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1 /*
2  * Driver for USB Mass Storage compliant devices
3  * SCSI layer glue code
4  *
5  * Current development and maintenance by:
6  *   (c) 1999-2002 Matthew Dharm (mdharm-usb@one-eyed-alien.net)
7  *
8  * Developed with the assistance of:
9  *   (c) 2000 David L. Brown, Jr. (usb-storage@davidb.org)
10  *   (c) 2000 Stephen J. Gowdy (SGowdy@lbl.gov)
11  *
12  * Initial work by:
13  *   (c) 1999 Michael Gee (michael@linuxspecific.com)
14  *
15  * This driver is based on the 'USB Mass Storage Class' document. This
16  * describes in detail the protocol used to communicate with such
17  * devices.  Clearly, the designers had SCSI and ATAPI commands in
18  * mind when they created this document.  The commands are all very
19  * similar to commands in the SCSI-II and ATAPI specifications.
20  *
21  * It is important to note that in a number of cases this class
22  * exhibits class-specific exemptions from the USB specification.
23  * Notably the usage of NAK, STALL and ACK differs from the norm, in
24  * that they are used to communicate wait, failed and OK on commands.
25  *
26  * Also, for certain devices, the interrupt endpoint is used to convey
27  * status of a command.
28  *
29  * Please see http://www.one-eyed-alien.net/~mdharm/linux-usb for more
30  * information about this driver.
31  *
32  * This program is free software; you can redistribute it and/or modify it
33  * under the terms of the GNU General Public License as published by the
34  * Free Software Foundation; either version 2, or (at your option) any
35  * later version.
36  *
37  * This program is distributed in the hope that it will be useful, but
38  * WITHOUT ANY WARRANTY; without even the implied warranty of
39  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
40  * General Public License for more details.
41  *
42  * You should have received a copy of the GNU General Public License along
43  * with this program; if not, write to the Free Software Foundation, Inc.,
44  * 675 Mass Ave, Cambridge, MA 02139, USA.
45  */
46 
47 #include <linux/module.h>
48 #include <linux/mutex.h>
49 
50 #include <scsi/scsi.h>
51 #include <scsi/scsi_cmnd.h>
52 #include <scsi/scsi_devinfo.h>
53 #include <scsi/scsi_device.h>
54 #include <scsi/scsi_eh.h>
55 
56 #include "usb.h"
57 #include "scsiglue.h"
58 #include "debug.h"
59 #include "transport.h"
60 #include "protocol.h"
61 
62 /*
63  * Vendor IDs for companies that seem to include the READ CAPACITY bug
64  * in all their devices
65  */
66 #define VENDOR_ID_NOKIA		0x0421
67 #define VENDOR_ID_NIKON		0x04b0
68 #define VENDOR_ID_PENTAX	0x0a17
69 #define VENDOR_ID_MOTOROLA	0x22b8
70 
71 /***********************************************************************
72  * Host functions
73  ***********************************************************************/
74 
host_info(struct Scsi_Host * host)75 static const char* host_info(struct Scsi_Host *host)
76 {
77 	struct us_data *us = host_to_us(host);
78 	return us->scsi_name;
79 }
80 
slave_alloc(struct scsi_device * sdev)81 static int slave_alloc (struct scsi_device *sdev)
82 {
83 	struct us_data *us = host_to_us(sdev->host);
84 
85 	/*
86 	 * Set the INQUIRY transfer length to 36.  We don't use any of
87 	 * the extra data and many devices choke if asked for more or
88 	 * less than 36 bytes.
89 	 */
90 	sdev->inquiry_len = 36;
91 
92 	/*
93 	 * Some host controllers may have alignment requirements.
94 	 * We'll play it safe by requiring 512-byte alignment always.
95 	 */
96 	blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
97 
98 	/* Tell the SCSI layer if we know there is more than one LUN */
99 	if (us->protocol == USB_PR_BULK && us->max_lun > 0)
100 		sdev->sdev_bflags |= BLIST_FORCELUN;
101 
102 	return 0;
103 }
104 
slave_configure(struct scsi_device * sdev)105 static int slave_configure(struct scsi_device *sdev)
106 {
107 	struct us_data *us = host_to_us(sdev->host);
108 
109 	/*
110 	 * Many devices have trouble transferring more than 32KB at a time,
111 	 * while others have trouble with more than 64K. At this time we
112 	 * are limiting both to 32K (64 sectores).
113 	 */
114 	if (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
115 		unsigned int max_sectors = 64;
116 
117 		if (us->fflags & US_FL_MAX_SECTORS_MIN)
118 			max_sectors = PAGE_SIZE >> 9;
119 		if (queue_max_hw_sectors(sdev->request_queue) > max_sectors)
120 			blk_queue_max_hw_sectors(sdev->request_queue,
121 					      max_sectors);
122 	} else if (sdev->type == TYPE_TAPE) {
123 		/*
124 		 * Tapes need much higher max_sector limits, so just
125 		 * raise it to the maximum possible (4 GB / 512) and
126 		 * let the queue segment size sort out the real limit.
127 		 */
128 		blk_queue_max_hw_sectors(sdev->request_queue, 0x7FFFFF);
129 	} else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
130 		/*
131 		 * USB3 devices will be limited to 2048 sectors. This gives us
132 		 * better throughput on most devices.
133 		 */
134 		blk_queue_max_hw_sectors(sdev->request_queue, 2048);
135 	}
136 
137 	/*
138 	 * Some USB host controllers can't do DMA; they have to use PIO.
139 	 * They indicate this by setting their dma_mask to NULL.  For
140 	 * such controllers we need to make sure the block layer sets
141 	 * up bounce buffers in addressable memory.
142 	 */
143 	if (!us->pusb_dev->bus->controller->dma_mask)
144 		blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_HIGH);
145 
146 	/*
147 	 * We can't put these settings in slave_alloc() because that gets
148 	 * called before the device type is known.  Consequently these
149 	 * settings can't be overridden via the scsi devinfo mechanism.
150 	 */
151 	if (sdev->type == TYPE_DISK) {
152 
153 		/*
154 		 * Some vendors seem to put the READ CAPACITY bug into
155 		 * all their devices -- primarily makers of cell phones
156 		 * and digital cameras.  Since these devices always use
157 		 * flash media and can be expected to have an even number
158 		 * of sectors, we will always enable the CAPACITY_HEURISTICS
159 		 * flag unless told otherwise.
160 		 */
161 		switch (le16_to_cpu(us->pusb_dev->descriptor.idVendor)) {
162 		case VENDOR_ID_NOKIA:
163 		case VENDOR_ID_NIKON:
164 		case VENDOR_ID_PENTAX:
165 		case VENDOR_ID_MOTOROLA:
166 			if (!(us->fflags & (US_FL_FIX_CAPACITY |
167 					US_FL_CAPACITY_OK)))
168 				us->fflags |= US_FL_CAPACITY_HEURISTICS;
169 			break;
170 		}
171 
172 		/*
173 		 * Disk-type devices use MODE SENSE(6) if the protocol
174 		 * (SubClass) is Transparent SCSI, otherwise they use
175 		 * MODE SENSE(10).
176 		 */
177 		if (us->subclass != USB_SC_SCSI && us->subclass != USB_SC_CYP_ATACB)
178 			sdev->use_10_for_ms = 1;
179 
180 		/*
181 		 *Many disks only accept MODE SENSE transfer lengths of
182 		 * 192 bytes (that's what Windows uses).
183 		 */
184 		sdev->use_192_bytes_for_3f = 1;
185 
186 		/*
187 		 * Some devices don't like MODE SENSE with page=0x3f,
188 		 * which is the command used for checking if a device
189 		 * is write-protected.  Now that we tell the sd driver
190 		 * to do a 192-byte transfer with this command the
191 		 * majority of devices work fine, but a few still can't
192 		 * handle it.  The sd driver will simply assume those
193 		 * devices are write-enabled.
194 		 */
195 		if (us->fflags & US_FL_NO_WP_DETECT)
196 			sdev->skip_ms_page_3f = 1;
197 
198 		/*
199 		 * A number of devices have problems with MODE SENSE for
200 		 * page x08, so we will skip it.
201 		 */
202 		sdev->skip_ms_page_8 = 1;
203 
204 		/* Some devices don't handle VPD pages correctly */
205 		sdev->skip_vpd_pages = 1;
206 
207 		/* Do not attempt to use REPORT SUPPORTED OPERATION CODES */
208 		sdev->no_report_opcodes = 1;
209 
210 		/* Do not attempt to use WRITE SAME */
211 		sdev->no_write_same = 1;
212 
213 		/*
214 		 * Some disks return the total number of blocks in response
215 		 * to READ CAPACITY rather than the highest block number.
216 		 * If this device makes that mistake, tell the sd driver.
217 		 */
218 		if (us->fflags & US_FL_FIX_CAPACITY)
219 			sdev->fix_capacity = 1;
220 
221 		/*
222 		 * A few disks have two indistinguishable version, one of
223 		 * which reports the correct capacity and the other does not.
224 		 * The sd driver has to guess which is the case.
225 		 */
226 		if (us->fflags & US_FL_CAPACITY_HEURISTICS)
227 			sdev->guess_capacity = 1;
228 
229 		/* Some devices cannot handle READ_CAPACITY_16 */
230 		if (us->fflags & US_FL_NO_READ_CAPACITY_16)
231 			sdev->no_read_capacity_16 = 1;
232 
233 		/*
234 		 * Many devices do not respond properly to READ_CAPACITY_16.
235 		 * Tell the SCSI layer to try READ_CAPACITY_10 first.
236 		 * However some USB 3.0 drive enclosures return capacity
237 		 * modulo 2TB. Those must use READ_CAPACITY_16
238 		 */
239 		if (!(us->fflags & US_FL_NEEDS_CAP16))
240 			sdev->try_rc_10_first = 1;
241 
242 		/*
243 		 * assume SPC3 or latter devices support sense size > 18
244 		 * unless US_FL_BAD_SENSE quirk is specified.
245 		 */
246 		if (sdev->scsi_level > SCSI_SPC_2 &&
247 		    !(us->fflags & US_FL_BAD_SENSE))
248 			us->fflags |= US_FL_SANE_SENSE;
249 
250 		/*
251 		 * USB-IDE bridges tend to report SK = 0x04 (Non-recoverable
252 		 * Hardware Error) when any low-level error occurs,
253 		 * recoverable or not.  Setting this flag tells the SCSI
254 		 * midlayer to retry such commands, which frequently will
255 		 * succeed and fix the error.  The worst this can lead to
256 		 * is an occasional series of retries that will all fail.
257 		 */
258 		sdev->retry_hwerror = 1;
259 
260 		/*
261 		 * USB disks should allow restart.  Some drives spin down
262 		 * automatically, requiring a START-STOP UNIT command.
263 		 */
264 		sdev->allow_restart = 1;
265 
266 		/*
267 		 * Some USB cardreaders have trouble reading an sdcard's last
268 		 * sector in a larger then 1 sector read, since the performance
269 		 * impact is negligible we set this flag for all USB disks
270 		 */
271 		sdev->last_sector_bug = 1;
272 
273 		/*
274 		 * Enable last-sector hacks for single-target devices using
275 		 * the Bulk-only transport, unless we already know the
276 		 * capacity will be decremented or is correct.
277 		 */
278 		if (!(us->fflags & (US_FL_FIX_CAPACITY | US_FL_CAPACITY_OK |
279 					US_FL_SCM_MULT_TARG)) &&
280 				us->protocol == USB_PR_BULK)
281 			us->use_last_sector_hacks = 1;
282 
283 		/* Check if write cache default on flag is set or not */
284 		if (us->fflags & US_FL_WRITE_CACHE)
285 			sdev->wce_default_on = 1;
286 
287 		/* A few buggy USB-ATA bridges don't understand FUA */
288 		if (us->fflags & US_FL_BROKEN_FUA)
289 			sdev->broken_fua = 1;
290 
291 		/* Some even totally fail to indicate a cache */
292 		if (us->fflags & US_FL_ALWAYS_SYNC) {
293 			/* don't read caching information */
294 			sdev->skip_ms_page_8 = 1;
295 			sdev->skip_ms_page_3f = 1;
296 			/* assume sync is needed */
297 			sdev->wce_default_on = 1;
298 		}
299 	} else {
300 
301 		/*
302 		 * Non-disk-type devices don't need to blacklist any pages
303 		 * or to force 192-byte transfer lengths for MODE SENSE.
304 		 * But they do need to use MODE SENSE(10).
305 		 */
306 		sdev->use_10_for_ms = 1;
307 
308 		/* Some (fake) usb cdrom devices don't like READ_DISC_INFO */
309 		if (us->fflags & US_FL_NO_READ_DISC_INFO)
310 			sdev->no_read_disc_info = 1;
311 	}
312 
313 	/*
314 	 * The CB and CBI transports have no way to pass LUN values
315 	 * other than the bits in the second byte of a CDB.  But those
316 	 * bits don't get set to the LUN value if the device reports
317 	 * scsi_level == 0 (UNKNOWN).  Hence such devices must necessarily
318 	 * be single-LUN.
319 	 */
320 	if ((us->protocol == USB_PR_CB || us->protocol == USB_PR_CBI) &&
321 			sdev->scsi_level == SCSI_UNKNOWN)
322 		us->max_lun = 0;
323 
324 	/*
325 	 * Some devices choke when they receive a PREVENT-ALLOW MEDIUM
326 	 * REMOVAL command, so suppress those commands.
327 	 */
328 	if (us->fflags & US_FL_NOT_LOCKABLE)
329 		sdev->lockable = 0;
330 
331 	/*
332 	 * this is to satisfy the compiler, tho I don't think the
333 	 * return code is ever checked anywhere.
334 	 */
335 	return 0;
336 }
337 
target_alloc(struct scsi_target * starget)338 static int target_alloc(struct scsi_target *starget)
339 {
340 	struct us_data *us = host_to_us(dev_to_shost(starget->dev.parent));
341 
342 	/*
343 	 * Some USB drives don't support REPORT LUNS, even though they
344 	 * report a SCSI revision level above 2.  Tell the SCSI layer
345 	 * not to issue that command; it will perform a normal sequential
346 	 * scan instead.
347 	 */
348 	starget->no_report_luns = 1;
349 
350 	/*
351 	 * The UFI spec treats the Peripheral Qualifier bits in an
352 	 * INQUIRY result as reserved and requires devices to set them
353 	 * to 0.  However the SCSI spec requires these bits to be set
354 	 * to 3 to indicate when a LUN is not present.
355 	 *
356 	 * Let the scanning code know if this target merely sets
357 	 * Peripheral Device Type to 0x1f to indicate no LUN.
358 	 */
359 	if (us->subclass == USB_SC_UFI)
360 		starget->pdt_1f_for_no_lun = 1;
361 
362 	return 0;
363 }
364 
365 /* queue a command */
366 /* This is always called with scsi_lock(host) held */
queuecommand_lck(struct scsi_cmnd * srb,void (* done)(struct scsi_cmnd *))367 static int queuecommand_lck(struct scsi_cmnd *srb,
368 			void (*done)(struct scsi_cmnd *))
369 {
370 	struct us_data *us = host_to_us(srb->device->host);
371 
372 	/* check for state-transition errors */
373 	if (us->srb != NULL) {
374 		printk(KERN_ERR USB_STORAGE "Error in %s: us->srb = %p\n",
375 			__func__, us->srb);
376 		return SCSI_MLQUEUE_HOST_BUSY;
377 	}
378 
379 	/* fail the command if we are disconnecting */
380 	if (test_bit(US_FLIDX_DISCONNECTING, &us->dflags)) {
381 		usb_stor_dbg(us, "Fail command during disconnect\n");
382 		srb->result = DID_NO_CONNECT << 16;
383 		done(srb);
384 		return 0;
385 	}
386 
387 	if ((us->fflags & US_FL_NO_ATA_1X) &&
388 			(srb->cmnd[0] == ATA_12 || srb->cmnd[0] == ATA_16)) {
389 		memcpy(srb->sense_buffer, usb_stor_sense_invalidCDB,
390 		       sizeof(usb_stor_sense_invalidCDB));
391 		srb->result = SAM_STAT_CHECK_CONDITION;
392 		done(srb);
393 		return 0;
394 	}
395 
396 	/* enqueue the command and wake up the control thread */
397 	srb->scsi_done = done;
398 	us->srb = srb;
399 	complete(&us->cmnd_ready);
400 
401 	return 0;
402 }
403 
DEF_SCSI_QCMD(queuecommand)404 static DEF_SCSI_QCMD(queuecommand)
405 
406 /***********************************************************************
407  * Error handling functions
408  ***********************************************************************/
409 
410 /* Command timeout and abort */
411 static int command_abort(struct scsi_cmnd *srb)
412 {
413 	struct us_data *us = host_to_us(srb->device->host);
414 
415 	usb_stor_dbg(us, "%s called\n", __func__);
416 
417 	/*
418 	 * us->srb together with the TIMED_OUT, RESETTING, and ABORTING
419 	 * bits are protected by the host lock.
420 	 */
421 	scsi_lock(us_to_host(us));
422 
423 	/* Is this command still active? */
424 	if (us->srb != srb) {
425 		scsi_unlock(us_to_host(us));
426 		usb_stor_dbg(us, "-- nothing to abort\n");
427 		return FAILED;
428 	}
429 
430 	/*
431 	 * Set the TIMED_OUT bit.  Also set the ABORTING bit, but only if
432 	 * a device reset isn't already in progress (to avoid interfering
433 	 * with the reset).  Note that we must retain the host lock while
434 	 * calling usb_stor_stop_transport(); otherwise it might interfere
435 	 * with an auto-reset that begins as soon as we release the lock.
436 	 */
437 	set_bit(US_FLIDX_TIMED_OUT, &us->dflags);
438 	if (!test_bit(US_FLIDX_RESETTING, &us->dflags)) {
439 		set_bit(US_FLIDX_ABORTING, &us->dflags);
440 		usb_stor_stop_transport(us);
441 	}
442 	scsi_unlock(us_to_host(us));
443 
444 	/* Wait for the aborted command to finish */
445 	wait_for_completion(&us->notify);
446 	return SUCCESS;
447 }
448 
449 /*
450  * This invokes the transport reset mechanism to reset the state of the
451  * device
452  */
device_reset(struct scsi_cmnd * srb)453 static int device_reset(struct scsi_cmnd *srb)
454 {
455 	struct us_data *us = host_to_us(srb->device->host);
456 	int result;
457 
458 	usb_stor_dbg(us, "%s called\n", __func__);
459 
460 	/* lock the device pointers and do the reset */
461 	mutex_lock(&(us->dev_mutex));
462 	result = us->transport_reset(us);
463 	mutex_unlock(&us->dev_mutex);
464 
465 	return result < 0 ? FAILED : SUCCESS;
466 }
467 
468 /* Simulate a SCSI bus reset by resetting the device's USB port. */
bus_reset(struct scsi_cmnd * srb)469 static int bus_reset(struct scsi_cmnd *srb)
470 {
471 	struct us_data *us = host_to_us(srb->device->host);
472 	int result;
473 
474 	usb_stor_dbg(us, "%s called\n", __func__);
475 
476 	result = usb_stor_port_reset(us);
477 	return result < 0 ? FAILED : SUCCESS;
478 }
479 
480 /*
481  * Report a driver-initiated device reset to the SCSI layer.
482  * Calling this for a SCSI-initiated reset is unnecessary but harmless.
483  * The caller must own the SCSI host lock.
484  */
usb_stor_report_device_reset(struct us_data * us)485 void usb_stor_report_device_reset(struct us_data *us)
486 {
487 	int i;
488 	struct Scsi_Host *host = us_to_host(us);
489 
490 	scsi_report_device_reset(host, 0, 0);
491 	if (us->fflags & US_FL_SCM_MULT_TARG) {
492 		for (i = 1; i < host->max_id; ++i)
493 			scsi_report_device_reset(host, 0, i);
494 	}
495 }
496 
497 /*
498  * Report a driver-initiated bus reset to the SCSI layer.
499  * Calling this for a SCSI-initiated reset is unnecessary but harmless.
500  * The caller must not own the SCSI host lock.
501  */
usb_stor_report_bus_reset(struct us_data * us)502 void usb_stor_report_bus_reset(struct us_data *us)
503 {
504 	struct Scsi_Host *host = us_to_host(us);
505 
506 	scsi_lock(host);
507 	scsi_report_bus_reset(host, 0);
508 	scsi_unlock(host);
509 }
510 
511 /***********************************************************************
512  * /proc/scsi/ functions
513  ***********************************************************************/
514 
write_info(struct Scsi_Host * host,char * buffer,int length)515 static int write_info(struct Scsi_Host *host, char *buffer, int length)
516 {
517 	/* if someone is sending us data, just throw it away */
518 	return length;
519 }
520 
show_info(struct seq_file * m,struct Scsi_Host * host)521 static int show_info (struct seq_file *m, struct Scsi_Host *host)
522 {
523 	struct us_data *us = host_to_us(host);
524 	const char *string;
525 
526 	/* print the controller name */
527 	seq_printf(m, "   Host scsi%d: usb-storage\n", host->host_no);
528 
529 	/* print product, vendor, and serial number strings */
530 	if (us->pusb_dev->manufacturer)
531 		string = us->pusb_dev->manufacturer;
532 	else if (us->unusual_dev->vendorName)
533 		string = us->unusual_dev->vendorName;
534 	else
535 		string = "Unknown";
536 	seq_printf(m, "       Vendor: %s\n", string);
537 	if (us->pusb_dev->product)
538 		string = us->pusb_dev->product;
539 	else if (us->unusual_dev->productName)
540 		string = us->unusual_dev->productName;
541 	else
542 		string = "Unknown";
543 	seq_printf(m, "      Product: %s\n", string);
544 	if (us->pusb_dev->serial)
545 		string = us->pusb_dev->serial;
546 	else
547 		string = "None";
548 	seq_printf(m, "Serial Number: %s\n", string);
549 
550 	/* show the protocol and transport */
551 	seq_printf(m, "     Protocol: %s\n", us->protocol_name);
552 	seq_printf(m, "    Transport: %s\n", us->transport_name);
553 
554 	/* show the device flags */
555 	seq_printf(m, "       Quirks:");
556 
557 #define US_FLAG(name, value) \
558 	if (us->fflags & value) seq_printf(m, " " #name);
559 US_DO_ALL_FLAGS
560 #undef US_FLAG
561 	seq_putc(m, '\n');
562 	return 0;
563 }
564 
565 /***********************************************************************
566  * Sysfs interface
567  ***********************************************************************/
568 
569 /* Output routine for the sysfs max_sectors file */
max_sectors_show(struct device * dev,struct device_attribute * attr,char * buf)570 static ssize_t max_sectors_show(struct device *dev, struct device_attribute *attr, char *buf)
571 {
572 	struct scsi_device *sdev = to_scsi_device(dev);
573 
574 	return sprintf(buf, "%u\n", queue_max_hw_sectors(sdev->request_queue));
575 }
576 
577 /* Input routine for the sysfs max_sectors file */
max_sectors_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)578 static ssize_t max_sectors_store(struct device *dev, struct device_attribute *attr, const char *buf,
579 		size_t count)
580 {
581 	struct scsi_device *sdev = to_scsi_device(dev);
582 	unsigned short ms;
583 
584 	if (sscanf(buf, "%hu", &ms) > 0) {
585 		blk_queue_max_hw_sectors(sdev->request_queue, ms);
586 		return count;
587 	}
588 	return -EINVAL;
589 }
590 static DEVICE_ATTR_RW(max_sectors);
591 
592 static struct device_attribute *sysfs_device_attr_list[] = {
593 	&dev_attr_max_sectors,
594 	NULL,
595 };
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 	/*
651 	 * merge commands... this seems to help performance, but
652 	 * periodically someone should test to see which setting is more
653 	 * optimal.
654 	 */
655 	.use_clustering =		1,
656 
657 	/* emulated HBA */
658 	.emulated =			1,
659 
660 	/* we do our own delay after a device or bus reset */
661 	.skip_settle_delay =		1,
662 
663 	/* sysfs device attributes */
664 	.sdev_attrs =			sysfs_device_attr_list,
665 
666 	/* module management */
667 	.module =			THIS_MODULE
668 };
669 
usb_stor_host_template_init(struct scsi_host_template * sht,const char * name,struct module * owner)670 void usb_stor_host_template_init(struct scsi_host_template *sht,
671 				 const char *name, struct module *owner)
672 {
673 	*sht = usb_stor_host_template;
674 	sht->name = name;
675 	sht->proc_name = name;
676 	sht->module = owner;
677 }
678 EXPORT_SYMBOL_GPL(usb_stor_host_template_init);
679 
680 /* To Report "Illegal Request: Invalid Field in CDB */
681 unsigned char usb_stor_sense_invalidCDB[18] = {
682 	[0]	= 0x70,			    /* current error */
683 	[2]	= ILLEGAL_REQUEST,	    /* Illegal Request = 0x05 */
684 	[7]	= 0x0a,			    /* additional length */
685 	[12]	= 0x24			    /* Invalid Field in CDB */
686 };
687 EXPORT_SYMBOL_GPL(usb_stor_sense_invalidCDB);
688