xref: /linux/drivers/usb/storage/datafab.c (revision de2fe5e07d58424bc286fff3fd3c1b0bf933cd58)
1 /* Driver for Datafab USB Compact Flash reader
2  *
3  * $Id: datafab.c,v 1.7 2002/02/25 00:40:13 mdharm Exp $
4  *
5  * datafab driver v0.1:
6  *
7  * First release
8  *
9  * Current development and maintenance by:
10  *   (c) 2000 Jimmie Mayfield (mayfield+datafab@sackheads.org)
11  *
12  *   Many thanks to Robert Baruch for the SanDisk SmartMedia reader driver
13  *   which I used as a template for this driver.
14  *
15  *   Some bugfixes and scatter-gather code by Gregory P. Smith
16  *   (greg-usb@electricrain.com)
17  *
18  *   Fix for media change by Joerg Schneider (js@joergschneider.com)
19  *
20  * Other contributors:
21  *   (c) 2002 Alan Stern <stern@rowland.org>
22  *
23  * This program is free software; you can redistribute it and/or modify it
24  * under the terms of the GNU General Public License as published by the
25  * Free Software Foundation; either version 2, or (at your option) any
26  * later version.
27  *
28  * This program is distributed in the hope that it will be useful, but
29  * WITHOUT ANY WARRANTY; without even the implied warranty of
30  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
31  * General Public License for more details.
32  *
33  * You should have received a copy of the GNU General Public License along
34  * with this program; if not, write to the Free Software Foundation, Inc.,
35  * 675 Mass Ave, Cambridge, MA 02139, USA.
36  */
37 
38 /*
39  * This driver attempts to support USB CompactFlash reader/writer devices
40  * based on Datafab USB-to-ATA chips.  It was specifically developed for the
41  * Datafab MDCFE-B USB CompactFlash reader but has since been found to work
42  * with a variety of Datafab-based devices from a number of manufacturers.
43  * I've received a report of this driver working with a Datafab-based
44  * SmartMedia device though please be aware that I'm personally unable to
45  * test SmartMedia support.
46  *
47  * This driver supports reading and writing.  If you're truly paranoid,
48  * however, you can force the driver into a write-protected state by setting
49  * the WP enable bits in datafab_handle_mode_sense().  See the comments
50  * in that routine.
51  */
52 
53 #include <linux/sched.h>
54 #include <linux/errno.h>
55 #include <linux/slab.h>
56 
57 #include <scsi/scsi.h>
58 #include <scsi/scsi_cmnd.h>
59 
60 #include "usb.h"
61 #include "transport.h"
62 #include "protocol.h"
63 #include "debug.h"
64 #include "datafab.h"
65 
66 static int datafab_determine_lun(struct us_data *us,
67 				 struct datafab_info *info);
68 
69 
70 static inline int
71 datafab_bulk_read(struct us_data *us, unsigned char *data, unsigned int len) {
72 	if (len == 0)
73 		return USB_STOR_XFER_GOOD;
74 
75 	US_DEBUGP("datafab_bulk_read:  len = %d\n", len);
76 	return usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
77 			data, len, NULL);
78 }
79 
80 
81 static inline int
82 datafab_bulk_write(struct us_data *us, unsigned char *data, unsigned int len) {
83 	if (len == 0)
84 		return USB_STOR_XFER_GOOD;
85 
86 	US_DEBUGP("datafab_bulk_write:  len = %d\n", len);
87 	return usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
88 			data, len, NULL);
89 }
90 
91 
92 static int datafab_read_data(struct us_data *us,
93 			     struct datafab_info *info,
94 			     u32 sector,
95 			     u32 sectors)
96 {
97 	unsigned char *command = us->iobuf;
98 	unsigned char *buffer;
99 	unsigned char  thistime;
100 	unsigned int totallen, alloclen;
101 	int len, result;
102 	unsigned int sg_idx = 0, sg_offset = 0;
103 
104 	// we're working in LBA mode.  according to the ATA spec,
105 	// we can support up to 28-bit addressing.  I don't know if Datafab
106 	// supports beyond 24-bit addressing.  It's kind of hard to test
107 	// since it requires > 8GB CF card.
108 	//
109 	if (sectors > 0x0FFFFFFF)
110 		return USB_STOR_TRANSPORT_ERROR;
111 
112 	if (info->lun == -1) {
113 		result = datafab_determine_lun(us, info);
114 		if (result != USB_STOR_TRANSPORT_GOOD)
115 			return result;
116 	}
117 
118 	totallen = sectors * info->ssize;
119 
120 	// Since we don't read more than 64 KB at a time, we have to create
121 	// a bounce buffer and move the data a piece at a time between the
122 	// bounce buffer and the actual transfer buffer.
123 
124 	alloclen = min(totallen, 65536u);
125 	buffer = kmalloc(alloclen, GFP_NOIO);
126 	if (buffer == NULL)
127 		return USB_STOR_TRANSPORT_ERROR;
128 
129 	do {
130 		// loop, never allocate or transfer more than 64k at once
131 		// (min(128k, 255*info->ssize) is the real limit)
132 
133 		len = min(totallen, alloclen);
134 		thistime = (len / info->ssize) & 0xff;
135 
136 		command[0] = 0;
137 		command[1] = thistime;
138 		command[2] = sector & 0xFF;
139 		command[3] = (sector >> 8) & 0xFF;
140 		command[4] = (sector >> 16) & 0xFF;
141 
142 		command[5] = 0xE0 + (info->lun << 4);
143 		command[5] |= (sector >> 24) & 0x0F;
144 		command[6] = 0x20;
145 		command[7] = 0x01;
146 
147 		// send the read command
148 		result = datafab_bulk_write(us, command, 8);
149 		if (result != USB_STOR_XFER_GOOD)
150 			goto leave;
151 
152 		// read the result
153 		result = datafab_bulk_read(us, buffer, len);
154 		if (result != USB_STOR_XFER_GOOD)
155 			goto leave;
156 
157 		// Store the data in the transfer buffer
158 		usb_stor_access_xfer_buf(buffer, len, us->srb,
159 				 &sg_idx, &sg_offset, TO_XFER_BUF);
160 
161 		sector += thistime;
162 		totallen -= len;
163 	} while (totallen > 0);
164 
165 	kfree(buffer);
166 	return USB_STOR_TRANSPORT_GOOD;
167 
168  leave:
169 	kfree(buffer);
170 	return USB_STOR_TRANSPORT_ERROR;
171 }
172 
173 
174 static int datafab_write_data(struct us_data *us,
175 			      struct datafab_info *info,
176 			      u32 sector,
177 			      u32 sectors)
178 {
179 	unsigned char *command = us->iobuf;
180 	unsigned char *reply = us->iobuf;
181 	unsigned char *buffer;
182 	unsigned char thistime;
183 	unsigned int totallen, alloclen;
184 	int len, result;
185 	unsigned int sg_idx = 0, sg_offset = 0;
186 
187 	// we're working in LBA mode.  according to the ATA spec,
188 	// we can support up to 28-bit addressing.  I don't know if Datafab
189 	// supports beyond 24-bit addressing.  It's kind of hard to test
190 	// since it requires > 8GB CF card.
191 	//
192 	if (sectors > 0x0FFFFFFF)
193 		return USB_STOR_TRANSPORT_ERROR;
194 
195 	if (info->lun == -1) {
196 		result = datafab_determine_lun(us, info);
197 		if (result != USB_STOR_TRANSPORT_GOOD)
198 			return result;
199 	}
200 
201 	totallen = sectors * info->ssize;
202 
203 	// Since we don't write more than 64 KB at a time, we have to create
204 	// a bounce buffer and move the data a piece at a time between the
205 	// bounce buffer and the actual transfer buffer.
206 
207 	alloclen = min(totallen, 65536u);
208 	buffer = kmalloc(alloclen, GFP_NOIO);
209 	if (buffer == NULL)
210 		return USB_STOR_TRANSPORT_ERROR;
211 
212 	do {
213 		// loop, never allocate or transfer more than 64k at once
214 		// (min(128k, 255*info->ssize) is the real limit)
215 
216 		len = min(totallen, alloclen);
217 		thistime = (len / info->ssize) & 0xff;
218 
219 		// Get the data from the transfer buffer
220 		usb_stor_access_xfer_buf(buffer, len, us->srb,
221 				&sg_idx, &sg_offset, FROM_XFER_BUF);
222 
223 		command[0] = 0;
224 		command[1] = thistime;
225 		command[2] = sector & 0xFF;
226 		command[3] = (sector >> 8) & 0xFF;
227 		command[4] = (sector >> 16) & 0xFF;
228 
229 		command[5] = 0xE0 + (info->lun << 4);
230 		command[5] |= (sector >> 24) & 0x0F;
231 		command[6] = 0x30;
232 		command[7] = 0x02;
233 
234 		// send the command
235 		result = datafab_bulk_write(us, command, 8);
236 		if (result != USB_STOR_XFER_GOOD)
237 			goto leave;
238 
239 		// send the data
240 		result = datafab_bulk_write(us, buffer, len);
241 		if (result != USB_STOR_XFER_GOOD)
242 			goto leave;
243 
244 		// read the result
245 		result = datafab_bulk_read(us, reply, 2);
246 		if (result != USB_STOR_XFER_GOOD)
247 			goto leave;
248 
249 		if (reply[0] != 0x50 && reply[1] != 0) {
250 			US_DEBUGP("datafab_write_data:  Gah! "
251 				  "write return code: %02x %02x\n",
252 				  reply[0], reply[1]);
253 			result = USB_STOR_TRANSPORT_ERROR;
254 			goto leave;
255 		}
256 
257 		sector += thistime;
258 		totallen -= len;
259 	} while (totallen > 0);
260 
261 	kfree(buffer);
262 	return USB_STOR_TRANSPORT_GOOD;
263 
264  leave:
265 	kfree(buffer);
266 	return USB_STOR_TRANSPORT_ERROR;
267 }
268 
269 
270 static int datafab_determine_lun(struct us_data *us,
271 				 struct datafab_info *info)
272 {
273 	// Dual-slot readers can be thought of as dual-LUN devices.
274 	// We need to determine which card slot is being used.
275 	// We'll send an IDENTIFY DEVICE command and see which LUN responds...
276 	//
277 	// There might be a better way of doing this?
278 
279 	static unsigned char scommand[8] = { 0, 1, 0, 0, 0, 0xa0, 0xec, 1 };
280 	unsigned char *command = us->iobuf;
281 	unsigned char *buf;
282 	int count = 0, rc;
283 
284 	if (!us || !info)
285 		return USB_STOR_TRANSPORT_ERROR;
286 
287 	memcpy(command, scommand, 8);
288 	buf = kmalloc(512, GFP_NOIO);
289 	if (!buf)
290 		return USB_STOR_TRANSPORT_ERROR;
291 
292 	US_DEBUGP("datafab_determine_lun:  locating...\n");
293 
294 	// we'll try 3 times before giving up...
295 	//
296 	while (count++ < 3) {
297 		command[5] = 0xa0;
298 
299 		rc = datafab_bulk_write(us, command, 8);
300 		if (rc != USB_STOR_XFER_GOOD) {
301 			rc = USB_STOR_TRANSPORT_ERROR;
302 			goto leave;
303 		}
304 
305 		rc = datafab_bulk_read(us, buf, 512);
306 		if (rc == USB_STOR_XFER_GOOD) {
307 			info->lun = 0;
308 			rc = USB_STOR_TRANSPORT_GOOD;
309 			goto leave;
310 		}
311 
312 		command[5] = 0xb0;
313 
314 		rc = datafab_bulk_write(us, command, 8);
315 		if (rc != USB_STOR_XFER_GOOD) {
316 			rc = USB_STOR_TRANSPORT_ERROR;
317 			goto leave;
318 		}
319 
320 		rc = datafab_bulk_read(us, buf, 512);
321 		if (rc == USB_STOR_XFER_GOOD) {
322 			info->lun = 1;
323 			rc = USB_STOR_TRANSPORT_GOOD;
324 			goto leave;
325 		}
326 
327 		msleep(20);
328 	}
329 
330 	rc = USB_STOR_TRANSPORT_ERROR;
331 
332  leave:
333 	kfree(buf);
334 	return rc;
335 }
336 
337 static int datafab_id_device(struct us_data *us,
338 			     struct datafab_info *info)
339 {
340 	// this is a variation of the ATA "IDENTIFY DEVICE" command...according
341 	// to the ATA spec, 'Sector Count' isn't used but the Windows driver
342 	// sets this bit so we do too...
343 	//
344 	static unsigned char scommand[8] = { 0, 1, 0, 0, 0, 0xa0, 0xec, 1 };
345 	unsigned char *command = us->iobuf;
346 	unsigned char *reply;
347 	int rc;
348 
349 	if (!us || !info)
350 		return USB_STOR_TRANSPORT_ERROR;
351 
352 	if (info->lun == -1) {
353 		rc = datafab_determine_lun(us, info);
354 		if (rc != USB_STOR_TRANSPORT_GOOD)
355 			return rc;
356 	}
357 
358 	memcpy(command, scommand, 8);
359 	reply = kmalloc(512, GFP_NOIO);
360 	if (!reply)
361 		return USB_STOR_TRANSPORT_ERROR;
362 
363 	command[5] += (info->lun << 4);
364 
365 	rc = datafab_bulk_write(us, command, 8);
366 	if (rc != USB_STOR_XFER_GOOD) {
367 		rc = USB_STOR_TRANSPORT_ERROR;
368 		goto leave;
369 	}
370 
371 	// we'll go ahead and extract the media capacity while we're here...
372 	//
373 	rc = datafab_bulk_read(us, reply, 512);
374 	if (rc == USB_STOR_XFER_GOOD) {
375 		// capacity is at word offset 57-58
376 		//
377 		info->sectors = ((u32)(reply[117]) << 24) |
378 				((u32)(reply[116]) << 16) |
379 				((u32)(reply[115]) <<  8) |
380 				((u32)(reply[114])      );
381 		rc = USB_STOR_TRANSPORT_GOOD;
382 		goto leave;
383 	}
384 
385 	rc = USB_STOR_TRANSPORT_ERROR;
386 
387  leave:
388 	kfree(reply);
389 	return rc;
390 }
391 
392 
393 static int datafab_handle_mode_sense(struct us_data *us,
394 				     struct scsi_cmnd * srb,
395 				     int sense_6)
396 {
397 	static unsigned char rw_err_page[12] = {
398 		0x1, 0xA, 0x21, 1, 0, 0, 0, 0, 1, 0, 0, 0
399 	};
400 	static unsigned char cache_page[12] = {
401 		0x8, 0xA, 0x1, 0, 0, 0, 0, 0, 0, 0, 0, 0
402 	};
403 	static unsigned char rbac_page[12] = {
404 		0x1B, 0xA, 0, 0x81, 0, 0, 0, 0, 0, 0, 0, 0
405 	};
406 	static unsigned char timer_page[8] = {
407 		0x1C, 0x6, 0, 0, 0, 0
408 	};
409 	unsigned char pc, page_code;
410 	unsigned int i = 0;
411 	struct datafab_info *info = (struct datafab_info *) (us->extra);
412 	unsigned char *ptr = us->iobuf;
413 
414 	// most of this stuff is just a hack to get things working.  the
415 	// datafab reader doesn't present a SCSI interface so we
416 	// fudge the SCSI commands...
417 	//
418 
419 	pc = srb->cmnd[2] >> 6;
420 	page_code = srb->cmnd[2] & 0x3F;
421 
422 	switch (pc) {
423 	   case 0x0:
424 		US_DEBUGP("datafab_handle_mode_sense:  Current values\n");
425 		break;
426 	   case 0x1:
427 		US_DEBUGP("datafab_handle_mode_sense:  Changeable values\n");
428 		break;
429 	   case 0x2:
430 		US_DEBUGP("datafab_handle_mode_sense:  Default values\n");
431 		break;
432 	   case 0x3:
433 		US_DEBUGP("datafab_handle_mode_sense:  Saves values\n");
434 		break;
435 	}
436 
437 	memset(ptr, 0, 8);
438 	if (sense_6) {
439 		ptr[2] = 0x00;		// WP enable: 0x80
440 		i = 4;
441 	} else {
442 		ptr[3] = 0x00;		// WP enable: 0x80
443 		i = 8;
444 	}
445 
446 	switch (page_code) {
447 	   default:
448 		// vendor-specific mode
449 		info->sense_key = 0x05;
450 		info->sense_asc = 0x24;
451 		info->sense_ascq = 0x00;
452 		return USB_STOR_TRANSPORT_FAILED;
453 
454 	   case 0x1:
455 		memcpy(ptr + i, rw_err_page, sizeof(rw_err_page));
456 		i += sizeof(rw_err_page);
457 		break;
458 
459 	   case 0x8:
460 		memcpy(ptr + i, cache_page, sizeof(cache_page));
461 		i += sizeof(cache_page);
462 		break;
463 
464 	   case 0x1B:
465 		memcpy(ptr + i, rbac_page, sizeof(rbac_page));
466 		i += sizeof(rbac_page);
467 		break;
468 
469 	   case 0x1C:
470 		memcpy(ptr + i, timer_page, sizeof(timer_page));
471 		i += sizeof(timer_page);
472 		break;
473 
474 	   case 0x3F:		// retrieve all pages
475 		memcpy(ptr + i, timer_page, sizeof(timer_page));
476 		i += sizeof(timer_page);
477 		memcpy(ptr + i, rbac_page, sizeof(rbac_page));
478 		i += sizeof(rbac_page);
479 		memcpy(ptr + i, cache_page, sizeof(cache_page));
480 		i += sizeof(cache_page);
481 		memcpy(ptr + i, rw_err_page, sizeof(rw_err_page));
482 		i += sizeof(rw_err_page);
483 		break;
484 	}
485 
486 	if (sense_6)
487 		ptr[0] = i - 1;
488 	else
489 		((__be16 *) ptr)[0] = cpu_to_be16(i - 2);
490 	usb_stor_set_xfer_buf(ptr, i, srb);
491 
492 	return USB_STOR_TRANSPORT_GOOD;
493 }
494 
495 static void datafab_info_destructor(void *extra)
496 {
497 	// this routine is a placeholder...
498 	// currently, we don't allocate any extra memory so we're okay
499 }
500 
501 
502 // Transport for the Datafab MDCFE-B
503 //
504 int datafab_transport(struct scsi_cmnd * srb, struct us_data *us)
505 {
506 	struct datafab_info *info;
507 	int rc;
508 	unsigned long block, blocks;
509 	unsigned char *ptr = us->iobuf;
510 	static unsigned char inquiry_reply[8] = {
511 		0x00, 0x80, 0x00, 0x01, 0x1F, 0x00, 0x00, 0x00
512 	};
513 
514 	if (!us->extra) {
515 		us->extra = kzalloc(sizeof(struct datafab_info), GFP_NOIO);
516 		if (!us->extra) {
517 			US_DEBUGP("datafab_transport:  Gah! "
518 				  "Can't allocate storage for Datafab info struct!\n");
519 			return USB_STOR_TRANSPORT_ERROR;
520 		}
521 		us->extra_destructor = datafab_info_destructor;
522   		((struct datafab_info *)us->extra)->lun = -1;
523 	}
524 
525 	info = (struct datafab_info *) (us->extra);
526 
527 	if (srb->cmnd[0] == INQUIRY) {
528 		US_DEBUGP("datafab_transport:  INQUIRY.  Returning bogus response");
529 		memcpy(ptr, inquiry_reply, sizeof(inquiry_reply));
530 		fill_inquiry_response(us, ptr, 36);
531 		return USB_STOR_TRANSPORT_GOOD;
532 	}
533 
534 	if (srb->cmnd[0] == READ_CAPACITY) {
535 		info->ssize = 0x200;  // hard coded 512 byte sectors as per ATA spec
536 		rc = datafab_id_device(us, info);
537 		if (rc != USB_STOR_TRANSPORT_GOOD)
538 			return rc;
539 
540 		US_DEBUGP("datafab_transport:  READ_CAPACITY:  %ld sectors, %ld bytes per sector\n",
541 			  info->sectors, info->ssize);
542 
543 		// build the reply
544 		// we need the last sector, not the number of sectors
545 		((__be32 *) ptr)[0] = cpu_to_be32(info->sectors - 1);
546 		((__be32 *) ptr)[1] = cpu_to_be32(info->ssize);
547 		usb_stor_set_xfer_buf(ptr, 8, srb);
548 
549 		return USB_STOR_TRANSPORT_GOOD;
550 	}
551 
552 	if (srb->cmnd[0] == MODE_SELECT_10) {
553 		US_DEBUGP("datafab_transport:  Gah! MODE_SELECT_10.\n");
554 		return USB_STOR_TRANSPORT_ERROR;
555 	}
556 
557 	// don't bother implementing READ_6 or WRITE_6.
558 	//
559 	if (srb->cmnd[0] == READ_10) {
560 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
561 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
562 
563 		blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
564 
565 		US_DEBUGP("datafab_transport:  READ_10: read block 0x%04lx  count %ld\n", block, blocks);
566 		return datafab_read_data(us, info, block, blocks);
567 	}
568 
569 	if (srb->cmnd[0] == READ_12) {
570 		// we'll probably never see a READ_12 but we'll do it anyway...
571 		//
572 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
573 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
574 
575 		blocks = ((u32)(srb->cmnd[6]) << 24) | ((u32)(srb->cmnd[7]) << 16) |
576 			 ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
577 
578 		US_DEBUGP("datafab_transport:  READ_12: read block 0x%04lx  count %ld\n", block, blocks);
579 		return datafab_read_data(us, info, block, blocks);
580 	}
581 
582 	if (srb->cmnd[0] == WRITE_10) {
583 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
584 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
585 
586 		blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
587 
588 		US_DEBUGP("datafab_transport:  WRITE_10: write block 0x%04lx  count %ld\n", block, blocks);
589 		return datafab_write_data(us, info, block, blocks);
590 	}
591 
592 	if (srb->cmnd[0] == WRITE_12) {
593 		// we'll probably never see a WRITE_12 but we'll do it anyway...
594 		//
595 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
596 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
597 
598 		blocks = ((u32)(srb->cmnd[6]) << 24) | ((u32)(srb->cmnd[7]) << 16) |
599 			 ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
600 
601 		US_DEBUGP("datafab_transport:  WRITE_12: write block 0x%04lx  count %ld\n", block, blocks);
602 		return datafab_write_data(us, info, block, blocks);
603 	}
604 
605 	if (srb->cmnd[0] == TEST_UNIT_READY) {
606 		US_DEBUGP("datafab_transport:  TEST_UNIT_READY.\n");
607 		return datafab_id_device(us, info);
608 	}
609 
610 	if (srb->cmnd[0] == REQUEST_SENSE) {
611 		US_DEBUGP("datafab_transport:  REQUEST_SENSE.  Returning faked response\n");
612 
613 		// this response is pretty bogus right now.  eventually if necessary
614 		// we can set the correct sense data.  so far though it hasn't been
615 		// necessary
616 		//
617 		memset(ptr, 0, 18);
618 		ptr[0] = 0xF0;
619 		ptr[2] = info->sense_key;
620 		ptr[7] = 11;
621 		ptr[12] = info->sense_asc;
622 		ptr[13] = info->sense_ascq;
623 		usb_stor_set_xfer_buf(ptr, 18, srb);
624 
625 		return USB_STOR_TRANSPORT_GOOD;
626 	}
627 
628 	if (srb->cmnd[0] == MODE_SENSE) {
629 		US_DEBUGP("datafab_transport:  MODE_SENSE_6 detected\n");
630 		return datafab_handle_mode_sense(us, srb, 1);
631 	}
632 
633 	if (srb->cmnd[0] == MODE_SENSE_10) {
634 		US_DEBUGP("datafab_transport:  MODE_SENSE_10 detected\n");
635 		return datafab_handle_mode_sense(us, srb, 0);
636 	}
637 
638 	if (srb->cmnd[0] == ALLOW_MEDIUM_REMOVAL) {
639 		// sure.  whatever.  not like we can stop the user from
640 		// popping the media out of the device (no locking doors, etc)
641 		//
642 		return USB_STOR_TRANSPORT_GOOD;
643 	}
644 
645 	if (srb->cmnd[0] == START_STOP) {
646 		/* this is used by sd.c'check_scsidisk_media_change to detect
647 		   media change */
648 		US_DEBUGP("datafab_transport:  START_STOP.\n");
649 		/* the first datafab_id_device after a media change returns
650 		   an error (determined experimentally) */
651 		rc = datafab_id_device(us, info);
652 		if (rc == USB_STOR_TRANSPORT_GOOD) {
653 			info->sense_key = NO_SENSE;
654 			srb->result = SUCCESS;
655 		} else {
656 			info->sense_key = UNIT_ATTENTION;
657 			srb->result = SAM_STAT_CHECK_CONDITION;
658 		}
659 		return rc;
660 	}
661 
662 	US_DEBUGP("datafab_transport:  Gah! Unknown command: %d (0x%x)\n",
663 		  srb->cmnd[0], srb->cmnd[0]);
664 	info->sense_key = 0x05;
665 	info->sense_asc = 0x20;
666 	info->sense_ascq = 0x00;
667 	return USB_STOR_TRANSPORT_FAILED;
668 }
669