aboutsummaryrefslogtreecommitdiff
path: root/drivers/usb/storage/transport.c
blob: e20dc525d17763642f65a07835a4a2ca462f1a4a (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
/* Driver for USB Mass Storage compliant devices
 *
 * Current development and maintenance by:
 *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
 *
 * Developed with the assistance of:
 *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
 *   (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
 *   (c) 2002 Alan Stern <stern@rowland.org>
 *
 * Initial work by:
 *   (c) 1999 Michael Gee (michael@linuxspecific.com)
 *
 * This driver is based on the 'USB Mass Storage Class' document. This
 * describes in detail the protocol used to communicate with such
 * devices.  Clearly, the designers had SCSI and ATAPI commands in
 * mind when they created this document.  The commands are all very
 * similar to commands in the SCSI-II and ATAPI specifications.
 *
 * It is important to note that in a number of cases this class
 * exhibits class-specific exemptions from the USB specification.
 * Notably the usage of NAK, STALL and ACK differs from the norm, in
 * that they are used to communicate wait, failed and OK on commands.
 *
 * Also, for certain devices, the interrupt endpoint is used to convey
 * status of a command.
 *
 * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
 * information about this driver.
 *
 * 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, 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.,
 * 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/slab.h>

#include <scsi/scsi.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_device.h>

#include "usb.h"
#include "transport.h"
#include "protocol.h"
#include "scsiglue.h"
#include "debug.h"

#include <linux/blkdev.h>
#include "../../scsi/sd.h"


/***********************************************************************
 * Data transfer routines
 ***********************************************************************/

/*
 * This is subtle, so pay attention:
 * ---------------------------------
 * We're very concerned about races with a command abort.  Hanging this code
 * is a sure fire way to hang the kernel.  (Note that this discussion applies
 * only to transactions resulting from a scsi queued-command, since only
 * these transactions are subject to a scsi abort.  Other transactions, such
 * as those occurring during device-specific initialization, must be handled
 * by a separate code path.)
 *
 * The abort function (usb_storage_command_abort() in scsiglue.c) first
 * sets the machine state and the ABORTING bit in us->dflags to prevent
 * new URBs from being submitted.  It then calls usb_stor_stop_transport()
 * below, which atomically tests-and-clears the URB_ACTIVE bit in us->dflags
 * to see if the current_urb needs to be stopped.  Likewise, the SG_ACTIVE
 * bit is tested to see if the current_sg scatter-gather request needs to be
 * stopped.  The timeout callback routine does much the same thing.
 *
 * When a disconnect occurs, the DISCONNECTING bit in us->dflags is set to
 * prevent new URBs from being submitted, and usb_stor_stop_transport() is
 * called to stop any ongoing requests.
 *
 * The submit function first verifies that the submitting is allowed
 * (neither ABORTING nor DISCONNECTING bits are set) and that the submit
 * completes without errors, and only then sets the URB_ACTIVE bit.  This
 * prevents the stop_transport() function from trying to cancel the URB
 * while the submit call is underway.  Next, the submit function must test
 * the flags to see if an abort or disconnect occurred during the submission
 * or before the URB_ACTIVE bit was set.  If so, it's essential to cancel
 * the URB if it hasn't been cancelled already (i.e., if the URB_ACTIVE bit
 * is still set).  Either way, the function must then wait for the URB to
 * finish.  Note that the URB can still be in progress even after a call to
 * usb_unlink_urb() returns.
 *
 * The idea is that (1) once the ABORTING or DISCONNECTING bit is set,
 * either the stop_transport() function or the submitting function
 * is guaranteed to call usb_unlink_urb() for an active URB,
 * and (2) test_and_clear_bit() prevents usb_unlink_urb() from being
 * called more than once or from being called during usb_submit_urb().
 */

/* This is the completion handler which will wake us up when an URB
 * completes.
 */
static void usb_stor_blocking_completion(struct urb *urb)
{
	struct completion *urb_done_ptr = urb->context;

	complete(urb_done_ptr);
}

/* This is the common part of the URB message submission code
 *
 * All URBs from the usb-storage driver involved in handling a queued scsi
 * command _must_ pass through this function (or something like it) for the
 * abort mechanisms to work properly.
 */
static int usb_stor_msg_common(struct us_data *us, int timeout)
{
	struct completion urb_done;
	long timeleft;
	int status;

	/* don't submit URBs during abort processing */
	if (test_bit(US_FLIDX_ABORTING, &us->dflags))
		return -EIO;

	/* set up data structures for the wakeup system */
	init_completion(&urb_done);

	/* fill the common fields in the URB */
	us->current_urb->context = &urb_done;
	us->current_urb->actual_length = 0;
	us->current_urb->error_count = 0;
	us->current_urb->status = 0;

	/* we assume that if transfer_buffer isn't us->iobuf then it
	 * hasn't been mapped for DMA.  Yes, this is clunky, but it's
	 * easier than always having the caller tell us whether the
	 * transfer buffer has already been mapped. */
	us->current_urb->transfer_flags = URB_NO_SETUP_DMA_MAP;
	if (us->current_urb->transfer_buffer == us->iobuf)
		us->current_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
	us->current_urb->transfer_dma = us->iobuf_dma;
	us->current_urb->setup_dma = us->cr_dma;

	/* submit the URB */
	status = usb_submit_urb(us->current_urb, GFP_NOIO);
	if (status) {
		/* something went wrong */
		return status;
	}

	/* since the URB has been submitted successfully, it's now okay
	 * to cancel it */
	set_bit(US_FLIDX_URB_ACTIVE, &us->dflags);

	/* did an abort occur during the submission? */
	if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {

		/* cancel the URB, if it hasn't been cancelled already */
		if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
			US_DEBUGP("-- cancelling URB\n");
			usb_unlink_urb(us->current_urb);
		}
	}
 
	/* wait for the completion of the URB */
	timeleft = wait_for_completion_interruptible_timeout(
			&urb_done, timeout ? : MAX_SCHEDULE_TIMEOUT);
 
	clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags);

	if (timeleft <= 0) {
		US_DEBUGP("%s -- cancelling URB\n",
			  timeleft == 0 ? "Timeout" : "Signal");
		usb_kill_urb(us->current_urb);
	}

	/* return the URB status */
	return us->current_urb->status;
}

/*
 * Transfer one control message, with timeouts, and allowing early
 * termination.  Return codes are usual -Exxx, *not* USB_STOR_XFER_xxx.
 */
int usb_stor_control_msg(struct us_data *us, unsigned int pipe,
		 u8 request, u8 requesttype, u16 value, u16 index, 
		 void *data, u16 size, int timeout)
{
	int status;

	US_DEBUGP("%s: rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
			__func__, request, requesttype,
			value, index, size);

	/* fill in the devrequest structure */
	us->cr->bRequestType = requesttype;
	us->cr->bRequest = request;
	us->cr->wValue = cpu_to_le16(value);
	us->cr->wIndex = cpu_to_le16(index);
	us->cr->wLength = cpu_to_le16(size);

	/* fill and submit the URB */
	usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe, 
			 (unsigned char*) us->cr, data, size, 
			 usb_stor_blocking_completion, NULL);
	status = usb_stor_msg_common(us, timeout);

	/* return the actual length of the data transferred if no error */
	if (status == 0)
		status = us->current_urb->actual_length;
	return status;
}
EXPORT_SYMBOL_GPL(usb_stor_control_msg);

/* This is a version of usb_clear_halt() that allows early termination and
 * doesn't read the status from the device -- this is because some devices
 * crash their internal firmware when the status is requested after a halt.
 *
 * A definitive list of these 'bad' devices is too difficult to maintain or
 * make complete enough to be useful.  This problem was first observed on the
 * Hagiwara FlashGate DUAL unit.  However, bus traces reveal that neither
 * MacOS nor Windows checks the status after clearing a halt.
 *
 * Since many vendors in this space limit their testing to interoperability
 * with these two OSes, specification violations like this one are common.
 */
int usb_stor_clear_halt(struct us_data *us, unsigned int pipe)
{
	int result;
	int endp = usb_pipeendpoint(pipe);

	if (usb_pipein (pipe))
		endp |= USB_DIR_IN;

	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
		USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
		USB_ENDPOINT_HALT, endp,
		NULL, 0, 3*HZ);

	if (result >= 0)
		usb_reset_endpoint(us->pusb_dev, endp);

	US_DEBUGP("%s: result = %d\n", __func__, result);
	return result;
}
EXPORT_SYMBOL_GPL(usb_stor_clear_halt);


/*
 * Interpret the results of a URB transfer
 *
 * This function prints appropriate debugging messages, clears halts on
 * non-control endpoints, and translates the status to the corresponding
 * USB_STOR_XFER_xxx return code.
 */
static int interpret_urb_result(struct us_data *us, unsigned int pipe,
		unsigned int length, int result, unsigned int partial)
{
	US_DEBUGP("Status code %d; transferred %u/%u\n",
			result, partial, length);
	switch (result) {

	/* no error code; did we send all the data? */
	case 0:
		if (partial != length) {
			US_DEBUGP("-- short transfer\n");
			return USB_STOR_XFER_SHORT;
		}

		US_DEBUGP("-- transfer complete\n");
		return USB_STOR_XFER_GOOD;

	/* stalled */
	case -EPIPE:
		/* for control endpoints, (used by CB[I]) a stall indicates
		 * a failed command */
		if (usb_pipecontrol(pipe)) {
			US_DEBUGP("-- stall on control pipe\n");
			return USB_STOR_XFER_STALLED;
		}

		/* for other sorts of endpoint, clear the stall */
		US_DEBUGP("clearing endpoint halt for pipe 0x%x\n", pipe);
		if (usb_stor_clear_halt(us, pipe) < 0)
			return USB_STOR_XFER_ERROR;
		return USB_STOR_XFER_STALLED;

	/* babble - the device tried to send more than we wanted to read */
	case -EOVERFLOW:
		US_DEBUGP("-- babble\n");
		return USB_STOR_XFER_LONG;

	/* the transfer was cancelled by abort, disconnect, or timeout */
	case -ECONNRESET:
		US_DEBUGP("-- transfer cancelled\n");
		return USB_STOR_XFER_ERROR;

	/* short scatter-gather read transfer */
	case -EREMOTEIO:
		US_DEBUGP("-- short read transfer\n");
		return USB_STOR_XFER_SHORT;

	/* abort or disconnect in progress */
	case -EIO:
		US_DEBUGP("-- abort or disconnect in progress\n");
		return USB_STOR_XFER_ERROR;

	/* the catch-all error case */
	default:
		US_DEBUGP("-- unknown error\n");
		return USB_STOR_XFER_ERROR;
	}
}

/*
 * Transfer one control message, without timeouts, but allowing early
 * termination.  Return codes are USB_STOR_XFER_xxx.
 */
int usb_stor_ctrl_transfer(struct us_data *us, unsigned int pipe,
		u8 request, u8 requesttype, u16 value, u16 index,
		void *data, u16 size)
{
	int result;

	US_DEBUGP("%s: rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
			__func__, request, requesttype,
			value, index, size);

	/* fill in the devrequest structure */
	us->cr->bRequestType = requesttype;
	us->cr->bRequest = request;
	us->cr->wValue = cpu_to_le16(value);
	us->cr->wIndex = cpu_to_le16(index);
	us->cr->wLength = cpu_to_le16(size);

	/* fill and submit the URB */
	usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe, 
			 (unsigned char*) us->cr, data, size, 
			 usb_stor_blocking_completion, NULL);
	result = usb_stor_msg_common(us, 0);

	return interpret_urb_result(us, pipe, size, result,
			us->current_urb->actual_length);
}
EXPORT_SYMBOL_GPL(usb_stor_ctrl_transfer);

/*
 * Receive one interrupt buffer, without timeouts, but allowing early
 * termination.  Return codes are USB_STOR_XFER_xxx.
 *
 * This routine always uses us->recv_intr_pipe as the pipe and
 * us->ep_bInterval as the interrupt interval.
 */
static int usb_stor_intr_transfer(struct us_data *us, void *buf,
				  unsigned int length)
{
	int result;
	unsigned int pipe = us->recv_intr_pipe;
	unsigned int maxp;

	US_DEBUGP("%s: xfer %u bytes\n", __func__, length);

	/* calculate the max packet size */
	maxp = usb_maxpacket(us->pusb_dev, pipe, usb_pipeout(pipe));
	if (maxp > length)
		maxp = length;

	/* fill and submit the URB */
	usb_fill_int_urb(us->current_urb, us->pusb_dev, pipe, buf,
			maxp, usb_stor_blocking_completion, NULL,
			us->ep_bInterval);
	result = usb_stor_msg_common(us, 0);

	return interpret_urb_result(us, pipe, length, result,
			us->current_urb->actual_length);
}

/*
 * Transfer one buffer via bulk pipe, without timeouts, but allowing early
 * termination.  Return codes are USB_STOR_XFER_xxx.  If the bulk pipe
 * stalls during the transfer, the halt is automatically cleared.
 */
int usb_stor_bulk_transfer_buf(struct us_data *us, unsigned int pipe,
	void *buf, unsigned int length, unsigned int *act_len)
{
	int result;

	US_DEBUGP("%s: xfer %u bytes\n", __func__, length);

	/* fill and submit the URB */
	usb_fill_bulk_urb(us->current_urb, us->pusb_dev, pipe, buf, length,
		      usb_stor_blocking_completion, NULL);
	result = usb_stor_msg_common(us, 0);

	/* store the actual length of the data transferred */
	if (act_len)
		*act_len = us->current_urb->actual_length;
	return interpret_urb_result(us, pipe, length, result, 
			us->current_urb->actual_length);
}
EXPORT_SYMBOL_GPL(usb_stor_bulk_transfer_buf);

/*
 * Transfer a scatter-gather list via bulk transfer
 *
 * This function does basically the same thing as usb_stor_bulk_transfer_buf()
 * above, but it uses the usbcore scatter-gather library.
 */
static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
		struct scatterlist *sg, int num_sg, unsigned int length,
		unsigned int *act_len)
{
	int result;

	/* don't submit s-g requests during abort processing */
	if (test_bit(US_FLIDX_ABORTING, &us->dflags))
		return USB_STOR_XFER_ERROR;

	/* initialize the scatter-gather request block */
	US_DEBUGP("%s: xfer %u bytes, %d entries\n", __func__,
			length, num_sg);
	result = usb_sg_init(&us->current_sg, us->pusb_dev, pipe, 0,
			sg, num_sg, length, GFP_NOIO);
	if (result) {
		US_DEBUGP("usb_sg_init returned %d\n", result);
		return USB_STOR_XFER_ERROR;
	}

	/* since the block has been initialized successfully, it's now
	 * okay to cancel it */
	set_bit(US_FLIDX_SG_ACTIVE, &us->dflags);

	/* did an abort occur during the submission? */
	if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {

		/* cancel the request, if it hasn't been cancelled already */
		if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {
			US_DEBUGP("-- cancelling sg request\n");
			usb_sg_cancel(&us->current_sg);
		}
	}

	/* wait for the completion of the transfer */
	usb_sg_wait(&us->current_sg);
	clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags);

	result = us->current_sg.status;
	if (act_len)
		*act_len = us->current_sg.bytes;
	return interpret_urb_result(us, pipe, length, result,
			us->current_sg.bytes);
}

/*
 * Common used function. Transfer a complete command
 * via usb_stor_bulk_transfer_sglist() above. Set cmnd resid
 */
int usb_stor_bulk_srb(struct us_data* us, unsigned int pipe,
		      struct scsi_cmnd* srb)
{
	unsigned int partial;
	int result = usb_stor_bulk_transfer_sglist(us, pipe, scsi_sglist(srb),
				      scsi_sg_count(srb), scsi_bufflen(srb),
				      &partial);

	scsi_set_resid(srb, scsi_bufflen(srb) - partial);
	return result;
}
EXPORT_SYMBOL_GPL(usb_stor_bulk_srb);

/*
 * Transfer an entire SCSI command's worth of data payload over the bulk
 * pipe.
 *
 * Note that this uses usb_stor_bulk_transfer_buf() and
 * usb_stor_bulk_transfer_sglist() to achieve its goals --
 * this function simply determines whether we're going to use
 * scatter-gather or not, and acts appropriately.
 */
int usb_stor_bulk_transfer_sg(struct us_data* us, unsigned int pipe,
		void *buf, unsigned int length_left, int use_sg, int *residual)
{
	int result;
	unsigned int partial;

	/* are we scatter-gathering? */
	if (use_sg) {
		/* use the usb core scatter-gather primitives */
		result = usb_stor_bulk_transfer_sglist(us, pipe,
				(struct scatterlist *) buf, use_sg,
				length_left, &partial);
		length_left -= partial;
	} else {
		/* no scatter-gather, just make the request */
		result = usb_stor_bulk_transfer_buf(us, pipe, buf, 
				length_left, &partial);
		length_left -= partial;
	}

	/* store the residual and return the error code */
	if (residual)
		*residual = length_left;
	return result;
}
EXPORT_SYMBOL_GPL(usb_stor_bulk_transfer_sg);

/***********************************************************************
 * Transport routines
 ***********************************************************************/

/* There are so many devices that report the capacity incorrectly,
 * this routine was written to counteract some of the resulting
 * problems.
 */
static void last_sector_hacks(struct us_data *us, struct scsi_cmnd *srb)
{
	struct gendisk *disk;
	struct scsi_disk *sdkp;
	u32 sector;

	/* To Report "Medium Error: Record Not Found */
	static unsigned char record_not_found[18] = {
		[0]	= 0x70,			/* current error */
		[2]	= MEDIUM_ERROR,		/* = 0x03 */
		[7]	= 0x0a,			/* additional length */
		[12]	= 0x14			/* Record Not Found */
	};

	/* If last-sector problems can't occur, whether because the
	 * capacity was already decremented or because the device is
	 * known to report the correct capacity, then we don't need
	 * to do anything.
	 */
	if (!us->use_last_sector_hacks)
		return;

	/* Was this command a READ(10) or a WRITE(10)? */
	if (srb->cmnd[0] != READ_10 && srb->cmnd[0] != WRITE_10)
		goto done;

	/* Did this command access the last sector? */
	sector = (srb->cmnd[2] << 24) | (srb->cmnd[3] << 16) |
			(srb->cmnd[4] << 8) | (srb->cmnd[5]);
	disk = srb->request->rq_disk;
	if (!disk)
		goto done;
	sdkp = scsi_disk(disk);
	if (!sdkp)
		goto done;
	if (sector + 1 != sdkp->capacity)
		goto done;

	if (srb->result == SAM_STAT_GOOD && scsi_get_resid(srb) == 0) {

		/* The command succeeded.  We know this device doesn't
		 * have the last-sector bug, so stop checking it.
		 */
		us->use_last_sector_hacks = 0;

	} else {
		/* The command failed.  Allow up to 3 retries in case this
		 * is some normal sort of failure.  After that, assume the
		 * capacity is wrong and we're trying to access the sector
		 * beyond the end.  Replace the result code and sense data
		 * with values that will cause the SCSI core to fail the
		 * command immediately, instead of going into an infinite
		 * (or even just a very long) retry loop.
		 */
		if (++us->last_sector_retries < 3)
			return;
		srb->result = SAM_STAT_CHECK_CONDITION;
		memcpy(srb->sense_buffer, record_not_found,
				sizeof(record_not_found));
	}

 done:
	/* Don't reset the retry counter for TEST UNIT READY commands,
	 * because they get issued after device resets which might be
	 * caused by a failed last-sector access.
	 */
	if (srb->cmnd[0] != TEST_UNIT_READY)
		us->last_sector_retries = 0;
}

/* Invoke the transport and basic error-handling/recovery methods
 *
 * This is used by the protocol layers to actually send the message to
 * the device and receive the response.
 */
void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
{
	int need_auto_sense;
	int result;

	/* send the command to the transport layer */
	scsi_set_resid(srb, 0);
	result = us->transport(srb, us);

	/* if the command gets aborted by the higher layers, we need to
	 * short-circuit all other processing
	 */
	if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
		US_DEBUGP("-- command was aborted\n");
		srb->result = DID_ABORT << 16;
		goto Handle_Errors;
	}

	/* if there is a transport error, reset and don't auto-sense */
	if (result == USB_STOR_TRANSPORT_ERROR) {
		US_DEBUGP("-- transport indicates error, resetting\n");
		srb->result = DID_ERROR << 16;
		goto Handle_Errors;
	}

	/* if the transport provided its own sense data, don't auto-sense */
	if (result == USB_STOR_TRANSPORT_NO_SENSE) {
		srb->result = SAM_STAT_CHECK_CONDITION;
		last_sector_hacks(us, srb);
		return;
	}

	srb->result = SAM_STAT_GOOD;

	/* Determine if we need to auto-sense
	 *
	 * I normally don't use a flag like this, but it's almost impossible
	 * to understand what's going on here if I don't.
	 */
	need_auto_sense = 0;

	/*
	 * If we're running the CB transport, which is incapable
	 * of determining status on its own, we will auto-sense
	 * unless the operation involved a data-in transfer.  Devices
	 * can signal most data-in errors by stalling the bulk-in pipe.
	 */
	if ((us->protocol == US_PR_CB || us->protocol == US_PR_DPCM_USB) &&
			srb->sc_data_direction != DMA_FROM_DEVICE) {
		US_DEBUGP("-- CB transport device requiring auto-sense\n");
		need_auto_sense = 1;
	}

	/*
	 * If we have a failure, we're going to do a REQUEST_SENSE 
	 * automatically.  Note that we differentiate between a command
	 * "failure" and an "error" in the transport mechanism.
	 */
	if (result == USB_STOR_TRANSPORT_FAILED) {
		US_DEBUGP("-- transport indicates command failure\n");
		need_auto_sense = 1;
	}

	/*
	 * Determine if this device is SAT by seeing if the
	 * command executed successfully.  Otherwise we'll have
	 * to wait for at least one CHECK_CONDITION to determine
	 * SANE_SENSE support
	 */
	if ((srb->cmnd[0] == ATA_16 || srb->cmnd[0] == ATA_12) &&
	    result == USB_STOR_TRANSPORT_GOOD &&
	    !(us->fflags & US_FL_SANE_SENSE) &&
	    !(srb->cmnd[2] & 0x20)) {
		US_DEBUGP("-- SAT supported, increasing auto-sense\n");
		us->fflags |= US_FL_SANE_SENSE;
	}

	/*
	 * A short transfer on a command where we don't expect it
	 * is unusual, but it doesn't mean we need to auto-sense.
	 */
	if ((scsi_get_resid(srb) > 0) &&
	    !((srb->cmnd[0] == REQUEST_SENSE) ||
	      (srb->cmnd[0] == INQUIRY) ||
	      (srb->cmnd[0] == MODE_SENSE) ||
	      (srb->cmnd[0] == LOG_SENSE) ||
	      (srb->cmnd[0] == MODE_SENSE_10))) {
		US_DEBUGP("-- unexpectedly short transfer\n");
	}

	/* Now, if we need to do the auto-sense, let's do it */
	if (need_auto_sense) {
		int temp_result;
		struct scsi_eh_save ses;
		int sense_size = US_SENSE_SIZE;

		/* device supports and needs bigger sense buffer */
		if (us->fflags & US_FL_SANE_SENSE)
			sense_size = ~0;

		US_DEBUGP("Issuing auto-REQUEST_SENSE\n");

		scsi_eh_prep_cmnd(srb, &ses, NULL, 0, sense_size);

		/* FIXME: we must do the protocol translation here */
		if (us->subclass == US_SC_RBC || us->subclass == US_SC_SCSI ||
				us->subclass == US_SC_CYP_ATACB)
			srb->cmd_len = 6;
		else
			srb->cmd_len = 12;

		/* issue the auto-sense command */
		scsi_set_resid(srb, 0);
		temp_result = us->transport(us->srb, us);

		/* let's clean up right away */
		scsi_eh_restore_cmnd(srb, &ses);

		if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
			US_DEBUGP("-- auto-sense aborted\n");
			srb->result = DID_ABORT << 16;
			goto Handle_Errors;
		}
		if (temp_result != USB_STOR_TRANSPORT_GOOD) {
			US_DEBUGP("-- auto-sense failure\n");

			/* we skip the reset if this happens to be a
			 * multi-target device, since failure of an
			 * auto-sense is perfectly valid
			 */
			srb->result = DID_ERROR << 16;
			if (!(us->fflags & US_FL_SCM_MULT_TARG))
				goto Handle_Errors;
			return;
		}

		/* If the sense data returned is larger than 18-bytes then we
		 * assume this device supports requesting more in the future.
		 * The response code must be 70h through 73h inclusive.
		 */
		if (srb->sense_buffer[7] > (US_SENSE_SIZE - 8) &&
		    !(us->fflags & US_FL_SANE_SENSE) &&
		    (srb->sense_buffer[0] & 0x7C) == 0x70) {
			US_DEBUGP("-- SANE_SENSE support enabled\n");
			us->fflags |= US_FL_SANE_SENSE;

			/* Indicate to the user that we truncated their sense
			 * because we didn't know it supported larger sense.
			 */
			US_DEBUGP("-- Sense data truncated to %i from %i\n",
			          US_SENSE_SIZE,
			          srb->sense_buffer[7] + 8);
			srb->sense_buffer[7] = (US_SENSE_SIZE - 8);
		}

		US_DEBUGP("-- Result from auto-sense is %d\n", temp_result);
		US_DEBUGP("-- code: 0x%x, key: 0x%x, ASC: 0x%x, ASCQ: 0x%x\n",
			  srb->sense_buffer[0],
			  srb->sense_buffer[2] & 0xf,
			  srb->sense_buffer[12], 
			  srb->sense_buffer[13]);
#ifdef CONFIG_USB_STORAGE_DEBUG
		usb_stor_show_sense(
			  srb->sense_buffer[2] & 0xf,
			  srb->sense_buffer[12], 
			  srb->sense_buffer[13]);
#endif

		/* set the result so the higher layers expect this data */
		srb->result = SAM_STAT_CHECK_CONDITION;

		/* If things are really okay, then let's show that.  Zero
		 * out the sense buffer so the higher layers won't realize
		 * we did an unsolicited auto-sense. */
		if (result == USB_STOR_TRANSPORT_GOOD &&
			/* Filemark 0, ignore EOM, ILI 0, no sense */
				(srb->sense_buffer[2] & 0xaf) == 0 &&
			/* No ASC or ASCQ */
				srb->sense_buffer[12] == 0 &&
				srb->sense_buffer[13] == 0) {
			srb->result = SAM_STAT_GOOD;
			srb->sense_buffer[0] = 0x0;
		}
	}

	/* Did we transfer less than the minimum amount required? */
	if ((srb->result == SAM_STAT_GOOD || srb->sense_buffer[2] == 0) &&
			scsi_bufflen(srb) - scsi_get_resid(srb) < srb->underflow)
		srb->result = DID_ERROR << 16;

	last_sector_hacks(us, srb);
	return;

	/* Error and abort processing: try to resynchronize with the device
	 * by issuing a port reset.  If that fails, try a class-specific
	 * device reset. */
  Handle_Errors:

	/* Set the RESETTING bit, and clear the ABORTING bit so that
	 * the reset may proceed. */
	scsi_lock(us_to_host(us));
	set_bit(US_FLIDX_RESETTING, &us->dflags);
	clear_bit(US_FLIDX_ABORTING, &us->dflags);
	scsi_unlock(us_to_host(us));

	/* We must release the device lock because the pre_reset routine
	 * will want to acquire it. */
	mutex_unlock(&us->dev_mutex);
	result = usb_stor_port_reset(us);
	mutex_lock(&us->dev_mutex);

	if (result < 0) {
		scsi_lock(us_to_host(us));
		usb_stor_report_device_reset(us);
		scsi_unlock(us_to_host(us));
		us->transport_reset(us);
	}
	clear_bit(US_FLIDX_RESETTING, &us->dflags);
	last_sector_hacks(us, srb);
}

/* Stop the current URB transfer */
void usb_stor_stop_transport(struct us_data *us)
{
	US_DEBUGP("%s called\n", __func__);

	/* If the state machine is blocked waiting for an URB,
	 * let's wake it up.  The test_and_clear_bit() call
	 * guarantees that if a URB has just been submitted,
	 * it won't be cancelled more than once. */
	if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
		US_DEBUGP("-- cancelling URB\n");
		usb_unlink_urb(us->current_urb);
	}

	/* If we are waiting for a scatter-gather operation, cancel it. */
	if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {
		US_DEBUGP("-- cancelling sg request\n");
		usb_sg_cancel(&us->current_sg);
	}
}

/*
 * Control/Bulk and Control/Bulk/Interrupt transport
 */

int usb_stor_CB_transport(struct scsi_cmnd *srb, struct us_data *us)
{
	unsigned int transfer_length = scsi_bufflen(srb);
	unsigned int pipe = 0;
	int result;

	/* COMMAND STAGE */
	/* let's send the command via the control pipe */
	result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
				      US_CBI_ADSC, 
				      USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0, 
				      us->ifnum, srb->cmnd, srb->cmd_len);

	/* check the return code for the command */
	US_DEBUGP("Call to usb_stor_ctrl_transfer() returned %d\n", result);

	/* if we stalled the command, it means command failed */
	if (result == USB_STOR_XFER_STALLED) {
		return USB_STOR_TRANSPORT_FAILED;
	}

	/* Uh oh... serious problem here */
	if (result != USB_STOR_XFER_GOOD) {
		return USB_STOR_TRANSPORT_ERROR;
	}

	/* DATA STAGE */
	/* transfer the data payload for this command, if one exists*/
	if (transfer_length) {
		pipe = srb->sc_data_direction == DMA_FROM_DEVICE ? 
				us->recv_bulk_pipe : us->send_bulk_pipe;
		result = usb_stor_bulk_srb(us, pipe, srb);
		US_DEBUGP("CBI data stage result is 0x%x\n", result);

		/* if we stalled the data transfer it means command failed */
		if (result == USB_STOR_XFER_STALLED)
			return USB_STOR_TRANSPORT_FAILED;
		if (result > USB_STOR_XFER_STALLED)
			return USB_STOR_TRANSPORT_ERROR;
	}

	/* STATUS STAGE */

	/* NOTE: CB does not have a status stage.  Silly, I know.  So
	 * we have to catch this at a higher level.
	 */
	if (us->protocol != US_PR_CBI)
		return USB_STOR_TRANSPORT_GOOD;

	result = usb_stor_intr_transfer(us, us->iobuf, 2);
	US_DEBUGP("Got interrupt data (0x%x, 0x%x)\n", 
			us->iobuf[0], us->iobuf[1]);
	if (result != USB_STOR_XFER_GOOD)
		return USB_STOR_TRANSPORT_ERROR;

	/* UFI gives us ASC and ASCQ, like a request sense
	 *
	 * REQUEST_SENSE and INQUIRY don't affect the sense data on UFI
	 * devices, so we ignore the information for those commands.  Note
	 * that this means we could be ignoring a real error on these
	 * commands, but that can't be helped.
	 */
	if (us->subclass == US_SC_UFI) {
		if (srb->cmnd[0] == REQUEST_SENSE ||
		    srb->cmnd[0] == INQUIRY)
			return USB_STOR_TRANSPORT_GOOD;
		if (us->iobuf[0])
			goto Failed;
		return USB_STOR_TRANSPORT_GOOD;
	}

	/* If not UFI, we interpret the data as a result code 
	 * The first byte should always be a 0x0.
	 *
	 * Some bogus devices don't follow that rule.  They stuff the ASC
	 * into the first byte -- so if it's non-zero, call it a failure.
	 */
	if (us->iobuf[0]) {
		US_DEBUGP("CBI IRQ data showed reserved bType 0x%x\n",
				us->iobuf[0]);
		goto Failed;

	}

	/* The second byte & 0x0F should be 0x0 for good, otherwise error */
	switch (us->iobuf[1] & 0x0F) {
		case 0x00: 
			return USB_STOR_TRANSPORT_GOOD;
		case 0x01: 
			goto Failed;
	}
	return USB_STOR_TRANSPORT_ERROR;

	/* the CBI spec requires that the bulk pipe must be cleared
	 * following any data-in/out command failure (section 2.4.3.1.3)
	 */
  Failed:
	if (pipe)
		usb_stor_clear_halt(us, pipe);
	return USB_STOR_TRANSPORT_FAILED;
}
EXPORT_SYMBOL_GPL(usb_stor_CB_transport);

/*
 * Bulk only transport
 */

/* Determine what the maximum LUN supported is */
int usb_stor_Bulk_max_lun(struct us_data *us)
{
	int result;

	/* issue the command */
	us->iobuf[0] = 0;
	result = usb_stor_control_msg(us, us->recv_ctrl_pipe,
				 US_BULK_GET_MAX_LUN, 
				 USB_DIR_IN | USB_TYPE_CLASS | 
				 USB_RECIP_INTERFACE,
				 0, us->ifnum, us->iobuf, 1, 10*HZ);

	US_DEBUGP("GetMaxLUN command result is %d, data is %d\n", 
		  result, us->iobuf[0]);

	/* if we have a successful request, return the result */
	if (result > 0)
		return us->iobuf[0];

	/*
	 * Some devices don't like GetMaxLUN.  They may STALL the control
	 * pipe, they may return a zero-length result, they may do nothing at
	 * all and timeout, or they may fail in even more bizarrely creative
	 * ways.  In these cases the best approach is to use the default
	 * value: only one LUN.
	 */
	return 0;
}

int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us)
{
	struct bulk_cb_wrap *bcb = (struct bulk_cb_wrap *) us->iobuf;
	struct bulk_cs_wrap *bcs = (struct bulk_cs_wrap *) us->iobuf;
	unsigned int transfer_length = scsi_bufflen(srb);
	unsigned int residue;
	int result;
	int fake_sense = 0;
	unsigned int cswlen;
	unsigned int cbwlen = US_BULK_CB_WRAP_LEN;

	/* Take care of BULK32 devices; set extra byte to 0 */
	if (unlikely(us->fflags & US_FL_BULK32)) {
		cbwlen = 32;
		us->iobuf[31] = 0;
	}

	/* set up the command wrapper */
	bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
	bcb->DataTransferLength = cpu_to_le32(transfer_length);
	bcb->Flags = srb->sc_data_direction == DMA_FROM_DEVICE ? 1 << 7 : 0;
	bcb->Tag = ++us->tag;
	bcb->Lun = srb->device->lun;
	if (us->fflags & US_FL_SCM_MULT_TARG)
		bcb->Lun |= srb->device->id << 4;
	bcb->Length = srb->cmd_len;

	/* copy the command payload */
	memset(bcb->CDB, 0, sizeof(bcb->CDB));
	memcpy(bcb->CDB, srb->cmnd, bcb->Length);

	/* send it to out endpoint */
	US_DEBUGP("Bulk Command S 0x%x T 0x%x L %d F %d Trg %d LUN %d CL %d\n",
			le32_to_cpu(bcb->Signature), bcb->Tag,
			le32_to_cpu(bcb->DataTransferLength), bcb->Flags,
			(bcb->Lun >> 4), (bcb->Lun & 0x0F), 
			bcb->Length);
	result = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
				bcb, cbwlen, NULL);
	US_DEBUGP("Bulk command transfer result=%d\n", result);
	if (result != USB_STOR_XFER_GOOD)
		return USB_STOR_TRANSPORT_ERROR;

	/* DATA STAGE */
	/* send/receive data payload, if there is any */

	/* Some USB-IDE converter chips need a 100us delay between the
	 * command phase and the data phase.  Some devices need a little
	 * more than that, probably because of clock rate inaccuracies. */
	if (unlikely(us->fflags & US_FL_GO_SLOW))
		udelay(125);

	if (transfer_length) {
		unsigned int pipe = srb->sc_data_direction == DMA_FROM_DEVICE ? 
				us->recv_bulk_pipe : us->send_bulk_pipe;
		result = usb_stor_bulk_srb(us, pipe, srb);
		US_DEBUGP("Bulk data transfer result 0x%x\n", result);
		if (result == USB_STOR_XFER_ERROR)
			return USB_STOR_TRANSPORT_ERROR;

		/* If the device tried to send back more data than the
		 * amount requested, the spec requires us to transfer
		 * the CSW anyway.  Since there's no point retrying the
		 * the command, we'll return fake sense data indicating
		 * Illegal Request, Invalid Field in CDB.
		 */
		if (result == USB_STOR_XFER_LONG)
			fake_sense = 1;
	}

	/* See flow chart on pg 15 of the Bulk Only Transport spec for
	 * an explanation of how this code works.
	 */

	/* get CSW for device status */
	US_DEBUGP("Attempting to get CSW...\n");
	result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
				bcs, US_BULK_CS_WRAP_LEN, &cswlen);

	/* Some broken devices add unnecessary zero-length packets to the
	 * end of their data transfers.  Such packets show up as 0-length
	 * CSWs.  If we encounter such a thing, try to read the CSW again.
	 */
	if (result == USB_STOR_XFER_SHORT && cswlen == 0) {
		US_DEBUGP("Received 0-length CSW; retrying...\n");
		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
				bcs, US_BULK_CS_WRAP_LEN, &cswlen);
	}

	/* did the attempt to read the CSW fail? */
	if (result == USB_STOR_XFER_STALLED) {

		/* get the status again */
		US_DEBUGP("Attempting to get CSW (2nd try)...\n");
		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
				bcs, US_BULK_CS_WRAP_LEN, NULL);
	}

	/* if we still have a failure at this point, we're in trouble */
	US_DEBUGP("Bulk status result = %d\n", result);
	if (result != USB_STOR_XFER_GOOD)
		return USB_STOR_TRANSPORT_ERROR;

	/* check bulk status */
	residue = le32_to_cpu(bcs->Residue);
	US_DEBUGP("Bulk Status S 0x%x T 0x%x R %u Stat 0x%x\n",
			le32_to_cpu(bcs->Signature), bcs->Tag, 
			residue, bcs->Status);
	if (!(bcs->Tag == us->tag || (us->fflags & US_FL_BULK_IGNORE_TAG)) ||
		bcs->Status > US_BULK_STAT_PHASE) {
		US_DEBUGP("Bulk logical error\n");
		return USB_STOR_TRANSPORT_ERROR;
	}

	/* Some broken devices report odd signatures, so we do not check them
	 * for validity against the spec. We store the first one we see,
	 * and check subsequent transfers for validity against this signature.
	 */
	if (!us->bcs_signature) {
		us->bcs_signature = bcs->Signature;
		if (us->bcs_signature != cpu_to_le32(US_BULK_CS_SIGN))
			US_DEBUGP("Learnt BCS signature 0x%08X\n",
					le32_to_cpu(us->bcs_signature));
	} else if (bcs->Signature != us->bcs_signature) {
		US_DEBUGP("Signature mismatch: got %08X, expecting %08X\n",
			  le32_to_cpu(bcs->Signature),
			  le32_to_cpu(us->bcs_signature));
		return USB_STOR_TRANSPORT_ERROR;
	}

	/* try to compute the actual residue, based on how much data
	 * was really transferred and what the device tells us */
	if (residue && !(us->fflags & US_FL_IGNORE_RESIDUE)) {

		/* Heuristically detect devices that generate bogus residues
		 * by seeing what happens with INQUIRY and READ CAPACITY
		 * commands.
		 */
		if (bcs->Status == US_BULK_STAT_OK &&
				scsi_get_resid(srb) == 0 &&
					((srb->cmnd[0] == INQUIRY &&
						transfer_length == 36) ||
					(srb->cmnd[0] == READ_CAPACITY &&
						transfer_length == 8))) {
			us->fflags |= US_FL_IGNORE_RESIDUE;

		} else {
			residue = min(residue, transfer_length);
			scsi_set_resid(srb, max(scsi_get_resid(srb),
			                                       (int) residue));
		}
	}

	/* based on the status code, we report good or bad */
	switch (bcs->Status) {
		case US_BULK_STAT_OK:
			/* device babbled -- return fake sense data */
			if (fake_sense) {
				memcpy(srb->sense_buffer, 
				       usb_stor_sense_invalidCDB, 
				       sizeof(usb_stor_sense_invalidCDB));
				return USB_STOR_TRANSPORT_NO_SENSE;
			}

			/* command good -- note that data could be short */
			return USB_STOR_TRANSPORT_GOOD;

		case US_BULK_STAT_FAIL:
			/* command failed */
			return USB_STOR_TRANSPORT_FAILED;

		case US_BULK_STAT_PHASE:
			/* phase error -- note that a transport reset will be
			 * invoked by the invoke_transport() function
			 */
			return USB_STOR_TRANSPORT_ERROR;
	}

	/* we should never get here, but if we do, we're in trouble */
	return USB_STOR_TRANSPORT_ERROR;
}
EXPORT_SYMBOL_GPL(usb_stor_Bulk_transport);

/***********************************************************************
 * Reset routines
 ***********************************************************************/

/* This is the common part of the device reset code.
 *
 * It's handy that every transport mechanism uses the control endpoint for
 * resets.
 *
 * Basically, we send a reset with a 5-second timeout, so we don't get
 * jammed attempting to do the reset.
 */
static int usb_stor_reset_common(struct us_data *us,
		u8 request, u8 requesttype,
		u16 value, u16 index, void *data, u16 size)
{
	int result;
	int result2;

	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
		US_DEBUGP("No reset during disconnect\n");
		return -EIO;
	}

	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
			request, requesttype, value, index, data, size,
			5*HZ);
	if (result < 0) {
		US_DEBUGP("Soft reset failed: %d\n", result);
		return result;
	}

	/* Give the device some time to recover from the reset,
	 * but don't delay disconnect processing. */
	wait_event_interruptible_timeout(us->delay_wait,
			test_bit(US_FLIDX_DISCONNECTING, &us->dflags),
			HZ*6);
	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
		US_DEBUGP("Reset interrupted by disconnect\n");
		return -EIO;
	}

	US_DEBUGP("Soft reset: clearing bulk-in endpoint halt\n");
	result = usb_stor_clear_halt(us, us->recv_bulk_pipe);

	US_DEBUGP("Soft reset: clearing bulk-out endpoint halt\n");
	result2 = usb_stor_clear_halt(us, us->send_bulk_pipe);

	/* return a result code based on the result of the clear-halts */
	if (result >= 0)
		result = result2;
	if (result < 0)
		US_DEBUGP("Soft reset failed\n");
	else
		US_DEBUGP("Soft reset done\n");
	return result;
}

/* This issues a CB[I] Reset to the device in question
 */
#define CB_RESET_CMD_SIZE	12

int usb_stor_CB_reset(struct us_data *us)
{
	US_DEBUGP("%s called\n", __func__);

	memset(us->iobuf, 0xFF, CB_RESET_CMD_SIZE);
	us->iobuf[0] = SEND_DIAGNOSTIC;
	us->iobuf[1] = 4;
	return usb_stor_reset_common(us, US_CBI_ADSC, 
				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
				 0, us->ifnum, us->iobuf, CB_RESET_CMD_SIZE);
}
EXPORT_SYMBOL_GPL(usb_stor_CB_reset);

/* This issues a Bulk-only Reset to the device in question, including
 * clearing the subsequent endpoint halts that may occur.
 */
int usb_stor_Bulk_reset(struct us_data *us)
{
	US_DEBUGP("%s called\n", __func__);

	return usb_stor_reset_common(us, US_BULK_RESET_REQUEST, 
				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
				 0, us->ifnum, NULL, 0);
}
EXPORT_SYMBOL_GPL(usb_stor_Bulk_reset);

/* Issue a USB port reset to the device.  The caller must not hold
 * us->dev_mutex.
 */
int usb_stor_port_reset(struct us_data *us)
{
	int result;

	result = usb_lock_device_for_reset(us->pusb_dev, us->pusb_intf);
	if (result < 0)
		US_DEBUGP("unable to lock device for reset: %d\n", result);
	else {
		/* Were we disconnected while waiting for the lock? */
		if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
			result = -EIO;
			US_DEBUGP("No reset during disconnect\n");
		} else {
			result = usb_reset_device(us->pusb_dev);
			US_DEBUGP("usb_reset_device returns %d\n",
					result);
		}
		usb_unlock_device(us->pusb_dev);
	}
	return result;
}