xref: /linux/drivers/usb/storage/scsiglue.c (revision 35bb670d65fc0f80c62383ab4f2544cec85ac57a)
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 
host_info(struct Scsi_Host * host)61 static 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 
slave_alloc(struct scsi_device * sdev)67 static 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 
device_configure(struct scsi_device * sdev,struct queue_limits * lim)91 static 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 
target_alloc(struct scsi_target * starget)331 static 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 */
queuecommand_lck(struct scsi_cmnd * srb)360 static 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 
DEF_SCSI_QCMD(queuecommand)396 static DEF_SCSI_QCMD(queuecommand)
397 
398 /***********************************************************************
399  * Error handling functions
400  ***********************************************************************/
401 
402 /* Command timeout and abort */
403 static 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 
command_abort(struct scsi_cmnd * srb)444 static 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  */
device_reset(struct scsi_cmnd * srb)456 static 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. */
bus_reset(struct scsi_cmnd * srb)475 static 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  */
usb_stor_report_device_reset(struct us_data * us)491 void 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  */
usb_stor_report_bus_reset(struct us_data * us)508 void 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 
write_info(struct Scsi_Host * host,char * buffer,int length)521 static 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 
show_info(struct seq_file * m,struct Scsi_Host * host)527 static 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);
565 US_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 */
max_sectors_show(struct device * dev,struct device_attribute * attr,char * buf)576 static 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 */
max_sectors_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)584 static 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 }
605 static DEVICE_ATTR_RW(max_sectors);
606 
607 static struct attribute *usb_sdev_attrs[] = {
608 	&dev_attr_max_sectors.attr,
609 	NULL,
610 };
611 
612 ATTRIBUTE_GROUPS(usb_sdev);
613 
614 /*
615  * this defines our host template, with which we'll allocate hosts
616  */
617 
618 static 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 
usb_stor_host_template_init(struct scsi_host_template * sht,const char * name,struct module * owner)685 void 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 }
693 EXPORT_SYMBOL_GPL(usb_stor_host_template_init);
694 
695 /* To Report "Illegal Request: Invalid Field in CDB */
696 unsigned 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 };
702 EXPORT_SYMBOL_GPL(usb_stor_sense_invalidCDB);
703