xref: /openbmc/linux/drivers/usb/storage/transport.c (revision bc5aa3a0)
1 /*
2  * Driver for USB Mass Storage compliant devices
3  *
4  * Current development and maintenance by:
5  *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
6  *
7  * Developed with the assistance of:
8  *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
9  *   (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
10  *   (c) 2002 Alan Stern <stern@rowland.org>
11  *
12  * Initial work by:
13  *   (c) 1999 Michael Gee (michael@linuxspecific.com)
14  *
15  * This driver is based on the 'USB Mass Storage Class' document. This
16  * describes in detail the protocol used to communicate with such
17  * devices.  Clearly, the designers had SCSI and ATAPI commands in
18  * mind when they created this document.  The commands are all very
19  * similar to commands in the SCSI-II and ATAPI specifications.
20  *
21  * It is important to note that in a number of cases this class
22  * exhibits class-specific exemptions from the USB specification.
23  * Notably the usage of NAK, STALL and ACK differs from the norm, in
24  * that they are used to communicate wait, failed and OK on commands.
25  *
26  * Also, for certain devices, the interrupt endpoint is used to convey
27  * status of a command.
28  *
29  * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
30  * information about this driver.
31  *
32  * This program is free software; you can redistribute it and/or modify it
33  * under the terms of the GNU General Public License as published by the
34  * Free Software Foundation; either version 2, or (at your option) any
35  * later version.
36  *
37  * This program is distributed in the hope that it will be useful, but
38  * WITHOUT ANY WARRANTY; without even the implied warranty of
39  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
40  * General Public License for more details.
41  *
42  * You should have received a copy of the GNU General Public License along
43  * with this program; if not, write to the Free Software Foundation, Inc.,
44  * 675 Mass Ave, Cambridge, MA 02139, USA.
45  */
46 
47 #include <linux/sched.h>
48 #include <linux/gfp.h>
49 #include <linux/errno.h>
50 #include <linux/export.h>
51 
52 #include <linux/usb/quirks.h>
53 
54 #include <scsi/scsi.h>
55 #include <scsi/scsi_eh.h>
56 #include <scsi/scsi_device.h>
57 
58 #include "usb.h"
59 #include "transport.h"
60 #include "protocol.h"
61 #include "scsiglue.h"
62 #include "debug.h"
63 
64 #include <linux/blkdev.h>
65 #include "../../scsi/sd.h"
66 
67 
68 /***********************************************************************
69  * Data transfer routines
70  ***********************************************************************/
71 
72 /*
73  * This is subtle, so pay attention:
74  * ---------------------------------
75  * We're very concerned about races with a command abort.  Hanging this code
76  * is a sure fire way to hang the kernel.  (Note that this discussion applies
77  * only to transactions resulting from a scsi queued-command, since only
78  * these transactions are subject to a scsi abort.  Other transactions, such
79  * as those occurring during device-specific initialization, must be handled
80  * by a separate code path.)
81  *
82  * The abort function (usb_storage_command_abort() in scsiglue.c) first
83  * sets the machine state and the ABORTING bit in us->dflags to prevent
84  * new URBs from being submitted.  It then calls usb_stor_stop_transport()
85  * below, which atomically tests-and-clears the URB_ACTIVE bit in us->dflags
86  * to see if the current_urb needs to be stopped.  Likewise, the SG_ACTIVE
87  * bit is tested to see if the current_sg scatter-gather request needs to be
88  * stopped.  The timeout callback routine does much the same thing.
89  *
90  * When a disconnect occurs, the DISCONNECTING bit in us->dflags is set to
91  * prevent new URBs from being submitted, and usb_stor_stop_transport() is
92  * called to stop any ongoing requests.
93  *
94  * The submit function first verifies that the submitting is allowed
95  * (neither ABORTING nor DISCONNECTING bits are set) and that the submit
96  * completes without errors, and only then sets the URB_ACTIVE bit.  This
97  * prevents the stop_transport() function from trying to cancel the URB
98  * while the submit call is underway.  Next, the submit function must test
99  * the flags to see if an abort or disconnect occurred during the submission
100  * or before the URB_ACTIVE bit was set.  If so, it's essential to cancel
101  * the URB if it hasn't been cancelled already (i.e., if the URB_ACTIVE bit
102  * is still set).  Either way, the function must then wait for the URB to
103  * finish.  Note that the URB can still be in progress even after a call to
104  * usb_unlink_urb() returns.
105  *
106  * The idea is that (1) once the ABORTING or DISCONNECTING bit is set,
107  * either the stop_transport() function or the submitting function
108  * is guaranteed to call usb_unlink_urb() for an active URB,
109  * and (2) test_and_clear_bit() prevents usb_unlink_urb() from being
110  * called more than once or from being called during usb_submit_urb().
111  */
112 
113 /*
114  * This is the completion handler which will wake us up when an URB
115  * completes.
116  */
117 static void usb_stor_blocking_completion(struct urb *urb)
118 {
119 	struct completion *urb_done_ptr = urb->context;
120 
121 	complete(urb_done_ptr);
122 }
123 
124 /*
125  * This is the common part of the URB message submission code
126  *
127  * All URBs from the usb-storage driver involved in handling a queued scsi
128  * command _must_ pass through this function (or something like it) for the
129  * abort mechanisms to work properly.
130  */
131 static int usb_stor_msg_common(struct us_data *us, int timeout)
132 {
133 	struct completion urb_done;
134 	long timeleft;
135 	int status;
136 
137 	/* don't submit URBs during abort processing */
138 	if (test_bit(US_FLIDX_ABORTING, &us->dflags))
139 		return -EIO;
140 
141 	/* set up data structures for the wakeup system */
142 	init_completion(&urb_done);
143 
144 	/* fill the common fields in the URB */
145 	us->current_urb->context = &urb_done;
146 	us->current_urb->transfer_flags = 0;
147 
148 	/*
149 	 * we assume that if transfer_buffer isn't us->iobuf then it
150 	 * hasn't been mapped for DMA.  Yes, this is clunky, but it's
151 	 * easier than always having the caller tell us whether the
152 	 * transfer buffer has already been mapped.
153 	 */
154 	if (us->current_urb->transfer_buffer == us->iobuf)
155 		us->current_urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
156 	us->current_urb->transfer_dma = us->iobuf_dma;
157 
158 	/* submit the URB */
159 	status = usb_submit_urb(us->current_urb, GFP_NOIO);
160 	if (status) {
161 		/* something went wrong */
162 		return status;
163 	}
164 
165 	/*
166 	 * since the URB has been submitted successfully, it's now okay
167 	 * to cancel it
168 	 */
169 	set_bit(US_FLIDX_URB_ACTIVE, &us->dflags);
170 
171 	/* did an abort occur during the submission? */
172 	if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {
173 
174 		/* cancel the URB, if it hasn't been cancelled already */
175 		if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
176 			usb_stor_dbg(us, "-- cancelling URB\n");
177 			usb_unlink_urb(us->current_urb);
178 		}
179 	}
180 
181 	/* wait for the completion of the URB */
182 	timeleft = wait_for_completion_interruptible_timeout(
183 			&urb_done, timeout ? : MAX_SCHEDULE_TIMEOUT);
184 
185 	clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags);
186 
187 	if (timeleft <= 0) {
188 		usb_stor_dbg(us, "%s -- cancelling URB\n",
189 			     timeleft == 0 ? "Timeout" : "Signal");
190 		usb_kill_urb(us->current_urb);
191 	}
192 
193 	/* return the URB status */
194 	return us->current_urb->status;
195 }
196 
197 /*
198  * Transfer one control message, with timeouts, and allowing early
199  * termination.  Return codes are usual -Exxx, *not* USB_STOR_XFER_xxx.
200  */
201 int usb_stor_control_msg(struct us_data *us, unsigned int pipe,
202 		 u8 request, u8 requesttype, u16 value, u16 index,
203 		 void *data, u16 size, int timeout)
204 {
205 	int status;
206 
207 	usb_stor_dbg(us, "rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
208 		     request, requesttype, value, index, size);
209 
210 	/* fill in the devrequest structure */
211 	us->cr->bRequestType = requesttype;
212 	us->cr->bRequest = request;
213 	us->cr->wValue = cpu_to_le16(value);
214 	us->cr->wIndex = cpu_to_le16(index);
215 	us->cr->wLength = cpu_to_le16(size);
216 
217 	/* fill and submit the URB */
218 	usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe,
219 			 (unsigned char*) us->cr, data, size,
220 			 usb_stor_blocking_completion, NULL);
221 	status = usb_stor_msg_common(us, timeout);
222 
223 	/* return the actual length of the data transferred if no error */
224 	if (status == 0)
225 		status = us->current_urb->actual_length;
226 	return status;
227 }
228 EXPORT_SYMBOL_GPL(usb_stor_control_msg);
229 
230 /*
231  * This is a version of usb_clear_halt() that allows early termination and
232  * doesn't read the status from the device -- this is because some devices
233  * crash their internal firmware when the status is requested after a halt.
234  *
235  * A definitive list of these 'bad' devices is too difficult to maintain or
236  * make complete enough to be useful.  This problem was first observed on the
237  * Hagiwara FlashGate DUAL unit.  However, bus traces reveal that neither
238  * MacOS nor Windows checks the status after clearing a halt.
239  *
240  * Since many vendors in this space limit their testing to interoperability
241  * with these two OSes, specification violations like this one are common.
242  */
243 int usb_stor_clear_halt(struct us_data *us, unsigned int pipe)
244 {
245 	int result;
246 	int endp = usb_pipeendpoint(pipe);
247 
248 	if (usb_pipein (pipe))
249 		endp |= USB_DIR_IN;
250 
251 	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
252 		USB_REQ_CLEAR_FEATURE, USB_RECIP_ENDPOINT,
253 		USB_ENDPOINT_HALT, endp,
254 		NULL, 0, 3*HZ);
255 
256 	if (result >= 0)
257 		usb_reset_endpoint(us->pusb_dev, endp);
258 
259 	usb_stor_dbg(us, "result = %d\n", result);
260 	return result;
261 }
262 EXPORT_SYMBOL_GPL(usb_stor_clear_halt);
263 
264 
265 /*
266  * Interpret the results of a URB transfer
267  *
268  * This function prints appropriate debugging messages, clears halts on
269  * non-control endpoints, and translates the status to the corresponding
270  * USB_STOR_XFER_xxx return code.
271  */
272 static int interpret_urb_result(struct us_data *us, unsigned int pipe,
273 		unsigned int length, int result, unsigned int partial)
274 {
275 	usb_stor_dbg(us, "Status code %d; transferred %u/%u\n",
276 		     result, partial, length);
277 	switch (result) {
278 
279 	/* no error code; did we send all the data? */
280 	case 0:
281 		if (partial != length) {
282 			usb_stor_dbg(us, "-- short transfer\n");
283 			return USB_STOR_XFER_SHORT;
284 		}
285 
286 		usb_stor_dbg(us, "-- transfer complete\n");
287 		return USB_STOR_XFER_GOOD;
288 
289 	/* stalled */
290 	case -EPIPE:
291 		/*
292 		 * for control endpoints, (used by CB[I]) a stall indicates
293 		 * a failed command
294 		 */
295 		if (usb_pipecontrol(pipe)) {
296 			usb_stor_dbg(us, "-- stall on control pipe\n");
297 			return USB_STOR_XFER_STALLED;
298 		}
299 
300 		/* for other sorts of endpoint, clear the stall */
301 		usb_stor_dbg(us, "clearing endpoint halt for pipe 0x%x\n",
302 			     pipe);
303 		if (usb_stor_clear_halt(us, pipe) < 0)
304 			return USB_STOR_XFER_ERROR;
305 		return USB_STOR_XFER_STALLED;
306 
307 	/* babble - the device tried to send more than we wanted to read */
308 	case -EOVERFLOW:
309 		usb_stor_dbg(us, "-- babble\n");
310 		return USB_STOR_XFER_LONG;
311 
312 	/* the transfer was cancelled by abort, disconnect, or timeout */
313 	case -ECONNRESET:
314 		usb_stor_dbg(us, "-- transfer cancelled\n");
315 		return USB_STOR_XFER_ERROR;
316 
317 	/* short scatter-gather read transfer */
318 	case -EREMOTEIO:
319 		usb_stor_dbg(us, "-- short read transfer\n");
320 		return USB_STOR_XFER_SHORT;
321 
322 	/* abort or disconnect in progress */
323 	case -EIO:
324 		usb_stor_dbg(us, "-- abort or disconnect in progress\n");
325 		return USB_STOR_XFER_ERROR;
326 
327 	/* the catch-all error case */
328 	default:
329 		usb_stor_dbg(us, "-- unknown error\n");
330 		return USB_STOR_XFER_ERROR;
331 	}
332 }
333 
334 /*
335  * Transfer one control message, without timeouts, but allowing early
336  * termination.  Return codes are USB_STOR_XFER_xxx.
337  */
338 int usb_stor_ctrl_transfer(struct us_data *us, unsigned int pipe,
339 		u8 request, u8 requesttype, u16 value, u16 index,
340 		void *data, u16 size)
341 {
342 	int result;
343 
344 	usb_stor_dbg(us, "rq=%02x rqtype=%02x value=%04x index=%02x len=%u\n",
345 		     request, requesttype, value, index, size);
346 
347 	/* fill in the devrequest structure */
348 	us->cr->bRequestType = requesttype;
349 	us->cr->bRequest = request;
350 	us->cr->wValue = cpu_to_le16(value);
351 	us->cr->wIndex = cpu_to_le16(index);
352 	us->cr->wLength = cpu_to_le16(size);
353 
354 	/* fill and submit the URB */
355 	usb_fill_control_urb(us->current_urb, us->pusb_dev, pipe,
356 			 (unsigned char*) us->cr, data, size,
357 			 usb_stor_blocking_completion, NULL);
358 	result = usb_stor_msg_common(us, 0);
359 
360 	return interpret_urb_result(us, pipe, size, result,
361 			us->current_urb->actual_length);
362 }
363 EXPORT_SYMBOL_GPL(usb_stor_ctrl_transfer);
364 
365 /*
366  * Receive one interrupt buffer, without timeouts, but allowing early
367  * termination.  Return codes are USB_STOR_XFER_xxx.
368  *
369  * This routine always uses us->recv_intr_pipe as the pipe and
370  * us->ep_bInterval as the interrupt interval.
371  */
372 static int usb_stor_intr_transfer(struct us_data *us, void *buf,
373 				  unsigned int length)
374 {
375 	int result;
376 	unsigned int pipe = us->recv_intr_pipe;
377 	unsigned int maxp;
378 
379 	usb_stor_dbg(us, "xfer %u bytes\n", length);
380 
381 	/* calculate the max packet size */
382 	maxp = usb_maxpacket(us->pusb_dev, pipe, usb_pipeout(pipe));
383 	if (maxp > length)
384 		maxp = length;
385 
386 	/* fill and submit the URB */
387 	usb_fill_int_urb(us->current_urb, us->pusb_dev, pipe, buf,
388 			maxp, usb_stor_blocking_completion, NULL,
389 			us->ep_bInterval);
390 	result = usb_stor_msg_common(us, 0);
391 
392 	return interpret_urb_result(us, pipe, length, result,
393 			us->current_urb->actual_length);
394 }
395 
396 /*
397  * Transfer one buffer via bulk pipe, without timeouts, but allowing early
398  * termination.  Return codes are USB_STOR_XFER_xxx.  If the bulk pipe
399  * stalls during the transfer, the halt is automatically cleared.
400  */
401 int usb_stor_bulk_transfer_buf(struct us_data *us, unsigned int pipe,
402 	void *buf, unsigned int length, unsigned int *act_len)
403 {
404 	int result;
405 
406 	usb_stor_dbg(us, "xfer %u bytes\n", length);
407 
408 	/* fill and submit the URB */
409 	usb_fill_bulk_urb(us->current_urb, us->pusb_dev, pipe, buf, length,
410 		      usb_stor_blocking_completion, NULL);
411 	result = usb_stor_msg_common(us, 0);
412 
413 	/* store the actual length of the data transferred */
414 	if (act_len)
415 		*act_len = us->current_urb->actual_length;
416 	return interpret_urb_result(us, pipe, length, result,
417 			us->current_urb->actual_length);
418 }
419 EXPORT_SYMBOL_GPL(usb_stor_bulk_transfer_buf);
420 
421 /*
422  * Transfer a scatter-gather list via bulk transfer
423  *
424  * This function does basically the same thing as usb_stor_bulk_transfer_buf()
425  * above, but it uses the usbcore scatter-gather library.
426  */
427 static int usb_stor_bulk_transfer_sglist(struct us_data *us, unsigned int pipe,
428 		struct scatterlist *sg, int num_sg, unsigned int length,
429 		unsigned int *act_len)
430 {
431 	int result;
432 
433 	/* don't submit s-g requests during abort processing */
434 	if (test_bit(US_FLIDX_ABORTING, &us->dflags))
435 		return USB_STOR_XFER_ERROR;
436 
437 	/* initialize the scatter-gather request block */
438 	usb_stor_dbg(us, "xfer %u bytes, %d entries\n", length, num_sg);
439 	result = usb_sg_init(&us->current_sg, us->pusb_dev, pipe, 0,
440 			sg, num_sg, length, GFP_NOIO);
441 	if (result) {
442 		usb_stor_dbg(us, "usb_sg_init returned %d\n", result);
443 		return USB_STOR_XFER_ERROR;
444 	}
445 
446 	/*
447 	 * since the block has been initialized successfully, it's now
448 	 * okay to cancel it
449 	 */
450 	set_bit(US_FLIDX_SG_ACTIVE, &us->dflags);
451 
452 	/* did an abort occur during the submission? */
453 	if (test_bit(US_FLIDX_ABORTING, &us->dflags)) {
454 
455 		/* cancel the request, if it hasn't been cancelled already */
456 		if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {
457 			usb_stor_dbg(us, "-- cancelling sg request\n");
458 			usb_sg_cancel(&us->current_sg);
459 		}
460 	}
461 
462 	/* wait for the completion of the transfer */
463 	usb_sg_wait(&us->current_sg);
464 	clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags);
465 
466 	result = us->current_sg.status;
467 	if (act_len)
468 		*act_len = us->current_sg.bytes;
469 	return interpret_urb_result(us, pipe, length, result,
470 			us->current_sg.bytes);
471 }
472 
473 /*
474  * Common used function. Transfer a complete command
475  * via usb_stor_bulk_transfer_sglist() above. Set cmnd resid
476  */
477 int usb_stor_bulk_srb(struct us_data* us, unsigned int pipe,
478 		      struct scsi_cmnd* srb)
479 {
480 	unsigned int partial;
481 	int result = usb_stor_bulk_transfer_sglist(us, pipe, scsi_sglist(srb),
482 				      scsi_sg_count(srb), scsi_bufflen(srb),
483 				      &partial);
484 
485 	scsi_set_resid(srb, scsi_bufflen(srb) - partial);
486 	return result;
487 }
488 EXPORT_SYMBOL_GPL(usb_stor_bulk_srb);
489 
490 /*
491  * Transfer an entire SCSI command's worth of data payload over the bulk
492  * pipe.
493  *
494  * Note that this uses usb_stor_bulk_transfer_buf() and
495  * usb_stor_bulk_transfer_sglist() to achieve its goals --
496  * this function simply determines whether we're going to use
497  * scatter-gather or not, and acts appropriately.
498  */
499 int usb_stor_bulk_transfer_sg(struct us_data* us, unsigned int pipe,
500 		void *buf, unsigned int length_left, int use_sg, int *residual)
501 {
502 	int result;
503 	unsigned int partial;
504 
505 	/* are we scatter-gathering? */
506 	if (use_sg) {
507 		/* use the usb core scatter-gather primitives */
508 		result = usb_stor_bulk_transfer_sglist(us, pipe,
509 				(struct scatterlist *) buf, use_sg,
510 				length_left, &partial);
511 		length_left -= partial;
512 	} else {
513 		/* no scatter-gather, just make the request */
514 		result = usb_stor_bulk_transfer_buf(us, pipe, buf,
515 				length_left, &partial);
516 		length_left -= partial;
517 	}
518 
519 	/* store the residual and return the error code */
520 	if (residual)
521 		*residual = length_left;
522 	return result;
523 }
524 EXPORT_SYMBOL_GPL(usb_stor_bulk_transfer_sg);
525 
526 /***********************************************************************
527  * Transport routines
528  ***********************************************************************/
529 
530 /*
531  * There are so many devices that report the capacity incorrectly,
532  * this routine was written to counteract some of the resulting
533  * problems.
534  */
535 static void last_sector_hacks(struct us_data *us, struct scsi_cmnd *srb)
536 {
537 	struct gendisk *disk;
538 	struct scsi_disk *sdkp;
539 	u32 sector;
540 
541 	/* To Report "Medium Error: Record Not Found */
542 	static unsigned char record_not_found[18] = {
543 		[0]	= 0x70,			/* current error */
544 		[2]	= MEDIUM_ERROR,		/* = 0x03 */
545 		[7]	= 0x0a,			/* additional length */
546 		[12]	= 0x14			/* Record Not Found */
547 	};
548 
549 	/*
550 	 * If last-sector problems can't occur, whether because the
551 	 * capacity was already decremented or because the device is
552 	 * known to report the correct capacity, then we don't need
553 	 * to do anything.
554 	 */
555 	if (!us->use_last_sector_hacks)
556 		return;
557 
558 	/* Was this command a READ(10) or a WRITE(10)? */
559 	if (srb->cmnd[0] != READ_10 && srb->cmnd[0] != WRITE_10)
560 		goto done;
561 
562 	/* Did this command access the last sector? */
563 	sector = (srb->cmnd[2] << 24) | (srb->cmnd[3] << 16) |
564 			(srb->cmnd[4] << 8) | (srb->cmnd[5]);
565 	disk = srb->request->rq_disk;
566 	if (!disk)
567 		goto done;
568 	sdkp = scsi_disk(disk);
569 	if (!sdkp)
570 		goto done;
571 	if (sector + 1 != sdkp->capacity)
572 		goto done;
573 
574 	if (srb->result == SAM_STAT_GOOD && scsi_get_resid(srb) == 0) {
575 
576 		/*
577 		 * The command succeeded.  We know this device doesn't
578 		 * have the last-sector bug, so stop checking it.
579 		 */
580 		us->use_last_sector_hacks = 0;
581 
582 	} else {
583 		/*
584 		 * The command failed.  Allow up to 3 retries in case this
585 		 * is some normal sort of failure.  After that, assume the
586 		 * capacity is wrong and we're trying to access the sector
587 		 * beyond the end.  Replace the result code and sense data
588 		 * with values that will cause the SCSI core to fail the
589 		 * command immediately, instead of going into an infinite
590 		 * (or even just a very long) retry loop.
591 		 */
592 		if (++us->last_sector_retries < 3)
593 			return;
594 		srb->result = SAM_STAT_CHECK_CONDITION;
595 		memcpy(srb->sense_buffer, record_not_found,
596 				sizeof(record_not_found));
597 	}
598 
599  done:
600 	/*
601 	 * Don't reset the retry counter for TEST UNIT READY commands,
602 	 * because they get issued after device resets which might be
603 	 * caused by a failed last-sector access.
604 	 */
605 	if (srb->cmnd[0] != TEST_UNIT_READY)
606 		us->last_sector_retries = 0;
607 }
608 
609 /*
610  * Invoke the transport and basic error-handling/recovery methods
611  *
612  * This is used by the protocol layers to actually send the message to
613  * the device and receive the response.
614  */
615 void usb_stor_invoke_transport(struct scsi_cmnd *srb, struct us_data *us)
616 {
617 	int need_auto_sense;
618 	int result;
619 
620 	/* send the command to the transport layer */
621 	scsi_set_resid(srb, 0);
622 	result = us->transport(srb, us);
623 
624 	/*
625 	 * if the command gets aborted by the higher layers, we need to
626 	 * short-circuit all other processing
627 	 */
628 	if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
629 		usb_stor_dbg(us, "-- command was aborted\n");
630 		srb->result = DID_ABORT << 16;
631 		goto Handle_Errors;
632 	}
633 
634 	/* if there is a transport error, reset and don't auto-sense */
635 	if (result == USB_STOR_TRANSPORT_ERROR) {
636 		usb_stor_dbg(us, "-- transport indicates error, resetting\n");
637 		srb->result = DID_ERROR << 16;
638 		goto Handle_Errors;
639 	}
640 
641 	/* if the transport provided its own sense data, don't auto-sense */
642 	if (result == USB_STOR_TRANSPORT_NO_SENSE) {
643 		srb->result = SAM_STAT_CHECK_CONDITION;
644 		last_sector_hacks(us, srb);
645 		return;
646 	}
647 
648 	srb->result = SAM_STAT_GOOD;
649 
650 	/*
651 	 * Determine if we need to auto-sense
652 	 *
653 	 * I normally don't use a flag like this, but it's almost impossible
654 	 * to understand what's going on here if I don't.
655 	 */
656 	need_auto_sense = 0;
657 
658 	/*
659 	 * If we're running the CB transport, which is incapable
660 	 * of determining status on its own, we will auto-sense
661 	 * unless the operation involved a data-in transfer.  Devices
662 	 * can signal most data-in errors by stalling the bulk-in pipe.
663 	 */
664 	if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_DPCM_USB) &&
665 			srb->sc_data_direction != DMA_FROM_DEVICE) {
666 		usb_stor_dbg(us, "-- CB transport device requiring auto-sense\n");
667 		need_auto_sense = 1;
668 	}
669 
670 	/*
671 	 * If we have a failure, we're going to do a REQUEST_SENSE
672 	 * automatically.  Note that we differentiate between a command
673 	 * "failure" and an "error" in the transport mechanism.
674 	 */
675 	if (result == USB_STOR_TRANSPORT_FAILED) {
676 		usb_stor_dbg(us, "-- transport indicates command failure\n");
677 		need_auto_sense = 1;
678 	}
679 
680 	/*
681 	 * Determine if this device is SAT by seeing if the
682 	 * command executed successfully.  Otherwise we'll have
683 	 * to wait for at least one CHECK_CONDITION to determine
684 	 * SANE_SENSE support
685 	 */
686 	if (unlikely((srb->cmnd[0] == ATA_16 || srb->cmnd[0] == ATA_12) &&
687 	    result == USB_STOR_TRANSPORT_GOOD &&
688 	    !(us->fflags & US_FL_SANE_SENSE) &&
689 	    !(us->fflags & US_FL_BAD_SENSE) &&
690 	    !(srb->cmnd[2] & 0x20))) {
691 		usb_stor_dbg(us, "-- SAT supported, increasing auto-sense\n");
692 		us->fflags |= US_FL_SANE_SENSE;
693 	}
694 
695 	/*
696 	 * A short transfer on a command where we don't expect it
697 	 * is unusual, but it doesn't mean we need to auto-sense.
698 	 */
699 	if ((scsi_get_resid(srb) > 0) &&
700 	    !((srb->cmnd[0] == REQUEST_SENSE) ||
701 	      (srb->cmnd[0] == INQUIRY) ||
702 	      (srb->cmnd[0] == MODE_SENSE) ||
703 	      (srb->cmnd[0] == LOG_SENSE) ||
704 	      (srb->cmnd[0] == MODE_SENSE_10))) {
705 		usb_stor_dbg(us, "-- unexpectedly short transfer\n");
706 	}
707 
708 	/* Now, if we need to do the auto-sense, let's do it */
709 	if (need_auto_sense) {
710 		int temp_result;
711 		struct scsi_eh_save ses;
712 		int sense_size = US_SENSE_SIZE;
713 		struct scsi_sense_hdr sshdr;
714 		const u8 *scdd;
715 		u8 fm_ili;
716 
717 		/* device supports and needs bigger sense buffer */
718 		if (us->fflags & US_FL_SANE_SENSE)
719 			sense_size = ~0;
720 Retry_Sense:
721 		usb_stor_dbg(us, "Issuing auto-REQUEST_SENSE\n");
722 
723 		scsi_eh_prep_cmnd(srb, &ses, NULL, 0, sense_size);
724 
725 		/* FIXME: we must do the protocol translation here */
726 		if (us->subclass == USB_SC_RBC || us->subclass == USB_SC_SCSI ||
727 				us->subclass == USB_SC_CYP_ATACB)
728 			srb->cmd_len = 6;
729 		else
730 			srb->cmd_len = 12;
731 
732 		/* issue the auto-sense command */
733 		scsi_set_resid(srb, 0);
734 		temp_result = us->transport(us->srb, us);
735 
736 		/* let's clean up right away */
737 		scsi_eh_restore_cmnd(srb, &ses);
738 
739 		if (test_bit(US_FLIDX_TIMED_OUT, &us->dflags)) {
740 			usb_stor_dbg(us, "-- auto-sense aborted\n");
741 			srb->result = DID_ABORT << 16;
742 
743 			/* If SANE_SENSE caused this problem, disable it */
744 			if (sense_size != US_SENSE_SIZE) {
745 				us->fflags &= ~US_FL_SANE_SENSE;
746 				us->fflags |= US_FL_BAD_SENSE;
747 			}
748 			goto Handle_Errors;
749 		}
750 
751 		/*
752 		 * Some devices claim to support larger sense but fail when
753 		 * trying to request it. When a transport failure happens
754 		 * using US_FS_SANE_SENSE, we always retry with a standard
755 		 * (small) sense request. This fixes some USB GSM modems
756 		 */
757 		if (temp_result == USB_STOR_TRANSPORT_FAILED &&
758 				sense_size != US_SENSE_SIZE) {
759 			usb_stor_dbg(us, "-- auto-sense failure, retry small sense\n");
760 			sense_size = US_SENSE_SIZE;
761 			us->fflags &= ~US_FL_SANE_SENSE;
762 			us->fflags |= US_FL_BAD_SENSE;
763 			goto Retry_Sense;
764 		}
765 
766 		/* Other failures */
767 		if (temp_result != USB_STOR_TRANSPORT_GOOD) {
768 			usb_stor_dbg(us, "-- auto-sense failure\n");
769 
770 			/*
771 			 * we skip the reset if this happens to be a
772 			 * multi-target device, since failure of an
773 			 * auto-sense is perfectly valid
774 			 */
775 			srb->result = DID_ERROR << 16;
776 			if (!(us->fflags & US_FL_SCM_MULT_TARG))
777 				goto Handle_Errors;
778 			return;
779 		}
780 
781 		/*
782 		 * If the sense data returned is larger than 18-bytes then we
783 		 * assume this device supports requesting more in the future.
784 		 * The response code must be 70h through 73h inclusive.
785 		 */
786 		if (srb->sense_buffer[7] > (US_SENSE_SIZE - 8) &&
787 		    !(us->fflags & US_FL_SANE_SENSE) &&
788 		    !(us->fflags & US_FL_BAD_SENSE) &&
789 		    (srb->sense_buffer[0] & 0x7C) == 0x70) {
790 			usb_stor_dbg(us, "-- SANE_SENSE support enabled\n");
791 			us->fflags |= US_FL_SANE_SENSE;
792 
793 			/*
794 			 * Indicate to the user that we truncated their sense
795 			 * because we didn't know it supported larger sense.
796 			 */
797 			usb_stor_dbg(us, "-- Sense data truncated to %i from %i\n",
798 				     US_SENSE_SIZE,
799 				     srb->sense_buffer[7] + 8);
800 			srb->sense_buffer[7] = (US_SENSE_SIZE - 8);
801 		}
802 
803 		scsi_normalize_sense(srb->sense_buffer, SCSI_SENSE_BUFFERSIZE,
804 				     &sshdr);
805 
806 		usb_stor_dbg(us, "-- Result from auto-sense is %d\n",
807 			     temp_result);
808 		usb_stor_dbg(us, "-- code: 0x%x, key: 0x%x, ASC: 0x%x, ASCQ: 0x%x\n",
809 			     sshdr.response_code, sshdr.sense_key,
810 			     sshdr.asc, sshdr.ascq);
811 #ifdef CONFIG_USB_STORAGE_DEBUG
812 		usb_stor_show_sense(us, sshdr.sense_key, sshdr.asc, sshdr.ascq);
813 #endif
814 
815 		/* set the result so the higher layers expect this data */
816 		srb->result = SAM_STAT_CHECK_CONDITION;
817 
818 		scdd = scsi_sense_desc_find(srb->sense_buffer,
819 					    SCSI_SENSE_BUFFERSIZE, 4);
820 		fm_ili = (scdd ? scdd[3] : srb->sense_buffer[2]) & 0xA0;
821 
822 		/*
823 		 * We often get empty sense data.  This could indicate that
824 		 * everything worked or that there was an unspecified
825 		 * problem.  We have to decide which.
826 		 */
827 		if (sshdr.sense_key == 0 && sshdr.asc == 0 && sshdr.ascq == 0 &&
828 		    fm_ili == 0) {
829 			/*
830 			 * If things are really okay, then let's show that.
831 			 * Zero out the sense buffer so the higher layers
832 			 * won't realize we did an unsolicited auto-sense.
833 			 */
834 			if (result == USB_STOR_TRANSPORT_GOOD) {
835 				srb->result = SAM_STAT_GOOD;
836 				srb->sense_buffer[0] = 0x0;
837 
838 			/*
839 			 * If there was a problem, report an unspecified
840 			 * hardware error to prevent the higher layers from
841 			 * entering an infinite retry loop.
842 			 */
843 			} else {
844 				srb->result = DID_ERROR << 16;
845 				if ((sshdr.response_code & 0x72) == 0x72)
846 					srb->sense_buffer[1] = HARDWARE_ERROR;
847 				else
848 					srb->sense_buffer[2] = HARDWARE_ERROR;
849 			}
850 		}
851 	}
852 
853 	/*
854 	 * Some devices don't work or return incorrect data the first
855 	 * time they get a READ(10) command, or for the first READ(10)
856 	 * after a media change.  If the INITIAL_READ10 flag is set,
857 	 * keep track of whether READ(10) commands succeed.  If the
858 	 * previous one succeeded and this one failed, set the REDO_READ10
859 	 * flag to force a retry.
860 	 */
861 	if (unlikely((us->fflags & US_FL_INITIAL_READ10) &&
862 			srb->cmnd[0] == READ_10)) {
863 		if (srb->result == SAM_STAT_GOOD) {
864 			set_bit(US_FLIDX_READ10_WORKED, &us->dflags);
865 		} else if (test_bit(US_FLIDX_READ10_WORKED, &us->dflags)) {
866 			clear_bit(US_FLIDX_READ10_WORKED, &us->dflags);
867 			set_bit(US_FLIDX_REDO_READ10, &us->dflags);
868 		}
869 
870 		/*
871 		 * Next, if the REDO_READ10 flag is set, return a result
872 		 * code that will cause the SCSI core to retry the READ(10)
873 		 * command immediately.
874 		 */
875 		if (test_bit(US_FLIDX_REDO_READ10, &us->dflags)) {
876 			clear_bit(US_FLIDX_REDO_READ10, &us->dflags);
877 			srb->result = DID_IMM_RETRY << 16;
878 			srb->sense_buffer[0] = 0;
879 		}
880 	}
881 
882 	/* Did we transfer less than the minimum amount required? */
883 	if ((srb->result == SAM_STAT_GOOD || srb->sense_buffer[2] == 0) &&
884 			scsi_bufflen(srb) - scsi_get_resid(srb) < srb->underflow)
885 		srb->result = DID_ERROR << 16;
886 
887 	last_sector_hacks(us, srb);
888 	return;
889 
890 	/*
891 	 * Error and abort processing: try to resynchronize with the device
892 	 * by issuing a port reset.  If that fails, try a class-specific
893 	 * device reset.
894 	 */
895   Handle_Errors:
896 
897 	/*
898 	 * Set the RESETTING bit, and clear the ABORTING bit so that
899 	 * the reset may proceed.
900 	 */
901 	scsi_lock(us_to_host(us));
902 	set_bit(US_FLIDX_RESETTING, &us->dflags);
903 	clear_bit(US_FLIDX_ABORTING, &us->dflags);
904 	scsi_unlock(us_to_host(us));
905 
906 	/*
907 	 * We must release the device lock because the pre_reset routine
908 	 * will want to acquire it.
909 	 */
910 	mutex_unlock(&us->dev_mutex);
911 	result = usb_stor_port_reset(us);
912 	mutex_lock(&us->dev_mutex);
913 
914 	if (result < 0) {
915 		scsi_lock(us_to_host(us));
916 		usb_stor_report_device_reset(us);
917 		scsi_unlock(us_to_host(us));
918 		us->transport_reset(us);
919 	}
920 	clear_bit(US_FLIDX_RESETTING, &us->dflags);
921 	last_sector_hacks(us, srb);
922 }
923 
924 /* Stop the current URB transfer */
925 void usb_stor_stop_transport(struct us_data *us)
926 {
927 	/*
928 	 * If the state machine is blocked waiting for an URB,
929 	 * let's wake it up.  The test_and_clear_bit() call
930 	 * guarantees that if a URB has just been submitted,
931 	 * it won't be cancelled more than once.
932 	 */
933 	if (test_and_clear_bit(US_FLIDX_URB_ACTIVE, &us->dflags)) {
934 		usb_stor_dbg(us, "-- cancelling URB\n");
935 		usb_unlink_urb(us->current_urb);
936 	}
937 
938 	/* If we are waiting for a scatter-gather operation, cancel it. */
939 	if (test_and_clear_bit(US_FLIDX_SG_ACTIVE, &us->dflags)) {
940 		usb_stor_dbg(us, "-- cancelling sg request\n");
941 		usb_sg_cancel(&us->current_sg);
942 	}
943 }
944 
945 /*
946  * Control/Bulk and Control/Bulk/Interrupt transport
947  */
948 
949 int usb_stor_CB_transport(struct scsi_cmnd *srb, struct us_data *us)
950 {
951 	unsigned int transfer_length = scsi_bufflen(srb);
952 	unsigned int pipe = 0;
953 	int result;
954 
955 	/* COMMAND STAGE */
956 	/* let's send the command via the control pipe */
957 	result = usb_stor_ctrl_transfer(us, us->send_ctrl_pipe,
958 				      US_CBI_ADSC,
959 				      USB_TYPE_CLASS | USB_RECIP_INTERFACE, 0,
960 				      us->ifnum, srb->cmnd, srb->cmd_len);
961 
962 	/* check the return code for the command */
963 	usb_stor_dbg(us, "Call to usb_stor_ctrl_transfer() returned %d\n",
964 		     result);
965 
966 	/* if we stalled the command, it means command failed */
967 	if (result == USB_STOR_XFER_STALLED) {
968 		return USB_STOR_TRANSPORT_FAILED;
969 	}
970 
971 	/* Uh oh... serious problem here */
972 	if (result != USB_STOR_XFER_GOOD) {
973 		return USB_STOR_TRANSPORT_ERROR;
974 	}
975 
976 	/* DATA STAGE */
977 	/* transfer the data payload for this command, if one exists*/
978 	if (transfer_length) {
979 		pipe = srb->sc_data_direction == DMA_FROM_DEVICE ?
980 				us->recv_bulk_pipe : us->send_bulk_pipe;
981 		result = usb_stor_bulk_srb(us, pipe, srb);
982 		usb_stor_dbg(us, "CBI data stage result is 0x%x\n", result);
983 
984 		/* if we stalled the data transfer it means command failed */
985 		if (result == USB_STOR_XFER_STALLED)
986 			return USB_STOR_TRANSPORT_FAILED;
987 		if (result > USB_STOR_XFER_STALLED)
988 			return USB_STOR_TRANSPORT_ERROR;
989 	}
990 
991 	/* STATUS STAGE */
992 
993 	/*
994 	 * NOTE: CB does not have a status stage.  Silly, I know.  So
995 	 * we have to catch this at a higher level.
996 	 */
997 	if (us->protocol != USB_PR_CBI)
998 		return USB_STOR_TRANSPORT_GOOD;
999 
1000 	result = usb_stor_intr_transfer(us, us->iobuf, 2);
1001 	usb_stor_dbg(us, "Got interrupt data (0x%x, 0x%x)\n",
1002 		     us->iobuf[0], us->iobuf[1]);
1003 	if (result != USB_STOR_XFER_GOOD)
1004 		return USB_STOR_TRANSPORT_ERROR;
1005 
1006 	/*
1007 	 * UFI gives us ASC and ASCQ, like a request sense
1008 	 *
1009 	 * REQUEST_SENSE and INQUIRY don't affect the sense data on UFI
1010 	 * devices, so we ignore the information for those commands.  Note
1011 	 * that this means we could be ignoring a real error on these
1012 	 * commands, but that can't be helped.
1013 	 */
1014 	if (us->subclass == USB_SC_UFI) {
1015 		if (srb->cmnd[0] == REQUEST_SENSE ||
1016 		    srb->cmnd[0] == INQUIRY)
1017 			return USB_STOR_TRANSPORT_GOOD;
1018 		if (us->iobuf[0])
1019 			goto Failed;
1020 		return USB_STOR_TRANSPORT_GOOD;
1021 	}
1022 
1023 	/*
1024 	 * If not UFI, we interpret the data as a result code
1025 	 * The first byte should always be a 0x0.
1026 	 *
1027 	 * Some bogus devices don't follow that rule.  They stuff the ASC
1028 	 * into the first byte -- so if it's non-zero, call it a failure.
1029 	 */
1030 	if (us->iobuf[0]) {
1031 		usb_stor_dbg(us, "CBI IRQ data showed reserved bType 0x%x\n",
1032 			     us->iobuf[0]);
1033 		goto Failed;
1034 
1035 	}
1036 
1037 	/* The second byte & 0x0F should be 0x0 for good, otherwise error */
1038 	switch (us->iobuf[1] & 0x0F) {
1039 		case 0x00:
1040 			return USB_STOR_TRANSPORT_GOOD;
1041 		case 0x01:
1042 			goto Failed;
1043 	}
1044 	return USB_STOR_TRANSPORT_ERROR;
1045 
1046 	/*
1047 	 * the CBI spec requires that the bulk pipe must be cleared
1048 	 * following any data-in/out command failure (section 2.4.3.1.3)
1049 	 */
1050   Failed:
1051 	if (pipe)
1052 		usb_stor_clear_halt(us, pipe);
1053 	return USB_STOR_TRANSPORT_FAILED;
1054 }
1055 EXPORT_SYMBOL_GPL(usb_stor_CB_transport);
1056 
1057 /*
1058  * Bulk only transport
1059  */
1060 
1061 /* Determine what the maximum LUN supported is */
1062 int usb_stor_Bulk_max_lun(struct us_data *us)
1063 {
1064 	int result;
1065 
1066 	/* issue the command */
1067 	us->iobuf[0] = 0;
1068 	result = usb_stor_control_msg(us, us->recv_ctrl_pipe,
1069 				 US_BULK_GET_MAX_LUN,
1070 				 USB_DIR_IN | USB_TYPE_CLASS |
1071 				 USB_RECIP_INTERFACE,
1072 				 0, us->ifnum, us->iobuf, 1, 10*HZ);
1073 
1074 	usb_stor_dbg(us, "GetMaxLUN command result is %d, data is %d\n",
1075 		     result, us->iobuf[0]);
1076 
1077 	/*
1078 	 * If we have a successful request, return the result if valid. The
1079 	 * CBW LUN field is 4 bits wide, so the value reported by the device
1080 	 * should fit into that.
1081 	 */
1082 	if (result > 0) {
1083 		if (us->iobuf[0] < 16) {
1084 			return us->iobuf[0];
1085 		} else {
1086 			dev_info(&us->pusb_intf->dev,
1087 				 "Max LUN %d is not valid, using 0 instead",
1088 				 us->iobuf[0]);
1089 		}
1090 	}
1091 
1092 	/*
1093 	 * Some devices don't like GetMaxLUN.  They may STALL the control
1094 	 * pipe, they may return a zero-length result, they may do nothing at
1095 	 * all and timeout, or they may fail in even more bizarrely creative
1096 	 * ways.  In these cases the best approach is to use the default
1097 	 * value: only one LUN.
1098 	 */
1099 	return 0;
1100 }
1101 
1102 int usb_stor_Bulk_transport(struct scsi_cmnd *srb, struct us_data *us)
1103 {
1104 	struct bulk_cb_wrap *bcb = (struct bulk_cb_wrap *) us->iobuf;
1105 	struct bulk_cs_wrap *bcs = (struct bulk_cs_wrap *) us->iobuf;
1106 	unsigned int transfer_length = scsi_bufflen(srb);
1107 	unsigned int residue;
1108 	int result;
1109 	int fake_sense = 0;
1110 	unsigned int cswlen;
1111 	unsigned int cbwlen = US_BULK_CB_WRAP_LEN;
1112 
1113 	/* Take care of BULK32 devices; set extra byte to 0 */
1114 	if (unlikely(us->fflags & US_FL_BULK32)) {
1115 		cbwlen = 32;
1116 		us->iobuf[31] = 0;
1117 	}
1118 
1119 	/* set up the command wrapper */
1120 	bcb->Signature = cpu_to_le32(US_BULK_CB_SIGN);
1121 	bcb->DataTransferLength = cpu_to_le32(transfer_length);
1122 	bcb->Flags = srb->sc_data_direction == DMA_FROM_DEVICE ?
1123 		US_BULK_FLAG_IN : 0;
1124 	bcb->Tag = ++us->tag;
1125 	bcb->Lun = srb->device->lun;
1126 	if (us->fflags & US_FL_SCM_MULT_TARG)
1127 		bcb->Lun |= srb->device->id << 4;
1128 	bcb->Length = srb->cmd_len;
1129 
1130 	/* copy the command payload */
1131 	memset(bcb->CDB, 0, sizeof(bcb->CDB));
1132 	memcpy(bcb->CDB, srb->cmnd, bcb->Length);
1133 
1134 	/* send it to out endpoint */
1135 	usb_stor_dbg(us, "Bulk Command S 0x%x T 0x%x L %d F %d Trg %d LUN %d CL %d\n",
1136 		     le32_to_cpu(bcb->Signature), bcb->Tag,
1137 		     le32_to_cpu(bcb->DataTransferLength), bcb->Flags,
1138 		     (bcb->Lun >> 4), (bcb->Lun & 0x0F),
1139 		     bcb->Length);
1140 	result = usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
1141 				bcb, cbwlen, NULL);
1142 	usb_stor_dbg(us, "Bulk command transfer result=%d\n", result);
1143 	if (result != USB_STOR_XFER_GOOD)
1144 		return USB_STOR_TRANSPORT_ERROR;
1145 
1146 	/* DATA STAGE */
1147 	/* send/receive data payload, if there is any */
1148 
1149 	/*
1150 	 * Some USB-IDE converter chips need a 100us delay between the
1151 	 * command phase and the data phase.  Some devices need a little
1152 	 * more than that, probably because of clock rate inaccuracies.
1153 	 */
1154 	if (unlikely(us->fflags & US_FL_GO_SLOW))
1155 		usleep_range(125, 150);
1156 
1157 	if (transfer_length) {
1158 		unsigned int pipe = srb->sc_data_direction == DMA_FROM_DEVICE ?
1159 				us->recv_bulk_pipe : us->send_bulk_pipe;
1160 		result = usb_stor_bulk_srb(us, pipe, srb);
1161 		usb_stor_dbg(us, "Bulk data transfer result 0x%x\n", result);
1162 		if (result == USB_STOR_XFER_ERROR)
1163 			return USB_STOR_TRANSPORT_ERROR;
1164 
1165 		/*
1166 		 * If the device tried to send back more data than the
1167 		 * amount requested, the spec requires us to transfer
1168 		 * the CSW anyway.  Since there's no point retrying the
1169 		 * the command, we'll return fake sense data indicating
1170 		 * Illegal Request, Invalid Field in CDB.
1171 		 */
1172 		if (result == USB_STOR_XFER_LONG)
1173 			fake_sense = 1;
1174 
1175 		/*
1176 		 * Sometimes a device will mistakenly skip the data phase
1177 		 * and go directly to the status phase without sending a
1178 		 * zero-length packet.  If we get a 13-byte response here,
1179 		 * check whether it really is a CSW.
1180 		 */
1181 		if (result == USB_STOR_XFER_SHORT &&
1182 				srb->sc_data_direction == DMA_FROM_DEVICE &&
1183 				transfer_length - scsi_get_resid(srb) ==
1184 					US_BULK_CS_WRAP_LEN) {
1185 			struct scatterlist *sg = NULL;
1186 			unsigned int offset = 0;
1187 
1188 			if (usb_stor_access_xfer_buf((unsigned char *) bcs,
1189 					US_BULK_CS_WRAP_LEN, srb, &sg,
1190 					&offset, FROM_XFER_BUF) ==
1191 						US_BULK_CS_WRAP_LEN &&
1192 					bcs->Signature ==
1193 						cpu_to_le32(US_BULK_CS_SIGN)) {
1194 				usb_stor_dbg(us, "Device skipped data phase\n");
1195 				scsi_set_resid(srb, transfer_length);
1196 				goto skipped_data_phase;
1197 			}
1198 		}
1199 	}
1200 
1201 	/*
1202 	 * See flow chart on pg 15 of the Bulk Only Transport spec for
1203 	 * an explanation of how this code works.
1204 	 */
1205 
1206 	/* get CSW for device status */
1207 	usb_stor_dbg(us, "Attempting to get CSW...\n");
1208 	result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
1209 				bcs, US_BULK_CS_WRAP_LEN, &cswlen);
1210 
1211 	/*
1212 	 * Some broken devices add unnecessary zero-length packets to the
1213 	 * end of their data transfers.  Such packets show up as 0-length
1214 	 * CSWs.  If we encounter such a thing, try to read the CSW again.
1215 	 */
1216 	if (result == USB_STOR_XFER_SHORT && cswlen == 0) {
1217 		usb_stor_dbg(us, "Received 0-length CSW; retrying...\n");
1218 		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
1219 				bcs, US_BULK_CS_WRAP_LEN, &cswlen);
1220 	}
1221 
1222 	/* did the attempt to read the CSW fail? */
1223 	if (result == USB_STOR_XFER_STALLED) {
1224 
1225 		/* get the status again */
1226 		usb_stor_dbg(us, "Attempting to get CSW (2nd try)...\n");
1227 		result = usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
1228 				bcs, US_BULK_CS_WRAP_LEN, NULL);
1229 	}
1230 
1231 	/* if we still have a failure at this point, we're in trouble */
1232 	usb_stor_dbg(us, "Bulk status result = %d\n", result);
1233 	if (result != USB_STOR_XFER_GOOD)
1234 		return USB_STOR_TRANSPORT_ERROR;
1235 
1236  skipped_data_phase:
1237 	/* check bulk status */
1238 	residue = le32_to_cpu(bcs->Residue);
1239 	usb_stor_dbg(us, "Bulk Status S 0x%x T 0x%x R %u Stat 0x%x\n",
1240 		     le32_to_cpu(bcs->Signature), bcs->Tag,
1241 		     residue, bcs->Status);
1242 	if (!(bcs->Tag == us->tag || (us->fflags & US_FL_BULK_IGNORE_TAG)) ||
1243 		bcs->Status > US_BULK_STAT_PHASE) {
1244 		usb_stor_dbg(us, "Bulk logical error\n");
1245 		return USB_STOR_TRANSPORT_ERROR;
1246 	}
1247 
1248 	/*
1249 	 * Some broken devices report odd signatures, so we do not check them
1250 	 * for validity against the spec. We store the first one we see,
1251 	 * and check subsequent transfers for validity against this signature.
1252 	 */
1253 	if (!us->bcs_signature) {
1254 		us->bcs_signature = bcs->Signature;
1255 		if (us->bcs_signature != cpu_to_le32(US_BULK_CS_SIGN))
1256 			usb_stor_dbg(us, "Learnt BCS signature 0x%08X\n",
1257 				     le32_to_cpu(us->bcs_signature));
1258 	} else if (bcs->Signature != us->bcs_signature) {
1259 		usb_stor_dbg(us, "Signature mismatch: got %08X, expecting %08X\n",
1260 			     le32_to_cpu(bcs->Signature),
1261 			     le32_to_cpu(us->bcs_signature));
1262 		return USB_STOR_TRANSPORT_ERROR;
1263 	}
1264 
1265 	/*
1266 	 * try to compute the actual residue, based on how much data
1267 	 * was really transferred and what the device tells us
1268 	 */
1269 	if (residue && !(us->fflags & US_FL_IGNORE_RESIDUE)) {
1270 
1271 		/*
1272 		 * Heuristically detect devices that generate bogus residues
1273 		 * by seeing what happens with INQUIRY and READ CAPACITY
1274 		 * commands.
1275 		 */
1276 		if (bcs->Status == US_BULK_STAT_OK &&
1277 				scsi_get_resid(srb) == 0 &&
1278 					((srb->cmnd[0] == INQUIRY &&
1279 						transfer_length == 36) ||
1280 					(srb->cmnd[0] == READ_CAPACITY &&
1281 						transfer_length == 8))) {
1282 			us->fflags |= US_FL_IGNORE_RESIDUE;
1283 
1284 		} else {
1285 			residue = min(residue, transfer_length);
1286 			scsi_set_resid(srb, max(scsi_get_resid(srb),
1287 			                                       (int) residue));
1288 		}
1289 	}
1290 
1291 	/* based on the status code, we report good or bad */
1292 	switch (bcs->Status) {
1293 		case US_BULK_STAT_OK:
1294 			/* device babbled -- return fake sense data */
1295 			if (fake_sense) {
1296 				memcpy(srb->sense_buffer,
1297 				       usb_stor_sense_invalidCDB,
1298 				       sizeof(usb_stor_sense_invalidCDB));
1299 				return USB_STOR_TRANSPORT_NO_SENSE;
1300 			}
1301 
1302 			/* command good -- note that data could be short */
1303 			return USB_STOR_TRANSPORT_GOOD;
1304 
1305 		case US_BULK_STAT_FAIL:
1306 			/* command failed */
1307 			return USB_STOR_TRANSPORT_FAILED;
1308 
1309 		case US_BULK_STAT_PHASE:
1310 			/*
1311 			 * phase error -- note that a transport reset will be
1312 			 * invoked by the invoke_transport() function
1313 			 */
1314 			return USB_STOR_TRANSPORT_ERROR;
1315 	}
1316 
1317 	/* we should never get here, but if we do, we're in trouble */
1318 	return USB_STOR_TRANSPORT_ERROR;
1319 }
1320 EXPORT_SYMBOL_GPL(usb_stor_Bulk_transport);
1321 
1322 /***********************************************************************
1323  * Reset routines
1324  ***********************************************************************/
1325 
1326 /*
1327  * This is the common part of the device reset code.
1328  *
1329  * It's handy that every transport mechanism uses the control endpoint for
1330  * resets.
1331  *
1332  * Basically, we send a reset with a 5-second timeout, so we don't get
1333  * jammed attempting to do the reset.
1334  */
1335 static int usb_stor_reset_common(struct us_data *us,
1336 		u8 request, u8 requesttype,
1337 		u16 value, u16 index, void *data, u16 size)
1338 {
1339 	int result;
1340 	int result2;
1341 
1342 	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
1343 		usb_stor_dbg(us, "No reset during disconnect\n");
1344 		return -EIO;
1345 	}
1346 
1347 	result = usb_stor_control_msg(us, us->send_ctrl_pipe,
1348 			request, requesttype, value, index, data, size,
1349 			5*HZ);
1350 	if (result < 0) {
1351 		usb_stor_dbg(us, "Soft reset failed: %d\n", result);
1352 		return result;
1353 	}
1354 
1355 	/*
1356 	 * Give the device some time to recover from the reset,
1357 	 * but don't delay disconnect processing.
1358 	 */
1359 	wait_event_interruptible_timeout(us->delay_wait,
1360 			test_bit(US_FLIDX_DISCONNECTING, &us->dflags),
1361 			HZ*6);
1362 	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
1363 		usb_stor_dbg(us, "Reset interrupted by disconnect\n");
1364 		return -EIO;
1365 	}
1366 
1367 	usb_stor_dbg(us, "Soft reset: clearing bulk-in endpoint halt\n");
1368 	result = usb_stor_clear_halt(us, us->recv_bulk_pipe);
1369 
1370 	usb_stor_dbg(us, "Soft reset: clearing bulk-out endpoint halt\n");
1371 	result2 = usb_stor_clear_halt(us, us->send_bulk_pipe);
1372 
1373 	/* return a result code based on the result of the clear-halts */
1374 	if (result >= 0)
1375 		result = result2;
1376 	if (result < 0)
1377 		usb_stor_dbg(us, "Soft reset failed\n");
1378 	else
1379 		usb_stor_dbg(us, "Soft reset done\n");
1380 	return result;
1381 }
1382 
1383 /* This issues a CB[I] Reset to the device in question */
1384 #define CB_RESET_CMD_SIZE	12
1385 
1386 int usb_stor_CB_reset(struct us_data *us)
1387 {
1388 	memset(us->iobuf, 0xFF, CB_RESET_CMD_SIZE);
1389 	us->iobuf[0] = SEND_DIAGNOSTIC;
1390 	us->iobuf[1] = 4;
1391 	return usb_stor_reset_common(us, US_CBI_ADSC,
1392 				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
1393 				 0, us->ifnum, us->iobuf, CB_RESET_CMD_SIZE);
1394 }
1395 EXPORT_SYMBOL_GPL(usb_stor_CB_reset);
1396 
1397 /*
1398  * This issues a Bulk-only Reset to the device in question, including
1399  * clearing the subsequent endpoint halts that may occur.
1400  */
1401 int usb_stor_Bulk_reset(struct us_data *us)
1402 {
1403 	return usb_stor_reset_common(us, US_BULK_RESET_REQUEST,
1404 				 USB_TYPE_CLASS | USB_RECIP_INTERFACE,
1405 				 0, us->ifnum, NULL, 0);
1406 }
1407 EXPORT_SYMBOL_GPL(usb_stor_Bulk_reset);
1408 
1409 /*
1410  * Issue a USB port reset to the device.  The caller must not hold
1411  * us->dev_mutex.
1412  */
1413 int usb_stor_port_reset(struct us_data *us)
1414 {
1415 	int result;
1416 
1417 	/*for these devices we must use the class specific method */
1418 	if (us->pusb_dev->quirks & USB_QUIRK_RESET)
1419 		return -EPERM;
1420 
1421 	result = usb_lock_device_for_reset(us->pusb_dev, us->pusb_intf);
1422 	if (result < 0)
1423 		usb_stor_dbg(us, "unable to lock device for reset: %d\n",
1424 			     result);
1425 	else {
1426 		/* Were we disconnected while waiting for the lock? */
1427 		if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
1428 			result = -EIO;
1429 			usb_stor_dbg(us, "No reset during disconnect\n");
1430 		} else {
1431 			result = usb_reset_device(us->pusb_dev);
1432 			usb_stor_dbg(us, "usb_reset_device returns %d\n",
1433 				     result);
1434 		}
1435 		usb_unlock_device(us->pusb_dev);
1436 	}
1437 	return result;
1438 }
1439