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v6.13.7
  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Driver for USB Mass Storage compliant devices
  4 * SCSI layer glue code
  5 *
  6 * Current development and maintenance by:
  7 *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
  8 *
  9 * Developed with the assistance of:
 10 *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
 11 *   (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
 12 *
 13 * Initial work by:
 14 *   (c) 1999 Michael Gee (michael@linuxspecific.com)
 15 *
 16 * This driver is based on the 'USB Mass Storage Class' document. This
 17 * describes in detail the protocol used to communicate with such
 18 * devices.  Clearly, the designers had SCSI and ATAPI commands in
 19 * mind when they created this document.  The commands are all very
 20 * similar to commands in the SCSI-II and ATAPI specifications.
 21 *
 22 * It is important to note that in a number of cases this class
 23 * exhibits class-specific exemptions from the USB specification.
 24 * Notably the usage of NAK, STALL and ACK differs from the norm, in
 25 * that they are used to communicate wait, failed and OK on commands.
 26 *
 27 * Also, for certain devices, the interrupt endpoint is used to convey
 28 * status of a command.
 29 */
 30
 31#include <linux/blkdev.h>
 32#include <linux/dma-mapping.h>
 33#include <linux/module.h>
 34#include <linux/mutex.h>
 35
 36#include <scsi/scsi.h>
 37#include <scsi/scsi_cmnd.h>
 38#include <scsi/scsi_devinfo.h>
 39#include <scsi/scsi_device.h>
 40#include <scsi/scsi_eh.h>
 41
 42#include "usb.h"
 
 43#include "scsiglue.h"
 44#include "debug.h"
 45#include "transport.h"
 46#include "protocol.h"
 47
 48/*
 49 * Vendor IDs for companies that seem to include the READ CAPACITY bug
 50 * in all their devices
 51 */
 52#define VENDOR_ID_NOKIA		0x0421
 53#define VENDOR_ID_NIKON		0x04b0
 54#define VENDOR_ID_PENTAX	0x0a17
 55#define VENDOR_ID_MOTOROLA	0x22b8
 56
 57/***********************************************************************
 58 * Host functions 
 59 ***********************************************************************/
 60
 61static const char* host_info(struct Scsi_Host *host)
 62{
 63	struct us_data *us = host_to_us(host);
 64	return us->scsi_name;
 65}
 66
 67static int slave_alloc (struct scsi_device *sdev)
 68{
 69	struct us_data *us = host_to_us(sdev->host);
 70
 71	/*
 72	 * Set the INQUIRY transfer length to 36.  We don't use any of
 73	 * the extra data and many devices choke if asked for more or
 74	 * less than 36 bytes.
 75	 */
 76	sdev->inquiry_len = 36;
 77
 
 
 
 
 
 
 78	/* Tell the SCSI layer if we know there is more than one LUN */
 79	if (us->protocol == USB_PR_BULK && us->max_lun > 0)
 80		sdev->sdev_bflags |= BLIST_FORCELUN;
 81
 82	/*
 83	 * Some USB storage devices reset if the IO advice hints grouping mode
 84	 * page is queried. Hence skip that mode page.
 85	 */
 86	sdev->sdev_bflags |= BLIST_SKIP_IO_HINTS;
 87
 88	return 0;
 89}
 90
 91static int device_configure(struct scsi_device *sdev, struct queue_limits *lim)
 92{
 93	struct us_data *us = host_to_us(sdev->host);
 94	struct device *dev = us->pusb_dev->bus->sysdev;
 95
 96	/*
 97	 * Many devices have trouble transferring more than 32KB at a time,
 98	 * while others have trouble with more than 64K. At this time we
 99	 * are limiting both to 32K (64 sectores).
100	 */
101	if (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
102		unsigned int max_sectors = 64;
103
104		if (us->fflags & US_FL_MAX_SECTORS_MIN)
105			max_sectors = PAGE_SIZE >> 9;
106		lim->max_hw_sectors = min(lim->max_hw_sectors, max_sectors);
 
 
107	} else if (sdev->type == TYPE_TAPE) {
108		/*
109		 * Tapes need much higher max_sector limits, so just
110		 * raise it to the maximum possible (4 GB / 512) and
111		 * let the queue segment size sort out the real limit.
112		 */
113		lim->max_hw_sectors = 0x7FFFFF;
114	} else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
115		/*
116		 * USB3 devices will be limited to 2048 sectors. This gives us
117		 * better throughput on most devices.
118		 */
119		lim->max_hw_sectors = 2048;
120	}
121
122	/*
123	 * The max_hw_sectors should be up to maximum size of a mapping for
124	 * the device. Otherwise, a DMA API might fail on swiotlb environment.
125	 */
126	lim->max_hw_sectors = min_t(size_t,
127		lim->max_hw_sectors, dma_max_mapping_size(dev) >> SECTOR_SHIFT);
 
 
 
 
 
 
 
 
 
128
129	/*
130	 * We can't put these settings in slave_alloc() because that gets
131	 * called before the device type is known.  Consequently these
132	 * settings can't be overridden via the scsi devinfo mechanism.
133	 */
134	if (sdev->type == TYPE_DISK) {
135
136		/*
137		 * Some vendors seem to put the READ CAPACITY bug into
138		 * all their devices -- primarily makers of cell phones
139		 * and digital cameras.  Since these devices always use
140		 * flash media and can be expected to have an even number
141		 * of sectors, we will always enable the CAPACITY_HEURISTICS
142		 * flag unless told otherwise.
143		 */
144		switch (le16_to_cpu(us->pusb_dev->descriptor.idVendor)) {
145		case VENDOR_ID_NOKIA:
146		case VENDOR_ID_NIKON:
147		case VENDOR_ID_PENTAX:
148		case VENDOR_ID_MOTOROLA:
149			if (!(us->fflags & (US_FL_FIX_CAPACITY |
150					US_FL_CAPACITY_OK)))
151				us->fflags |= US_FL_CAPACITY_HEURISTICS;
152			break;
153		}
154
155		/*
156		 * Disk-type devices use MODE SENSE(6) if the protocol
157		 * (SubClass) is Transparent SCSI, otherwise they use
158		 * MODE SENSE(10).
159		 */
160		if (us->subclass != USB_SC_SCSI && us->subclass != USB_SC_CYP_ATACB)
161			sdev->use_10_for_ms = 1;
162
163		/*
164		 *Many disks only accept MODE SENSE transfer lengths of
165		 * 192 bytes (that's what Windows uses).
166		 */
167		sdev->use_192_bytes_for_3f = 1;
168
169		/*
170		 * Some devices report generic values until the media has been
171		 * accessed. Force a READ(10) prior to querying device
172		 * characteristics.
173		 */
174		sdev->read_before_ms = 1;
175
176		/*
177		 * Some devices don't like MODE SENSE with page=0x3f,
178		 * which is the command used for checking if a device
179		 * is write-protected.  Now that we tell the sd driver
180		 * to do a 192-byte transfer with this command the
181		 * majority of devices work fine, but a few still can't
182		 * handle it.  The sd driver will simply assume those
183		 * devices are write-enabled.
184		 */
185		if (us->fflags & US_FL_NO_WP_DETECT)
186			sdev->skip_ms_page_3f = 1;
187
188		/*
189		 * A number of devices have problems with MODE SENSE for
190		 * page x08, so we will skip it.
191		 */
192		sdev->skip_ms_page_8 = 1;
193
194		/*
195		 * Some devices don't handle VPD pages correctly, so skip vpd
196		 * pages if not forced by SCSI layer.
197		 */
198		sdev->skip_vpd_pages = !sdev->try_vpd_pages;
199
200		/* Do not attempt to use REPORT SUPPORTED OPERATION CODES */
201		sdev->no_report_opcodes = 1;
202
203		/* Do not attempt to use WRITE SAME */
204		sdev->no_write_same = 1;
205
206		/*
207		 * Some disks return the total number of blocks in response
208		 * to READ CAPACITY rather than the highest block number.
209		 * If this device makes that mistake, tell the sd driver.
210		 */
211		if (us->fflags & US_FL_FIX_CAPACITY)
212			sdev->fix_capacity = 1;
213
214		/*
215		 * A few disks have two indistinguishable version, one of
216		 * which reports the correct capacity and the other does not.
217		 * The sd driver has to guess which is the case.
218		 */
219		if (us->fflags & US_FL_CAPACITY_HEURISTICS)
220			sdev->guess_capacity = 1;
221
222		/* Some devices cannot handle READ_CAPACITY_16 */
223		if (us->fflags & US_FL_NO_READ_CAPACITY_16)
224			sdev->no_read_capacity_16 = 1;
225
226		/*
227		 * Many devices do not respond properly to READ_CAPACITY_16.
228		 * Tell the SCSI layer to try READ_CAPACITY_10 first.
229		 * However some USB 3.0 drive enclosures return capacity
230		 * modulo 2TB. Those must use READ_CAPACITY_16
231		 */
232		if (!(us->fflags & US_FL_NEEDS_CAP16))
233			sdev->try_rc_10_first = 1;
234
235		/*
236		 * assume SPC3 or latter devices support sense size > 18
237		 * unless US_FL_BAD_SENSE quirk is specified.
238		 */
239		if (sdev->scsi_level > SCSI_SPC_2 &&
240		    !(us->fflags & US_FL_BAD_SENSE))
241			us->fflags |= US_FL_SANE_SENSE;
242
243		/*
244		 * USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
245		 * Hardware Error) when any low-level error occurs,
246		 * recoverable or not.  Setting this flag tells the SCSI
247		 * midlayer to retry such commands, which frequently will
248		 * succeed and fix the error.  The worst this can lead to
249		 * is an occasional series of retries that will all fail.
250		 */
251		sdev->retry_hwerror = 1;
252
253		/*
254		 * USB disks should allow restart.  Some drives spin down
255		 * automatically, requiring a START-STOP UNIT command.
256		 */
257		sdev->allow_restart = 1;
258
259		/*
260		 * Some USB cardreaders have trouble reading an sdcard's last
261		 * sector in a larger then 1 sector read, since the performance
262		 * impact is negligible we set this flag for all USB disks
263		 */
264		sdev->last_sector_bug = 1;
265
266		/*
267		 * Enable last-sector hacks for single-target devices using
268		 * the Bulk-only transport, unless we already know the
269		 * capacity will be decremented or is correct.
270		 */
271		if (!(us->fflags & (US_FL_FIX_CAPACITY | US_FL_CAPACITY_OK |
272					US_FL_SCM_MULT_TARG)) &&
273				us->protocol == USB_PR_BULK)
274			us->use_last_sector_hacks = 1;
275
276		/* Check if write cache default on flag is set or not */
277		if (us->fflags & US_FL_WRITE_CACHE)
278			sdev->wce_default_on = 1;
279
280		/* A few buggy USB-ATA bridges don't understand FUA */
281		if (us->fflags & US_FL_BROKEN_FUA)
282			sdev->broken_fua = 1;
283
284		/* Some even totally fail to indicate a cache */
285		if (us->fflags & US_FL_ALWAYS_SYNC) {
286			/* don't read caching information */
287			sdev->skip_ms_page_8 = 1;
288			sdev->skip_ms_page_3f = 1;
289			/* assume sync is needed */
290			sdev->wce_default_on = 1;
291		}
292	} else {
293
294		/*
295		 * Non-disk-type devices don't need to ignore any pages
296		 * or to force 192-byte transfer lengths for MODE SENSE.
297		 * But they do need to use MODE SENSE(10).
298		 */
299		sdev->use_10_for_ms = 1;
300
301		/* Some (fake) usb cdrom devices don't like READ_DISC_INFO */
302		if (us->fflags & US_FL_NO_READ_DISC_INFO)
303			sdev->no_read_disc_info = 1;
304	}
305
306	/*
307	 * The CB and CBI transports have no way to pass LUN values
308	 * other than the bits in the second byte of a CDB.  But those
309	 * bits don't get set to the LUN value if the device reports
310	 * scsi_level == 0 (UNKNOWN).  Hence such devices must necessarily
311	 * be single-LUN.
312	 */
313	if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_CBI) &&
314			sdev->scsi_level == SCSI_UNKNOWN)
315		us->max_lun = 0;
316
317	/*
318	 * Some devices choke when they receive a PREVENT-ALLOW MEDIUM
319	 * REMOVAL command, so suppress those commands.
320	 */
321	if (us->fflags & US_FL_NOT_LOCKABLE)
322		sdev->lockable = 0;
323
324	/*
325	 * this is to satisfy the compiler, tho I don't think the 
326	 * return code is ever checked anywhere.
327	 */
328	return 0;
329}
330
331static int target_alloc(struct scsi_target *starget)
332{
333	struct us_data *us = host_to_us(dev_to_shost(starget->dev.parent));
334
335	/*
336	 * Some USB drives don't support REPORT LUNS, even though they
337	 * report a SCSI revision level above 2.  Tell the SCSI layer
338	 * not to issue that command; it will perform a normal sequential
339	 * scan instead.
340	 */
341	starget->no_report_luns = 1;
342
343	/*
344	 * The UFI spec treats the Peripheral Qualifier bits in an
345	 * INQUIRY result as reserved and requires devices to set them
346	 * to 0.  However the SCSI spec requires these bits to be set
347	 * to 3 to indicate when a LUN is not present.
348	 *
349	 * Let the scanning code know if this target merely sets
350	 * Peripheral Device Type to 0x1f to indicate no LUN.
351	 */
352	if (us->subclass == USB_SC_UFI)
353		starget->pdt_1f_for_no_lun = 1;
354
355	return 0;
356}
357
358/* queue a command */
359/* This is always called with scsi_lock(host) held */
360static int queuecommand_lck(struct scsi_cmnd *srb)
 
361{
362	void (*done)(struct scsi_cmnd *) = scsi_done;
363	struct us_data *us = host_to_us(srb->device->host);
364
365	/* check for state-transition errors */
366	if (us->srb != NULL) {
367		dev_err(&us->pusb_intf->dev,
368			"Error in %s: us->srb = %p\n", __func__, us->srb);
369		return SCSI_MLQUEUE_HOST_BUSY;
370	}
371
372	/* fail the command if we are disconnecting */
373	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
374		usb_stor_dbg(us, "Fail command during disconnect\n");
375		srb->result = DID_NO_CONNECT << 16;
376		done(srb);
377		return 0;
378	}
379
380	if ((us->fflags & US_FL_NO_ATA_1X) &&
381			(srb->cmnd[0] == ATA_12 || srb->cmnd[0] == ATA_16)) {
382		memcpy(srb->sense_buffer, usb_stor_sense_invalidCDB,
383		       sizeof(usb_stor_sense_invalidCDB));
384		srb->result = SAM_STAT_CHECK_CONDITION;
385		done(srb);
386		return 0;
387	}
388
389	/* enqueue the command and wake up the control thread */
 
390	us->srb = srb;
391	complete(&us->cmnd_ready);
392
393	return 0;
394}
395
396static DEF_SCSI_QCMD(queuecommand)
397
398/***********************************************************************
399 * Error handling functions
400 ***********************************************************************/
401
402/* Command timeout and abort */
403static int command_abort_matching(struct us_data *us, struct scsi_cmnd *srb_match)
404{
 
 
 
 
405	/*
406	 * us->srb together with the TIMED_OUT, RESETTING, and ABORTING
407	 * bits are protected by the host lock.
408	 */
409	scsi_lock(us_to_host(us));
410
411	/* is there any active pending command to abort ? */
412	if (!us->srb) {
413		scsi_unlock(us_to_host(us));
414		usb_stor_dbg(us, "-- nothing to abort\n");
415		return SUCCESS;
416	}
417
418	/* Does the command match the passed srb if any ? */
419	if (srb_match && us->srb != srb_match) {
420		scsi_unlock(us_to_host(us));
421		usb_stor_dbg(us, "-- pending command mismatch\n");
422		return FAILED;
423	}
424
425	/*
426	 * Set the TIMED_OUT bit.  Also set the ABORTING bit, but only if
427	 * a device reset isn't already in progress (to avoid interfering
428	 * with the reset).  Note that we must retain the host lock while
429	 * calling usb_stor_stop_transport(); otherwise it might interfere
430	 * with an auto-reset that begins as soon as we release the lock.
431	 */
432	set_bit(US_FLIDX_TIMED_OUT, &us->dflags);
433	if (!test_bit(US_FLIDX_RESETTING, &us->dflags)) {
434		set_bit(US_FLIDX_ABORTING, &us->dflags);
435		usb_stor_stop_transport(us);
436	}
437	scsi_unlock(us_to_host(us));
438
439	/* Wait for the aborted command to finish */
440	wait_for_completion(&us->notify);
441	return SUCCESS;
442}
443
444static int command_abort(struct scsi_cmnd *srb)
445{
446	struct us_data *us = host_to_us(srb->device->host);
447
448	usb_stor_dbg(us, "%s called\n", __func__);
449	return command_abort_matching(us, srb);
450}
451
452/*
453 * This invokes the transport reset mechanism to reset the state of the
454 * device
455 */
456static int device_reset(struct scsi_cmnd *srb)
457{
458	struct us_data *us = host_to_us(srb->device->host);
459	int result;
460
461	usb_stor_dbg(us, "%s called\n", __func__);
462
463	/* abort any pending command before reset */
464	command_abort_matching(us, NULL);
465
466	/* lock the device pointers and do the reset */
467	mutex_lock(&(us->dev_mutex));
468	result = us->transport_reset(us);
469	mutex_unlock(&us->dev_mutex);
470
471	return result < 0 ? FAILED : SUCCESS;
472}
473
474/* Simulate a SCSI bus reset by resetting the device's USB port. */
475static int bus_reset(struct scsi_cmnd *srb)
476{
477	struct us_data *us = host_to_us(srb->device->host);
478	int result;
479
480	usb_stor_dbg(us, "%s called\n", __func__);
481
482	result = usb_stor_port_reset(us);
483	return result < 0 ? FAILED : SUCCESS;
484}
485
486/*
487 * Report a driver-initiated device reset to the SCSI layer.
488 * Calling this for a SCSI-initiated reset is unnecessary but harmless.
489 * The caller must own the SCSI host lock.
490 */
491void usb_stor_report_device_reset(struct us_data *us)
492{
493	int i;
494	struct Scsi_Host *host = us_to_host(us);
495
496	scsi_report_device_reset(host, 0, 0);
497	if (us->fflags & US_FL_SCM_MULT_TARG) {
498		for (i = 1; i < host->max_id; ++i)
499			scsi_report_device_reset(host, 0, i);
500	}
501}
502
503/*
504 * Report a driver-initiated bus reset to the SCSI layer.
505 * Calling this for a SCSI-initiated reset is unnecessary but harmless.
506 * The caller must not own the SCSI host lock.
507 */
508void usb_stor_report_bus_reset(struct us_data *us)
509{
510	struct Scsi_Host *host = us_to_host(us);
511
512	scsi_lock(host);
513	scsi_report_bus_reset(host, 0);
514	scsi_unlock(host);
515}
516
517/***********************************************************************
518 * /proc/scsi/ functions
519 ***********************************************************************/
520
521static int write_info(struct Scsi_Host *host, char *buffer, int length)
522{
523	/* if someone is sending us data, just throw it away */
524	return length;
525}
526
527static int show_info (struct seq_file *m, struct Scsi_Host *host)
528{
529	struct us_data *us = host_to_us(host);
530	const char *string;
531
532	/* print the controller name */
533	seq_printf(m, "   Host scsi%d: usb-storage\n", host->host_no);
534
535	/* print product, vendor, and serial number strings */
536	if (us->pusb_dev->manufacturer)
537		string = us->pusb_dev->manufacturer;
538	else if (us->unusual_dev->vendorName)
539		string = us->unusual_dev->vendorName;
540	else
541		string = "Unknown";
542	seq_printf(m, "       Vendor: %s\n", string);
543	if (us->pusb_dev->product)
544		string = us->pusb_dev->product;
545	else if (us->unusual_dev->productName)
546		string = us->unusual_dev->productName;
547	else
548		string = "Unknown";
549	seq_printf(m, "      Product: %s\n", string);
550	if (us->pusb_dev->serial)
551		string = us->pusb_dev->serial;
552	else
553		string = "None";
554	seq_printf(m, "Serial Number: %s\n", string);
555
556	/* show the protocol and transport */
557	seq_printf(m, "     Protocol: %s\n", us->protocol_name);
558	seq_printf(m, "    Transport: %s\n", us->transport_name);
559
560	/* show the device flags */
561	seq_printf(m, "       Quirks:");
562
563#define US_FLAG(name, value) \
564	if (us->fflags & value) seq_printf(m, " " #name);
565US_DO_ALL_FLAGS
566#undef US_FLAG
567	seq_putc(m, '\n');
568	return 0;
569}
570
571/***********************************************************************
572 * Sysfs interface
573 ***********************************************************************/
574
575/* Output routine for the sysfs max_sectors file */
576static ssize_t max_sectors_show(struct device *dev, struct device_attribute *attr, char *buf)
577{
578	struct scsi_device *sdev = to_scsi_device(dev);
579
580	return sprintf(buf, "%u\n", queue_max_hw_sectors(sdev->request_queue));
581}
582
583/* Input routine for the sysfs max_sectors file */
584static ssize_t max_sectors_store(struct device *dev, struct device_attribute *attr, const char *buf,
585		size_t count)
586{
587	struct scsi_device *sdev = to_scsi_device(dev);
588	struct queue_limits lim;
589	unsigned short ms;
590	int ret;
591
592	if (sscanf(buf, "%hu", &ms) <= 0)
593		return -EINVAL;
594
595	blk_mq_freeze_queue(sdev->request_queue);
596	lim = queue_limits_start_update(sdev->request_queue);
597	lim.max_hw_sectors = ms;
598	ret = queue_limits_commit_update(sdev->request_queue, &lim);
599	blk_mq_unfreeze_queue(sdev->request_queue);
600
601	if (ret)
602		return ret;
603	return count;
604}
605static DEVICE_ATTR_RW(max_sectors);
606
607static struct attribute *usb_sdev_attrs[] = {
608	&dev_attr_max_sectors.attr,
609	NULL,
610};
611
612ATTRIBUTE_GROUPS(usb_sdev);
613
614/*
615 * this defines our host template, with which we'll allocate hosts
616 */
617
618static const struct scsi_host_template usb_stor_host_template = {
619	/* basic userland interface stuff */
620	.name =				"usb-storage",
621	.proc_name =			"usb-storage",
622	.show_info =			show_info,
623	.write_info =			write_info,
624	.info =				host_info,
625
626	/* command interface -- queued only */
627	.queuecommand =			queuecommand,
628
629	/* error and abort handlers */
630	.eh_abort_handler =		command_abort,
631	.eh_device_reset_handler =	device_reset,
632	.eh_bus_reset_handler =		bus_reset,
633
634	/* queue commands only, only one command per LUN */
635	.can_queue =			1,
636
637	/* unknown initiator id */
638	.this_id =			-1,
639
640	.slave_alloc =			slave_alloc,
641	.device_configure =		device_configure,
642	.target_alloc =			target_alloc,
643
644	/* lots of sg segments can be handled */
645	.sg_tablesize =			SG_MAX_SEGMENTS,
646
647	/*
648	 * Some host controllers may have alignment requirements.
649	 * We'll play it safe by requiring 512-byte alignment always.
650	 */
651	.dma_alignment =		511,
652
653	/*
654	 * Limit the total size of a transfer to 120 KB.
655	 *
656	 * Some devices are known to choke with anything larger. It seems like
657	 * the problem stems from the fact that original IDE controllers had
658	 * only an 8-bit register to hold the number of sectors in one transfer
659	 * and even those couldn't handle a full 256 sectors.
660	 *
661	 * Because we want to make sure we interoperate with as many devices as
662	 * possible, we will maintain a 240 sector transfer size limit for USB
663	 * Mass Storage devices.
664	 *
665	 * Tests show that other operating have similar limits with Microsoft
666	 * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
667	 * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
668	 * and 2048 for USB3 devices.
669	 */
670	.max_sectors =                  240,
671
672	/* emulated HBA */
673	.emulated =			1,
674
675	/* we do our own delay after a device or bus reset */
676	.skip_settle_delay =		1,
677
678	/* sysfs device attributes */
679	.sdev_groups =			usb_sdev_groups,
680
681	/* module management */
682	.module =			THIS_MODULE
683};
684
685void usb_stor_host_template_init(struct scsi_host_template *sht,
686				 const char *name, struct module *owner)
687{
688	*sht = usb_stor_host_template;
689	sht->name = name;
690	sht->proc_name = name;
691	sht->module = owner;
692}
693EXPORT_SYMBOL_GPL(usb_stor_host_template_init);
694
695/* To Report "Illegal Request: Invalid Field in CDB */
696unsigned char usb_stor_sense_invalidCDB[18] = {
697	[0]	= 0x70,			    /* current error */
698	[2]	= ILLEGAL_REQUEST,	    /* Illegal Request = 0x05 */
699	[7]	= 0x0a,			    /* additional length */
700	[12]	= 0x24			    /* Invalid Field in CDB */
701};
702EXPORT_SYMBOL_GPL(usb_stor_sense_invalidCDB);
v5.4
  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Driver for USB Mass Storage compliant devices
  4 * SCSI layer glue code
  5 *
  6 * Current development and maintenance by:
  7 *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
  8 *
  9 * Developed with the assistance of:
 10 *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
 11 *   (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
 12 *
 13 * Initial work by:
 14 *   (c) 1999 Michael Gee (michael@linuxspecific.com)
 15 *
 16 * This driver is based on the 'USB Mass Storage Class' document. This
 17 * describes in detail the protocol used to communicate with such
 18 * devices.  Clearly, the designers had SCSI and ATAPI commands in
 19 * mind when they created this document.  The commands are all very
 20 * similar to commands in the SCSI-II and ATAPI specifications.
 21 *
 22 * It is important to note that in a number of cases this class
 23 * exhibits class-specific exemptions from the USB specification.
 24 * Notably the usage of NAK, STALL and ACK differs from the norm, in
 25 * that they are used to communicate wait, failed and OK on commands.
 26 *
 27 * Also, for certain devices, the interrupt endpoint is used to convey
 28 * status of a command.
 29 */
 30
 31#include <linux/blkdev.h>
 32#include <linux/dma-mapping.h>
 33#include <linux/module.h>
 34#include <linux/mutex.h>
 35
 36#include <scsi/scsi.h>
 37#include <scsi/scsi_cmnd.h>
 38#include <scsi/scsi_devinfo.h>
 39#include <scsi/scsi_device.h>
 40#include <scsi/scsi_eh.h>
 41
 42#include "usb.h"
 43#include <linux/usb/hcd.h>
 44#include "scsiglue.h"
 45#include "debug.h"
 46#include "transport.h"
 47#include "protocol.h"
 48
 49/*
 50 * Vendor IDs for companies that seem to include the READ CAPACITY bug
 51 * in all their devices
 52 */
 53#define VENDOR_ID_NOKIA		0x0421
 54#define VENDOR_ID_NIKON		0x04b0
 55#define VENDOR_ID_PENTAX	0x0a17
 56#define VENDOR_ID_MOTOROLA	0x22b8
 57
 58/***********************************************************************
 59 * Host functions 
 60 ***********************************************************************/
 61
 62static const char* host_info(struct Scsi_Host *host)
 63{
 64	struct us_data *us = host_to_us(host);
 65	return us->scsi_name;
 66}
 67
 68static int slave_alloc (struct scsi_device *sdev)
 69{
 70	struct us_data *us = host_to_us(sdev->host);
 71
 72	/*
 73	 * Set the INQUIRY transfer length to 36.  We don't use any of
 74	 * the extra data and many devices choke if asked for more or
 75	 * less than 36 bytes.
 76	 */
 77	sdev->inquiry_len = 36;
 78
 79	/*
 80	 * Some host controllers may have alignment requirements.
 81	 * We'll play it safe by requiring 512-byte alignment always.
 82	 */
 83	blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
 84
 85	/* Tell the SCSI layer if we know there is more than one LUN */
 86	if (us->protocol == USB_PR_BULK && us->max_lun > 0)
 87		sdev->sdev_bflags |= BLIST_FORCELUN;
 88
 
 
 
 
 
 
 89	return 0;
 90}
 91
 92static int slave_configure(struct scsi_device *sdev)
 93{
 94	struct us_data *us = host_to_us(sdev->host);
 95	struct device *dev = us->pusb_dev->bus->sysdev;
 96
 97	/*
 98	 * Many devices have trouble transferring more than 32KB at a time,
 99	 * while others have trouble with more than 64K. At this time we
100	 * are limiting both to 32K (64 sectores).
101	 */
102	if (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
103		unsigned int max_sectors = 64;
104
105		if (us->fflags & US_FL_MAX_SECTORS_MIN)
106			max_sectors = PAGE_SIZE >> 9;
107		if (queue_max_hw_sectors(sdev->request_queue) > max_sectors)
108			blk_queue_max_hw_sectors(sdev->request_queue,
109					      max_sectors);
110	} else if (sdev->type == TYPE_TAPE) {
111		/*
112		 * Tapes need much higher max_sector limits, so just
113		 * raise it to the maximum possible (4 GB / 512) and
114		 * let the queue segment size sort out the real limit.
115		 */
116		blk_queue_max_hw_sectors(sdev->request_queue, 0x7FFFFF);
117	} else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
118		/*
119		 * USB3 devices will be limited to 2048 sectors. This gives us
120		 * better throughput on most devices.
121		 */
122		blk_queue_max_hw_sectors(sdev->request_queue, 2048);
123	}
124
125	/*
126	 * The max_hw_sectors should be up to maximum size of a mapping for
127	 * the device. Otherwise, a DMA API might fail on swiotlb environment.
128	 */
129	blk_queue_max_hw_sectors(sdev->request_queue,
130		min_t(size_t, queue_max_hw_sectors(sdev->request_queue),
131		      dma_max_mapping_size(dev) >> SECTOR_SHIFT));
132
133	/*
134	 * Some USB host controllers can't do DMA; they have to use PIO.
135	 * For such controllers we need to make sure the block layer sets
136	 * up bounce buffers in addressable memory.
137	 */
138	if (!hcd_uses_dma(bus_to_hcd(us->pusb_dev->bus)))
139		blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_HIGH);
140
141	/*
142	 * We can't put these settings in slave_alloc() because that gets
143	 * called before the device type is known.  Consequently these
144	 * settings can't be overridden via the scsi devinfo mechanism.
145	 */
146	if (sdev->type == TYPE_DISK) {
147
148		/*
149		 * Some vendors seem to put the READ CAPACITY bug into
150		 * all their devices -- primarily makers of cell phones
151		 * and digital cameras.  Since these devices always use
152		 * flash media and can be expected to have an even number
153		 * of sectors, we will always enable the CAPACITY_HEURISTICS
154		 * flag unless told otherwise.
155		 */
156		switch (le16_to_cpu(us->pusb_dev->descriptor.idVendor)) {
157		case VENDOR_ID_NOKIA:
158		case VENDOR_ID_NIKON:
159		case VENDOR_ID_PENTAX:
160		case VENDOR_ID_MOTOROLA:
161			if (!(us->fflags & (US_FL_FIX_CAPACITY |
162					US_FL_CAPACITY_OK)))
163				us->fflags |= US_FL_CAPACITY_HEURISTICS;
164			break;
165		}
166
167		/*
168		 * Disk-type devices use MODE SENSE(6) if the protocol
169		 * (SubClass) is Transparent SCSI, otherwise they use
170		 * MODE SENSE(10).
171		 */
172		if (us->subclass != USB_SC_SCSI && us->subclass != USB_SC_CYP_ATACB)
173			sdev->use_10_for_ms = 1;
174
175		/*
176		 *Many disks only accept MODE SENSE transfer lengths of
177		 * 192 bytes (that's what Windows uses).
178		 */
179		sdev->use_192_bytes_for_3f = 1;
180
181		/*
 
 
 
 
 
 
 
182		 * Some devices don't like MODE SENSE with page=0x3f,
183		 * which is the command used for checking if a device
184		 * is write-protected.  Now that we tell the sd driver
185		 * to do a 192-byte transfer with this command the
186		 * majority of devices work fine, but a few still can't
187		 * handle it.  The sd driver will simply assume those
188		 * devices are write-enabled.
189		 */
190		if (us->fflags & US_FL_NO_WP_DETECT)
191			sdev->skip_ms_page_3f = 1;
192
193		/*
194		 * A number of devices have problems with MODE SENSE for
195		 * page x08, so we will skip it.
196		 */
197		sdev->skip_ms_page_8 = 1;
198
199		/*
200		 * Some devices don't handle VPD pages correctly, so skip vpd
201		 * pages if not forced by SCSI layer.
202		 */
203		sdev->skip_vpd_pages = !sdev->try_vpd_pages;
204
205		/* Do not attempt to use REPORT SUPPORTED OPERATION CODES */
206		sdev->no_report_opcodes = 1;
207
208		/* Do not attempt to use WRITE SAME */
209		sdev->no_write_same = 1;
210
211		/*
212		 * Some disks return the total number of blocks in response
213		 * to READ CAPACITY rather than the highest block number.
214		 * If this device makes that mistake, tell the sd driver.
215		 */
216		if (us->fflags & US_FL_FIX_CAPACITY)
217			sdev->fix_capacity = 1;
218
219		/*
220		 * A few disks have two indistinguishable version, one of
221		 * which reports the correct capacity and the other does not.
222		 * The sd driver has to guess which is the case.
223		 */
224		if (us->fflags & US_FL_CAPACITY_HEURISTICS)
225			sdev->guess_capacity = 1;
226
227		/* Some devices cannot handle READ_CAPACITY_16 */
228		if (us->fflags & US_FL_NO_READ_CAPACITY_16)
229			sdev->no_read_capacity_16 = 1;
230
231		/*
232		 * Many devices do not respond properly to READ_CAPACITY_16.
233		 * Tell the SCSI layer to try READ_CAPACITY_10 first.
234		 * However some USB 3.0 drive enclosures return capacity
235		 * modulo 2TB. Those must use READ_CAPACITY_16
236		 */
237		if (!(us->fflags & US_FL_NEEDS_CAP16))
238			sdev->try_rc_10_first = 1;
239
240		/*
241		 * assume SPC3 or latter devices support sense size > 18
242		 * unless US_FL_BAD_SENSE quirk is specified.
243		 */
244		if (sdev->scsi_level > SCSI_SPC_2 &&
245		    !(us->fflags & US_FL_BAD_SENSE))
246			us->fflags |= US_FL_SANE_SENSE;
247
248		/*
249		 * USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
250		 * Hardware Error) when any low-level error occurs,
251		 * recoverable or not.  Setting this flag tells the SCSI
252		 * midlayer to retry such commands, which frequently will
253		 * succeed and fix the error.  The worst this can lead to
254		 * is an occasional series of retries that will all fail.
255		 */
256		sdev->retry_hwerror = 1;
257
258		/*
259		 * USB disks should allow restart.  Some drives spin down
260		 * automatically, requiring a START-STOP UNIT command.
261		 */
262		sdev->allow_restart = 1;
263
264		/*
265		 * Some USB cardreaders have trouble reading an sdcard's last
266		 * sector in a larger then 1 sector read, since the performance
267		 * impact is negligible we set this flag for all USB disks
268		 */
269		sdev->last_sector_bug = 1;
270
271		/*
272		 * Enable last-sector hacks for single-target devices using
273		 * the Bulk-only transport, unless we already know the
274		 * capacity will be decremented or is correct.
275		 */
276		if (!(us->fflags & (US_FL_FIX_CAPACITY | US_FL_CAPACITY_OK |
277					US_FL_SCM_MULT_TARG)) &&
278				us->protocol == USB_PR_BULK)
279			us->use_last_sector_hacks = 1;
280
281		/* Check if write cache default on flag is set or not */
282		if (us->fflags & US_FL_WRITE_CACHE)
283			sdev->wce_default_on = 1;
284
285		/* A few buggy USB-ATA bridges don't understand FUA */
286		if (us->fflags & US_FL_BROKEN_FUA)
287			sdev->broken_fua = 1;
288
289		/* Some even totally fail to indicate a cache */
290		if (us->fflags & US_FL_ALWAYS_SYNC) {
291			/* don't read caching information */
292			sdev->skip_ms_page_8 = 1;
293			sdev->skip_ms_page_3f = 1;
294			/* assume sync is needed */
295			sdev->wce_default_on = 1;
296		}
297	} else {
298
299		/*
300		 * Non-disk-type devices don't need to blacklist any pages
301		 * or to force 192-byte transfer lengths for MODE SENSE.
302		 * But they do need to use MODE SENSE(10).
303		 */
304		sdev->use_10_for_ms = 1;
305
306		/* Some (fake) usb cdrom devices don't like READ_DISC_INFO */
307		if (us->fflags & US_FL_NO_READ_DISC_INFO)
308			sdev->no_read_disc_info = 1;
309	}
310
311	/*
312	 * The CB and CBI transports have no way to pass LUN values
313	 * other than the bits in the second byte of a CDB.  But those
314	 * bits don't get set to the LUN value if the device reports
315	 * scsi_level == 0 (UNKNOWN).  Hence such devices must necessarily
316	 * be single-LUN.
317	 */
318	if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_CBI) &&
319			sdev->scsi_level == SCSI_UNKNOWN)
320		us->max_lun = 0;
321
322	/*
323	 * Some devices choke when they receive a PREVENT-ALLOW MEDIUM
324	 * REMOVAL command, so suppress those commands.
325	 */
326	if (us->fflags & US_FL_NOT_LOCKABLE)
327		sdev->lockable = 0;
328
329	/*
330	 * this is to satisfy the compiler, tho I don't think the 
331	 * return code is ever checked anywhere.
332	 */
333	return 0;
334}
335
336static int target_alloc(struct scsi_target *starget)
337{
338	struct us_data *us = host_to_us(dev_to_shost(starget->dev.parent));
339
340	/*
341	 * Some USB drives don't support REPORT LUNS, even though they
342	 * report a SCSI revision level above 2.  Tell the SCSI layer
343	 * not to issue that command; it will perform a normal sequential
344	 * scan instead.
345	 */
346	starget->no_report_luns = 1;
347
348	/*
349	 * The UFI spec treats the Peripheral Qualifier bits in an
350	 * INQUIRY result as reserved and requires devices to set them
351	 * to 0.  However the SCSI spec requires these bits to be set
352	 * to 3 to indicate when a LUN is not present.
353	 *
354	 * Let the scanning code know if this target merely sets
355	 * Peripheral Device Type to 0x1f to indicate no LUN.
356	 */
357	if (us->subclass == USB_SC_UFI)
358		starget->pdt_1f_for_no_lun = 1;
359
360	return 0;
361}
362
363/* queue a command */
364/* This is always called with scsi_lock(host) held */
365static int queuecommand_lck(struct scsi_cmnd *srb,
366			void (*done)(struct scsi_cmnd *))
367{
 
368	struct us_data *us = host_to_us(srb->device->host);
369
370	/* check for state-transition errors */
371	if (us->srb != NULL) {
372		printk(KERN_ERR "usb-storage: Error in %s: us->srb = %p\n",
373			__func__, us->srb);
374		return SCSI_MLQUEUE_HOST_BUSY;
375	}
376
377	/* fail the command if we are disconnecting */
378	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
379		usb_stor_dbg(us, "Fail command during disconnect\n");
380		srb->result = DID_NO_CONNECT << 16;
381		done(srb);
382		return 0;
383	}
384
385	if ((us->fflags & US_FL_NO_ATA_1X) &&
386			(srb->cmnd[0] == ATA_12 || srb->cmnd[0] == ATA_16)) {
387		memcpy(srb->sense_buffer, usb_stor_sense_invalidCDB,
388		       sizeof(usb_stor_sense_invalidCDB));
389		srb->result = SAM_STAT_CHECK_CONDITION;
390		done(srb);
391		return 0;
392	}
393
394	/* enqueue the command and wake up the control thread */
395	srb->scsi_done = done;
396	us->srb = srb;
397	complete(&us->cmnd_ready);
398
399	return 0;
400}
401
402static DEF_SCSI_QCMD(queuecommand)
403
404/***********************************************************************
405 * Error handling functions
406 ***********************************************************************/
407
408/* Command timeout and abort */
409static int command_abort(struct scsi_cmnd *srb)
410{
411	struct us_data *us = host_to_us(srb->device->host);
412
413	usb_stor_dbg(us, "%s called\n", __func__);
414
415	/*
416	 * us->srb together with the TIMED_OUT, RESETTING, and ABORTING
417	 * bits are protected by the host lock.
418	 */
419	scsi_lock(us_to_host(us));
420
421	/* Is this command still active? */
422	if (us->srb != srb) {
423		scsi_unlock(us_to_host(us));
424		usb_stor_dbg(us, "-- nothing to abort\n");
 
 
 
 
 
 
 
425		return FAILED;
426	}
427
428	/*
429	 * Set the TIMED_OUT bit.  Also set the ABORTING bit, but only if
430	 * a device reset isn't already in progress (to avoid interfering
431	 * with the reset).  Note that we must retain the host lock while
432	 * calling usb_stor_stop_transport(); otherwise it might interfere
433	 * with an auto-reset that begins as soon as we release the lock.
434	 */
435	set_bit(US_FLIDX_TIMED_OUT, &us->dflags);
436	if (!test_bit(US_FLIDX_RESETTING, &us->dflags)) {
437		set_bit(US_FLIDX_ABORTING, &us->dflags);
438		usb_stor_stop_transport(us);
439	}
440	scsi_unlock(us_to_host(us));
441
442	/* Wait for the aborted command to finish */
443	wait_for_completion(&us->notify);
444	return SUCCESS;
445}
446
 
 
 
 
 
 
 
 
447/*
448 * This invokes the transport reset mechanism to reset the state of the
449 * device
450 */
451static int device_reset(struct scsi_cmnd *srb)
452{
453	struct us_data *us = host_to_us(srb->device->host);
454	int result;
455
456	usb_stor_dbg(us, "%s called\n", __func__);
457
 
 
 
458	/* lock the device pointers and do the reset */
459	mutex_lock(&(us->dev_mutex));
460	result = us->transport_reset(us);
461	mutex_unlock(&us->dev_mutex);
462
463	return result < 0 ? FAILED : SUCCESS;
464}
465
466/* Simulate a SCSI bus reset by resetting the device's USB port. */
467static int bus_reset(struct scsi_cmnd *srb)
468{
469	struct us_data *us = host_to_us(srb->device->host);
470	int result;
471
472	usb_stor_dbg(us, "%s called\n", __func__);
473
474	result = usb_stor_port_reset(us);
475	return result < 0 ? FAILED : SUCCESS;
476}
477
478/*
479 * Report a driver-initiated device reset to the SCSI layer.
480 * Calling this for a SCSI-initiated reset is unnecessary but harmless.
481 * The caller must own the SCSI host lock.
482 */
483void usb_stor_report_device_reset(struct us_data *us)
484{
485	int i;
486	struct Scsi_Host *host = us_to_host(us);
487
488	scsi_report_device_reset(host, 0, 0);
489	if (us->fflags & US_FL_SCM_MULT_TARG) {
490		for (i = 1; i < host->max_id; ++i)
491			scsi_report_device_reset(host, 0, i);
492	}
493}
494
495/*
496 * Report a driver-initiated bus reset to the SCSI layer.
497 * Calling this for a SCSI-initiated reset is unnecessary but harmless.
498 * The caller must not own the SCSI host lock.
499 */
500void usb_stor_report_bus_reset(struct us_data *us)
501{
502	struct Scsi_Host *host = us_to_host(us);
503
504	scsi_lock(host);
505	scsi_report_bus_reset(host, 0);
506	scsi_unlock(host);
507}
508
509/***********************************************************************
510 * /proc/scsi/ functions
511 ***********************************************************************/
512
513static int write_info(struct Scsi_Host *host, char *buffer, int length)
514{
515	/* if someone is sending us data, just throw it away */
516	return length;
517}
518
519static int show_info (struct seq_file *m, struct Scsi_Host *host)
520{
521	struct us_data *us = host_to_us(host);
522	const char *string;
523
524	/* print the controller name */
525	seq_printf(m, "   Host scsi%d: usb-storage\n", host->host_no);
526
527	/* print product, vendor, and serial number strings */
528	if (us->pusb_dev->manufacturer)
529		string = us->pusb_dev->manufacturer;
530	else if (us->unusual_dev->vendorName)
531		string = us->unusual_dev->vendorName;
532	else
533		string = "Unknown";
534	seq_printf(m, "       Vendor: %s\n", string);
535	if (us->pusb_dev->product)
536		string = us->pusb_dev->product;
537	else if (us->unusual_dev->productName)
538		string = us->unusual_dev->productName;
539	else
540		string = "Unknown";
541	seq_printf(m, "      Product: %s\n", string);
542	if (us->pusb_dev->serial)
543		string = us->pusb_dev->serial;
544	else
545		string = "None";
546	seq_printf(m, "Serial Number: %s\n", string);
547
548	/* show the protocol and transport */
549	seq_printf(m, "     Protocol: %s\n", us->protocol_name);
550	seq_printf(m, "    Transport: %s\n", us->transport_name);
551
552	/* show the device flags */
553	seq_printf(m, "       Quirks:");
554
555#define US_FLAG(name, value) \
556	if (us->fflags & value) seq_printf(m, " " #name);
557US_DO_ALL_FLAGS
558#undef US_FLAG
559	seq_putc(m, '\n');
560	return 0;
561}
562
563/***********************************************************************
564 * Sysfs interface
565 ***********************************************************************/
566
567/* Output routine for the sysfs max_sectors file */
568static ssize_t max_sectors_show(struct device *dev, struct device_attribute *attr, char *buf)
569{
570	struct scsi_device *sdev = to_scsi_device(dev);
571
572	return sprintf(buf, "%u\n", queue_max_hw_sectors(sdev->request_queue));
573}
574
575/* Input routine for the sysfs max_sectors file */
576static ssize_t max_sectors_store(struct device *dev, struct device_attribute *attr, const char *buf,
577		size_t count)
578{
579	struct scsi_device *sdev = to_scsi_device(dev);
 
580	unsigned short ms;
 
 
 
 
581
582	if (sscanf(buf, "%hu", &ms) > 0) {
583		blk_queue_max_hw_sectors(sdev->request_queue, ms);
584		return count;
585	}
586	return -EINVAL;
 
 
 
 
587}
588static DEVICE_ATTR_RW(max_sectors);
589
590static struct device_attribute *sysfs_device_attr_list[] = {
591	&dev_attr_max_sectors,
592	NULL,
593};
594
 
 
595/*
596 * this defines our host template, with which we'll allocate hosts
597 */
598
599static const struct scsi_host_template usb_stor_host_template = {
600	/* basic userland interface stuff */
601	.name =				"usb-storage",
602	.proc_name =			"usb-storage",
603	.show_info =			show_info,
604	.write_info =			write_info,
605	.info =				host_info,
606
607	/* command interface -- queued only */
608	.queuecommand =			queuecommand,
609
610	/* error and abort handlers */
611	.eh_abort_handler =		command_abort,
612	.eh_device_reset_handler =	device_reset,
613	.eh_bus_reset_handler =		bus_reset,
614
615	/* queue commands only, only one command per LUN */
616	.can_queue =			1,
617
618	/* unknown initiator id */
619	.this_id =			-1,
620
621	.slave_alloc =			slave_alloc,
622	.slave_configure =		slave_configure,
623	.target_alloc =			target_alloc,
624
625	/* lots of sg segments can be handled */
626	.sg_tablesize =			SG_MAX_SEGMENTS,
627
 
 
 
 
 
628
629	/*
630	 * Limit the total size of a transfer to 120 KB.
631	 *
632	 * Some devices are known to choke with anything larger. It seems like
633	 * the problem stems from the fact that original IDE controllers had
634	 * only an 8-bit register to hold the number of sectors in one transfer
635	 * and even those couldn't handle a full 256 sectors.
636	 *
637	 * Because we want to make sure we interoperate with as many devices as
638	 * possible, we will maintain a 240 sector transfer size limit for USB
639	 * Mass Storage devices.
640	 *
641	 * Tests show that other operating have similar limits with Microsoft
642	 * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
643	 * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
644	 * and 2048 for USB3 devices.
645	 */
646	.max_sectors =                  240,
647
648	/* emulated HBA */
649	.emulated =			1,
650
651	/* we do our own delay after a device or bus reset */
652	.skip_settle_delay =		1,
653
654	/* sysfs device attributes */
655	.sdev_attrs =			sysfs_device_attr_list,
656
657	/* module management */
658	.module =			THIS_MODULE
659};
660
661void usb_stor_host_template_init(struct scsi_host_template *sht,
662				 const char *name, struct module *owner)
663{
664	*sht = usb_stor_host_template;
665	sht->name = name;
666	sht->proc_name = name;
667	sht->module = owner;
668}
669EXPORT_SYMBOL_GPL(usb_stor_host_template_init);
670
671/* To Report "Illegal Request: Invalid Field in CDB */
672unsigned char usb_stor_sense_invalidCDB[18] = {
673	[0]	= 0x70,			    /* current error */
674	[2]	= ILLEGAL_REQUEST,	    /* Illegal Request = 0x05 */
675	[7]	= 0x0a,			    /* additional length */
676	[12]	= 0x24			    /* Invalid Field in CDB */
677};
678EXPORT_SYMBOL_GPL(usb_stor_sense_invalidCDB);