	if (nousb)
		return -ENODEV;

	new_driver->driver.name = (char *)new_driver->name;
	new_driver->driver.bus = &usb_bus_type;
	new_driver->driver.probe = usb_probe_interface;
	new_driver->driver.remove = usb_unbind_interface;
	new_driver->driver.owner = new_driver->owner;

	usb_lock_all_devices();
	retval = driver_register(&new_driver->driver);
	usb_unlock_all_devices();

	if (!retval) {
		pr_info("%s: registered new driver %s\n",
			usbcore_name, new_driver->name);
		usbfs_update_special();
	} else {
		printk(KERN_ERR "%s: error %d registering driver %s\n",
			usbcore_name, retval, new_driver->name);
	}

	return retval;
}

/**
 * usb_deregister - unregister a USB driver
 * @driver: USB operations of the driver to unregister
 * Context: must be able to sleep
 *
 * Unlinks the specified driver from the internal USB driver list.
 * 
 * NOTE: If you called usb_register_dev(), you still need to call
 * usb_deregister_dev() to clean up your driver's allocated minor numbers,
 * this * call will no longer do it for you.
 */
void usb_deregister(struct usb_driver *driver)
{
	pr_info("%s: deregistering driver %s\n", usbcore_name, driver->name);

	usb_lock_all_devices();
	driver_unregister (&driver->driver);
	usb_unlock_all_devices();

	usbfs_update_special();
}

/**
 * usb_ifnum_to_if - get the interface object with a given interface number
 * @dev: the device whose current configuration is considered
 * @ifnum: the desired interface
 *
 * This walks the device descriptor for the currently active configuration
 * and returns a pointer to the interface with that particular interface
 * number, or null.
 *
 * Note that configuration descriptors are not required to assign interface
 * numbers sequentially, so that it would be incorrect to assume that
 * the first interface in that descriptor corresponds to interface zero.
 * This routine helps device drivers avoid such mistakes.
 * However, you should make sure that you do the right thing with any
 * alternate settings available for this interfaces.
 *
 * Don't call this function unless you are bound to one of the interfaces
 * on this device or you have locked the device!
 */
struct usb_interface *usb_ifnum_to_if(struct usb_device *dev, unsigned ifnum)
{
	struct usb_host_config *config = dev->actconfig;
	int i;

	if (!config)
		return NULL;
	for (i = 0; i < config->desc.bNumInterfaces; i++)
		if (config->interface[i]->altsetting[0]
				.desc.bInterfaceNumber == ifnum)
			return config->interface[i];

	return NULL;
}

/**
 * usb_altnum_to_altsetting - get the altsetting structure with a given
 *	alternate setting number.
 * @intf: the interface containing the altsetting in question
 * @altnum: the desired alternate setting number
 *
 * This searches the altsetting array of the specified interface for
 * an entry with the correct bAlternateSetting value and returns a pointer
 * to that entry, or null.
 *
 * Note that altsettings need not be stored sequentially by number, so
 * it would be incorrect to assume that the first altsetting entry in
 * the array corresponds to altsetting zero.  This routine helps device
 * drivers avoid such mistakes.
 *
 * Don't call this function unless you are bound to the intf interface
 * or you have locked the device!
 */
struct usb_host_interface *usb_altnum_to_altsetting(struct usb_interface *intf,
		unsigned int altnum)
{
	int i;

	for (i = 0; i < intf->num_altsetting; i++) {
		if (intf->altsetting[i].desc.bAlternateSetting == altnum)
			return &intf->altsetting[i];
	}
	return NULL;
}

/**
 * usb_driver_claim_interface - bind a driver to an interface
 * @driver: the driver to be bound
 * @iface: the interface to which it will be bound; must be in the
 *	usb device's active configuration
 * @priv: driver data associated with that interface
 *
 * This is used by usb device drivers that need to claim more than one
 * interface on a device when probing (audio and acm are current examples).
 * No device driver should directly modify internal usb_interface or
 * usb_device structure members.
 *
 * Few drivers should need to use this routine, since the most natural
 * way to bind to an interface is to return the private data from
 * the driver's probe() method.
 *
 * Callers must own the device lock and the driver model's usb_bus_type.subsys
 * writelock.  So driver probe() entries don't need extra locking,
 * but other call contexts may need to explicitly claim those locks.
 */
int usb_driver_claim_interface(struct usb_driver *driver,
				struct usb_interface *iface, void* priv)
{
	struct device *dev = &iface->dev;

	if (dev->driver)
		return -EBUSY;

	dev->driver = &driver->driver;
	usb_set_intfdata(iface, priv);
	iface->condition = USB_INTERFACE_BOUND;

	/* if interface was already added, bind now; else let
	 * the future device_add() bind it, bypassing probe()
	 */
	if (klist_node_attached(&dev->knode_bus))
		device_bind_driver(dev);

	return 0;
}

/**
 * usb_driver_release_interface - unbind a driver from an interface
 * @driver: the driver to be unbound
 * @iface: the interface from which it will be unbound
 *
 * This can be used by drivers to release an interface without waiting
 * for their disconnect() methods to be called.  In typical cases this
 * also causes the driver disconnect() method to be called.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 * Callers must own the device lock and the driver model's usb_bus_type.subsys
 * writelock.  So driver disconnect() entries don't need extra locking,
 * but other call contexts may need to explicitly claim those locks.
 */
void usb_driver_release_interface(struct usb_driver *driver,
					struct usb_interface *iface)
{
	struct device *dev = &iface->dev;

	/* this should never happen, don't release something that's not ours */
	if (!dev->driver || dev->driver != &driver->driver)
		return;

	/* don't release from within disconnect() */
	if (iface->condition != USB_INTERFACE_BOUND)
		return;

	/* release only after device_add() */
	if (klist_node_attached(&dev->knode_bus)) {
		iface->condition = USB_INTERFACE_UNBINDING;
		device_release_driver(dev);
	}

	dev->driver = NULL;
	usb_set_intfdata(iface, NULL);
	iface->condition = USB_INTERFACE_UNBOUND;
}

/**
 * usb_match_id - find first usb_device_id matching device or interface
 * @interface: the interface of interest
 * @id: array of usb_device_id structures, terminated by zero entry
 *
 * usb_match_id searches an array of usb_device_id's and returns
 * the first one matching the device or interface, or null.
 * This is used when binding (or rebinding) a driver to an interface.
 * Most USB device drivers will use this indirectly, through the usb core,
 * but some layered driver frameworks use it directly.
 * These device tables are exported with MODULE_DEVICE_TABLE, through
 * modutils and "modules.usbmap", to support the driver loading
 * functionality of USB hotplugging.
 *
 * What Matches:
 *
 * The "match_flags" element in a usb_device_id controls which
 * members are used.  If the corresponding bit is set, the
 * value in the device_id must match its corresponding member
 * in the device or interface descriptor, or else the device_id
 * does not match.
 *
 * "driver_info" is normally used only by device drivers,
 * but you can create a wildcard "matches anything" usb_device_id
 * as a driver's "modules.usbmap" entry if you provide an id with
 * only a nonzero "driver_info" field.  If you do this, the USB device
 * driver's probe() routine should use additional intelligence to
 * decide whether to bind to the specified interface.
 * 
 * What Makes Good usb_device_id Tables:
 *
 * The match algorithm is very simple, so that intelligence in
 * driver selection must come from smart driver id records.
 * Unless you have good reasons to use another selection policy,
 * provide match elements only in related groups, and order match
 * specifiers from specific to general.  Use the macros provided
 * for that purpose if you can.
 *
 * The most specific match specifiers use device descriptor
 * data.  These are commonly used with product-specific matches;
 * the USB_DEVICE macro lets you provide vendor and product IDs,
 * and you can also match against ranges of product revisions.
 * These are widely used for devices with application or vendor
 * specific bDeviceClass values.
 *
 * Matches based on device class/subclass/protocol specifications
 * are slightly more general; use the USB_DEVICE_INFO macro, or
 * its siblings.  These are used with single-function devices
 * where bDeviceClass doesn't specify that each interface has
 * its own class. 
 *
 * Matches based on interface class/subclass/protocol are the
 * most general; they let drivers bind to any interface on a
 * multiple-function device.  Use the USB_INTERFACE_INFO
 * macro, or its siblings, to match class-per-interface style 
 * devices (as recorded in bDeviceClass).
 *  
 * Within those groups, remember that not all combinations are
 * meaningful.  For example, don't give a product version range
 * without vendor and product IDs; or specify a protocol without
 * its associated class and subclass.
 */   
const struct usb_device_id *
usb_match_id(struct usb_interface *interface, const struct usb_device_id *id)
{
	struct usb_host_interface *intf;
	struct usb_device *dev;

	/* proc_connectinfo in devio.c may call us with id == NULL. */
	if (id == NULL)
		return NULL;

	intf = interface->cur_altsetting;
	dev = interface_to_usbdev(interface);

	/* It is important to check that id->driver_info is nonzero,
	   since an entry that is all zeroes except for a nonzero
	   id->driver_info is the way to create an entry that
	   indicates that the driver want to examine every
	   device and interface. */
	for (; id->idVendor || id->bDeviceClass || id->bInterfaceClass ||
	       id->driver_info; id++) {

		if ((id->match_flags & USB_DEVICE_ID_MATCH_VENDOR) &&
		    id->idVendor != le16_to_cpu(dev->descriptor.idVendor))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT) &&
		    id->idProduct != le16_to_cpu(dev->descriptor.idProduct))
			continue;

		/* No need to test id->bcdDevice_lo != 0, since 0 is never
		   greater than any unsigned number. */
		if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO) &&
		    (id->bcdDevice_lo > le16_to_cpu(dev->descriptor.bcdDevice)))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI) &&
		    (id->bcdDevice_hi < le16_to_cpu(dev->descriptor.bcdDevice)))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS) &&
		    (id->bDeviceClass != dev->descriptor.bDeviceClass))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS) &&
		    (id->bDeviceSubClass!= dev->descriptor.bDeviceSubClass))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL) &&
		    (id->bDeviceProtocol != dev->descriptor.bDeviceProtocol))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS) &&
		    (id->bInterfaceClass != intf->desc.bInterfaceClass))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS) &&
		    (id->bInterfaceSubClass != intf->desc.bInterfaceSubClass))
			continue;

		if ((id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL) &&
		    (id->bInterfaceProtocol != intf->desc.bInterfaceProtocol))
			continue;

		return id;
	}

	return NULL;
}


static int __find_interface(struct device * dev, void * data)
{
	struct usb_interface ** ret = (struct usb_interface **)data;
	struct usb_interface * intf = *ret;
	int *minor = (int *)data;

	/* can't look at usb devices, only interfaces */
	if (dev->driver == &usb_generic_driver)
		return 0;

	intf = to_usb_interface(dev);
	if (intf->minor != -1 && intf->minor == *minor) {
		*ret = intf;
		return 1;
	}
	return 0;
}

/**
 * usb_find_interface - find usb_interface pointer for driver and device
 * @drv: the driver whose current configuration is considered
 * @minor: the minor number of the desired device
 *
 * This walks the driver device list and returns a pointer to the interface 
 * with the matching minor.  Note, this only works for devices that share the
 * USB major number.
 */
struct usb_interface *usb_find_interface(struct usb_driver *drv, int minor)
{
	struct usb_interface *intf = (struct usb_interface *)(long)minor;
	int ret;

	ret = driver_for_each_device(&drv->driver, NULL, &intf, __find_interface);

	return ret ? intf : NULL;
}

static int usb_device_match (struct device *dev, struct device_driver *drv)
{
	struct usb_interface *intf;
	struct usb_driver *usb_drv;
	const struct usb_device_id *id;

	/* check for generic driver, which we don't match any device with */
	if (drv == &usb_generic_driver)
		return 0;

	intf = to_usb_interface(dev);
	usb_drv = to_usb_driver(drv);
	
	id = usb_match_id (intf, usb_drv->id_table);
	if (id)
		return 1;

	return 0;
}


#ifdef	CONFIG_HOTPLUG

/*
 * USB hotplugging invokes what /proc/sys/kernel/hotplug says
 * (normally /sbin/hotplug) when USB devices get added or removed.
 *
 * This invokes a user mode policy agent, typically helping to load driver
 * or other modules, configure the device, and more.  Drivers can provide
 * a MODULE_DEVICE_TABLE to help with module loading subtasks.
 *
 * We're called either from khubd (the typical case) or from root hub
 * (init, kapmd, modprobe, rmmod, etc), but the agents need to handle
 * delays in event delivery.  Use sysfs (and DEVPATH) to make sure the
 * device (and this configuration!) are still present.
 */
static int usb_hotplug (struct device *dev, char **envp, int num_envp,
			char *buffer, int buffer_size)
{
	struct usb_interface *intf;
	struct usb_device *usb_dev;
	int i = 0;
	int length = 0;

	if (!dev)
		return -ENODEV;

	/* driver is often null here; dev_dbg() would oops */
	pr_debug ("usb %s: hotplug\n", dev->bus_id);

	/* Must check driver_data here, as on remove driver is always NULL */
	if ((dev->driver == &usb_generic_driver) || 
	    (dev->driver_data == &usb_generic_driver_data))
		return 0;

	intf = to_usb_interface(dev);
	usb_dev = interface_to_usbdev (intf);
	
	if (usb_dev->devnum < 0) {
		pr_debug ("usb %s: already deleted?\n", dev->bus_id);
		return -ENODEV;
	}
	if (!usb_dev->bus) {
		pr_debug ("usb %s: bus removed?\n", dev->bus_id);
		return -ENODEV;
	}

#ifdef	CONFIG_USB_DEVICEFS
	/* If this is available, userspace programs can directly read
	 * all the device descriptors we don't tell them about.  Or
	 * even act as usermode drivers.
	 *
	 * FIXME reduce hardwired intelligence here
	 */
	if (add_hotplug_env_var(envp, num_envp, &i,
				buffer, buffer_size, &length,
				"DEVICE=/proc/bus/usb/%03d/%03d",
				usb_dev->bus->busnum, usb_dev->devnum))
		return -ENOMEM;
#endif

	/* per-device configurations are common */
	if (add_hotplug_env_var(envp, num_envp, &i,
				buffer, buffer_size, &length,
				"PRODUCT=%x/%x/%x",
				le16_to_cpu(usb_dev->descriptor.idVendor),
				le16_to_cpu(usb_dev->descriptor.idProduct),
				le16_to_cpu(usb_dev->descriptor.bcdDevice)))
		return -ENOMEM;

	/* class-based driver binding models */
	if (add_hotplug_env_var(envp, num_envp, &i,
				buffer, buffer_size, &length,
				"TYPE=%d/%d/%d",
				usb_dev->descriptor.bDeviceClass,
				usb_dev->descriptor.bDeviceSubClass,
				usb_dev->descriptor.bDeviceProtocol))
		return -ENOMEM;

	if (usb_dev->descriptor.bDeviceClass == 0) {
		struct usb_host_interface *alt = intf->cur_altsetting;

		/* 2.4 only exposed interface zero.  in 2.5, hotplug
		 * agents are called for all interfaces, and can use
		 * $DEVPATH/bInterfaceNumber if necessary.
		 */
		if (add_hotplug_env_var(envp, num_envp, &i,
					buffer, buffer_size, &length,
					"INTERFACE=%d/%d/%d",
					alt->desc.bInterfaceClass,
					alt->desc.bInterfaceSubClass,
					alt->desc.bInterfaceProtocol))
			return -ENOMEM;

		if (add_hotplug_env_var(envp, num_envp, &i,
					buffer, buffer_size, &length,
					"MODALIAS=usb:v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02Xic%02Xisc%02Xip%02X",
					le16_to_cpu(usb_dev->descriptor.idVendor),
					le16_to_cpu(usb_dev->descriptor.idProduct),
					le16_to_cpu(usb_dev->descriptor.bcdDevice),
					usb_dev->descriptor.bDeviceClass,
					usb_dev->descriptor.bDeviceSubClass,
					usb_dev->descriptor.bDeviceProtocol,
					alt->desc.bInterfaceClass,
					alt->desc.bInterfaceSubClass,
					alt->desc.bInterfaceProtocol))
			return -ENOMEM;
 	} else {
		if (add_hotplug_env_var(envp, num_envp, &i,
					buffer, buffer_size, &length,
					"MODALIAS=usb:v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02Xic*isc*ip*",
					le16_to_cpu(usb_dev->descriptor.idVendor),
					le16_to_cpu(usb_dev->descriptor.idProduct),
					le16_to_cpu(usb_dev->descriptor.bcdDevice),
					usb_dev->descriptor.bDeviceClass,
					usb_dev->descriptor.bDeviceSubClass,
					usb_dev->descriptor.bDeviceProtocol))
			return -ENOMEM;
	}

	envp[i] = NULL;

	return 0;
}

#else

static int usb_hotplug (struct device *dev, char **envp,
			int num_envp, char *buffer, int buffer_size)
{
	return -ENODEV;
}

#endif	/* CONFIG_HOTPLUG */

/**
 * usb_release_dev - free a usb device structure when all users of it are finished.
 * @dev: device that's been disconnected
 *
 * Will be called only by the device core when all users of this usb device are
 * done.
 */
static void usb_release_dev(struct device *dev)
{
	struct usb_device *udev;

	udev = to_usb_device(dev);

	usb_destroy_configuration(udev);
	usb_bus_put(udev->bus);
	kfree(udev->product);
	kfree(udev->manufacturer);
	kfree(udev->serial);
	kfree(udev);
}

/**
 * usb_alloc_dev - usb device constructor (usbcore-internal)
 * @parent: hub to which device is connected; null to allocate a root hub
 * @bus: bus used to access the device
 * @port1: one-based index of port; ignored for root hubs
 * Context: !in_interrupt ()
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 *
 * This call may not be used in a non-sleeping context.
 */
struct usb_device *
usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
{
	struct usb_device *dev;

	dev = kmalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev)
		return NULL;

	memset(dev, 0, sizeof(*dev));

	bus = usb_bus_get(bus);
	if (!bus) {
		kfree(dev);
		return NULL;
	}

	device_initialize(&dev->dev);
	dev->dev.bus = &usb_bus_type;
	dev->dev.dma_mask = bus->controller->dma_mask;
	dev->dev.driver_data = &usb_generic_driver_data;
	dev->dev.driver = &usb_generic_driver;
	dev->dev.release = usb_release_dev;
	dev->state = USB_STATE_ATTACHED;

	INIT_LIST_HEAD(&dev->ep0.urb_list);
	dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
	dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
	/* ep0 maxpacket comes later, from device descriptor */
	dev->ep_in[0] = dev->ep_out[0] = &dev->ep0;

	/* Save readable and stable topology id, distinguishing devices
	 * by location for diagnostics, tools, driver model, etc.  The
	 * string is a path along hub ports, from the root.  Each device's
	 * dev->devpath will be stable until USB is re-cabled, and hubs
	 * are often labeled with these port numbers.  The bus_id isn't
	 * as stable:  bus->busnum changes easily from modprobe order,
	 * cardbus or pci hotplugging, and so on.
	 */
	if (unlikely (!parent)) {
		dev->devpath [0] = '0';

		dev->dev.parent = bus->controller;
		sprintf (&dev->dev.bus_id[0], "usb%d", bus->busnum);
	} else {
		/* match any labeling on the hubs; it's one-based */
		if (parent->devpath [0] == '0')
			snprintf (dev->devpath, sizeof dev->devpath,
				"%d", port1);
		else
			snprintf (dev->devpath, sizeof dev->devpath,
				"%s.%d", parent->devpath, port1);

		dev->dev.parent = &parent->dev;
		sprintf (&dev->dev.bus_id[0], "%d-%s",
			bus->busnum, dev->devpath);

		/* hub driver sets up TT records */
	}

	dev->bus = bus;
	dev->parent = parent;
	INIT_LIST_HEAD(&dev->filelist);

	init_MUTEX(&dev->serialize);

	return dev;
}

/**
 * usb_get_dev - increments the reference count of the usb device structure
 * @dev: the device being referenced
 *
 * Each live reference to a device should be refcounted.
 *
 * Drivers for USB interfaces should normally record such references in
 * their probe() methods, when they bind to an interface, and release
 * them by calling usb_put_dev(), in their disconnect() methods.
 *
 * A pointer to the device with the incremented reference counter is returned.
 */
struct usb_device *usb_get_dev(struct usb_device *dev)
{
	if (dev)
		get_device(&dev->dev);
	return dev;
}

/**
 * usb_put_dev - release a use of the usb device structure
 * @dev: device that's been disconnected
 *
 * Must be called when a user of a device is finished with it.  When the last
 * user of the device calls this function, the memory of the device is freed.
 */
void usb_put_dev(struct usb_device *dev)
{
	if (dev)
		put_device(&dev->dev);
}

/**
 * usb_get_intf - increments the reference count of the usb interface structure
 * @intf: the interface being referenced
 *
 * Each live reference to a interface must be refcounted.
 *
 * Drivers for USB interfaces should normally record such references in
 * their probe() methods, when they bind to an interface, and release
 * them by calling usb_put_intf(), in their disconnect() methods.
 *
 * A pointer to the interface with the incremented reference counter is
 * returned.
 */
struct usb_interface *usb_get_intf(struct usb_interface *intf)
{
	if (intf)
		get_device(&intf->dev);
	return intf;
}

/**
 * usb_put_intf - release a use of the usb interface structure
 * @intf: interface that's been decremented
 *
 * Must be called when a user of an interface is finished with it.  When the
 * last user of the interface calls this function, the memory of the interface
 * is freed.
 */
void usb_put_intf(struct usb_interface *intf)
{
	if (intf)
		put_device(&intf->dev);
}


/*			USB device locking
 *
 * Although locking USB devices should be straightforward, it is
 * complicated by the way the driver-model core works.  When a new USB
 * driver is registered or unregistered, the core will automatically
 * probe or disconnect all matching interfaces on all USB devices while
 * holding the USB subsystem writelock.  There's no good way for us to
 * tell which devices will be used or to lock them beforehand; our only
 * option is to effectively lock all the USB devices.
 *
 * We do that by using a private rw-semaphore, usb_all_devices_rwsem.
 * When locking an individual device you must first acquire the rwsem's
 * readlock.  When a driver is registered or unregistered the writelock
 * must be held.  These actions are encapsulated in the subroutines
 * below, so all a driver needs to do is call usb_lock_device() and
 * usb_unlock_device().
 *
 * Complications arise when several devices are to be locked at the same
 * time.  Only hub-aware drivers that are part of usbcore ever have to
 * do this; nobody else needs to worry about it.  The problem is that
 * usb_lock_device() must not be called to lock a second device since it
 * would acquire the rwsem's readlock reentrantly, leading to deadlock if
 * another thread was waiting for the writelock.  The solution is simple:
 *
 *	When locking more than one device, call usb_lock_device()
 *	to lock the first one.  Lock the others by calling
 *	down(&udev->serialize) directly.
 *
 *	When unlocking multiple devices, use up(&udev->serialize)
 *	to unlock all but the last one.  Unlock the last one by
 *	calling usb_unlock_device().
 *
 *	When locking both a device and its parent, always lock the
 *	the parent first.
 */

/**
 * usb_lock_device - acquire the lock for a usb device structure
 * @udev: device that's being locked
 *
 * Use this routine when you don't hold any other device locks;
 * to acquire nested inner locks call down(&udev->serialize) directly.
 * This is necessary for proper interaction with usb_lock_all_devices().
 */
void usb_lock_device(struct usb_device *udev)
{
	down_read(&usb_all_devices_rwsem);
	down(&udev->serialize);
}

/**
 * usb_trylock_device - attempt to acquire the lock for a usb device structure
 * @udev: device that's being locked
 *
 * Don't use this routine if you already hold a device lock;
 * use down_trylock(&udev->serialize) instead.
 * This is necessary for proper interaction with usb_lock_all_devices().
 *
 * Returns 1 if successful, 0 if contention.
 */
int usb_trylock_device(struct usb_device *udev)
{
	if (!down_read_trylock(&usb_all_devices_rwsem))
		return 0;
	if (down_trylock(&udev->serialize)) {
		up_read(&usb_all_devices_rwsem);
		return 0;
	}
	return 1;
}

/**
 * usb_lock_device_for_reset - cautiously acquire the lock for a
 *	usb device structure
 * @udev: device that's being locked
 * @iface: interface bound to the driver making the request (optional)
 *
 * Attempts to acquire the device lock, but fails if the device is
 * NOTATTACHED or SUSPENDED, or if iface is specified and the interface
 * is neither BINDING nor BOUND.  Rather than sleeping to wait for the
 * lock, the routine polls repeatedly.  This is to prevent deadlock with
 * disconnect; in some drivers (such as usb-storage) the disconnect()
 * or suspend() method will block waiting for a device reset to complete.
 *
 * Returns a negative error code for failure, otherwise 1 or 0 to indicate
 * that the device will or will not have to be unlocked.  (0 can be
 * returned when an interface is given and is BINDING, because in that
 * case the driver already owns the device lock.)
 */
int usb_lock_device_for_reset(struct usb_device *udev,
		struct usb_interface *iface)
{
	unsigned long jiffies_expire = jiffies + HZ;

	if (udev->state == USB_STATE_NOTATTACHED)
		return -ENODEV;
	if (udev->state == USB_STATE_SUSPENDED)
		return -EHOSTUNREACH;
	if (iface) {
		switch (iface->condition) {
		  case USB_INTERFACE_BINDING:
			return 0;
		  case USB_INTERFACE_BOUND:
			break;
		  default:
			return -EINTR;
		}
	}

	while (!usb_trylock_device(udev)) {

		/* If we can't acquire the lock after waiting one second,
		 * we're probably deadlocked */
		if (time_after(jiffies, jiffies_expire))
			return -EBUSY;

		msleep(15);
		if (udev->state == USB_STATE_NOTATTACHED)
			return -ENODEV;
		if (udev->state == USB_STATE_SUSPENDED)
			return -EHOSTUNREACH;
		if (iface && iface->condition != USB_INTERFACE_BOUND)
			return -EINTR;
	}
	return 1;
}

/**
 * usb_unlock_device - release the lock for a usb device structure
 * @udev: device that's being unlocked
 *
 * Use this routine when releasing the only device lock you hold;
 * to release inner nested locks call up(&udev->serialize) directly.
 * This is necessary for proper interaction with usb_lock_all_devices().
 */
void usb_unlock_device(struct usb_device *udev)
{
	up(&udev->serialize);
	up_read(&usb_all_devices_rwsem);
}

/**
 * usb_lock_all_devices - acquire the lock for all usb device structures
 *
 * This is necessary when registering a new driver or probing a bus,
 * since the driver-model core may try to use any usb_device.
 */
void usb_lock_all_devices(void)
{
	down_write(&usb_all_devices_rwsem);
}

/**
 * usb_unlock_all_devices - release the lock for all usb device structures
 */
void usb_unlock_all_devices(void)
{
	up_write(&usb_all_devices_rwsem);
}


static struct usb_device *match_device(struct usb_device *dev,
				       u16 vendor_id, u16 product_id)
{
	struct usb_device *ret_dev = NULL;
	int child;

	dev_dbg(&dev->dev, "check for vendor %04x, product %04x ...\n",
	    le16_to_cpu(dev->descriptor.idVendor),
	    le16_to_cpu(dev->descriptor.idProduct));

	/* see if this device matches */
	if ((vendor_id == le16_to_cpu(dev->descriptor.idVendor)) &&
	    (product_id == le16_to_cpu(dev->descriptor.idProduct))) {
		dev_dbg (&dev->dev, "matched this device!\n");
		ret_dev = usb_get_dev(dev);
		goto exit;
	}

	/* look through all of the children of this device */
	for (child = 0; child < dev->maxchild; ++child) {
		if (dev->children[child]) {
			down(&dev->children[child]->serialize);
			ret_dev = match_device(dev->children[child],
					       vendor_id, product_id);
			up(&dev->children[child]->serialize);
			if (ret_dev)
				goto exit;
		}
	}
exit:
	return ret_dev;
}

/**
 * usb_find_device - find a specific usb device in the system
 * @vendor_id: the vendor id of the device to find
 * @product_id: the product id of the device to find
 *
 * Returns a pointer to a struct usb_device if such a specified usb
 * device is present in the system currently.  The usage count of the
 * device will be incremented if a device is found.  Make sure to call
 * usb_put_dev() when the caller is finished with the device.
 *
 * If a device with the specified vendor and product id is not found,
 * NULL is returned.
 */
struct usb_device *usb_find_device(u16 vendor_id, u16 product_id)
{
	struct list_head *buslist;
	struct usb_bus *bus;
	struct usb_device *dev = NULL;
	
	down(&usb_bus_list_lock);
	for (buslist = usb_bus_list.next;
	     buslist != &usb_bus_list; 
	     buslist = buslist->next) {
		bus = container_of(buslist, struct usb_bus, bus_list);
		if (!bus->root_hub)
			continue;
		usb_lock_device(bus->root_hub);
		dev = match_device(bus->root_hub, vendor_id, product_id);
		usb_unlock_device(bus->root_hub);
		if (dev)
			goto exit;
	}
exit:
	up(&usb_bus_list_lock);
	return dev;
}

/**
 * usb_get_current_frame_number - return current bus frame number
 * @dev: the device whose bus is being queried
 *
 * Returns the current frame number for the USB host controller
 * used with the given USB device.  This can be used when scheduling
 * isochronous requests.
 *
 * Note that different kinds of host controller have different
 * "scheduling horizons".  While one type might support scheduling only
 * 32 frames into the future, others could support scheduling up to
 * 1024 frames into the future.
 */
int usb_get_current_frame_number(struct usb_device *dev)
{
	return dev->bus->op->get_frame_number (dev);
}

/*-------------------------------------------------------------------*/
/*
 * __usb_get_extra_descriptor() finds a descriptor of specific type in the
 * extra field of the interface and endpoint descriptor structs.
 */

int __usb_get_extra_descriptor(char *buffer, unsigned size,
	unsigned char type, void **ptr)
{
	struct usb_descriptor_header *header;

	while (size >= sizeof(struct usb_descriptor_header)) {
		header = (struct usb_descriptor_header *)buffer;

		if (header->bLength < 2) {
			printk(KERN_ERR
				"%s: bogus descriptor, type %d length %d\n",
				usbcore_name,
				header->bDescriptorType, 
				header->bLength);
			return -1;
		}

		if (header->bDescriptorType == type) {
			*ptr = header;
			return 0;
		}

		buffer += header->bLength;
		size -= header->bLength;
	}
	return -1;
}

/**
 * usb_buffer_alloc - allocate dma-consistent buffer for URB_NO_xxx_DMA_MAP
 * @dev: device the buffer will be used with
 * @size: requested buffer size
 * @mem_flags: affect whether allocation may block
 * @dma: used to return DMA address of buffer
 *
 * Return value is either null (indicating no buffer could be allocated), or
 * the cpu-space pointer to a buffer that may be used to perform DMA to the
 * specified device.  Such cpu-space buffers are returned along with the DMA
 * address (through the pointer provided).
 *
 * These buffers are used with URB_NO_xxx_DMA_MAP set in urb->transfer_flags
 * to avoid behaviors like using "DMA bounce buffers", or tying down I/O
 * mapping hardware for long idle periods.  The implementation varies between
 * platforms, depending on details of how DMA will work to this device.
 * Using these buffers also helps prevent cacheline sharing problems on
 * architectures where CPU caches are not DMA-coherent.
 *
 * When the buffer is no longer used, free it with usb_buffer_free().
 */
void *usb_buffer_alloc (
	struct usb_device *dev,
	size_t size,
	unsigned mem_flags,
	dma_addr_t *dma
)
{
	if (!dev || !dev->bus || !dev->bus->op || !dev->bus->op->buffer_alloc)
		return NULL;
	return dev->bus->op->buffer_alloc (dev->bus, size, mem_flags, dma);
}

/**
 * usb_buffer_free - free memory allocated with usb_buffer_alloc()
 * @dev: device the buffer was used with
 * @size: requested buffer size
 * @addr: CPU address of buffer
 * @dma: DMA address of buffer
 *
 * This reclaims an I/O buffer, letting it be reused.  The memory must have
 * been allocated using usb_buffer_alloc(), and the parameters must match
 * those provided in that allocation request. 
 */
void usb_buffer_free (
	struct usb_device *dev,
	size_t size,
	void *addr,
	dma_addr_t dma
)
{
	if (!dev || !dev->bus || !dev->bus->op || !dev->bus->op->buffer_free)
	    	return;
	dev->bus->op->buffer_free (dev->bus, size, addr, dma);
}

/**
 * usb_buffer_map - create DMA mapping(s) for an urb
 * @urb: urb whose transfer_buffer/setup_packet will be mapped
 *
 * Return value is either null (indicating no buffer could be mapped), or
 * the parameter.  URB_NO_TRANSFER_DMA_MAP and URB_NO_SETUP_DMA_MAP are
 * added to urb->transfer_flags if the operation succeeds.  If the device
 * is connected to this system through a non-DMA controller, this operation
 * always succeeds.
 *
 * This call would normally be used for an urb which is reused, perhaps
 * as the target of a large periodic transfer, with usb_buffer_dmasync()
 * calls to synchronize memory and dma state.
 *
 * Reverse the effect of this call with usb_buffer_unmap().
 */
#if 0
struct urb *usb_buffer_map (struct urb *urb)
{
	struct usb_bus		*bus;
	struct device		*controller;

	if (!urb
			|| !urb->dev
			|| !(bus = urb->dev->bus)
			|| !(controller = bus->controller))
		return NULL;

	if (controller->dma_mask) {
		urb->transfer_dma = dma_map_single (controller,
			urb->transfer_buffer, urb->transfer_buffer_length,
			usb_pipein (urb->pipe)
				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
		if (usb_pipecontrol (urb->pipe))
			urb->setup_dma = dma_map_single (controller,
					urb->setup_packet,
					sizeof (struct usb_ctrlrequest),
					DMA_TO_DEVICE);
	// FIXME generic api broken like pci, can't report errors
	// if (urb->transfer_dma == DMA_ADDR_INVALID) return 0;
	} else
		urb->transfer_dma = ~0;
	urb->transfer_flags |= (URB_NO_TRANSFER_DMA_MAP
				| URB_NO_SETUP_DMA_MAP);
	return urb;
}
#endif  /*  0  */

/* XXX DISABLED, no users currently.  If you wish to re-enable this
 * XXX please determine whether the sync is to transfer ownership of
 * XXX the buffer from device to cpu or vice verse, and thusly use the
 * XXX appropriate _for_{cpu,device}() method.  -DaveM
 */
#if 0

/**
 * usb_buffer_dmasync - synchronize DMA and CPU view of buffer(s)
 * @urb: urb whose transfer_buffer/setup_packet will be synchronized
 */
void usb_buffer_dmasync (struct urb *urb)
{
	struct usb_bus		*bus;
	struct device		*controller;

	if (!urb
			|| !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
			|| !urb->dev
			|| !(bus = urb->dev->bus)
			|| !(controller = bus->controller))
		return;

	if (controller->dma_mask) {
		dma_sync_single (controller,
			urb->transfer_dma, urb->transfer_buffer_length,
			usb_pipein (urb->pipe)
				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
		if (usb_pipecontrol (urb->pipe))
			dma_sync_single (controller,
					urb->setup_dma,
					sizeof (struct usb_ctrlrequest),
					DMA_TO_DEVICE);
	}
}
#endif

/**
 * usb_buffer_unmap - free DMA mapping(s) for an urb
 * @urb: urb whose transfer_buffer will be unmapped
 *
 * Reverses the effect of usb_buffer_map().
 */
#if 0
void usb_buffer_unmap (struct urb *urb)
{
	struct usb_bus		*bus;
	struct device		*controller;

	if (!urb
			|| !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
			|| !urb->dev
			|| !(bus = urb->dev->bus)
			|| !(controller = bus->controller))
		return;

	if (controller->dma_mask) {
		dma_unmap_single (controller,
			urb->transfer_dma, urb->transfer_buffer_length,
			usb_pipein (urb->pipe)
				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
		if (usb_pipecontrol (urb->pipe))
			dma_unmap_single (controller,
					urb->setup_dma,
					sizeof (struct usb_ctrlrequest),
					DMA_TO_DEVICE);
	}
	urb->transfer_flags &= ~(URB_NO_TRANSFER_DMA_MAP
				| URB_NO_SETUP_DMA_MAP);
}
#endif  /*  0  */

/**
 * usb_buffer_map_sg - create scatterlist DMA mapping(s) for an endpoint
 * @dev: device to which the scatterlist will be mapped
 * @pipe: endpoint defining the mapping direction
 * @sg: the scatterlist to map
 * @nents: the number of entries in the scatterlist
 *
 * Return value is either < 0 (indicating no buffers could be mapped), or
 * the number of DMA mapping array entries in the scatterlist.
 *
 * The caller is responsible for placing the resulting DMA addresses from
 * the scatterlist into URB transfer buffer pointers, and for setting the
 * URB_NO_TRANSFER_DMA_MAP transfer flag in each of those URBs.
 *
 * Top I/O rates come from queuing URBs, instead of waiting for each one
 * to complete before starting the next I/O.   This is particularly easy
 * to do with scatterlists.  Just allocate and submit one URB for each DMA
 * mapping entry returned, stopping on the first error or when all succeed.
 * Better yet, use the usb_sg_*() calls, which do that (and more) for you.
 *
 * This call would normally be used when translating scatterlist requests,
 * rather than usb_buffer_map(), since on some hardware (with IOMMUs) it
 * may be able to coalesce mappings for improved I/O efficiency.
 *
 * Reverse the effect of this call with usb_buffer_unmap_sg().
 */
int usb_buffer_map_sg (struct usb_device *dev, unsigned pipe,
		struct scatterlist *sg, int nents)
{
	struct usb_bus		*bus;
	struct device		*controller;

	if (!dev
			|| usb_pipecontrol (pipe)
			|| !(bus = dev->bus)
			|| !(controller = bus->controller)
			|| !controller->dma_mask)
		return -1;

	// FIXME generic api broken like pci, can't report errors
	return dma_map_sg (controller, sg, nents,
			usb_pipein (pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}

/* XXX DISABLED, no users currently.  If you wish to re-enable this
 * XXX please determine whether the sync is to transfer ownership of
 * XXX the buffer from device to cpu or vice verse, and thusly use the
 * XXX appropriate _for_{cpu,device}() method.  -DaveM
 */
#if 0

/**
 * usb_buffer_dmasync_sg - synchronize DMA and CPU view of scatterlist buffer(s)
 * @dev: device to which the scatterlist will be mapped
 * @pipe: endpoint defining the mapping direction
 * @sg: the scatterlist to synchronize
 * @n_hw_ents: the positive return value from usb_buffer_map_sg
 *
 * Use this when you are re-using a scatterlist's data buffers for
 * another USB request.
 */
void usb_buffer_dmasync_sg (struct usb_device *dev, unsigned pipe,
		struct scatterlist *sg, int n_hw_ents)
{
	struct usb_bus		*bus;
	struct device		*controller;

	if (!dev
			|| !(bus = dev->bus)
			|| !(controller = bus->controller)
			|| !controller->dma_mask)
		return;

	dma_sync_sg (controller, sg, n_hw_ents,
			usb_pipein (pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}
#endif

/**
 * usb_buffer_unmap_sg - free DMA mapping(s) for a scatterlist
 * @dev: device to which the scatterlist will be mapped
 * @pipe: endpoint defining the mapping direction
 * @sg: the scatterlist to unmap
 * @n_hw_ents: the positive return value from usb_buffer_map_sg
 *
 * Reverses the effect of usb_buffer_map_sg().
 */
void usb_buffer_unmap_sg (struct usb_device *dev, unsigned pipe,
		struct scatterlist *sg, int n_hw_ents)
{
	struct usb_bus		*bus;
	struct device		*controller;

	if (!dev
			|| !(bus = dev->bus)
			|| !(controller = bus->controller)
			|| !controller->dma_mask)
		return;

	dma_unmap_sg (controller, sg, n_hw_ents,
			usb_pipein (pipe) ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
}

static int usb_generic_suspend(struct device *dev, pm_message_t message)
{
	struct usb_interface *intf;
	struct usb_driver *driver;

	if (dev->driver == &usb_generic_driver)
		return usb_suspend_device (to_usb_device(dev), message);

	if ((dev->driver == NULL) ||
	    (dev->driver_data == &usb_generic_driver_data))
		return 0;

	intf = to_usb_interface(dev);
	driver = to_usb_driver(dev->driver);

	/* there's only one USB suspend state */
	if (intf->dev.power.power_state.event)
		return 0;

	if (driver->suspend)
		return driver->suspend(intf, message);
	return 0;
}

static int usb_generic_resume(struct device *dev)
{
	struct usb_interface *intf;
	struct usb_driver *driver;

	/* devices resume through their hub */
	if (dev->driver == &usb_generic_driver)
		return usb_resume_device (to_usb_device(dev));

	if ((dev->driver == NULL) ||
	    (dev->driver_data == &usb_generic_driver_data))
		return 0;

	intf = to_usb_interface(dev);
	driver = to_usb_driver(dev->driver);

	if (driver->resume)
		return driver->resume(intf);
	return 0;
}

struct bus_type usb_bus_type = {
	.name =		"usb",
	.match =	usb_device_match,
	.hotplug =	usb_hotplug,
	.suspend =	usb_generic_suspend,
	.resume =	usb_generic_resume,
};

#ifndef MODULE

static int __init usb_setup_disable(char *str)
{
	nousb = 1;
	return 1;
}

/* format to disable USB on kernel command line is: nousb */
__setup("nousb", usb_setup_disable);

#endif

/*
 * for external read access to <nousb>
 */
int usb_disabled(void)
{
	return nousb;
}

/*
 * Init
 */
static int __init usb_init(void)
{
	int retval;
	if (nousb) {
		pr_info ("%s: USB support disabled\n", usbcore_name);
		return 0;
	}

	retval = bus_register(&usb_bus_type);
	if (retval) 
		goto out;
	retval = usb_host_init();
	if (retval)
		goto host_init_failed;
	retval = usb_major_init();
	if (retval)
		goto major_init_failed;
	retval = usb_register(&usbfs_driver);
	if (retval)
		goto driver_register_failed;
	retval = usbdev_init();
	if (retval)
		goto usbdevice_init_failed;
	retval = usbfs_init();
	if (retval)
		goto fs_init_failed;
	retval = usb_hub_init();
	if (retval)
		goto hub_init_failed;
	retval = driver_register(&usb_generic_driver);
	if (!retval)
		goto out;

	usb_hub_cleanup();
hub_init_failed:
	usbfs_cleanup();
fs_init_failed:
	usbdev_cleanup();
usbdevice_init_failed:
	usb_deregister(&usbfs_driver);
driver_register_failed:
	usb_major_cleanup();
major_init_failed:
	usb_host_cleanup();
host_init_failed:
	bus_unregister(&usb_bus_type);
out:
	return retval;
}

/*
 * Cleanup
 */
static void __exit usb_exit(void)
{
	/* This will matter if shutdown/reboot does exitcalls. */
	if (nousb)
		return;

	driver_unregister(&usb_generic_driver);
	usb_major_cleanup();
	usbfs_cleanup();
	usb_deregister(&usbfs_driver);
	usbdev_cleanup();
	usb_hub_cleanup();
	usb_host_cleanup();
	bus_unregister(&usb_bus_type);
}

subsys_initcall(usb_init);
module_exit(usb_exit);

/*
 * USB may be built into the kernel or be built as modules.
 * These symbols are exported for device (or host controller)
 * driver modules to use.
 */

EXPORT_SYMBOL(usb_register);
EXPORT_SYMBOL(usb_deregister);
EXPORT_SYMBOL(usb_disabled);

EXPORT_SYMBOL_GPL(usb_get_intf);
EXPORT_SYMBOL_GPL(usb_put_intf);

EXPORT_SYMBOL(usb_alloc_dev);
EXPORT_SYMBOL(usb_put_dev);
EXPORT_SYMBOL(usb_get_dev);
EXPORT_SYMBOL(usb_hub_tt_clear_buffer);

EXPORT_SYMBOL(usb_lock_device);
EXPORT_SYMBOL(usb_trylock_device);
EXPORT_SYMBOL(usb_lock_device_for_reset);
EXPORT_SYMBOL(usb_unlock_device);

EXPORT_SYMBOL(usb_driver_claim_interface);
EXPORT_SYMBOL(usb_driver_release_interface);
EXPORT_SYMBOL(usb_match_id);
EXPORT_SYMBOL(usb_find_interface);
EXPORT_SYMBOL(usb_ifnum_to_if);
EXPORT_SYMBOL(usb_altnum_to_altsetting);

EXPORT_SYMBOL(usb_reset_device);
EXPORT_SYMBOL(usb_disconnect);

EXPORT_SYMBOL(__usb_get_extra_descriptor);

EXPORT_SYMBOL(usb_find_device);
EXPORT_SYMBOL(usb_get_current_frame_number);

EXPORT_SYMBOL (usb_buffer_alloc);
EXPORT_SYMBOL (usb_buffer_free);

#if 0
EXPORT_SYMBOL (usb_buffer_map);
EXPORT_SYMBOL (usb_buffer_dmasync);
EXPORT_SYMBOL (usb_buffer_unmap);
#endif

EXPORT_SYMBOL (usb_buffer_map_sg);
#if 0
EXPORT_SYMBOL (usb_buffer_dmasync_sg);
#endif
EXPORT_SYMBOL (usb_buffer_unmap_sg);

MODULE_LICENSE("GPL");