xref: /openbmc/linux/drivers/usb/storage/datafab.c (revision 545e4006)
1 /* Driver for Datafab USB Compact Flash reader
2  *
3  * datafab driver v0.1:
4  *
5  * First release
6  *
7  * Current development and maintenance by:
8  *   (c) 2000 Jimmie Mayfield (mayfield+datafab@sackheads.org)
9  *
10  *   Many thanks to Robert Baruch for the SanDisk SmartMedia reader driver
11  *   which I used as a template for this driver.
12  *
13  *   Some bugfixes and scatter-gather code by Gregory P. Smith
14  *   (greg-usb@electricrain.com)
15  *
16  *   Fix for media change by Joerg Schneider (js@joergschneider.com)
17  *
18  * Other contributors:
19  *   (c) 2002 Alan Stern <stern@rowland.org>
20  *
21  * This program is free software; you can redistribute it and/or modify it
22  * under the terms of the GNU General Public License as published by the
23  * Free Software Foundation; either version 2, or (at your option) any
24  * later version.
25  *
26  * This program is distributed in the hope that it will be useful, but
27  * WITHOUT ANY WARRANTY; without even the implied warranty of
28  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
29  * General Public License for more details.
30  *
31  * You should have received a copy of the GNU General Public License along
32  * with this program; if not, write to the Free Software Foundation, Inc.,
33  * 675 Mass Ave, Cambridge, MA 02139, USA.
34  */
35 
36 /*
37  * This driver attempts to support USB CompactFlash reader/writer devices
38  * based on Datafab USB-to-ATA chips.  It was specifically developed for the
39  * Datafab MDCFE-B USB CompactFlash reader but has since been found to work
40  * with a variety of Datafab-based devices from a number of manufacturers.
41  * I've received a report of this driver working with a Datafab-based
42  * SmartMedia device though please be aware that I'm personally unable to
43  * test SmartMedia support.
44  *
45  * This driver supports reading and writing.  If you're truly paranoid,
46  * however, you can force the driver into a write-protected state by setting
47  * the WP enable bits in datafab_handle_mode_sense().  See the comments
48  * in that routine.
49  */
50 
51 #include <linux/errno.h>
52 #include <linux/slab.h>
53 
54 #include <scsi/scsi.h>
55 #include <scsi/scsi_cmnd.h>
56 
57 #include "usb.h"
58 #include "transport.h"
59 #include "protocol.h"
60 #include "debug.h"
61 #include "datafab.h"
62 
63 static int datafab_determine_lun(struct us_data *us,
64 				 struct datafab_info *info);
65 
66 
67 static inline int
68 datafab_bulk_read(struct us_data *us, unsigned char *data, unsigned int len) {
69 	if (len == 0)
70 		return USB_STOR_XFER_GOOD;
71 
72 	US_DEBUGP("datafab_bulk_read:  len = %d\n", len);
73 	return usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
74 			data, len, NULL);
75 }
76 
77 
78 static inline int
79 datafab_bulk_write(struct us_data *us, unsigned char *data, unsigned int len) {
80 	if (len == 0)
81 		return USB_STOR_XFER_GOOD;
82 
83 	US_DEBUGP("datafab_bulk_write:  len = %d\n", len);
84 	return usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
85 			data, len, NULL);
86 }
87 
88 
89 static int datafab_read_data(struct us_data *us,
90 			     struct datafab_info *info,
91 			     u32 sector,
92 			     u32 sectors)
93 {
94 	unsigned char *command = us->iobuf;
95 	unsigned char *buffer;
96 	unsigned char  thistime;
97 	unsigned int totallen, alloclen;
98 	int len, result;
99 	unsigned int sg_offset = 0;
100 	struct scatterlist *sg = NULL;
101 
102 	// we're working in LBA mode.  according to the ATA spec,
103 	// we can support up to 28-bit addressing.  I don't know if Datafab
104 	// supports beyond 24-bit addressing.  It's kind of hard to test
105 	// since it requires > 8GB CF card.
106 	//
107 	if (sectors > 0x0FFFFFFF)
108 		return USB_STOR_TRANSPORT_ERROR;
109 
110 	if (info->lun == -1) {
111 		result = datafab_determine_lun(us, info);
112 		if (result != USB_STOR_TRANSPORT_GOOD)
113 			return result;
114 	}
115 
116 	totallen = sectors * info->ssize;
117 
118 	// Since we don't read more than 64 KB at a time, we have to create
119 	// a bounce buffer and move the data a piece at a time between the
120 	// bounce buffer and the actual transfer buffer.
121 
122 	alloclen = min(totallen, 65536u);
123 	buffer = kmalloc(alloclen, GFP_NOIO);
124 	if (buffer == NULL)
125 		return USB_STOR_TRANSPORT_ERROR;
126 
127 	do {
128 		// loop, never allocate or transfer more than 64k at once
129 		// (min(128k, 255*info->ssize) is the real limit)
130 
131 		len = min(totallen, alloclen);
132 		thistime = (len / info->ssize) & 0xff;
133 
134 		command[0] = 0;
135 		command[1] = thistime;
136 		command[2] = sector & 0xFF;
137 		command[3] = (sector >> 8) & 0xFF;
138 		command[4] = (sector >> 16) & 0xFF;
139 
140 		command[5] = 0xE0 + (info->lun << 4);
141 		command[5] |= (sector >> 24) & 0x0F;
142 		command[6] = 0x20;
143 		command[7] = 0x01;
144 
145 		// send the read command
146 		result = datafab_bulk_write(us, command, 8);
147 		if (result != USB_STOR_XFER_GOOD)
148 			goto leave;
149 
150 		// read the result
151 		result = datafab_bulk_read(us, buffer, len);
152 		if (result != USB_STOR_XFER_GOOD)
153 			goto leave;
154 
155 		// Store the data in the transfer buffer
156 		usb_stor_access_xfer_buf(buffer, len, us->srb,
157 				 &sg, &sg_offset, TO_XFER_BUF);
158 
159 		sector += thistime;
160 		totallen -= len;
161 	} while (totallen > 0);
162 
163 	kfree(buffer);
164 	return USB_STOR_TRANSPORT_GOOD;
165 
166  leave:
167 	kfree(buffer);
168 	return USB_STOR_TRANSPORT_ERROR;
169 }
170 
171 
172 static int datafab_write_data(struct us_data *us,
173 			      struct datafab_info *info,
174 			      u32 sector,
175 			      u32 sectors)
176 {
177 	unsigned char *command = us->iobuf;
178 	unsigned char *reply = us->iobuf;
179 	unsigned char *buffer;
180 	unsigned char thistime;
181 	unsigned int totallen, alloclen;
182 	int len, result;
183 	unsigned int sg_offset = 0;
184 	struct scatterlist *sg = NULL;
185 
186 	// we're working in LBA mode.  according to the ATA spec,
187 	// we can support up to 28-bit addressing.  I don't know if Datafab
188 	// supports beyond 24-bit addressing.  It's kind of hard to test
189 	// since it requires > 8GB CF card.
190 	//
191 	if (sectors > 0x0FFFFFFF)
192 		return USB_STOR_TRANSPORT_ERROR;
193 
194 	if (info->lun == -1) {
195 		result = datafab_determine_lun(us, info);
196 		if (result != USB_STOR_TRANSPORT_GOOD)
197 			return result;
198 	}
199 
200 	totallen = sectors * info->ssize;
201 
202 	// Since we don't write more than 64 KB at a time, we have to create
203 	// a bounce buffer and move the data a piece at a time between the
204 	// bounce buffer and the actual transfer buffer.
205 
206 	alloclen = min(totallen, 65536u);
207 	buffer = kmalloc(alloclen, GFP_NOIO);
208 	if (buffer == NULL)
209 		return USB_STOR_TRANSPORT_ERROR;
210 
211 	do {
212 		// loop, never allocate or transfer more than 64k at once
213 		// (min(128k, 255*info->ssize) is the real limit)
214 
215 		len = min(totallen, alloclen);
216 		thistime = (len / info->ssize) & 0xff;
217 
218 		// Get the data from the transfer buffer
219 		usb_stor_access_xfer_buf(buffer, len, us->srb,
220 				&sg, &sg_offset, FROM_XFER_BUF);
221 
222 		command[0] = 0;
223 		command[1] = thistime;
224 		command[2] = sector & 0xFF;
225 		command[3] = (sector >> 8) & 0xFF;
226 		command[4] = (sector >> 16) & 0xFF;
227 
228 		command[5] = 0xE0 + (info->lun << 4);
229 		command[5] |= (sector >> 24) & 0x0F;
230 		command[6] = 0x30;
231 		command[7] = 0x02;
232 
233 		// send the command
234 		result = datafab_bulk_write(us, command, 8);
235 		if (result != USB_STOR_XFER_GOOD)
236 			goto leave;
237 
238 		// send the data
239 		result = datafab_bulk_write(us, buffer, len);
240 		if (result != USB_STOR_XFER_GOOD)
241 			goto leave;
242 
243 		// read the result
244 		result = datafab_bulk_read(us, reply, 2);
245 		if (result != USB_STOR_XFER_GOOD)
246 			goto leave;
247 
248 		if (reply[0] != 0x50 && reply[1] != 0) {
249 			US_DEBUGP("datafab_write_data:  Gah! "
250 				  "write return code: %02x %02x\n",
251 				  reply[0], reply[1]);
252 			result = USB_STOR_TRANSPORT_ERROR;
253 			goto leave;
254 		}
255 
256 		sector += thistime;
257 		totallen -= len;
258 	} while (totallen > 0);
259 
260 	kfree(buffer);
261 	return USB_STOR_TRANSPORT_GOOD;
262 
263  leave:
264 	kfree(buffer);
265 	return USB_STOR_TRANSPORT_ERROR;
266 }
267 
268 
269 static int datafab_determine_lun(struct us_data *us,
270 				 struct datafab_info *info)
271 {
272 	// Dual-slot readers can be thought of as dual-LUN devices.
273 	// We need to determine which card slot is being used.
274 	// We'll send an IDENTIFY DEVICE command and see which LUN responds...
275 	//
276 	// There might be a better way of doing this?
277 
278 	static unsigned char scommand[8] = { 0, 1, 0, 0, 0, 0xa0, 0xec, 1 };
279 	unsigned char *command = us->iobuf;
280 	unsigned char *buf;
281 	int count = 0, rc;
282 
283 	if (!us || !info)
284 		return USB_STOR_TRANSPORT_ERROR;
285 
286 	memcpy(command, scommand, 8);
287 	buf = kmalloc(512, GFP_NOIO);
288 	if (!buf)
289 		return USB_STOR_TRANSPORT_ERROR;
290 
291 	US_DEBUGP("datafab_determine_lun:  locating...\n");
292 
293 	// we'll try 3 times before giving up...
294 	//
295 	while (count++ < 3) {
296 		command[5] = 0xa0;
297 
298 		rc = datafab_bulk_write(us, command, 8);
299 		if (rc != USB_STOR_XFER_GOOD) {
300 			rc = USB_STOR_TRANSPORT_ERROR;
301 			goto leave;
302 		}
303 
304 		rc = datafab_bulk_read(us, buf, 512);
305 		if (rc == USB_STOR_XFER_GOOD) {
306 			info->lun = 0;
307 			rc = USB_STOR_TRANSPORT_GOOD;
308 			goto leave;
309 		}
310 
311 		command[5] = 0xb0;
312 
313 		rc = datafab_bulk_write(us, command, 8);
314 		if (rc != USB_STOR_XFER_GOOD) {
315 			rc = USB_STOR_TRANSPORT_ERROR;
316 			goto leave;
317 		}
318 
319 		rc = datafab_bulk_read(us, buf, 512);
320 		if (rc == USB_STOR_XFER_GOOD) {
321 			info->lun = 1;
322 			rc = USB_STOR_TRANSPORT_GOOD;
323 			goto leave;
324 		}
325 
326 		msleep(20);
327 	}
328 
329 	rc = USB_STOR_TRANSPORT_ERROR;
330 
331  leave:
332 	kfree(buf);
333 	return rc;
334 }
335 
336 static int datafab_id_device(struct us_data *us,
337 			     struct datafab_info *info)
338 {
339 	// this is a variation of the ATA "IDENTIFY DEVICE" command...according
340 	// to the ATA spec, 'Sector Count' isn't used but the Windows driver
341 	// sets this bit so we do too...
342 	//
343 	static unsigned char scommand[8] = { 0, 1, 0, 0, 0, 0xa0, 0xec, 1 };
344 	unsigned char *command = us->iobuf;
345 	unsigned char *reply;
346 	int rc;
347 
348 	if (!us || !info)
349 		return USB_STOR_TRANSPORT_ERROR;
350 
351 	if (info->lun == -1) {
352 		rc = datafab_determine_lun(us, info);
353 		if (rc != USB_STOR_TRANSPORT_GOOD)
354 			return rc;
355 	}
356 
357 	memcpy(command, scommand, 8);
358 	reply = kmalloc(512, GFP_NOIO);
359 	if (!reply)
360 		return USB_STOR_TRANSPORT_ERROR;
361 
362 	command[5] += (info->lun << 4);
363 
364 	rc = datafab_bulk_write(us, command, 8);
365 	if (rc != USB_STOR_XFER_GOOD) {
366 		rc = USB_STOR_TRANSPORT_ERROR;
367 		goto leave;
368 	}
369 
370 	// we'll go ahead and extract the media capacity while we're here...
371 	//
372 	rc = datafab_bulk_read(us, reply, 512);
373 	if (rc == USB_STOR_XFER_GOOD) {
374 		// capacity is at word offset 57-58
375 		//
376 		info->sectors = ((u32)(reply[117]) << 24) |
377 				((u32)(reply[116]) << 16) |
378 				((u32)(reply[115]) <<  8) |
379 				((u32)(reply[114])      );
380 		rc = USB_STOR_TRANSPORT_GOOD;
381 		goto leave;
382 	}
383 
384 	rc = USB_STOR_TRANSPORT_ERROR;
385 
386  leave:
387 	kfree(reply);
388 	return rc;
389 }
390 
391 
392 static int datafab_handle_mode_sense(struct us_data *us,
393 				     struct scsi_cmnd * srb,
394 				     int sense_6)
395 {
396 	static unsigned char rw_err_page[12] = {
397 		0x1, 0xA, 0x21, 1, 0, 0, 0, 0, 1, 0, 0, 0
398 	};
399 	static unsigned char cache_page[12] = {
400 		0x8, 0xA, 0x1, 0, 0, 0, 0, 0, 0, 0, 0, 0
401 	};
402 	static unsigned char rbac_page[12] = {
403 		0x1B, 0xA, 0, 0x81, 0, 0, 0, 0, 0, 0, 0, 0
404 	};
405 	static unsigned char timer_page[8] = {
406 		0x1C, 0x6, 0, 0, 0, 0
407 	};
408 	unsigned char pc, page_code;
409 	unsigned int i = 0;
410 	struct datafab_info *info = (struct datafab_info *) (us->extra);
411 	unsigned char *ptr = us->iobuf;
412 
413 	// most of this stuff is just a hack to get things working.  the
414 	// datafab reader doesn't present a SCSI interface so we
415 	// fudge the SCSI commands...
416 	//
417 
418 	pc = srb->cmnd[2] >> 6;
419 	page_code = srb->cmnd[2] & 0x3F;
420 
421 	switch (pc) {
422 	   case 0x0:
423 		US_DEBUGP("datafab_handle_mode_sense:  Current values\n");
424 		break;
425 	   case 0x1:
426 		US_DEBUGP("datafab_handle_mode_sense:  Changeable values\n");
427 		break;
428 	   case 0x2:
429 		US_DEBUGP("datafab_handle_mode_sense:  Default values\n");
430 		break;
431 	   case 0x3:
432 		US_DEBUGP("datafab_handle_mode_sense:  Saves values\n");
433 		break;
434 	}
435 
436 	memset(ptr, 0, 8);
437 	if (sense_6) {
438 		ptr[2] = 0x00;		// WP enable: 0x80
439 		i = 4;
440 	} else {
441 		ptr[3] = 0x00;		// WP enable: 0x80
442 		i = 8;
443 	}
444 
445 	switch (page_code) {
446 	   default:
447 		// vendor-specific mode
448 		info->sense_key = 0x05;
449 		info->sense_asc = 0x24;
450 		info->sense_ascq = 0x00;
451 		return USB_STOR_TRANSPORT_FAILED;
452 
453 	   case 0x1:
454 		memcpy(ptr + i, rw_err_page, sizeof(rw_err_page));
455 		i += sizeof(rw_err_page);
456 		break;
457 
458 	   case 0x8:
459 		memcpy(ptr + i, cache_page, sizeof(cache_page));
460 		i += sizeof(cache_page);
461 		break;
462 
463 	   case 0x1B:
464 		memcpy(ptr + i, rbac_page, sizeof(rbac_page));
465 		i += sizeof(rbac_page);
466 		break;
467 
468 	   case 0x1C:
469 		memcpy(ptr + i, timer_page, sizeof(timer_page));
470 		i += sizeof(timer_page);
471 		break;
472 
473 	   case 0x3F:		// retrieve all pages
474 		memcpy(ptr + i, timer_page, sizeof(timer_page));
475 		i += sizeof(timer_page);
476 		memcpy(ptr + i, rbac_page, sizeof(rbac_page));
477 		i += sizeof(rbac_page);
478 		memcpy(ptr + i, cache_page, sizeof(cache_page));
479 		i += sizeof(cache_page);
480 		memcpy(ptr + i, rw_err_page, sizeof(rw_err_page));
481 		i += sizeof(rw_err_page);
482 		break;
483 	}
484 
485 	if (sense_6)
486 		ptr[0] = i - 1;
487 	else
488 		((__be16 *) ptr)[0] = cpu_to_be16(i - 2);
489 	usb_stor_set_xfer_buf(ptr, i, srb);
490 
491 	return USB_STOR_TRANSPORT_GOOD;
492 }
493 
494 static void datafab_info_destructor(void *extra)
495 {
496 	// this routine is a placeholder...
497 	// currently, we don't allocate any extra memory so we're okay
498 }
499 
500 
501 // Transport for the Datafab MDCFE-B
502 //
503 int datafab_transport(struct scsi_cmnd * srb, struct us_data *us)
504 {
505 	struct datafab_info *info;
506 	int rc;
507 	unsigned long block, blocks;
508 	unsigned char *ptr = us->iobuf;
509 	static unsigned char inquiry_reply[8] = {
510 		0x00, 0x80, 0x00, 0x01, 0x1F, 0x00, 0x00, 0x00
511 	};
512 
513 	if (!us->extra) {
514 		us->extra = kzalloc(sizeof(struct datafab_info), GFP_NOIO);
515 		if (!us->extra) {
516 			US_DEBUGP("datafab_transport:  Gah! "
517 				  "Can't allocate storage for Datafab info struct!\n");
518 			return USB_STOR_TRANSPORT_ERROR;
519 		}
520 		us->extra_destructor = datafab_info_destructor;
521   		((struct datafab_info *)us->extra)->lun = -1;
522 	}
523 
524 	info = (struct datafab_info *) (us->extra);
525 
526 	if (srb->cmnd[0] == INQUIRY) {
527 		US_DEBUGP("datafab_transport:  INQUIRY.  Returning bogus response");
528 		memcpy(ptr, inquiry_reply, sizeof(inquiry_reply));
529 		fill_inquiry_response(us, ptr, 36);
530 		return USB_STOR_TRANSPORT_GOOD;
531 	}
532 
533 	if (srb->cmnd[0] == READ_CAPACITY) {
534 		info->ssize = 0x200;  // hard coded 512 byte sectors as per ATA spec
535 		rc = datafab_id_device(us, info);
536 		if (rc != USB_STOR_TRANSPORT_GOOD)
537 			return rc;
538 
539 		US_DEBUGP("datafab_transport:  READ_CAPACITY:  %ld sectors, %ld bytes per sector\n",
540 			  info->sectors, info->ssize);
541 
542 		// build the reply
543 		// we need the last sector, not the number of sectors
544 		((__be32 *) ptr)[0] = cpu_to_be32(info->sectors - 1);
545 		((__be32 *) ptr)[1] = cpu_to_be32(info->ssize);
546 		usb_stor_set_xfer_buf(ptr, 8, srb);
547 
548 		return USB_STOR_TRANSPORT_GOOD;
549 	}
550 
551 	if (srb->cmnd[0] == MODE_SELECT_10) {
552 		US_DEBUGP("datafab_transport:  Gah! MODE_SELECT_10.\n");
553 		return USB_STOR_TRANSPORT_ERROR;
554 	}
555 
556 	// don't bother implementing READ_6 or WRITE_6.
557 	//
558 	if (srb->cmnd[0] == READ_10) {
559 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
560 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
561 
562 		blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
563 
564 		US_DEBUGP("datafab_transport:  READ_10: read block 0x%04lx  count %ld\n", block, blocks);
565 		return datafab_read_data(us, info, block, blocks);
566 	}
567 
568 	if (srb->cmnd[0] == READ_12) {
569 		// we'll probably never see a READ_12 but we'll do it anyway...
570 		//
571 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
572 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
573 
574 		blocks = ((u32)(srb->cmnd[6]) << 24) | ((u32)(srb->cmnd[7]) << 16) |
575 			 ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
576 
577 		US_DEBUGP("datafab_transport:  READ_12: read block 0x%04lx  count %ld\n", block, blocks);
578 		return datafab_read_data(us, info, block, blocks);
579 	}
580 
581 	if (srb->cmnd[0] == WRITE_10) {
582 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
583 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
584 
585 		blocks = ((u32)(srb->cmnd[7]) << 8) | ((u32)(srb->cmnd[8]));
586 
587 		US_DEBUGP("datafab_transport:  WRITE_10: write block 0x%04lx  count %ld\n", block, blocks);
588 		return datafab_write_data(us, info, block, blocks);
589 	}
590 
591 	if (srb->cmnd[0] == WRITE_12) {
592 		// we'll probably never see a WRITE_12 but we'll do it anyway...
593 		//
594 		block = ((u32)(srb->cmnd[2]) << 24) | ((u32)(srb->cmnd[3]) << 16) |
595 			((u32)(srb->cmnd[4]) <<  8) | ((u32)(srb->cmnd[5]));
596 
597 		blocks = ((u32)(srb->cmnd[6]) << 24) | ((u32)(srb->cmnd[7]) << 16) |
598 			 ((u32)(srb->cmnd[8]) <<  8) | ((u32)(srb->cmnd[9]));
599 
600 		US_DEBUGP("datafab_transport:  WRITE_12: write block 0x%04lx  count %ld\n", block, blocks);
601 		return datafab_write_data(us, info, block, blocks);
602 	}
603 
604 	if (srb->cmnd[0] == TEST_UNIT_READY) {
605 		US_DEBUGP("datafab_transport:  TEST_UNIT_READY.\n");
606 		return datafab_id_device(us, info);
607 	}
608 
609 	if (srb->cmnd[0] == REQUEST_SENSE) {
610 		US_DEBUGP("datafab_transport:  REQUEST_SENSE.  Returning faked response\n");
611 
612 		// this response is pretty bogus right now.  eventually if necessary
613 		// we can set the correct sense data.  so far though it hasn't been
614 		// necessary
615 		//
616 		memset(ptr, 0, 18);
617 		ptr[0] = 0xF0;
618 		ptr[2] = info->sense_key;
619 		ptr[7] = 11;
620 		ptr[12] = info->sense_asc;
621 		ptr[13] = info->sense_ascq;
622 		usb_stor_set_xfer_buf(ptr, 18, srb);
623 
624 		return USB_STOR_TRANSPORT_GOOD;
625 	}
626 
627 	if (srb->cmnd[0] == MODE_SENSE) {
628 		US_DEBUGP("datafab_transport:  MODE_SENSE_6 detected\n");
629 		return datafab_handle_mode_sense(us, srb, 1);
630 	}
631 
632 	if (srb->cmnd[0] == MODE_SENSE_10) {
633 		US_DEBUGP("datafab_transport:  MODE_SENSE_10 detected\n");
634 		return datafab_handle_mode_sense(us, srb, 0);
635 	}
636 
637 	if (srb->cmnd[0] == ALLOW_MEDIUM_REMOVAL) {
638 		// sure.  whatever.  not like we can stop the user from
639 		// popping the media out of the device (no locking doors, etc)
640 		//
641 		return USB_STOR_TRANSPORT_GOOD;
642 	}
643 
644 	if (srb->cmnd[0] == START_STOP) {
645 		/* this is used by sd.c'check_scsidisk_media_change to detect
646 		   media change */
647 		US_DEBUGP("datafab_transport:  START_STOP.\n");
648 		/* the first datafab_id_device after a media change returns
649 		   an error (determined experimentally) */
650 		rc = datafab_id_device(us, info);
651 		if (rc == USB_STOR_TRANSPORT_GOOD) {
652 			info->sense_key = NO_SENSE;
653 			srb->result = SUCCESS;
654 		} else {
655 			info->sense_key = UNIT_ATTENTION;
656 			srb->result = SAM_STAT_CHECK_CONDITION;
657 		}
658 		return rc;
659 	}
660 
661 	US_DEBUGP("datafab_transport:  Gah! Unknown command: %d (0x%x)\n",
662 		  srb->cmnd[0], srb->cmnd[0]);
663 	info->sense_key = 0x05;
664 	info->sense_asc = 0x20;
665 	info->sense_ascq = 0x00;
666 	return USB_STOR_TRANSPORT_FAILED;
667 }
668