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 
host_info(struct Scsi_Host * host)62 static 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 
slave_alloc(struct scsi_device * sdev)68 static 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 
slave_configure(struct scsi_device * sdev)92 static 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 			(bus_to_hcd(us->pusb_dev->bus)->localmem_pool != NULL))
140 		blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_HIGH);
141 
142 	/*
143 	 * We can't put these settings in slave_alloc() because that gets
144 	 * called before the device type is known.  Consequently these
145 	 * settings can't be overridden via the scsi devinfo mechanism.
146 	 */
147 	if (sdev->type == TYPE_DISK) {
148 
149 		/*
150 		 * Some vendors seem to put the READ CAPACITY bug into
151 		 * all their devices -- primarily makers of cell phones
152 		 * and digital cameras.  Since these devices always use
153 		 * flash media and can be expected to have an even number
154 		 * of sectors, we will always enable the CAPACITY_HEURISTICS
155 		 * flag unless told otherwise.
156 		 */
157 		switch (le16_to_cpu(us->pusb_dev->descriptor.idVendor)) {
158 		case VENDOR_ID_NOKIA:
159 		case VENDOR_ID_NIKON:
160 		case VENDOR_ID_PENTAX:
161 		case VENDOR_ID_MOTOROLA:
162 			if (!(us->fflags & (US_FL_FIX_CAPACITY |
163 					US_FL_CAPACITY_OK)))
164 				us->fflags |= US_FL_CAPACITY_HEURISTICS;
165 			break;
166 		}
167 
168 		/*
169 		 * Disk-type devices use MODE SENSE(6) if the protocol
170 		 * (SubClass) is Transparent SCSI, otherwise they use
171 		 * MODE SENSE(10).
172 		 */
173 		if (us->subclass != USB_SC_SCSI && us->subclass != USB_SC_CYP_ATACB)
174 			sdev->use_10_for_ms = 1;
175 
176 		/*
177 		 *Many disks only accept MODE SENSE transfer lengths of
178 		 * 192 bytes (that's what Windows uses).
179 		 */
180 		sdev->use_192_bytes_for_3f = 1;
181 
182 		/*
183 		 * Some devices don't like MODE SENSE with page=0x3f,
184 		 * which is the command used for checking if a device
185 		 * is write-protected.  Now that we tell the sd driver
186 		 * to do a 192-byte transfer with this command the
187 		 * majority of devices work fine, but a few still can't
188 		 * handle it.  The sd driver will simply assume those
189 		 * devices are write-enabled.
190 		 */
191 		if (us->fflags & US_FL_NO_WP_DETECT)
192 			sdev->skip_ms_page_3f = 1;
193 
194 		/*
195 		 * A number of devices have problems with MODE SENSE for
196 		 * page x08, so we will skip it.
197 		 */
198 		sdev->skip_ms_page_8 = 1;
199 
200 		/*
201 		 * Some devices don't handle VPD pages correctly, so skip vpd
202 		 * pages if not forced by SCSI layer.
203 		 */
204 		sdev->skip_vpd_pages = !sdev->try_vpd_pages;
205 
206 		/* Do not attempt to use REPORT SUPPORTED OPERATION CODES */
207 		sdev->no_report_opcodes = 1;
208 
209 		/* Do not attempt to use WRITE SAME */
210 		sdev->no_write_same = 1;
211 
212 		/*
213 		 * Some disks return the total number of blocks in response
214 		 * to READ CAPACITY rather than the highest block number.
215 		 * If this device makes that mistake, tell the sd driver.
216 		 */
217 		if (us->fflags & US_FL_FIX_CAPACITY)
218 			sdev->fix_capacity = 1;
219 
220 		/*
221 		 * A few disks have two indistinguishable version, one of
222 		 * which reports the correct capacity and the other does not.
223 		 * The sd driver has to guess which is the case.
224 		 */
225 		if (us->fflags & US_FL_CAPACITY_HEURISTICS)
226 			sdev->guess_capacity = 1;
227 
228 		/* Some devices cannot handle READ_CAPACITY_16 */
229 		if (us->fflags & US_FL_NO_READ_CAPACITY_16)
230 			sdev->no_read_capacity_16 = 1;
231 
232 		/*
233 		 * Many devices do not respond properly to READ_CAPACITY_16.
234 		 * Tell the SCSI layer to try READ_CAPACITY_10 first.
235 		 * However some USB 3.0 drive enclosures return capacity
236 		 * modulo 2TB. Those must use READ_CAPACITY_16
237 		 */
238 		if (!(us->fflags & US_FL_NEEDS_CAP16))
239 			sdev->try_rc_10_first = 1;
240 
241 		/*
242 		 * assume SPC3 or latter devices support sense size > 18
243 		 * unless US_FL_BAD_SENSE quirk is specified.
244 		 */
245 		if (sdev->scsi_level > SCSI_SPC_2 &&
246 		    !(us->fflags & US_FL_BAD_SENSE))
247 			us->fflags |= US_FL_SANE_SENSE;
248 
249 		/*
250 		 * USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
251 		 * Hardware Error) when any low-level error occurs,
252 		 * recoverable or not.  Setting this flag tells the SCSI
253 		 * midlayer to retry such commands, which frequently will
254 		 * succeed and fix the error.  The worst this can lead to
255 		 * is an occasional series of retries that will all fail.
256 		 */
257 		sdev->retry_hwerror = 1;
258 
259 		/*
260 		 * USB disks should allow restart.  Some drives spin down
261 		 * automatically, requiring a START-STOP UNIT command.
262 		 */
263 		sdev->allow_restart = 1;
264 
265 		/*
266 		 * Some USB cardreaders have trouble reading an sdcard's last
267 		 * sector in a larger then 1 sector read, since the performance
268 		 * impact is negligible we set this flag for all USB disks
269 		 */
270 		sdev->last_sector_bug = 1;
271 
272 		/*
273 		 * Enable last-sector hacks for single-target devices using
274 		 * the Bulk-only transport, unless we already know the
275 		 * capacity will be decremented or is correct.
276 		 */
277 		if (!(us->fflags & (US_FL_FIX_CAPACITY | US_FL_CAPACITY_OK |
278 					US_FL_SCM_MULT_TARG)) &&
279 				us->protocol == USB_PR_BULK)
280 			us->use_last_sector_hacks = 1;
281 
282 		/* Check if write cache default on flag is set or not */
283 		if (us->fflags & US_FL_WRITE_CACHE)
284 			sdev->wce_default_on = 1;
285 
286 		/* A few buggy USB-ATA bridges don't understand FUA */
287 		if (us->fflags & US_FL_BROKEN_FUA)
288 			sdev->broken_fua = 1;
289 
290 		/* Some even totally fail to indicate a cache */
291 		if (us->fflags & US_FL_ALWAYS_SYNC) {
292 			/* don't read caching information */
293 			sdev->skip_ms_page_8 = 1;
294 			sdev->skip_ms_page_3f = 1;
295 			/* assume sync is needed */
296 			sdev->wce_default_on = 1;
297 		}
298 	} else {
299 
300 		/*
301 		 * Non-disk-type devices don't need to ignore any pages
302 		 * or to force 192-byte transfer lengths for MODE SENSE.
303 		 * But they do need to use MODE SENSE(10).
304 		 */
305 		sdev->use_10_for_ms = 1;
306 
307 		/* Some (fake) usb cdrom devices don't like READ_DISC_INFO */
308 		if (us->fflags & US_FL_NO_READ_DISC_INFO)
309 			sdev->no_read_disc_info = 1;
310 	}
311 
312 	/*
313 	 * The CB and CBI transports have no way to pass LUN values
314 	 * other than the bits in the second byte of a CDB.  But those
315 	 * bits don't get set to the LUN value if the device reports
316 	 * scsi_level == 0 (UNKNOWN).  Hence such devices must necessarily
317 	 * be single-LUN.
318 	 */
319 	if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_CBI) &&
320 			sdev->scsi_level == SCSI_UNKNOWN)
321 		us->max_lun = 0;
322 
323 	/*
324 	 * Some devices choke when they receive a PREVENT-ALLOW MEDIUM
325 	 * REMOVAL command, so suppress those commands.
326 	 */
327 	if (us->fflags & US_FL_NOT_LOCKABLE)
328 		sdev->lockable = 0;
329 
330 	/*
331 	 * this is to satisfy the compiler, tho I don't think the
332 	 * return code is ever checked anywhere.
333 	 */
334 	return 0;
335 }
336 
target_alloc(struct scsi_target * starget)337 static int target_alloc(struct scsi_target *starget)
338 {
339 	struct us_data *us = host_to_us(dev_to_shost(starget->dev.parent));
340 
341 	/*
342 	 * Some USB drives don't support REPORT LUNS, even though they
343 	 * report a SCSI revision level above 2.  Tell the SCSI layer
344 	 * not to issue that command; it will perform a normal sequential
345 	 * scan instead.
346 	 */
347 	starget->no_report_luns = 1;
348 
349 	/*
350 	 * The UFI spec treats the Peripheral Qualifier bits in an
351 	 * INQUIRY result as reserved and requires devices to set them
352 	 * to 0.  However the SCSI spec requires these bits to be set
353 	 * to 3 to indicate when a LUN is not present.
354 	 *
355 	 * Let the scanning code know if this target merely sets
356 	 * Peripheral Device Type to 0x1f to indicate no LUN.
357 	 */
358 	if (us->subclass == USB_SC_UFI)
359 		starget->pdt_1f_for_no_lun = 1;
360 
361 	return 0;
362 }
363 
364 /* queue a command */
365 /* This is always called with scsi_lock(host) held */
queuecommand_lck(struct scsi_cmnd * srb)366 static int queuecommand_lck(struct scsi_cmnd *srb)
367 {
368 	void (*done)(struct scsi_cmnd *) = scsi_done;
369 	struct us_data *us = host_to_us(srb->device->host);
370 
371 	/* check for state-transition errors */
372 	if (us->srb != NULL) {
373 		dev_err(&us->pusb_intf->dev,
374 			"Error in %s: us->srb = %p\n", __func__, us->srb);
375 		return SCSI_MLQUEUE_HOST_BUSY;
376 	}
377 
378 	/* fail the command if we are disconnecting */
379 	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
380 		usb_stor_dbg(us, "Fail command during disconnect\n");
381 		srb->result = DID_NO_CONNECT << 16;
382 		done(srb);
383 		return 0;
384 	}
385 
386 	if ((us->fflags & US_FL_NO_ATA_1X) &&
387 			(srb->cmnd[0] == ATA_12 || srb->cmnd[0] == ATA_16)) {
388 		memcpy(srb->sense_buffer, usb_stor_sense_invalidCDB,
389 		       sizeof(usb_stor_sense_invalidCDB));
390 		srb->result = SAM_STAT_CHECK_CONDITION;
391 		done(srb);
392 		return 0;
393 	}
394 
395 	/* enqueue the command and wake up the control thread */
396 	us->srb = srb;
397 	complete(&us->cmnd_ready);
398 
399 	return 0;
400 }
401 
DEF_SCSI_QCMD(queuecommand)402 static DEF_SCSI_QCMD(queuecommand)
403 
404 /***********************************************************************
405  * Error handling functions
406  ***********************************************************************/
407 
408 /* Command timeout and abort */
409 static 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  */
device_reset(struct scsi_cmnd * srb)451 static 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. */
bus_reset(struct scsi_cmnd * srb)467 static 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  */
usb_stor_report_device_reset(struct us_data * us)483 void 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  */
usb_stor_report_bus_reset(struct us_data * us)500 void 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 
write_info(struct Scsi_Host * host,char * buffer,int length)513 static 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 
show_info(struct seq_file * m,struct Scsi_Host * host)519 static 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);
557 US_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 */
max_sectors_show(struct device * dev,struct device_attribute * attr,char * buf)568 static 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 */
max_sectors_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)576 static 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 }
588 static DEVICE_ATTR_RW(max_sectors);
589 
590 static struct attribute *usb_sdev_attrs[] = {
591 	&dev_attr_max_sectors.attr,
592 	NULL,
593 };
594 
595 ATTRIBUTE_GROUPS(usb_sdev);
596 
597 /*
598  * this defines our host template, with which we'll allocate hosts
599  */
600 
601 static const struct scsi_host_template usb_stor_host_template = {
602 	/* basic userland interface stuff */
603 	.name =				"usb-storage",
604 	.proc_name =			"usb-storage",
605 	.show_info =			show_info,
606 	.write_info =			write_info,
607 	.info =				host_info,
608 
609 	/* command interface -- queued only */
610 	.queuecommand =			queuecommand,
611 
612 	/* error and abort handlers */
613 	.eh_abort_handler =		command_abort,
614 	.eh_device_reset_handler =	device_reset,
615 	.eh_bus_reset_handler =		bus_reset,
616 
617 	/* queue commands only, only one command per LUN */
618 	.can_queue =			1,
619 
620 	/* unknown initiator id */
621 	.this_id =			-1,
622 
623 	.slave_alloc =			slave_alloc,
624 	.slave_configure =		slave_configure,
625 	.target_alloc =			target_alloc,
626 
627 	/* lots of sg segments can be handled */
628 	.sg_tablesize =			SG_MAX_SEGMENTS,
629 
630 
631 	/*
632 	 * Limit the total size of a transfer to 120 KB.
633 	 *
634 	 * Some devices are known to choke with anything larger. It seems like
635 	 * the problem stems from the fact that original IDE controllers had
636 	 * only an 8-bit register to hold the number of sectors in one transfer
637 	 * and even those couldn't handle a full 256 sectors.
638 	 *
639 	 * Because we want to make sure we interoperate with as many devices as
640 	 * possible, we will maintain a 240 sector transfer size limit for USB
641 	 * Mass Storage devices.
642 	 *
643 	 * Tests show that other operating have similar limits with Microsoft
644 	 * Windows 7 limiting transfers to 128 sectors for both USB2 and USB3
645 	 * and Apple Mac OS X 10.11 limiting transfers to 256 sectors for USB2
646 	 * and 2048 for USB3 devices.
647 	 */
648 	.max_sectors =                  240,
649 
650 	/* emulated HBA */
651 	.emulated =			1,
652 
653 	/* we do our own delay after a device or bus reset */
654 	.skip_settle_delay =		1,
655 
656 	/* sysfs device attributes */
657 	.sdev_groups =			usb_sdev_groups,
658 
659 	/* module management */
660 	.module =			THIS_MODULE
661 };
662 
usb_stor_host_template_init(struct scsi_host_template * sht,const char * name,struct module * owner)663 void usb_stor_host_template_init(struct scsi_host_template *sht,
664 				 const char *name, struct module *owner)
665 {
666 	*sht = usb_stor_host_template;
667 	sht->name = name;
668 	sht->proc_name = name;
669 	sht->module = owner;
670 }
671 EXPORT_SYMBOL_GPL(usb_stor_host_template_init);
672 
673 /* To Report "Illegal Request: Invalid Field in CDB */
674 unsigned char usb_stor_sense_invalidCDB[18] = {
675 	[0]	= 0x70,			    /* current error */
676 	[2]	= ILLEGAL_REQUEST,	    /* Illegal Request = 0x05 */
677 	[7]	= 0x0a,			    /* additional length */
678 	[12]	= 0x24			    /* Invalid Field in CDB */
679 };
680 EXPORT_SYMBOL_GPL(usb_stor_sense_invalidCDB);
681