git.oblomov.eu Git - linux-2.6/blob - drivers/ide/ide-atapi.c

   1 /*
   2  * ATAPI support.
   3  */
   4
   5 #include <linux/kernel.h>
   6 #include <linux/delay.h>
   7 #include <linux/ide.h>
   8 #include <scsi/scsi.h>
   9
  10 #ifdef DEBUG
  11 #define debug_log(fmt, args...) \
  12         printk(KERN_INFO "ide: " fmt, ## args)
  13 #else
  14 #define debug_log(fmt, args...) do {} while (0)
  15 #endif
  16
  17 /*
  18  * Check whether we can support a device,
  19  * based on the ATAPI IDENTIFY command results.
  20  */
  21 int ide_check_atapi_device(ide_drive_t *drive, const char *s)
  22 {
  23         u16 *id = drive->id;
  24         u8 gcw[2], protocol, device_type, removable, drq_type, packet_size;
  25
  26         *((u16 *)&gcw) = id[ATA_ID_CONFIG];
  27
  28         protocol    = (gcw[1] & 0xC0) >> 6;
  29         device_type =  gcw[1] & 0x1F;
  30         removable   = (gcw[0] & 0x80) >> 7;
  31         drq_type    = (gcw[0] & 0x60) >> 5;
  32         packet_size =  gcw[0] & 0x03;
  33
  34 #ifdef CONFIG_PPC
  35         /* kludge for Apple PowerBook internal zip */
  36         if (drive->media == ide_floppy && device_type == 5 &&
  37             !strstr((char *)&id[ATA_ID_PROD], "CD-ROM") &&
  38             strstr((char *)&id[ATA_ID_PROD], "ZIP"))
  39                 device_type = 0;
  40 #endif
  41
  42         if (protocol != 2)
  43                 printk(KERN_ERR "%s: %s: protocol (0x%02x) is not ATAPI\n",
  44                         s, drive->name, protocol);
  45         else if ((drive->media == ide_floppy && device_type != 0) ||
  46                  (drive->media == ide_tape && device_type != 1))
  47                 printk(KERN_ERR "%s: %s: invalid device type (0x%02x)\n",
  48                         s, drive->name, device_type);
  49         else if (removable == 0)
  50                 printk(KERN_ERR "%s: %s: the removable flag is not set\n",
  51                         s, drive->name);
  52         else if (drive->media == ide_floppy && drq_type == 3)
  53                 printk(KERN_ERR "%s: %s: sorry, DRQ type (0x%02x) not "
  54                         "supported\n", s, drive->name, drq_type);
  55         else if (packet_size != 0)
  56                 printk(KERN_ERR "%s: %s: packet size (0x%02x) is not 12 "
  57                         "bytes\n", s, drive->name, packet_size);
  58         else
  59                 return 1;
  60         return 0;
  61 }
  62 EXPORT_SYMBOL_GPL(ide_check_atapi_device);
  63
  64 /* PIO data transfer routine using the scatter gather table. */
  65 int ide_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
  66                     unsigned int bcount, int write)
  67 {
  68         ide_hwif_t *hwif = drive->hwif;
  69         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
  70         xfer_func_t *xf = write ? tp_ops->output_data : tp_ops->input_data;
  71         struct scatterlist *sg = pc->sg;
  72         char *buf;
  73         int count, done = 0;
  74
  75         while (bcount) {
  76                 count = min(sg->length - pc->b_count, bcount);
  77
  78                 if (PageHighMem(sg_page(sg))) {
  79                         unsigned long flags;
  80
  81                         local_irq_save(flags);
  82                         buf = kmap_atomic(sg_page(sg), KM_IRQ0) + sg->offset;
  83                         xf(drive, NULL, buf + pc->b_count, count);
  84                         kunmap_atomic(buf - sg->offset, KM_IRQ0);
  85                         local_irq_restore(flags);
  86                 } else {
  87                         buf = sg_virt(sg);
  88                         xf(drive, NULL, buf + pc->b_count, count);
  89                 }
  90
  91                 bcount -= count;
  92                 pc->b_count += count;
  93                 done += count;
  94
  95                 if (pc->b_count == sg->length) {
  96                         if (!--pc->sg_cnt)
  97                                 break;
  98                         pc->sg = sg = sg_next(sg);
  99                         pc->b_count = 0;
 100                 }
 101         }
 102
 103         if (bcount) {
 104                 printk(KERN_ERR "%s: %d leftover bytes, %s\n", drive->name,
 105                         bcount, write ? "padding with zeros"
 106                                       : "discarding data");
 107                 ide_pad_transfer(drive, write, bcount);
 108         }
 109
 110         return done;
 111 }
 112 EXPORT_SYMBOL_GPL(ide_io_buffers);
 113
 114 void ide_init_pc(struct ide_atapi_pc *pc)
 115 {
 116         memset(pc, 0, sizeof(*pc));
 117         pc->buf = pc->pc_buf;
 118         pc->buf_size = IDE_PC_BUFFER_SIZE;
 119 }
 120 EXPORT_SYMBOL_GPL(ide_init_pc);
 121
 122 /*
 123  * Generate a new packet command request in front of the request queue, before
 124  * the current request, so that it will be processed immediately, on the next
 125  * pass through the driver.
 126  */
 127 static void ide_queue_pc_head(ide_drive_t *drive, struct gendisk *disk,
 128                               struct ide_atapi_pc *pc, struct request *rq)
 129 {
 130         blk_rq_init(NULL, rq);
 131         rq->cmd_type = REQ_TYPE_SPECIAL;
 132         rq->cmd_flags |= REQ_PREEMPT;
 133         rq->buffer = (char *)pc;
 134         rq->rq_disk = disk;
 135         memcpy(rq->cmd, pc->c, 12);
 136         if (drive->media == ide_tape)
 137                 rq->cmd[13] = REQ_IDETAPE_PC1;
 138         ide_do_drive_cmd(drive, rq);
 139 }
 140
 141 /*
 142  * Add a special packet command request to the tail of the request queue,
 143  * and wait for it to be serviced.
 144  */
 145 int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,
 146                       struct ide_atapi_pc *pc)
 147 {
 148         struct request *rq;
 149         int error;
 150
 151         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
 152         rq->cmd_type = REQ_TYPE_SPECIAL;
 153         rq->buffer = (char *)pc;
 154         memcpy(rq->cmd, pc->c, 12);
 155         if (drive->media == ide_tape)
 156                 rq->cmd[13] = REQ_IDETAPE_PC1;
 157         error = blk_execute_rq(drive->queue, disk, rq, 0);
 158         blk_put_request(rq);
 159
 160         return error;
 161 }
 162 EXPORT_SYMBOL_GPL(ide_queue_pc_tail);
 163
 164 int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
 165 {
 166         struct ide_atapi_pc pc;
 167
 168         ide_init_pc(&pc);
 169         pc.c[0] = TEST_UNIT_READY;
 170
 171         return ide_queue_pc_tail(drive, disk, &pc);
 172 }
 173 EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);
 174
 175 int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
 176 {
 177         struct ide_atapi_pc pc;
 178
 179         ide_init_pc(&pc);
 180         pc.c[0] = START_STOP;
 181         pc.c[4] = start;
 182
 183         if (drive->media == ide_tape)
 184                 pc.flags |= PC_FLAG_WAIT_FOR_DSC;
 185
 186         return ide_queue_pc_tail(drive, disk, &pc);
 187 }
 188 EXPORT_SYMBOL_GPL(ide_do_start_stop);
 189
 190 int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
 191 {
 192         struct ide_atapi_pc pc;
 193
 194         if (drive->atapi_flags & IDE_AFLAG_NO_DOORLOCK)
 195                 return 0;
 196
 197         ide_init_pc(&pc);
 198         pc.c[0] = ALLOW_MEDIUM_REMOVAL;
 199         pc.c[4] = on;
 200
 201         return ide_queue_pc_tail(drive, disk, &pc);
 202 }
 203 EXPORT_SYMBOL_GPL(ide_set_media_lock);
 204
 205 void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
 206 {
 207         ide_init_pc(pc);
 208         pc->c[0] = REQUEST_SENSE;
 209         if (drive->media == ide_floppy) {
 210                 pc->c[4] = 255;
 211                 pc->req_xfer = 18;
 212         } else {
 213                 pc->c[4] = 20;
 214                 pc->req_xfer = 20;
 215         }
 216 }
 217 EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);
 218
 219 /*
 220  * Called when an error was detected during the last packet command.
 221  * We queue a request sense packet command in the head of the request list.
 222  */
 223 void ide_retry_pc(ide_drive_t *drive, struct gendisk *disk)
 224 {
 225         struct request *rq = &drive->request_sense_rq;
 226         struct ide_atapi_pc *pc = &drive->request_sense_pc;
 227
 228         (void)ide_read_error(drive);
 229         ide_create_request_sense_cmd(drive, pc);
 230         if (drive->media == ide_tape)
 231                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
 232         ide_queue_pc_head(drive, disk, pc, rq);
 233 }
 234 EXPORT_SYMBOL_GPL(ide_retry_pc);
 235
 236 int ide_scsi_expiry(ide_drive_t *drive)
 237 {
 238         struct ide_atapi_pc *pc = drive->pc;
 239
 240         debug_log("%s called for %lu at %lu\n", __func__,
 241                   pc->scsi_cmd->serial_number, jiffies);
 242
 243         pc->flags |= PC_FLAG_TIMEDOUT;
 244
 245         return 0; /* we do not want the IDE subsystem to retry */
 246 }
 247 EXPORT_SYMBOL_GPL(ide_scsi_expiry);
 248
 249 /*
 250  * This is the usual interrupt handler which will be called during a packet
 251  * command.  We will transfer some of the data (as requested by the drive)
 252  * and will re-point interrupt handler to us.
 253  */
 254 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
 255 {
 256         struct ide_atapi_pc *pc = drive->pc;
 257         ide_hwif_t *hwif = drive->hwif;
 258         struct request *rq = hwif->hwgroup->rq;
 259         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 260         xfer_func_t *xferfunc;
 261         ide_expiry_t *expiry;
 262         unsigned int timeout, temp;
 263         u16 bcount;
 264         u8 stat, ireason, scsi = !!(drive->dev_flags & IDE_DFLAG_SCSI), dsc = 0;
 265
 266         debug_log("Enter %s - interrupt handler\n", __func__);
 267
 268         if (scsi) {
 269                 timeout = ide_scsi_get_timeout(pc);
 270                 expiry = ide_scsi_expiry;
 271         } else {
 272                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 273                                                        : WAIT_TAPE_CMD;
 274                 expiry = NULL;
 275         }
 276
 277         if (pc->flags & PC_FLAG_TIMEDOUT) {
 278                 drive->pc_callback(drive, 0);
 279                 return ide_stopped;
 280         }
 281
 282         /* Clear the interrupt */
 283         stat = tp_ops->read_status(hwif);
 284
 285         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 286                 if (hwif->dma_ops->dma_end(drive) ||
 287                     (drive->media == ide_tape && !scsi && (stat & ATA_ERR))) {
 288                         if (drive->media == ide_floppy && !scsi)
 289                                 printk(KERN_ERR "%s: DMA %s error\n",
 290                                         drive->name, rq_data_dir(pc->rq)
 291                                                      ? "write" : "read");
 292                         pc->flags |= PC_FLAG_DMA_ERROR;
 293                 } else {
 294                         pc->xferred = pc->req_xfer;
 295                         if (drive->pc_update_buffers)
 296                                 drive->pc_update_buffers(drive, pc);
 297                 }
 298                 debug_log("%s: DMA finished\n", drive->name);
 299         }
 300
 301         /* No more interrupts */
 302         if ((stat & ATA_DRQ) == 0) {
 303                 debug_log("Packet command completed, %d bytes transferred\n",
 304                           pc->xferred);
 305
 306                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 307
 308                 local_irq_enable_in_hardirq();
 309
 310                 if (drive->media == ide_tape && !scsi &&
 311                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
 312                         stat &= ~ATA_ERR;
 313
 314                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
 315                         /* Error detected */
 316                         debug_log("%s: I/O error\n", drive->name);
 317
 318                         if (drive->media != ide_tape || scsi) {
 319                                 pc->rq->errors++;
 320                                 if (scsi)
 321                                         goto cmd_finished;
 322                         }
 323
 324                         if (rq->cmd[0] == REQUEST_SENSE) {
 325                                 printk(KERN_ERR "%s: I/O error in request sense"
 326                                                 " command\n", drive->name);
 327                                 return ide_do_reset(drive);
 328                         }
 329
 330                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
 331
 332                         /* Retry operation */
 333                         ide_retry_pc(drive, rq->rq_disk);
 334
 335                         /* queued, but not started */
 336                         return ide_stopped;
 337                 }
 338 cmd_finished:
 339                 pc->error = 0;
 340
 341                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
 342                         dsc = 1;
 343
 344                 /* Command finished - Call the callback function */
 345                 drive->pc_callback(drive, dsc);
 346
 347                 return ide_stopped;
 348         }
 349
 350         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 351                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 352                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
 353                                 "in DMA mode\n", drive->name);
 354                 ide_dma_off(drive);
 355                 return ide_do_reset(drive);
 356         }
 357
 358         /* Get the number of bytes to transfer on this interrupt. */
 359         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
 360
 361         if (ireason & ATAPI_COD) {
 362                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
 363                 return ide_do_reset(drive);
 364         }
 365
 366         if (((ireason & ATAPI_IO) == ATAPI_IO) ==
 367                 !!(pc->flags & PC_FLAG_WRITING)) {
 368                 /* Hopefully, we will never get here */
 369                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
 370                                 "to %s!\n", drive->name,
 371                                 (ireason & ATAPI_IO) ? "Write" : "Read",
 372                                 (ireason & ATAPI_IO) ? "Read" : "Write");
 373                 return ide_do_reset(drive);
 374         }
 375
 376         if (!(pc->flags & PC_FLAG_WRITING)) {
 377                 /* Reading - Check that we have enough space */
 378                 temp = pc->xferred + bcount;
 379                 if (temp > pc->req_xfer) {
 380                         if (temp > pc->buf_size) {
 381                                 printk(KERN_ERR "%s: The device wants to send "
 382                                                 "us more data than expected - "
 383                                                 "discarding data\n",
 384                                                 drive->name);
 385                                 if (scsi)
 386                                         temp = pc->buf_size - pc->xferred;
 387                                 else
 388                                         temp = 0;
 389                                 if (temp) {
 390                                         if (pc->sg)
 391                                                 drive->pc_io_buffers(drive, pc,
 392                                                                      temp, 0);
 393                                         else
 394                                                 tp_ops->input_data(drive, NULL,
 395                                                         pc->cur_pos, temp);
 396                                         printk(KERN_ERR "%s: transferred %d of "
 397                                                         "%d bytes\n",
 398                                                         drive->name,
 399                                                         temp, bcount);
 400                                 }
 401                                 pc->xferred += temp;
 402                                 pc->cur_pos += temp;
 403                                 ide_pad_transfer(drive, 0, bcount - temp);
 404                                 goto next_irq;
 405                         }
 406                         debug_log("The device wants to send us more data than "
 407                                   "expected - allowing transfer\n");
 408                 }
 409                 xferfunc = tp_ops->input_data;
 410         } else
 411                 xferfunc = tp_ops->output_data;
 412
 413         if ((drive->media == ide_floppy && !scsi && !pc->buf) ||
 414             (drive->media == ide_tape && !scsi && pc->bh) ||
 415             (scsi && pc->sg)) {
 416                 int done = drive->pc_io_buffers(drive, pc, bcount,
 417                                   !!(pc->flags & PC_FLAG_WRITING));
 418
 419                 /* FIXME: don't do partial completions */
 420                 if (drive->media == ide_floppy && !scsi)
 421                         ide_end_request(drive, 1, done >> 9);
 422         } else
 423                 xferfunc(drive, NULL, pc->cur_pos, bcount);
 424
 425         /* Update the current position */
 426         pc->xferred += bcount;
 427         pc->cur_pos += bcount;
 428
 429         debug_log("[cmd %x] transferred %d bytes on that intr.\n",
 430                   rq->cmd[0], bcount);
 431 next_irq:
 432         /* And set the interrupt handler again */
 433         ide_set_handler(drive, ide_pc_intr, timeout, expiry);
 434         return ide_started;
 435 }
 436
 437 static u8 ide_read_ireason(ide_drive_t *drive)
 438 {
 439         ide_task_t task;
 440
 441         memset(&task, 0, sizeof(task));
 442         task.tf_flags = IDE_TFLAG_IN_NSECT;
 443
 444         drive->hwif->tp_ops->tf_read(drive, &task);
 445
 446         return task.tf.nsect & 3;
 447 }
 448
 449 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
 450 {
 451         int retries = 100;
 452
 453         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
 454                 (ireason & ATAPI_IO))) {
 455                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 456                                 "a packet command, retrying\n", drive->name);
 457                 udelay(100);
 458                 ireason = ide_read_ireason(drive);
 459                 if (retries == 0) {
 460                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 461                                         "a packet command, ignoring\n",
 462                                         drive->name);
 463                         ireason |= ATAPI_COD;
 464                         ireason &= ~ATAPI_IO;
 465                 }
 466         }
 467
 468         return ireason;
 469 }
 470
 471 static int ide_delayed_transfer_pc(ide_drive_t *drive)
 472 {
 473         /* Send the actual packet */
 474         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
 475
 476         /* Timeout for the packet command */
 477         return WAIT_FLOPPY_CMD;
 478 }
 479
 480 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 481 {
 482         struct ide_atapi_pc *pc = drive->pc;
 483         ide_hwif_t *hwif = drive->hwif;
 484         struct request *rq = hwif->hwgroup->rq;
 485         ide_expiry_t *expiry;
 486         unsigned int timeout;
 487         ide_startstop_t startstop;
 488         u8 ireason;
 489
 490         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
 491                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
 492                                 "DRQ isn't asserted\n", drive->name);
 493                 return startstop;
 494         }
 495
 496         ireason = ide_read_ireason(drive);
 497         if (drive->media == ide_tape &&
 498             (drive->dev_flags & IDE_DFLAG_SCSI) == 0)
 499                 ireason = ide_wait_ireason(drive, ireason);
 500
 501         if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
 502                 printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
 503                                 "a packet command\n", drive->name);
 504                 return ide_do_reset(drive);
 505         }
 506
 507         /*
 508          * If necessary schedule the packet transfer to occur 'timeout'
 509          * miliseconds later in ide_delayed_transfer_pc() after the device
 510          * says it's ready for a packet.
 511          */
 512         if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
 513                 timeout = drive->pc_delay;
 514                 expiry = &ide_delayed_transfer_pc;
 515         } else {
 516                 if (drive->dev_flags & IDE_DFLAG_SCSI) {
 517                         timeout = ide_scsi_get_timeout(pc);
 518                         expiry = ide_scsi_expiry;
 519                 } else {
 520                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 521                                                                : WAIT_TAPE_CMD;
 522                         expiry = NULL;
 523                 }
 524         }
 525
 526         /* Set the interrupt routine */
 527         ide_set_handler(drive, ide_pc_intr, timeout, expiry);
 528
 529         /* Begin DMA, if necessary */
 530         if (pc->flags & PC_FLAG_DMA_OK) {
 531                 pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
 532                 hwif->dma_ops->dma_start(drive);
 533         }
 534
 535         /* Send the actual packet */
 536         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
 537                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, 12);
 538
 539         return ide_started;
 540 }
 541
 542 ide_startstop_t ide_issue_pc(ide_drive_t *drive, unsigned int timeout,
 543                              ide_expiry_t *expiry)
 544 {
 545         struct ide_atapi_pc *pc = drive->pc;
 546         ide_hwif_t *hwif = drive->hwif;
 547         u32 tf_flags;
 548         u16 bcount;
 549         u8 scsi = !!(drive->dev_flags & IDE_DFLAG_SCSI);
 550
 551         /* We haven't transferred any data yet */
 552         pc->xferred = 0;
 553         pc->cur_pos = pc->buf;
 554
 555         /* Request to transfer the entire buffer at once */
 556         if (drive->media == ide_tape && scsi == 0)
 557                 bcount = pc->req_xfer;
 558         else
 559                 bcount = min(pc->req_xfer, 63 * 1024);
 560
 561         if (pc->flags & PC_FLAG_DMA_ERROR) {
 562                 pc->flags &= ~PC_FLAG_DMA_ERROR;
 563                 ide_dma_off(drive);
 564         }
 565
 566         if ((pc->flags & PC_FLAG_DMA_OK) &&
 567             (drive->dev_flags & IDE_DFLAG_USING_DMA)) {
 568                 if (scsi)
 569                         hwif->sg_mapped = 1;
 570                 drive->dma = !hwif->dma_ops->dma_setup(drive);
 571                 if (scsi)
 572                         hwif->sg_mapped = 0;
 573         }
 574
 575         if (!drive->dma)
 576                 pc->flags &= ~PC_FLAG_DMA_OK;
 577
 578         if (scsi)
 579                 tf_flags = 0;
 580         else if (drive->media == ide_cdrom || drive->media == ide_optical)
 581                 tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
 582         else
 583                 tf_flags = IDE_TFLAG_OUT_DEVICE;
 584
 585         ide_pktcmd_tf_load(drive, tf_flags, bcount, drive->dma);
 586
 587         /* Issue the packet command */
 588         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 589                 ide_execute_command(drive, ATA_CMD_PACKET, ide_transfer_pc,
 590                                     timeout, NULL);
 591                 return ide_started;
 592         } else {
 593                 ide_execute_pkt_cmd(drive);
 594                 return ide_transfer_pc(drive);
 595         }
 596 }
 597 EXPORT_SYMBOL_GPL(ide_issue_pc);