drivers/ide/ide-atapi.c

   1 /*
   2  * ATAPI support.
   3  */
   4
   5 #include <linux/kernel.h>
   6 #include <linux/cdrom.h>
   7 #include <linux/delay.h>
   8 #include <linux/ide.h>
   9 #include <linux/scatterlist.h>
  10
  11 #include <scsi/scsi.h>
  12
  13 #ifdef DEBUG
  14 #define debug_log(fmt, args...) \
  15         printk(KERN_INFO "ide: " fmt, ## args)
  16 #else
  17 #define debug_log(fmt, args...) do {} while (0)
  18 #endif
  19
  20 #define ATAPI_MIN_CDB_BYTES     12
  21
  22 static inline int dev_is_idecd(ide_drive_t *drive)
  23 {
  24         return drive->media == ide_cdrom || drive->media == ide_optical;
  25 }
  26
  27 /*
  28  * Check whether we can support a device,
  29  * based on the ATAPI IDENTIFY command results.
  30  */
  31 int ide_check_atapi_device(ide_drive_t *drive, const char *s)
  32 {
  33         u16 *id = drive->id;
  34         u8 gcw[2], protocol, device_type, removable, drq_type, packet_size;
  35
  36         *((u16 *)&gcw) = id[ATA_ID_CONFIG];
  37
  38         protocol    = (gcw[1] & 0xC0) >> 6;
  39         device_type =  gcw[1] & 0x1F;
  40         removable   = (gcw[0] & 0x80) >> 7;
  41         drq_type    = (gcw[0] & 0x60) >> 5;
  42         packet_size =  gcw[0] & 0x03;
  43
  44 #ifdef CONFIG_PPC
  45         /* kludge for Apple PowerBook internal zip */
  46         if (drive->media == ide_floppy && device_type == 5 &&
  47             !strstr((char *)&id[ATA_ID_PROD], "CD-ROM") &&
  48             strstr((char *)&id[ATA_ID_PROD], "ZIP"))
  49                 device_type = 0;
  50 #endif
  51
  52         if (protocol != 2)
  53                 printk(KERN_ERR "%s: %s: protocol (0x%02x) is not ATAPI\n",
  54                         s, drive->name, protocol);
  55         else if ((drive->media == ide_floppy && device_type != 0) ||
  56                  (drive->media == ide_tape && device_type != 1))
  57                 printk(KERN_ERR "%s: %s: invalid device type (0x%02x)\n",
  58                         s, drive->name, device_type);
  59         else if (removable == 0)
  60                 printk(KERN_ERR "%s: %s: the removable flag is not set\n",
  61                         s, drive->name);
  62         else if (drive->media == ide_floppy && drq_type == 3)
  63                 printk(KERN_ERR "%s: %s: sorry, DRQ type (0x%02x) not "
  64                         "supported\n", s, drive->name, drq_type);
  65         else if (packet_size != 0)
  66                 printk(KERN_ERR "%s: %s: packet size (0x%02x) is not 12 "
  67                         "bytes\n", s, drive->name, packet_size);
  68         else
  69                 return 1;
  70         return 0;
  71 }
  72 EXPORT_SYMBOL_GPL(ide_check_atapi_device);
  73
  74 void ide_init_pc(struct ide_atapi_pc *pc)
  75 {
  76         memset(pc, 0, sizeof(*pc));
  77         pc->buf = pc->pc_buf;
  78         pc->buf_size = IDE_PC_BUFFER_SIZE;
  79 }
  80 EXPORT_SYMBOL_GPL(ide_init_pc);
  81
  82 /*
  83  * Add a special packet command request to the tail of the request queue,
  84  * and wait for it to be serviced.
  85  */
  86 int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,
  87                       struct ide_atapi_pc *pc)
  88 {
  89         struct request *rq;
  90         int error;
  91
  92         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
  93         rq->cmd_type = REQ_TYPE_SPECIAL;
  94         rq->special = (char *)pc;
  95
  96         if (pc->req_xfer) {
  97                 error = blk_rq_map_kern(drive->queue, rq, pc->buf, pc->req_xfer,
  98                                         GFP_NOIO);
  99                 if (error)
 100                         goto put_req;
 101         }
 102
 103         memcpy(rq->cmd, pc->c, 12);
 104         if (drive->media == ide_tape)
 105                 rq->cmd[13] = REQ_IDETAPE_PC1;
 106         error = blk_execute_rq(drive->queue, disk, rq, 0);
 107 put_req:
 108         blk_put_request(rq);
 109         return error;
 110 }
 111 EXPORT_SYMBOL_GPL(ide_queue_pc_tail);
 112
 113 int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
 114 {
 115         struct ide_atapi_pc pc;
 116
 117         ide_init_pc(&pc);
 118         pc.c[0] = TEST_UNIT_READY;
 119
 120         return ide_queue_pc_tail(drive, disk, &pc);
 121 }
 122 EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);
 123
 124 int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
 125 {
 126         struct ide_atapi_pc pc;
 127
 128         ide_init_pc(&pc);
 129         pc.c[0] = START_STOP;
 130         pc.c[4] = start;
 131
 132         if (drive->media == ide_tape)
 133                 pc.flags |= PC_FLAG_WAIT_FOR_DSC;
 134
 135         return ide_queue_pc_tail(drive, disk, &pc);
 136 }
 137 EXPORT_SYMBOL_GPL(ide_do_start_stop);
 138
 139 int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
 140 {
 141         struct ide_atapi_pc pc;
 142
 143         if ((drive->dev_flags & IDE_DFLAG_DOORLOCKING) == 0)
 144                 return 0;
 145
 146         ide_init_pc(&pc);
 147         pc.c[0] = ALLOW_MEDIUM_REMOVAL;
 148         pc.c[4] = on;
 149
 150         return ide_queue_pc_tail(drive, disk, &pc);
 151 }
 152 EXPORT_SYMBOL_GPL(ide_set_media_lock);
 153
 154 void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
 155 {
 156         ide_init_pc(pc);
 157         pc->c[0] = REQUEST_SENSE;
 158         if (drive->media == ide_floppy) {
 159                 pc->c[4] = 255;
 160                 pc->req_xfer = 18;
 161         } else {
 162                 pc->c[4] = 20;
 163                 pc->req_xfer = 20;
 164         }
 165 }
 166 EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);
 167
 168 void ide_prep_sense(ide_drive_t *drive, struct request *rq)
 169 {
 170         struct request_sense *sense = &drive->sense_data;
 171         struct request *sense_rq = &drive->sense_rq;
 172         unsigned int cmd_len, sense_len;
 173         int err;
 174
 175         debug_log("%s: enter\n", __func__);
 176
 177         switch (drive->media) {
 178         case ide_floppy:
 179                 cmd_len = 255;
 180                 sense_len = 18;
 181                 break;
 182         case ide_tape:
 183                 cmd_len = 20;
 184                 sense_len = 20;
 185                 break;
 186         default:
 187                 cmd_len = 18;
 188                 sense_len = 18;
 189         }
 190
 191         BUG_ON(sense_len > sizeof(*sense));
 192
 193         if (blk_sense_request(rq) || drive->sense_rq_armed)
 194                 return;
 195
 196         memset(sense, 0, sizeof(*sense));
 197
 198         blk_rq_init(rq->q, sense_rq);
 199
 200         err = blk_rq_map_kern(drive->queue, sense_rq, sense, sense_len,
 201                               GFP_NOIO);
 202         if (unlikely(err)) {
 203                 if (printk_ratelimit())
 204                         printk(KERN_WARNING "%s: failed to map sense buffer\n",
 205                                drive->name);
 206                 return;
 207         }
 208
 209         sense_rq->rq_disk = rq->rq_disk;
 210         sense_rq->cmd[0] = GPCMD_REQUEST_SENSE;
 211         sense_rq->cmd[4] = cmd_len;
 212         sense_rq->cmd_type = REQ_TYPE_SENSE;
 213         sense_rq->cmd_flags |= REQ_PREEMPT;
 214
 215         if (drive->media == ide_tape)
 216                 sense_rq->cmd[13] = REQ_IDETAPE_PC1;
 217
 218         drive->sense_rq_armed = true;
 219 }
 220 EXPORT_SYMBOL_GPL(ide_prep_sense);
 221
 222 int ide_queue_sense_rq(ide_drive_t *drive, void *special)
 223 {
 224         /* deferred failure from ide_prep_sense() */
 225         if (!drive->sense_rq_armed) {
 226                 printk(KERN_WARNING "%s: failed queue sense request\n",
 227                        drive->name);
 228                 return -ENOMEM;
 229         }
 230
 231         drive->sense_rq.special = special;
 232         drive->sense_rq_armed = false;
 233
 234         drive->hwif->rq = NULL;
 235
 236         elv_add_request(drive->queue, &drive->sense_rq,
 237                         ELEVATOR_INSERT_FRONT, 0);
 238         return 0;
 239 }
 240 EXPORT_SYMBOL_GPL(ide_queue_sense_rq);
 241
 242 /*
 243  * Called when an error was detected during the last packet command.
 244  * We queue a request sense packet command at the head of the request
 245  * queue.
 246  */
 247 void ide_retry_pc(ide_drive_t *drive)
 248 {
 249         struct request *sense_rq = &drive->sense_rq;
 250         struct ide_atapi_pc *pc = &drive->request_sense_pc;
 251
 252         (void)ide_read_error(drive);
 253
 254         /* init pc from sense_rq */
 255         ide_init_pc(pc);
 256         memcpy(pc->c, sense_rq->cmd, 12);
 257         pc->buf = bio_data(sense_rq->bio);      /* pointer to mapped address */
 258         pc->req_xfer = sense_rq->data_len;
 259
 260         if (drive->media == ide_tape)
 261                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
 262
 263         if (ide_queue_sense_rq(drive, pc))
 264                 ide_complete_rq(drive, -EIO, blk_rq_bytes(drive->hwif->rq));
 265 }
 266 EXPORT_SYMBOL_GPL(ide_retry_pc);
 267
 268 int ide_cd_expiry(ide_drive_t *drive)
 269 {
 270         struct request *rq = drive->hwif->rq;
 271         unsigned long wait = 0;
 272
 273         debug_log("%s: rq->cmd[0]: 0x%x\n", __func__, rq->cmd[0]);
 274
 275         /*
 276          * Some commands are *slow* and normally take a long time to complete.
 277          * Usually we can use the ATAPI "disconnect" to bypass this, but not all
 278          * commands/drives support that. Let ide_timer_expiry keep polling us
 279          * for these.
 280          */
 281         switch (rq->cmd[0]) {
 282         case GPCMD_BLANK:
 283         case GPCMD_FORMAT_UNIT:
 284         case GPCMD_RESERVE_RZONE_TRACK:
 285         case GPCMD_CLOSE_TRACK:
 286         case GPCMD_FLUSH_CACHE:
 287                 wait = ATAPI_WAIT_PC;
 288                 break;
 289         default:
 290                 if (!(rq->cmd_flags & REQ_QUIET))
 291                         printk(KERN_INFO "cmd 0x%x timed out\n",
 292                                          rq->cmd[0]);
 293                 wait = 0;
 294                 break;
 295         }
 296         return wait;
 297 }
 298 EXPORT_SYMBOL_GPL(ide_cd_expiry);
 299
 300 int ide_cd_get_xferlen(struct request *rq)
 301 {
 302         if (blk_fs_request(rq))
 303                 return 32768;
 304         else if (blk_sense_request(rq) || blk_pc_request(rq) ||
 305                          rq->cmd_type == REQ_TYPE_ATA_PC)
 306                 return rq->data_len;
 307         else
 308                 return 0;
 309 }
 310 EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);
 311
 312 void ide_read_bcount_and_ireason(ide_drive_t *drive, u16 *bcount, u8 *ireason)
 313 {
 314         struct ide_taskfile tf;
 315
 316         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT |
 317                                      IDE_VALID_LBAM | IDE_VALID_LBAH);
 318
 319         *bcount = (tf.lbah << 8) | tf.lbam;
 320         *ireason = tf.nsect & 3;
 321 }
 322 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
 323
 324 /*
 325  * This is the usual interrupt handler which will be called during a packet
 326  * command.  We will transfer some of the data (as requested by the drive)
 327  * and will re-point interrupt handler to us.
 328  */
 329 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
 330 {
 331         struct ide_atapi_pc *pc = drive->pc;
 332         ide_hwif_t *hwif = drive->hwif;
 333         struct ide_cmd *cmd = &hwif->cmd;
 334         struct request *rq = hwif->rq;
 335         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 336         unsigned int timeout, done;
 337         u16 bcount;
 338         u8 stat, ireason, dsc = 0;
 339         u8 write = !!(pc->flags & PC_FLAG_WRITING);
 340
 341         debug_log("Enter %s - interrupt handler\n", __func__);
 342
 343         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 344                                                : WAIT_TAPE_CMD;
 345
 346         /* Clear the interrupt */
 347         stat = tp_ops->read_status(hwif);
 348
 349         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 350                 int rc;
 351
 352                 drive->waiting_for_dma = 0;
 353                 rc = hwif->dma_ops->dma_end(drive);
 354                 ide_dma_unmap_sg(drive, cmd);
 355
 356                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
 357                         if (drive->media == ide_floppy)
 358                                 printk(KERN_ERR "%s: DMA %s error\n",
 359                                         drive->name, rq_data_dir(pc->rq)
 360                                                      ? "write" : "read");
 361                         pc->flags |= PC_FLAG_DMA_ERROR;
 362                 } else
 363                         pc->xferred = pc->req_xfer;
 364                 debug_log("%s: DMA finished\n", drive->name);
 365         }
 366
 367         /* No more interrupts */
 368         if ((stat & ATA_DRQ) == 0) {
 369                 int uptodate, error;
 370
 371                 debug_log("Packet command completed, %d bytes transferred\n",
 372                           pc->xferred);
 373
 374                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 375
 376                 local_irq_enable_in_hardirq();
 377
 378                 if (drive->media == ide_tape &&
 379                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
 380                         stat &= ~ATA_ERR;
 381
 382                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
 383                         /* Error detected */
 384                         debug_log("%s: I/O error\n", drive->name);
 385
 386                         if (drive->media != ide_tape)
 387                                 pc->rq->errors++;
 388
 389                         if (rq->cmd[0] == REQUEST_SENSE) {
 390                                 printk(KERN_ERR "%s: I/O error in request sense"
 391                                                 " command\n", drive->name);
 392                                 return ide_do_reset(drive);
 393                         }
 394
 395                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
 396
 397                         /* Retry operation */
 398                         ide_retry_pc(drive);
 399
 400                         /* queued, but not started */
 401                         return ide_stopped;
 402                 }
 403                 pc->error = 0;
 404
 405                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
 406                         dsc = 1;
 407
 408                 /* Command finished - Call the callback function */
 409                 uptodate = drive->pc_callback(drive, dsc);
 410
 411                 if (uptodate == 0)
 412                         drive->failed_pc = NULL;
 413
 414                 if (blk_special_request(rq)) {
 415                         rq->errors = 0;
 416                         error = 0;
 417                 } else {
 418
 419                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
 420                                 if (rq->errors == 0)
 421                                         rq->errors = -EIO;
 422                         }
 423
 424                         error = uptodate ? 0 : -EIO;
 425                 }
 426
 427                 ide_complete_rq(drive, error, blk_rq_bytes(rq));
 428                 return ide_stopped;
 429         }
 430
 431         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 432                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 433                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
 434                                 "in DMA mode\n", drive->name);
 435                 ide_dma_off(drive);
 436                 return ide_do_reset(drive);
 437         }
 438
 439         /* Get the number of bytes to transfer on this interrupt. */
 440         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
 441
 442         if (ireason & ATAPI_COD) {
 443                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
 444                 return ide_do_reset(drive);
 445         }
 446
 447         if (((ireason & ATAPI_IO) == ATAPI_IO) == write) {
 448                 /* Hopefully, we will never get here */
 449                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
 450                                 "to %s!\n", drive->name,
 451                                 (ireason & ATAPI_IO) ? "Write" : "Read",
 452                                 (ireason & ATAPI_IO) ? "Read" : "Write");
 453                 return ide_do_reset(drive);
 454         }
 455
 456         done = min_t(unsigned int, bcount, cmd->nleft);
 457         ide_pio_bytes(drive, cmd, write, done);
 458
 459         /* Update transferred byte count */
 460         pc->xferred += done;
 461
 462         bcount -= done;
 463
 464         if (bcount)
 465                 ide_pad_transfer(drive, write, bcount);
 466
 467         debug_log("[cmd %x] transferred %d bytes, padded %d bytes\n",
 468                   rq->cmd[0], done, bcount);
 469
 470         /* And set the interrupt handler again */
 471         ide_set_handler(drive, ide_pc_intr, timeout);
 472         return ide_started;
 473 }
 474
 475 static void ide_init_packet_cmd(struct ide_cmd *cmd, u8 valid_tf,
 476                                 u16 bcount, u8 dma)
 477 {
 478         cmd->protocol = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
 479         cmd->valid.out.tf = IDE_VALID_LBAH | IDE_VALID_LBAM |
 480                             IDE_VALID_FEATURE | valid_tf;
 481         cmd->tf.command = ATA_CMD_PACKET;
 482         cmd->tf.feature = dma;          /* Use PIO/DMA */
 483         cmd->tf.lbam    = bcount & 0xff;
 484         cmd->tf.lbah    = (bcount >> 8) & 0xff;
 485 }
 486
 487 static u8 ide_read_ireason(ide_drive_t *drive)
 488 {
 489         struct ide_taskfile tf;
 490
 491         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT);
 492
 493         return tf.nsect & 3;
 494 }
 495
 496 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
 497 {
 498         int retries = 100;
 499
 500         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
 501                 (ireason & ATAPI_IO))) {
 502                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 503                                 "a packet command, retrying\n", drive->name);
 504                 udelay(100);
 505                 ireason = ide_read_ireason(drive);
 506                 if (retries == 0) {
 507                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 508                                         "a packet command, ignoring\n",
 509                                         drive->name);
 510                         ireason |= ATAPI_COD;
 511                         ireason &= ~ATAPI_IO;
 512                 }
 513         }
 514
 515         return ireason;
 516 }
 517
 518 static int ide_delayed_transfer_pc(ide_drive_t *drive)
 519 {
 520         /* Send the actual packet */
 521         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
 522
 523         /* Timeout for the packet command */
 524         return WAIT_FLOPPY_CMD;
 525 }
 526
 527 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 528 {
 529         struct ide_atapi_pc *uninitialized_var(pc);
 530         ide_hwif_t *hwif = drive->hwif;
 531         struct request *rq = hwif->rq;
 532         ide_expiry_t *expiry;
 533         unsigned int timeout;
 534         int cmd_len;
 535         ide_startstop_t startstop;
 536         u8 ireason;
 537
 538         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
 539                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
 540                                 "DRQ isn't asserted\n", drive->name);
 541                 return startstop;
 542         }
 543
 544         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 545                 if (drive->dma)
 546                         drive->waiting_for_dma = 1;
 547         }
 548
 549         if (dev_is_idecd(drive)) {
 550                 /* ATAPI commands get padded out to 12 bytes minimum */
 551                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
 552                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
 553                         cmd_len = ATAPI_MIN_CDB_BYTES;
 554
 555                 timeout = rq->timeout;
 556                 expiry  = ide_cd_expiry;
 557         } else {
 558                 pc = drive->pc;
 559
 560                 cmd_len = ATAPI_MIN_CDB_BYTES;
 561
 562                 /*
 563                  * If necessary schedule the packet transfer to occur 'timeout'
 564                  * miliseconds later in ide_delayed_transfer_pc() after the
 565                  * device says it's ready for a packet.
 566                  */
 567                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
 568                         timeout = drive->pc_delay;
 569                         expiry = &ide_delayed_transfer_pc;
 570                 } else {
 571                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 572                                                                : WAIT_TAPE_CMD;
 573                         expiry = NULL;
 574                 }
 575
 576                 ireason = ide_read_ireason(drive);
 577                 if (drive->media == ide_tape)
 578                         ireason = ide_wait_ireason(drive, ireason);
 579
 580                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
 581                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
 582                                         "a packet command\n", drive->name);
 583
 584                         return ide_do_reset(drive);
 585                 }
 586         }
 587
 588         hwif->expiry = expiry;
 589
 590         /* Set the interrupt routine */
 591         ide_set_handler(drive,
 592                         (dev_is_idecd(drive) ? drive->irq_handler
 593                                              : ide_pc_intr),
 594                         timeout);
 595
 596         /* Send the actual packet */
 597         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
 598                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
 599
 600         /* Begin DMA, if necessary */
 601         if (dev_is_idecd(drive)) {
 602                 if (drive->dma)
 603                         hwif->dma_ops->dma_start(drive);
 604         } else {
 605                 if (pc->flags & PC_FLAG_DMA_OK) {
 606                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
 607                         hwif->dma_ops->dma_start(drive);
 608                 }
 609         }
 610
 611         return ide_started;
 612 }
 613
 614 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
 615 {
 616         struct ide_atapi_pc *pc;
 617         ide_hwif_t *hwif = drive->hwif;
 618         ide_expiry_t *expiry = NULL;
 619         struct request *rq = hwif->rq;
 620         unsigned int timeout;
 621         u16 bcount;
 622         u8 valid_tf;
 623         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
 624
 625         if (dev_is_idecd(drive)) {
 626                 valid_tf = IDE_VALID_NSECT | IDE_VALID_LBAL;
 627                 bcount = ide_cd_get_xferlen(rq);
 628                 expiry = ide_cd_expiry;
 629                 timeout = ATAPI_WAIT_PC;
 630
 631                 if (drive->dma)
 632                         drive->dma = !ide_dma_prepare(drive, cmd);
 633         } else {
 634                 pc = drive->pc;
 635
 636                 /* We haven't transferred any data yet */
 637                 pc->xferred = 0;
 638
 639                 valid_tf = IDE_VALID_DEVICE;
 640                 bcount = ((drive->media == ide_tape) ?
 641                                 pc->req_xfer :
 642                                 min(pc->req_xfer, 63 * 1024));
 643
 644                 if (pc->flags & PC_FLAG_DMA_ERROR) {
 645                         pc->flags &= ~PC_FLAG_DMA_ERROR;
 646                         ide_dma_off(drive);
 647                 }
 648
 649                 if (pc->flags & PC_FLAG_DMA_OK)
 650                         drive->dma = !ide_dma_prepare(drive, cmd);
 651
 652                 if (!drive->dma)
 653                         pc->flags &= ~PC_FLAG_DMA_OK;
 654
 655                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 656                                                        : WAIT_TAPE_CMD;
 657         }
 658
 659         ide_init_packet_cmd(cmd, valid_tf, bcount, drive->dma);
 660
 661         (void)do_rw_taskfile(drive, cmd);
 662
 663         if (drq_int) {
 664                 if (drive->dma)
 665                         drive->waiting_for_dma = 0;
 666                 hwif->expiry = expiry;
 667         }
 668
 669         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
 670
 671         return drq_int ? ide_started : ide_transfer_pc(drive);
 672 }
 673 EXPORT_SYMBOL_GPL(ide_issue_pc);