drivers/ide/ide-io.c

   1 /*
   2  *      IDE I/O functions
   3  *
   4  *      Basic PIO and command management functionality.
   5  *
   6  * This code was split off from ide.c. See ide.c for history and original
   7  * copyrights.
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License as published by the
  11  * Free Software Foundation; either version 2, or (at your option) any
  12  * later version.
  13  *
  14  * This program is distributed in the hope that it will be useful, but
  15  * WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * General Public License for more details.
  18  *
  19  * For the avoidance of doubt the "preferred form" of this code is one which
  20  * is in an open non patent encumbered format. Where cryptographic key signing
  21  * forms part of the process of creating an executable the information
  22  * including keys needed to generate an equivalently functional executable
  23  * are deemed to be part of the source code.
  24  */
  25
  26
  27 #include <linux/module.h>
  28 #include <linux/types.h>
  29 #include <linux/string.h>
  30 #include <linux/kernel.h>
  31 #include <linux/timer.h>
  32 #include <linux/mm.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/major.h>
  35 #include <linux/errno.h>
  36 #include <linux/genhd.h>
  37 #include <linux/blkpg.h>
  38 #include <linux/slab.h>
  39 #include <linux/init.h>
  40 #include <linux/pci.h>
  41 #include <linux/delay.h>
  42 #include <linux/ide.h>
  43 #include <linux/hdreg.h>
  44 #include <linux/completion.h>
  45 #include <linux/reboot.h>
  46 #include <linux/cdrom.h>
  47 #include <linux/seq_file.h>
  48 #include <linux/device.h>
  49 #include <linux/kmod.h>
  50 #include <linux/scatterlist.h>
  51 #include <linux/bitops.h>
  52
  53 #include <asm/byteorder.h>
  54 #include <asm/irq.h>
  55 #include <asm/uaccess.h>
  56 #include <asm/io.h>
  57
  58 static int __ide_end_request(ide_drive_t *drive, struct request *rq,
  59                              int uptodate, unsigned int nr_bytes, int dequeue)
  60 {
  61         int ret = 1;
  62         int error = 0;
  63
  64         if (uptodate <= 0)
  65                 error = uptodate ? uptodate : -EIO;
  66
  67         /*
  68          * if failfast is set on a request, override number of sectors and
  69          * complete the whole request right now
  70          */
  71         if (blk_noretry_request(rq) && error)
  72                 nr_bytes = rq->hard_nr_sectors << 9;
  73
  74         if (!blk_fs_request(rq) && error && !rq->errors)
  75                 rq->errors = -EIO;
  76
  77         /*
  78          * decide whether to reenable DMA -- 3 is a random magic for now,
  79          * if we DMA timeout more than 3 times, just stay in PIO
  80          */
  81         if ((drive->dev_flags & IDE_DFLAG_DMA_PIO_RETRY) &&
  82             drive->retry_pio <= 3) {
  83                 drive->dev_flags &= ~IDE_DFLAG_DMA_PIO_RETRY;
  84                 ide_dma_on(drive);
  85         }
  86
  87         if (!blk_end_request(rq, error, nr_bytes))
  88                 ret = 0;
  89
  90         if (ret == 0 && dequeue)
  91                 drive->hwif->rq = NULL;
  92
  93         return ret;
  94 }
  95
  96 /**
  97  *      ide_end_request         -       complete an IDE I/O
  98  *      @drive: IDE device for the I/O
  99  *      @uptodate:
 100  *      @nr_sectors: number of sectors completed
 101  *
 102  *      This is our end_request wrapper function. We complete the I/O
 103  *      update random number input and dequeue the request, which if
 104  *      it was tagged may be out of order.
 105  */
 106
 107 int ide_end_request (ide_drive_t *drive, int uptodate, int nr_sectors)
 108 {
 109         unsigned int nr_bytes = nr_sectors << 9;
 110         struct request *rq = drive->hwif->rq;
 111
 112         if (!nr_bytes) {
 113                 if (blk_pc_request(rq))
 114                         nr_bytes = rq->data_len;
 115                 else
 116                         nr_bytes = rq->hard_cur_sectors << 9;
 117         }
 118
 119         return __ide_end_request(drive, rq, uptodate, nr_bytes, 1);
 120 }
 121 EXPORT_SYMBOL(ide_end_request);
 122
 123 /**
 124  *      ide_end_dequeued_request        -       complete an IDE I/O
 125  *      @drive: IDE device for the I/O
 126  *      @uptodate:
 127  *      @nr_sectors: number of sectors completed
 128  *
 129  *      Complete an I/O that is no longer on the request queue. This
 130  *      typically occurs when we pull the request and issue a REQUEST_SENSE.
 131  *      We must still finish the old request but we must not tamper with the
 132  *      queue in the meantime.
 133  *
 134  *      NOTE: This path does not handle barrier, but barrier is not supported
 135  *      on ide-cd anyway.
 136  */
 137
 138 int ide_end_dequeued_request(ide_drive_t *drive, struct request *rq,
 139                              int uptodate, int nr_sectors)
 140 {
 141         BUG_ON(!blk_rq_started(rq));
 142
 143         return __ide_end_request(drive, rq, uptodate, nr_sectors << 9, 0);
 144 }
 145 EXPORT_SYMBOL_GPL(ide_end_dequeued_request);
 146
 147 void ide_complete_task(ide_drive_t *drive, ide_task_t *task, u8 stat, u8 err)
 148 {
 149         struct ide_taskfile *tf = &task->tf;
 150         struct request *rq = task->rq;
 151
 152         tf->error = err;
 153         tf->status = stat;
 154
 155         drive->hwif->tp_ops->tf_read(drive, task);
 156
 157         if (rq && rq->cmd_type == REQ_TYPE_ATA_TASKFILE)
 158                 memcpy(rq->special, task, sizeof(*task));
 159
 160         if (task->tf_flags & IDE_TFLAG_DYN)
 161                 kfree(task);
 162 }
 163
 164 void ide_complete_rq(ide_drive_t *drive, u8 err)
 165 {
 166         ide_hwif_t *hwif = drive->hwif;
 167         struct request *rq = hwif->rq;
 168
 169         hwif->rq = NULL;
 170
 171         rq->errors = err;
 172
 173         if (unlikely(blk_end_request(rq, (rq->errors ? -EIO : 0),
 174                                      blk_rq_bytes(rq))))
 175                 BUG();
 176 }
 177 EXPORT_SYMBOL(ide_complete_rq);
 178
 179 void ide_kill_rq(ide_drive_t *drive, struct request *rq)
 180 {
 181         if (rq->rq_disk) {
 182                 struct ide_driver *drv;
 183
 184                 drv = *(struct ide_driver **)rq->rq_disk->private_data;
 185                 drv->end_request(drive, 0, 0);
 186         } else
 187                 ide_end_request(drive, 0, 0);
 188 }
 189
 190 static void ide_tf_set_specify_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
 191 {
 192         tf->nsect   = drive->sect;
 193         tf->lbal    = drive->sect;
 194         tf->lbam    = drive->cyl;
 195         tf->lbah    = drive->cyl >> 8;
 196         tf->device  = (drive->head - 1) | drive->select;
 197         tf->command = ATA_CMD_INIT_DEV_PARAMS;
 198 }
 199
 200 static void ide_tf_set_restore_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
 201 {
 202         tf->nsect   = drive->sect;
 203         tf->command = ATA_CMD_RESTORE;
 204 }
 205
 206 static void ide_tf_set_setmult_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
 207 {
 208         tf->nsect   = drive->mult_req;
 209         tf->command = ATA_CMD_SET_MULTI;
 210 }
 211
 212 static ide_startstop_t ide_disk_special(ide_drive_t *drive)
 213 {
 214         special_t *s = &drive->special;
 215         ide_task_t args;
 216
 217         memset(&args, 0, sizeof(ide_task_t));
 218         args.data_phase = TASKFILE_NO_DATA;
 219
 220         if (s->b.set_geometry) {
 221                 s->b.set_geometry = 0;
 222                 ide_tf_set_specify_cmd(drive, &args.tf);
 223         } else if (s->b.recalibrate) {
 224                 s->b.recalibrate = 0;
 225                 ide_tf_set_restore_cmd(drive, &args.tf);
 226         } else if (s->b.set_multmode) {
 227                 s->b.set_multmode = 0;
 228                 ide_tf_set_setmult_cmd(drive, &args.tf);
 229         } else if (s->all) {
 230                 int special = s->all;
 231                 s->all = 0;
 232                 printk(KERN_ERR "%s: bad special flag: 0x%02x\n", drive->name, special);
 233                 return ide_stopped;
 234         }
 235
 236         args.tf_flags = IDE_TFLAG_TF | IDE_TFLAG_DEVICE |
 237                         IDE_TFLAG_CUSTOM_HANDLER;
 238
 239         do_rw_taskfile(drive, &args);
 240
 241         return ide_started;
 242 }
 243
 244 /**
 245  *      do_special              -       issue some special commands
 246  *      @drive: drive the command is for
 247  *
 248  *      do_special() is used to issue ATA_CMD_INIT_DEV_PARAMS,
 249  *      ATA_CMD_RESTORE and ATA_CMD_SET_MULTI commands to a drive.
 250  *
 251  *      It used to do much more, but has been scaled back.
 252  */
 253
 254 static ide_startstop_t do_special (ide_drive_t *drive)
 255 {
 256         special_t *s = &drive->special;
 257
 258 #ifdef DEBUG
 259         printk("%s: do_special: 0x%02x\n", drive->name, s->all);
 260 #endif
 261         if (drive->media == ide_disk)
 262                 return ide_disk_special(drive);
 263
 264         s->all = 0;
 265         drive->mult_req = 0;
 266         return ide_stopped;
 267 }
 268
 269 void ide_map_sg(ide_drive_t *drive, struct request *rq)
 270 {
 271         ide_hwif_t *hwif = drive->hwif;
 272         struct scatterlist *sg = hwif->sg_table;
 273
 274         if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
 275                 sg_init_one(sg, rq->buffer, rq->nr_sectors * SECTOR_SIZE);
 276                 hwif->sg_nents = 1;
 277         } else if (!rq->bio) {
 278                 sg_init_one(sg, rq->data, rq->data_len);
 279                 hwif->sg_nents = 1;
 280         } else {
 281                 hwif->sg_nents = blk_rq_map_sg(drive->queue, rq, sg);
 282         }
 283 }
 284
 285 EXPORT_SYMBOL_GPL(ide_map_sg);
 286
 287 void ide_init_sg_cmd(ide_drive_t *drive, struct request *rq)
 288 {
 289         ide_hwif_t *hwif = drive->hwif;
 290
 291         hwif->nsect = hwif->nleft = rq->nr_sectors;
 292         hwif->cursg_ofs = 0;
 293         hwif->cursg = NULL;
 294 }
 295
 296 EXPORT_SYMBOL_GPL(ide_init_sg_cmd);
 297
 298 /**
 299  *      execute_drive_command   -       issue special drive command
 300  *      @drive: the drive to issue the command on
 301  *      @rq: the request structure holding the command
 302  *
 303  *      execute_drive_cmd() issues a special drive command,  usually
 304  *      initiated by ioctl() from the external hdparm program. The
 305  *      command can be a drive command, drive task or taskfile
 306  *      operation. Weirdly you can call it with NULL to wait for
 307  *      all commands to finish. Don't do this as that is due to change
 308  */
 309
 310 static ide_startstop_t execute_drive_cmd (ide_drive_t *drive,
 311                 struct request *rq)
 312 {
 313         ide_task_t *task = rq->special;
 314
 315         if (task) {
 316                 switch (task->data_phase) {
 317                 case TASKFILE_MULTI_OUT:
 318                 case TASKFILE_OUT:
 319                 case TASKFILE_MULTI_IN:
 320                 case TASKFILE_IN:
 321                         ide_init_sg_cmd(drive, rq);
 322                         ide_map_sg(drive, rq);
 323                 default:
 324                         break;
 325                 }
 326
 327                 return do_rw_taskfile(drive, task);
 328         }
 329
 330         /*
 331          * NULL is actually a valid way of waiting for
 332          * all current requests to be flushed from the queue.
 333          */
 334 #ifdef DEBUG
 335         printk("%s: DRIVE_CMD (null)\n", drive->name);
 336 #endif
 337         ide_complete_rq(drive, 0);
 338
 339         return ide_stopped;
 340 }
 341
 342 static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
 343 {
 344         u8 cmd = rq->cmd[0];
 345
 346         switch (cmd) {
 347         case REQ_PARK_HEADS:
 348         case REQ_UNPARK_HEADS:
 349                 return ide_do_park_unpark(drive, rq);
 350         case REQ_DEVSET_EXEC:
 351                 return ide_do_devset(drive, rq);
 352         case REQ_DRIVE_RESET:
 353                 return ide_do_reset(drive);
 354         default:
 355                 blk_dump_rq_flags(rq, "ide_special_rq - bad request");
 356                 ide_end_request(drive, 0, 0);
 357                 return ide_stopped;
 358         }
 359 }
 360
 361 /**
 362  *      start_request   -       start of I/O and command issuing for IDE
 363  *
 364  *      start_request() initiates handling of a new I/O request. It
 365  *      accepts commands and I/O (read/write) requests.
 366  *
 367  *      FIXME: this function needs a rename
 368  */
 369
 370 static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
 371 {
 372         ide_startstop_t startstop;
 373
 374         BUG_ON(!blk_rq_started(rq));
 375
 376 #ifdef DEBUG
 377         printk("%s: start_request: current=0x%08lx\n",
 378                 drive->hwif->name, (unsigned long) rq);
 379 #endif
 380
 381         /* bail early if we've exceeded max_failures */
 382         if (drive->max_failures && (drive->failures > drive->max_failures)) {
 383                 rq->cmd_flags |= REQ_FAILED;
 384                 goto kill_rq;
 385         }
 386
 387         if (blk_pm_request(rq))
 388                 ide_check_pm_state(drive, rq);
 389
 390         SELECT_DRIVE(drive);
 391         if (ide_wait_stat(&startstop, drive, drive->ready_stat,
 392                           ATA_BUSY | ATA_DRQ, WAIT_READY)) {
 393                 printk(KERN_ERR "%s: drive not ready for command\n", drive->name);
 394                 return startstop;
 395         }
 396         if (!drive->special.all) {
 397                 struct ide_driver *drv;
 398
 399                 /*
 400                  * We reset the drive so we need to issue a SETFEATURES.
 401                  * Do it _after_ do_special() restored device parameters.
 402                  */
 403                 if (drive->current_speed == 0xff)
 404                         ide_config_drive_speed(drive, drive->desired_speed);
 405
 406                 if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE)
 407                         return execute_drive_cmd(drive, rq);
 408                 else if (blk_pm_request(rq)) {
 409                         struct request_pm_state *pm = rq->data;
 410 #ifdef DEBUG_PM
 411                         printk("%s: start_power_step(step: %d)\n",
 412                                 drive->name, pm->pm_step);
 413 #endif
 414                         startstop = ide_start_power_step(drive, rq);
 415                         if (startstop == ide_stopped &&
 416                             pm->pm_step == IDE_PM_COMPLETED)
 417                                 ide_complete_pm_rq(drive, rq);
 418                         return startstop;
 419                 } else if (!rq->rq_disk && blk_special_request(rq))
 420                         /*
 421                          * TODO: Once all ULDs have been modified to
 422                          * check for specific op codes rather than
 423                          * blindly accepting any special request, the
 424                          * check for ->rq_disk above may be replaced
 425                          * by a more suitable mechanism or even
 426                          * dropped entirely.
 427                          */
 428                         return ide_special_rq(drive, rq);
 429
 430                 drv = *(struct ide_driver **)rq->rq_disk->private_data;
 431
 432                 return drv->do_request(drive, rq, rq->sector);
 433         }
 434         return do_special(drive);
 435 kill_rq:
 436         ide_kill_rq(drive, rq);
 437         return ide_stopped;
 438 }
 439
 440 /**
 441  *      ide_stall_queue         -       pause an IDE device
 442  *      @drive: drive to stall
 443  *      @timeout: time to stall for (jiffies)
 444  *
 445  *      ide_stall_queue() can be used by a drive to give excess bandwidth back
 446  *      to the port by sleeping for timeout jiffies.
 447  */
 448
 449 void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
 450 {
 451         if (timeout > WAIT_WORSTCASE)
 452                 timeout = WAIT_WORSTCASE;
 453         drive->sleep = timeout + jiffies;
 454         drive->dev_flags |= IDE_DFLAG_SLEEPING;
 455 }
 456 EXPORT_SYMBOL(ide_stall_queue);
 457
 458 static inline int ide_lock_port(ide_hwif_t *hwif)
 459 {
 460         if (hwif->busy)
 461                 return 1;
 462
 463         hwif->busy = 1;
 464
 465         return 0;
 466 }
 467
 468 static inline void ide_unlock_port(ide_hwif_t *hwif)
 469 {
 470         hwif->busy = 0;
 471 }
 472
 473 static inline int ide_lock_host(struct ide_host *host, ide_hwif_t *hwif)
 474 {
 475         int rc = 0;
 476
 477         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
 478                 rc = test_and_set_bit_lock(IDE_HOST_BUSY, &host->host_busy);
 479                 if (rc == 0) {
 480                         if (host->get_lock)
 481                                 host->get_lock(ide_intr, hwif);
 482                 }
 483         }
 484         return rc;
 485 }
 486
 487 static inline void ide_unlock_host(struct ide_host *host)
 488 {
 489         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
 490                 if (host->release_lock)
 491                         host->release_lock();
 492                 clear_bit_unlock(IDE_HOST_BUSY, &host->host_busy);
 493         }
 494 }
 495
 496 /*
 497  * Issue a new request to a device.
 498  */
 499 void do_ide_request(struct request_queue *q)
 500 {
 501         ide_drive_t     *drive = q->queuedata;
 502         ide_hwif_t      *hwif = drive->hwif;
 503         struct ide_host *host = hwif->host;
 504         struct request  *rq = NULL;
 505         ide_startstop_t startstop;
 506
 507         /*
 508          * drive is doing pre-flush, ordered write, post-flush sequence. even
 509          * though that is 3 requests, it must be seen as a single transaction.
 510          * we must not preempt this drive until that is complete
 511          */
 512         if (blk_queue_flushing(q))
 513                 /*
 514                  * small race where queue could get replugged during
 515                  * the 3-request flush cycle, just yank the plug since
 516                  * we want it to finish asap
 517                  */
 518                 blk_remove_plug(q);
 519
 520         spin_unlock_irq(q->queue_lock);
 521
 522         if (ide_lock_host(host, hwif))
 523                 goto plug_device_2;
 524
 525         spin_lock_irq(&hwif->lock);
 526
 527         if (!ide_lock_port(hwif)) {
 528                 ide_hwif_t *prev_port;
 529 repeat:
 530                 prev_port = hwif->host->cur_port;
 531                 hwif->rq = NULL;
 532
 533                 if (drive->dev_flags & IDE_DFLAG_SLEEPING) {
 534                         if (time_before(drive->sleep, jiffies)) {
 535                                 ide_unlock_port(hwif);
 536                                 goto plug_device;
 537                         }
 538                 }
 539
 540                 if ((hwif->host->host_flags & IDE_HFLAG_SERIALIZE) &&
 541                     hwif != prev_port) {
 542                         /*
 543                          * set nIEN for previous port, drives in the
 544                          * quirk_list may not like intr setups/cleanups
 545                          */
 546                         if (prev_port && prev_port->cur_dev->quirk_list == 0)
 547                                 prev_port->tp_ops->set_irq(prev_port, 0);
 548
 549                         hwif->host->cur_port = hwif;
 550                 }
 551                 hwif->cur_dev = drive;
 552                 drive->dev_flags &= ~(IDE_DFLAG_SLEEPING | IDE_DFLAG_PARKED);
 553
 554                 spin_unlock_irq(&hwif->lock);
 555                 spin_lock_irq(q->queue_lock);
 556                 /*
 557                  * we know that the queue isn't empty, but this can happen
 558                  * if the q->prep_rq_fn() decides to kill a request
 559                  */
 560                 rq = elv_next_request(drive->queue);
 561                 spin_unlock_irq(q->queue_lock);
 562                 spin_lock_irq(&hwif->lock);
 563
 564                 if (!rq) {
 565                         ide_unlock_port(hwif);
 566                         goto out;
 567                 }
 568
 569                 /*
 570                  * Sanity: don't accept a request that isn't a PM request
 571                  * if we are currently power managed. This is very important as
 572                  * blk_stop_queue() doesn't prevent the elv_next_request()
 573                  * above to return us whatever is in the queue. Since we call
 574                  * ide_do_request() ourselves, we end up taking requests while
 575                  * the queue is blocked...
 576                  *
 577                  * We let requests forced at head of queue with ide-preempt
 578                  * though. I hope that doesn't happen too much, hopefully not
 579                  * unless the subdriver triggers such a thing in its own PM
 580                  * state machine.
 581                  */
 582                 if ((drive->dev_flags & IDE_DFLAG_BLOCKED) &&
 583                     blk_pm_request(rq) == 0 &&
 584                     (rq->cmd_flags & REQ_PREEMPT) == 0) {
 585                         /* there should be no pending command at this point */
 586                         ide_unlock_port(hwif);
 587                         goto plug_device;
 588                 }
 589
 590                 hwif->rq = rq;
 591
 592                 spin_unlock_irq(&hwif->lock);
 593                 startstop = start_request(drive, rq);
 594                 spin_lock_irq(&hwif->lock);
 595
 596                 if (startstop == ide_stopped)
 597                         goto repeat;
 598         } else
 599                 goto plug_device;
 600 out:
 601         spin_unlock_irq(&hwif->lock);
 602         if (rq == NULL)
 603                 ide_unlock_host(host);
 604         spin_lock_irq(q->queue_lock);
 605         return;
 606
 607 plug_device:
 608         spin_unlock_irq(&hwif->lock);
 609         ide_unlock_host(host);
 610 plug_device_2:
 611         spin_lock_irq(q->queue_lock);
 612
 613         if (!elv_queue_empty(q))
 614                 blk_plug_device(q);
 615 }
 616
 617 static void ide_plug_device(ide_drive_t *drive)
 618 {
 619         struct request_queue *q = drive->queue;
 620         unsigned long flags;
 621
 622         spin_lock_irqsave(q->queue_lock, flags);
 623         if (!elv_queue_empty(q))
 624                 blk_plug_device(q);
 625         spin_unlock_irqrestore(q->queue_lock, flags);
 626 }
 627
 628 static int drive_is_ready(ide_drive_t *drive)
 629 {
 630         ide_hwif_t *hwif = drive->hwif;
 631         u8 stat = 0;
 632
 633         if (drive->waiting_for_dma)
 634                 return hwif->dma_ops->dma_test_irq(drive);
 635
 636         if (hwif->io_ports.ctl_addr &&
 637             (hwif->host_flags & IDE_HFLAG_BROKEN_ALTSTATUS) == 0)
 638                 stat = hwif->tp_ops->read_altstatus(hwif);
 639         else
 640                 /* Note: this may clear a pending IRQ!! */
 641                 stat = hwif->tp_ops->read_status(hwif);
 642
 643         if (stat & ATA_BUSY)
 644                 /* drive busy: definitely not interrupting */
 645                 return 0;
 646
 647         /* drive ready: *might* be interrupting */
 648         return 1;
 649 }
 650
 651 /**
 652  *      ide_timer_expiry        -       handle lack of an IDE interrupt
 653  *      @data: timer callback magic (hwif)
 654  *
 655  *      An IDE command has timed out before the expected drive return
 656  *      occurred. At this point we attempt to clean up the current
 657  *      mess. If the current handler includes an expiry handler then
 658  *      we invoke the expiry handler, and providing it is happy the
 659  *      work is done. If that fails we apply generic recovery rules
 660  *      invoking the handler and checking the drive DMA status. We
 661  *      have an excessively incestuous relationship with the DMA
 662  *      logic that wants cleaning up.
 663  */
 664
 665 void ide_timer_expiry (unsigned long data)
 666 {
 667         ide_hwif_t      *hwif = (ide_hwif_t *)data;
 668         ide_drive_t     *uninitialized_var(drive);
 669         ide_handler_t   *handler;
 670         unsigned long   flags;
 671         int             wait = -1;
 672         int             plug_device = 0;
 673
 674         spin_lock_irqsave(&hwif->lock, flags);
 675
 676         handler = hwif->handler;
 677
 678         if (handler == NULL || hwif->req_gen != hwif->req_gen_timer) {
 679                 /*
 680                  * Either a marginal timeout occurred
 681                  * (got the interrupt just as timer expired),
 682                  * or we were "sleeping" to give other devices a chance.
 683                  * Either way, we don't really want to complain about anything.
 684                  */
 685         } else {
 686                 ide_expiry_t *expiry = hwif->expiry;
 687                 ide_startstop_t startstop = ide_stopped;
 688
 689                 drive = hwif->cur_dev;
 690
 691                 if (expiry) {
 692                         wait = expiry(drive);
 693                         if (wait > 0) { /* continue */
 694                                 /* reset timer */
 695                                 hwif->timer.expires = jiffies + wait;
 696                                 hwif->req_gen_timer = hwif->req_gen;
 697                                 add_timer(&hwif->timer);
 698                                 spin_unlock_irqrestore(&hwif->lock, flags);
 699                                 return;
 700                         }
 701                 }
 702                 hwif->handler = NULL;
 703                 /*
 704                  * We need to simulate a real interrupt when invoking
 705                  * the handler() function, which means we need to
 706                  * globally mask the specific IRQ:
 707                  */
 708                 spin_unlock(&hwif->lock);
 709                 /* disable_irq_nosync ?? */
 710                 disable_irq(hwif->irq);
 711                 /* local CPU only, as if we were handling an interrupt */
 712                 local_irq_disable();
 713                 if (hwif->polling) {
 714                         startstop = handler(drive);
 715                 } else if (drive_is_ready(drive)) {
 716                         if (drive->waiting_for_dma)
 717                                 hwif->dma_ops->dma_lost_irq(drive);
 718                         if (hwif->ack_intr)
 719                                 hwif->ack_intr(hwif);
 720                         printk(KERN_WARNING "%s: lost interrupt\n",
 721                                 drive->name);
 722                         startstop = handler(drive);
 723                 } else {
 724                         if (drive->waiting_for_dma)
 725                                 startstop = ide_dma_timeout_retry(drive, wait);
 726                         else
 727                                 startstop = ide_error(drive, "irq timeout",
 728                                         hwif->tp_ops->read_status(hwif));
 729                 }
 730                 spin_lock_irq(&hwif->lock);
 731                 enable_irq(hwif->irq);
 732                 if (startstop == ide_stopped) {
 733                         ide_unlock_port(hwif);
 734                         plug_device = 1;
 735                 }
 736         }
 737         spin_unlock_irqrestore(&hwif->lock, flags);
 738
 739         if (plug_device) {
 740                 ide_unlock_host(hwif->host);
 741                 ide_plug_device(drive);
 742         }
 743 }
 744
 745 /**
 746  *      unexpected_intr         -       handle an unexpected IDE interrupt
 747  *      @irq: interrupt line
 748  *      @hwif: port being processed
 749  *
 750  *      There's nothing really useful we can do with an unexpected interrupt,
 751  *      other than reading the status register (to clear it), and logging it.
 752  *      There should be no way that an irq can happen before we're ready for it,
 753  *      so we needn't worry much about losing an "important" interrupt here.
 754  *
 755  *      On laptops (and "green" PCs), an unexpected interrupt occurs whenever
 756  *      the drive enters "idle", "standby", or "sleep" mode, so if the status
 757  *      looks "good", we just ignore the interrupt completely.
 758  *
 759  *      This routine assumes __cli() is in effect when called.
 760  *
 761  *      If an unexpected interrupt happens on irq15 while we are handling irq14
 762  *      and if the two interfaces are "serialized" (CMD640), then it looks like
 763  *      we could screw up by interfering with a new request being set up for
 764  *      irq15.
 765  *
 766  *      In reality, this is a non-issue.  The new command is not sent unless
 767  *      the drive is ready to accept one, in which case we know the drive is
 768  *      not trying to interrupt us.  And ide_set_handler() is always invoked
 769  *      before completing the issuance of any new drive command, so we will not
 770  *      be accidentally invoked as a result of any valid command completion
 771  *      interrupt.
 772  */
 773
 774 static void unexpected_intr(int irq, ide_hwif_t *hwif)
 775 {
 776         u8 stat = hwif->tp_ops->read_status(hwif);
 777
 778         if (!OK_STAT(stat, ATA_DRDY, BAD_STAT)) {
 779                 /* Try to not flood the console with msgs */
 780                 static unsigned long last_msgtime, count;
 781                 ++count;
 782
 783                 if (time_after(jiffies, last_msgtime + HZ)) {
 784                         last_msgtime = jiffies;
 785                         printk(KERN_ERR "%s: unexpected interrupt, "
 786                                 "status=0x%02x, count=%ld\n",
 787                                 hwif->name, stat, count);
 788                 }
 789         }
 790 }
 791
 792 /**
 793  *      ide_intr        -       default IDE interrupt handler
 794  *      @irq: interrupt number
 795  *      @dev_id: hwif
 796  *      @regs: unused weirdness from the kernel irq layer
 797  *
 798  *      This is the default IRQ handler for the IDE layer. You should
 799  *      not need to override it. If you do be aware it is subtle in
 800  *      places
 801  *
 802  *      hwif is the interface in the group currently performing
 803  *      a command. hwif->cur_dev is the drive and hwif->handler is
 804  *      the IRQ handler to call. As we issue a command the handlers
 805  *      step through multiple states, reassigning the handler to the
 806  *      next step in the process. Unlike a smart SCSI controller IDE
 807  *      expects the main processor to sequence the various transfer
 808  *      stages. We also manage a poll timer to catch up with most
 809  *      timeout situations. There are still a few where the handlers
 810  *      don't ever decide to give up.
 811  *
 812  *      The handler eventually returns ide_stopped to indicate the
 813  *      request completed. At this point we issue the next request
 814  *      on the port and the process begins again.
 815  */
 816
 817 irqreturn_t ide_intr (int irq, void *dev_id)
 818 {
 819         ide_hwif_t *hwif = (ide_hwif_t *)dev_id;
 820         struct ide_host *host = hwif->host;
 821         ide_drive_t *uninitialized_var(drive);
 822         ide_handler_t *handler;
 823         unsigned long flags;
 824         ide_startstop_t startstop;
 825         irqreturn_t irq_ret = IRQ_NONE;
 826         int plug_device = 0;
 827
 828         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
 829                 if (hwif != host->cur_port)
 830                         goto out_early;
 831         }
 832
 833         spin_lock_irqsave(&hwif->lock, flags);
 834
 835         if (hwif->ack_intr && hwif->ack_intr(hwif) == 0)
 836                 goto out;
 837
 838         handler = hwif->handler;
 839
 840         if (handler == NULL || hwif->polling) {
 841                 /*
 842                  * Not expecting an interrupt from this drive.
 843                  * That means this could be:
 844                  *      (1) an interrupt from another PCI device
 845                  *      sharing the same PCI INT# as us.
 846                  * or   (2) a drive just entered sleep or standby mode,
 847                  *      and is interrupting to let us know.
 848                  * or   (3) a spurious interrupt of unknown origin.
 849                  *
 850                  * For PCI, we cannot tell the difference,
 851                  * so in that case we just ignore it and hope it goes away.
 852                  */
 853                 if ((host->irq_flags & IRQF_SHARED) == 0) {
 854                         /*
 855                          * Probably not a shared PCI interrupt,
 856                          * so we can safely try to do something about it:
 857                          */
 858                         unexpected_intr(irq, hwif);
 859                 } else {
 860                         /*
 861                          * Whack the status register, just in case
 862                          * we have a leftover pending IRQ.
 863                          */
 864                         (void)hwif->tp_ops->read_status(hwif);
 865                 }
 866                 goto out;
 867         }
 868
 869         drive = hwif->cur_dev;
 870
 871         if (!drive_is_ready(drive))
 872                 /*
 873                  * This happens regularly when we share a PCI IRQ with
 874                  * another device.  Unfortunately, it can also happen
 875                  * with some buggy drives that trigger the IRQ before
 876                  * their status register is up to date.  Hopefully we have
 877                  * enough advance overhead that the latter isn't a problem.
 878                  */
 879                 goto out;
 880
 881         hwif->handler = NULL;
 882         hwif->req_gen++;
 883         del_timer(&hwif->timer);
 884         spin_unlock(&hwif->lock);
 885
 886         if (hwif->port_ops && hwif->port_ops->clear_irq)
 887                 hwif->port_ops->clear_irq(drive);
 888
 889         if (drive->dev_flags & IDE_DFLAG_UNMASK)
 890                 local_irq_enable_in_hardirq();
 891
 892         /* service this interrupt, may set handler for next interrupt */
 893         startstop = handler(drive);
 894
 895         spin_lock_irq(&hwif->lock);
 896         /*
 897          * Note that handler() may have set things up for another
 898          * interrupt to occur soon, but it cannot happen until
 899          * we exit from this routine, because it will be the
 900          * same irq as is currently being serviced here, and Linux
 901          * won't allow another of the same (on any CPU) until we return.
 902          */
 903         if (startstop == ide_stopped) {
 904                 BUG_ON(hwif->handler);
 905                 ide_unlock_port(hwif);
 906                 plug_device = 1;
 907         }
 908         irq_ret = IRQ_HANDLED;
 909 out:
 910         spin_unlock_irqrestore(&hwif->lock, flags);
 911 out_early:
 912         if (plug_device) {
 913                 ide_unlock_host(hwif->host);
 914                 ide_plug_device(drive);
 915         }
 916
 917         return irq_ret;
 918 }
 919 EXPORT_SYMBOL_GPL(ide_intr);
 920
 921 void ide_pad_transfer(ide_drive_t *drive, int write, int len)
 922 {
 923         ide_hwif_t *hwif = drive->hwif;
 924         u8 buf[4] = { 0 };
 925
 926         while (len > 0) {
 927                 if (write)
 928                         hwif->tp_ops->output_data(drive, NULL, buf, min(4, len));
 929                 else
 930                         hwif->tp_ops->input_data(drive, NULL, buf, min(4, len));
 931                 len -= 4;
 932         }
 933 }
 934 EXPORT_SYMBOL_GPL(ide_pad_transfer);