drivers/usb/storage/datafab.c

   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/errno.h>
  54 #include <linux/slab.h>
  55
  56 #include <scsi/scsi.h>
  57 #include <scsi/scsi_cmnd.h>
  58
  59 #include "usb.h"
  60 #include "transport.h"
  61 #include "protocol.h"
  62 #include "debug.h"
  63 #include "datafab.h"
  64
  65 static int datafab_determine_lun(struct us_data *us,
  66                                  struct datafab_info *info);
  67
  68
  69 static inline int
  70 datafab_bulk_read(struct us_data *us, unsigned char *data, unsigned int len) {
  71         if (len == 0)
  72                 return USB_STOR_XFER_GOOD;
  73
  74         US_DEBUGP("datafab_bulk_read:  len = %d\n", len);
  75         return usb_stor_bulk_transfer_buf(us, us->recv_bulk_pipe,
  76                         data, len, NULL);
  77 }
  78
  79
  80 static inline int
  81 datafab_bulk_write(struct us_data *us, unsigned char *data, unsigned int len) {
  82         if (len == 0)
  83                 return USB_STOR_XFER_GOOD;
  84
  85         US_DEBUGP("datafab_bulk_write:  len = %d\n", len);
  86         return usb_stor_bulk_transfer_buf(us, us->send_bulk_pipe,
  87                         data, len, NULL);
  88 }
  89
  90
  91 static int datafab_read_data(struct us_data *us,
  92                              struct datafab_info *info,
  93                              u32 sector,
  94                              u32 sectors)
  95 {
  96         unsigned char *command = us->iobuf;
  97         unsigned char *buffer;
  98         unsigned char  thistime;
  99         unsigned int totallen, alloclen;
 100         int len, result;
 101         unsigned int sg_idx = 0, sg_offset = 0;
 102
 103         // we're working in LBA mode.  according to the ATA spec,
 104         // we can support up to 28-bit addressing.  I don't know if Datafab
 105         // supports beyond 24-bit addressing.  It's kind of hard to test
 106         // since it requires > 8GB CF card.
 107         //
 108         if (sectors > 0x0FFFFFFF)
 109                 return USB_STOR_TRANSPORT_ERROR;
 110
 111         if (info->lun == -1) {
 112                 result = datafab_determine_lun(us, info);
 113                 if (result != USB_STOR_TRANSPORT_GOOD)
 114                         return result;
 115         }
 116
 117         totallen = sectors * info->ssize;
 118
 119         // Since we don't read more than 64 KB at a time, we have to create
 120         // a bounce buffer and move the data a piece at a time between the
 121         // bounce buffer and the actual transfer buffer.
 122
 123         alloclen = min(totallen, 65536u);
 124         buffer = kmalloc(alloclen, GFP_NOIO);
 125         if (buffer == NULL)
 126                 return USB_STOR_TRANSPORT_ERROR;
 127
 128         do {
 129                 // loop, never allocate or transfer more than 64k at once
 130                 // (min(128k, 255*info->ssize) is the real limit)
 131
 132                 len = min(totallen, alloclen);
 133                 thistime = (len / info->ssize) & 0xff;
 134
 135                 command[0] = 0;
 136                 command[1] = thistime;
 137                 command[2] = sector & 0xFF;
 138                 command[3] = (sector >> 8) & 0xFF;
 139                 command[4] = (sector >> 16) & 0xFF;
 140
 141                 command[5] = 0xE0 + (info->lun << 4);
 142                 command[5] |= (sector >> 24) & 0x0F;
 143                 command[6] = 0x20;
 144                 command[7] = 0x01;
 145
 146                 // send the read command
 147                 result = datafab_bulk_write(us, command, 8);
 148                 if (result != USB_STOR_XFER_GOOD)
 149                         goto leave;
 150
 151                 // read the result
 152                 result = datafab_bulk_read(us, buffer, len);
 153                 if (result != USB_STOR_XFER_GOOD)
 154                         goto leave;
 155
 156                 // Store the data in the transfer buffer
 157                 usb_stor_access_xfer_buf(buffer, len, us->srb,
 158                                  &sg_idx, &sg_offset, TO_XFER_BUF);
 159
 160                 sector += thistime;
 161                 totallen -= len;
 162         } while (totallen > 0);
 163
 164         kfree(buffer);
 165         return USB_STOR_TRANSPORT_GOOD;
 166
 167  leave:
 168         kfree(buffer);
 169         return USB_STOR_TRANSPORT_ERROR;
 170 }
 171
 172
 173 static int datafab_write_data(struct us_data *us,
 174                               struct datafab_info *info,
 175                               u32 sector,
 176                               u32 sectors)
 177 {
 178         unsigned char *command = us->iobuf;
 179         unsigned char *reply = us->iobuf;
 180         unsigned char *buffer;
 181         unsigned char thistime;
 182         unsigned int totallen, alloclen;
 183         int len, result;
 184         unsigned int sg_idx = 0, sg_offset = 0;
 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_idx, &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 }