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, void *buf, unsigned int bufflen)
  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 (buf && bufflen) {
  97                 error = blk_rq_map_kern(drive->queue, rq, buf, bufflen,
  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, NULL, 0);
 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, NULL, 0);
 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, NULL, 0);
 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         switch (drive->media) {
 176         case ide_floppy:
 177                 cmd_len = 255;
 178                 sense_len = 18;
 179                 break;
 180         case ide_tape:
 181                 cmd_len = 20;
 182                 sense_len = 20;
 183                 break;
 184         default:
 185                 cmd_len = 18;
 186                 sense_len = 18;
 187         }
 188
 189         BUG_ON(sense_len > sizeof(*sense));
 190
 191         if (blk_sense_request(rq) || drive->sense_rq_armed)
 192                 return;
 193
 194         memset(sense, 0, sizeof(*sense));
 195
 196         blk_rq_init(rq->q, sense_rq);
 197
 198         err = blk_rq_map_kern(drive->queue, sense_rq, sense, sense_len,
 199                               GFP_NOIO);
 200         if (unlikely(err)) {
 201                 if (printk_ratelimit())
 202                         printk(KERN_WARNING "%s: failed to map sense buffer\n",
 203                                drive->name);
 204                 return;
 205         }
 206
 207         sense_rq->rq_disk = rq->rq_disk;
 208         sense_rq->cmd[0] = GPCMD_REQUEST_SENSE;
 209         sense_rq->cmd[4] = cmd_len;
 210         sense_rq->cmd_type = REQ_TYPE_SENSE;
 211         sense_rq->cmd_flags |= REQ_PREEMPT;
 212
 213         if (drive->media == ide_tape)
 214                 sense_rq->cmd[13] = REQ_IDETAPE_PC1;
 215
 216         drive->sense_rq_armed = true;
 217 }
 218 EXPORT_SYMBOL_GPL(ide_prep_sense);
 219
 220 int ide_queue_sense_rq(ide_drive_t *drive, void *special)
 221 {
 222         /* deferred failure from ide_prep_sense() */
 223         if (!drive->sense_rq_armed) {
 224                 printk(KERN_WARNING "%s: failed queue sense request\n",
 225                        drive->name);
 226                 return -ENOMEM;
 227         }
 228
 229         drive->sense_rq.special = special;
 230         drive->sense_rq_armed = false;
 231
 232         drive->hwif->rq = NULL;
 233
 234         elv_add_request(drive->queue, &drive->sense_rq,
 235                         ELEVATOR_INSERT_FRONT, 0);
 236         return 0;
 237 }
 238 EXPORT_SYMBOL_GPL(ide_queue_sense_rq);
 239
 240 /*
 241  * Called when an error was detected during the last packet command.
 242  * We queue a request sense packet command at the head of the request
 243  * queue.
 244  */
 245 void ide_retry_pc(ide_drive_t *drive)
 246 {
 247         struct request *failed_rq = drive->hwif->rq;
 248         struct request *sense_rq = &drive->sense_rq;
 249         struct ide_atapi_pc *pc = &drive->request_sense_pc;
 250
 251         (void)ide_read_error(drive);
 252
 253         /* init pc from sense_rq */
 254         ide_init_pc(pc);
 255         memcpy(pc->c, sense_rq->cmd, 12);
 256
 257         /* pointer to mapped address */
 258         pc->buf = bio_data(sense_rq->bio);
 259         pc->req_xfer = blk_rq_bytes(sense_rq);
 260
 261         if (drive->media == ide_tape)
 262                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
 263
 264         /*
 265          * Push back the failed request and put request sense on top
 266          * of it.  The failed command will be retried after sense data
 267          * is acquired.
 268          */
 269         blk_requeue_request(failed_rq->q, failed_rq);
 270         drive->hwif->rq = NULL;
 271         if (ide_queue_sense_rq(drive, pc)) {
 272                 blk_start_request(failed_rq);
 273                 ide_complete_rq(drive, -EIO, blk_rq_bytes(failed_rq));
 274         }
 275 }
 276 EXPORT_SYMBOL_GPL(ide_retry_pc);
 277
 278 int ide_cd_expiry(ide_drive_t *drive)
 279 {
 280         struct request *rq = drive->hwif->rq;
 281         unsigned long wait = 0;
 282
 283         debug_log("%s: rq->cmd[0]: 0x%x\n", __func__, rq->cmd[0]);
 284
 285         /*
 286          * Some commands are *slow* and normally take a long time to complete.
 287          * Usually we can use the ATAPI "disconnect" to bypass this, but not all
 288          * commands/drives support that. Let ide_timer_expiry keep polling us
 289          * for these.
 290          */
 291         switch (rq->cmd[0]) {
 292         case GPCMD_BLANK:
 293         case GPCMD_FORMAT_UNIT:
 294         case GPCMD_RESERVE_RZONE_TRACK:
 295         case GPCMD_CLOSE_TRACK:
 296         case GPCMD_FLUSH_CACHE:
 297                 wait = ATAPI_WAIT_PC;
 298                 break;
 299         default:
 300                 if (!(rq->cmd_flags & REQ_QUIET))
 301                         printk(KERN_INFO "cmd 0x%x timed out\n",
 302                                          rq->cmd[0]);
 303                 wait = 0;
 304                 break;
 305         }
 306         return wait;
 307 }
 308 EXPORT_SYMBOL_GPL(ide_cd_expiry);
 309
 310 int ide_cd_get_xferlen(struct request *rq)
 311 {
 312         if (blk_fs_request(rq))
 313                 return 32768;
 314         else if (blk_sense_request(rq) || blk_pc_request(rq) ||
 315                          rq->cmd_type == REQ_TYPE_ATA_PC)
 316                 return blk_rq_bytes(rq);
 317         else
 318                 return 0;
 319 }
 320 EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);
 321
 322 void ide_read_bcount_and_ireason(ide_drive_t *drive, u16 *bcount, u8 *ireason)
 323 {
 324         struct ide_taskfile tf;
 325
 326         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT |
 327                                      IDE_VALID_LBAM | IDE_VALID_LBAH);
 328
 329         *bcount = (tf.lbah << 8) | tf.lbam;
 330         *ireason = tf.nsect & 3;
 331 }
 332 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
 333
 334 /*
 335  * This is the usual interrupt handler which will be called during a packet
 336  * command.  We will transfer some of the data (as requested by the drive)
 337  * and will re-point interrupt handler to us.
 338  */
 339 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
 340 {
 341         struct ide_atapi_pc *pc = drive->pc;
 342         ide_hwif_t *hwif = drive->hwif;
 343         struct ide_cmd *cmd = &hwif->cmd;
 344         struct request *rq = hwif->rq;
 345         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 346         unsigned int timeout, done;
 347         u16 bcount;
 348         u8 stat, ireason, dsc = 0;
 349         u8 write = !!(pc->flags & PC_FLAG_WRITING);
 350
 351         debug_log("Enter %s - interrupt handler\n", __func__);
 352
 353         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 354                                                : WAIT_TAPE_CMD;
 355
 356         /* Clear the interrupt */
 357         stat = tp_ops->read_status(hwif);
 358
 359         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 360                 int rc;
 361
 362                 drive->waiting_for_dma = 0;
 363                 rc = hwif->dma_ops->dma_end(drive);
 364                 ide_dma_unmap_sg(drive, cmd);
 365
 366                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
 367                         if (drive->media == ide_floppy)
 368                                 printk(KERN_ERR "%s: DMA %s error\n",
 369                                         drive->name, rq_data_dir(pc->rq)
 370                                                      ? "write" : "read");
 371                         pc->flags |= PC_FLAG_DMA_ERROR;
 372                 } else
 373                         rq->resid_len = 0;
 374                 debug_log("%s: DMA finished\n", drive->name);
 375         }
 376
 377         /* No more interrupts */
 378         if ((stat & ATA_DRQ) == 0) {
 379                 int uptodate, error;
 380
 381                 debug_log("Packet command completed, %d bytes transferred\n",
 382                           blk_rq_bytes(rq));
 383
 384                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 385
 386                 local_irq_enable_in_hardirq();
 387
 388                 if (drive->media == ide_tape &&
 389                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
 390                         stat &= ~ATA_ERR;
 391
 392                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
 393                         /* Error detected */
 394                         debug_log("%s: I/O error\n", drive->name);
 395
 396                         if (drive->media != ide_tape)
 397                                 pc->rq->errors++;
 398
 399                         if (rq->cmd[0] == REQUEST_SENSE) {
 400                                 printk(KERN_ERR "%s: I/O error in request sense"
 401                                                 " command\n", drive->name);
 402                                 return ide_do_reset(drive);
 403                         }
 404
 405                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
 406
 407                         /* Retry operation */
 408                         ide_retry_pc(drive);
 409
 410                         /* queued, but not started */
 411                         return ide_stopped;
 412                 }
 413                 pc->error = 0;
 414
 415                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
 416                         dsc = 1;
 417
 418                 /* Command finished - Call the callback function */
 419                 uptodate = drive->pc_callback(drive, dsc);
 420
 421                 if (uptodate == 0)
 422                         drive->failed_pc = NULL;
 423
 424                 if (blk_special_request(rq)) {
 425                         rq->errors = 0;
 426                         error = 0;
 427                 } else {
 428
 429                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
 430                                 if (rq->errors == 0)
 431                                         rq->errors = -EIO;
 432                         }
 433
 434                         error = uptodate ? 0 : -EIO;
 435                 }
 436
 437                 ide_complete_rq(drive, error, blk_rq_bytes(rq));
 438                 return ide_stopped;
 439         }
 440
 441         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 442                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 443                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
 444                                 "in DMA mode\n", drive->name);
 445                 ide_dma_off(drive);
 446                 return ide_do_reset(drive);
 447         }
 448
 449         /* Get the number of bytes to transfer on this interrupt. */
 450         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
 451
 452         if (ireason & ATAPI_COD) {
 453                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
 454                 return ide_do_reset(drive);
 455         }
 456
 457         if (((ireason & ATAPI_IO) == ATAPI_IO) == write) {
 458                 /* Hopefully, we will never get here */
 459                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
 460                                 "to %s!\n", drive->name,
 461                                 (ireason & ATAPI_IO) ? "Write" : "Read",
 462                                 (ireason & ATAPI_IO) ? "Read" : "Write");
 463                 return ide_do_reset(drive);
 464         }
 465
 466         done = min_t(unsigned int, bcount, cmd->nleft);
 467         ide_pio_bytes(drive, cmd, write, done);
 468
 469         /* Update transferred byte count */
 470         rq->resid_len -= done;
 471
 472         bcount -= done;
 473
 474         if (bcount)
 475                 ide_pad_transfer(drive, write, bcount);
 476
 477         debug_log("[cmd %x] transferred %d bytes, padded %d bytes, resid: %u\n",
 478                   rq->cmd[0], done, bcount, rq->resid_len);
 479
 480         /* And set the interrupt handler again */
 481         ide_set_handler(drive, ide_pc_intr, timeout);
 482         return ide_started;
 483 }
 484
 485 static void ide_init_packet_cmd(struct ide_cmd *cmd, u8 valid_tf,
 486                                 u16 bcount, u8 dma)
 487 {
 488         cmd->protocol = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
 489         cmd->valid.out.tf = IDE_VALID_LBAH | IDE_VALID_LBAM |
 490                             IDE_VALID_FEATURE | valid_tf;
 491         cmd->tf.command = ATA_CMD_PACKET;
 492         cmd->tf.feature = dma;          /* Use PIO/DMA */
 493         cmd->tf.lbam    = bcount & 0xff;
 494         cmd->tf.lbah    = (bcount >> 8) & 0xff;
 495 }
 496
 497 static u8 ide_read_ireason(ide_drive_t *drive)
 498 {
 499         struct ide_taskfile tf;
 500
 501         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT);
 502
 503         return tf.nsect & 3;
 504 }
 505
 506 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
 507 {
 508         int retries = 100;
 509
 510         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
 511                 (ireason & ATAPI_IO))) {
 512                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 513                                 "a packet command, retrying\n", drive->name);
 514                 udelay(100);
 515                 ireason = ide_read_ireason(drive);
 516                 if (retries == 0) {
 517                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 518                                         "a packet command, ignoring\n",
 519                                         drive->name);
 520                         ireason |= ATAPI_COD;
 521                         ireason &= ~ATAPI_IO;
 522                 }
 523         }
 524
 525         return ireason;
 526 }
 527
 528 static int ide_delayed_transfer_pc(ide_drive_t *drive)
 529 {
 530         /* Send the actual packet */
 531         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
 532
 533         /* Timeout for the packet command */
 534         return WAIT_FLOPPY_CMD;
 535 }
 536
 537 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 538 {
 539         struct ide_atapi_pc *uninitialized_var(pc);
 540         ide_hwif_t *hwif = drive->hwif;
 541         struct request *rq = hwif->rq;
 542         ide_expiry_t *expiry;
 543         unsigned int timeout;
 544         int cmd_len;
 545         ide_startstop_t startstop;
 546         u8 ireason;
 547
 548         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
 549                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
 550                                 "DRQ isn't asserted\n", drive->name);
 551                 return startstop;
 552         }
 553
 554         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 555                 if (drive->dma)
 556                         drive->waiting_for_dma = 1;
 557         }
 558
 559         if (dev_is_idecd(drive)) {
 560                 /* ATAPI commands get padded out to 12 bytes minimum */
 561                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
 562                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
 563                         cmd_len = ATAPI_MIN_CDB_BYTES;
 564
 565                 timeout = rq->timeout;
 566                 expiry  = ide_cd_expiry;
 567         } else {
 568                 pc = drive->pc;
 569
 570                 cmd_len = ATAPI_MIN_CDB_BYTES;
 571
 572                 /*
 573                  * If necessary schedule the packet transfer to occur 'timeout'
 574                  * miliseconds later in ide_delayed_transfer_pc() after the
 575                  * device says it's ready for a packet.
 576                  */
 577                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
 578                         timeout = drive->pc_delay;
 579                         expiry = &ide_delayed_transfer_pc;
 580                 } else {
 581                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 582                                                                : WAIT_TAPE_CMD;
 583                         expiry = NULL;
 584                 }
 585
 586                 ireason = ide_read_ireason(drive);
 587                 if (drive->media == ide_tape)
 588                         ireason = ide_wait_ireason(drive, ireason);
 589
 590                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
 591                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
 592                                         "a packet command\n", drive->name);
 593
 594                         return ide_do_reset(drive);
 595                 }
 596         }
 597
 598         hwif->expiry = expiry;
 599
 600         /* Set the interrupt routine */
 601         ide_set_handler(drive,
 602                         (dev_is_idecd(drive) ? drive->irq_handler
 603                                              : ide_pc_intr),
 604                         timeout);
 605
 606         /* Send the actual packet */
 607         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
 608                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
 609
 610         /* Begin DMA, if necessary */
 611         if (dev_is_idecd(drive)) {
 612                 if (drive->dma)
 613                         hwif->dma_ops->dma_start(drive);
 614         } else {
 615                 if (pc->flags & PC_FLAG_DMA_OK) {
 616                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
 617                         hwif->dma_ops->dma_start(drive);
 618                 }
 619         }
 620
 621         return ide_started;
 622 }
 623
 624 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
 625 {
 626         struct ide_atapi_pc *pc;
 627         ide_hwif_t *hwif = drive->hwif;
 628         ide_expiry_t *expiry = NULL;
 629         struct request *rq = hwif->rq;
 630         unsigned int timeout, bytes;
 631         u16 bcount;
 632         u8 valid_tf;
 633         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
 634
 635         if (dev_is_idecd(drive)) {
 636                 valid_tf = IDE_VALID_NSECT | IDE_VALID_LBAL;
 637                 bcount = ide_cd_get_xferlen(rq);
 638                 expiry = ide_cd_expiry;
 639                 timeout = ATAPI_WAIT_PC;
 640
 641                 if (drive->dma)
 642                         drive->dma = !ide_dma_prepare(drive, cmd);
 643         } else {
 644                 pc = drive->pc;
 645
 646                 valid_tf = IDE_VALID_DEVICE;
 647                 bytes = blk_rq_bytes(rq);
 648                 bcount = ((drive->media == ide_tape) ? bytes
 649                                                      : min_t(unsigned int,
 650                                                              bytes, 63 * 1024));
 651
 652                 /* We haven't transferred any data yet */
 653                 rq->resid_len = bcount;
 654
 655                 if (pc->flags & PC_FLAG_DMA_ERROR) {
 656                         pc->flags &= ~PC_FLAG_DMA_ERROR;
 657                         ide_dma_off(drive);
 658                 }
 659
 660                 if (pc->flags & PC_FLAG_DMA_OK)
 661                         drive->dma = !ide_dma_prepare(drive, cmd);
 662
 663                 if (!drive->dma)
 664                         pc->flags &= ~PC_FLAG_DMA_OK;
 665
 666                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 667                                                        : WAIT_TAPE_CMD;
 668         }
 669
 670         ide_init_packet_cmd(cmd, valid_tf, bcount, drive->dma);
 671
 672         (void)do_rw_taskfile(drive, cmd);
 673
 674         if (drq_int) {
 675                 if (drive->dma)
 676                         drive->waiting_for_dma = 0;
 677                 hwif->expiry = expiry;
 678         }
 679
 680         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
 681
 682         return drq_int ? ide_started : ide_transfer_pc(drive);
 683 }
 684 EXPORT_SYMBOL_GPL(ide_issue_pc);