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/completion.h>
  44 #include <linux/reboot.h>
  45 #include <linux/cdrom.h>
  46 #include <linux/seq_file.h>
  47 #include <linux/device.h>
  48 #include <linux/kmod.h>
  49 #include <linux/scatterlist.h>
  50 #include <linux/bitops.h>
  51
  52 #include <asm/byteorder.h>
  53 #include <asm/irq.h>
  54 #include <asm/uaccess.h>
  55 #include <asm/io.h>
  56
  57 int ide_end_rq(ide_drive_t *drive, struct request *rq, int error,
  58                unsigned int nr_bytes)
  59 {
  60         /*
  61          * decide whether to reenable DMA -- 3 is a random magic for now,
  62          * if we DMA timeout more than 3 times, just stay in PIO
  63          */
  64         if ((drive->dev_flags & IDE_DFLAG_DMA_PIO_RETRY) &&
  65             drive->retry_pio <= 3) {
  66                 drive->dev_flags &= ~IDE_DFLAG_DMA_PIO_RETRY;
  67                 ide_dma_on(drive);
  68         }
  69
  70         return blk_end_request(rq, error, nr_bytes);
  71 }
  72 EXPORT_SYMBOL_GPL(ide_end_rq);
  73
  74 void ide_complete_cmd(ide_drive_t *drive, struct ide_cmd *cmd, u8 stat, u8 err)
  75 {
  76         const struct ide_tp_ops *tp_ops = drive->hwif->tp_ops;
  77         struct ide_taskfile *tf = &cmd->tf;
  78         struct request *rq = cmd->rq;
  79         u8 tf_cmd = tf->command;
  80
  81         tf->error = err;
  82         tf->status = stat;
  83
  84         if (cmd->ftf_flags & IDE_FTFLAG_IN_DATA) {
  85                 u8 data[2];
  86
  87                 tp_ops->input_data(drive, cmd, data, 2);
  88
  89                 cmd->tf.data  = data[0];
  90                 cmd->hob.data = data[1];
  91         }
  92
  93         ide_tf_readback(drive, cmd);
  94
  95         if ((cmd->tf_flags & IDE_TFLAG_CUSTOM_HANDLER) &&
  96             tf_cmd == ATA_CMD_IDLEIMMEDIATE) {
  97                 if (tf->lbal != 0xc4) {
  98                         printk(KERN_ERR "%s: head unload failed!\n",
  99                                drive->name);
 100                         ide_tf_dump(drive->name, cmd);
 101                 } else
 102                         drive->dev_flags |= IDE_DFLAG_PARKED;
 103         }
 104
 105         if (rq && rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
 106                 struct ide_cmd *orig_cmd = rq->special;
 107
 108                 if (cmd->tf_flags & IDE_TFLAG_DYN)
 109                         kfree(orig_cmd);
 110                 else
 111                         memcpy(orig_cmd, cmd, sizeof(*cmd));
 112         }
 113 }
 114
 115 /* obsolete, blk_rq_bytes() should be used instead */
 116 unsigned int ide_rq_bytes(struct request *rq)
 117 {
 118         if (blk_pc_request(rq))
 119                 return blk_rq_bytes(rq);
 120         else
 121                 return blk_rq_cur_sectors(rq) << 9;
 122 }
 123 EXPORT_SYMBOL_GPL(ide_rq_bytes);
 124
 125 int ide_complete_rq(ide_drive_t *drive, int error, unsigned int nr_bytes)
 126 {
 127         ide_hwif_t *hwif = drive->hwif;
 128         struct request *rq = hwif->rq;
 129         int rc;
 130
 131         /*
 132          * if failfast is set on a request, override number of sectors
 133          * and complete the whole request right now
 134          */
 135         if (blk_noretry_request(rq) && error <= 0)
 136                 nr_bytes = blk_rq_sectors(rq) << 9;
 137
 138         rc = ide_end_rq(drive, rq, error, nr_bytes);
 139         if (rc == 0)
 140                 hwif->rq = NULL;
 141
 142         return rc;
 143 }
 144 EXPORT_SYMBOL(ide_complete_rq);
 145
 146 void ide_kill_rq(ide_drive_t *drive, struct request *rq)
 147 {
 148         u8 drv_req = blk_special_request(rq) && rq->rq_disk;
 149         u8 media = drive->media;
 150
 151         drive->failed_pc = NULL;
 152
 153         if ((media == ide_floppy || media == ide_tape) && drv_req) {
 154                 rq->errors = 0;
 155                 ide_complete_rq(drive, 0, blk_rq_bytes(rq));
 156         } else {
 157                 if (media == ide_tape)
 158                         rq->errors = IDE_DRV_ERROR_GENERAL;
 159                 else if (blk_fs_request(rq) == 0 && rq->errors == 0)
 160                         rq->errors = -EIO;
 161                 ide_complete_rq(drive, -EIO, ide_rq_bytes(rq));
 162         }
 163 }
 164
 165 static void ide_tf_set_specify_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
 166 {
 167         tf->nsect   = drive->sect;
 168         tf->lbal    = drive->sect;
 169         tf->lbam    = drive->cyl;
 170         tf->lbah    = drive->cyl >> 8;
 171         tf->device  = (drive->head - 1) | drive->select;
 172         tf->command = ATA_CMD_INIT_DEV_PARAMS;
 173 }
 174
 175 static void ide_tf_set_restore_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
 176 {
 177         tf->nsect   = drive->sect;
 178         tf->command = ATA_CMD_RESTORE;
 179 }
 180
 181 static void ide_tf_set_setmult_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
 182 {
 183         tf->nsect   = drive->mult_req;
 184         tf->command = ATA_CMD_SET_MULTI;
 185 }
 186
 187 /**
 188  *      do_special              -       issue some special commands
 189  *      @drive: drive the command is for
 190  *
 191  *      do_special() is used to issue ATA_CMD_INIT_DEV_PARAMS,
 192  *      ATA_CMD_RESTORE and ATA_CMD_SET_MULTI commands to a drive.
 193  */
 194
 195 static ide_startstop_t do_special(ide_drive_t *drive)
 196 {
 197         struct ide_cmd cmd;
 198
 199 #ifdef DEBUG
 200         printk(KERN_DEBUG "%s: %s: 0x%02x\n", drive->name, __func__,
 201                 drive->special_flags);
 202 #endif
 203         if (drive->media != ide_disk) {
 204                 drive->special_flags = 0;
 205                 drive->mult_req = 0;
 206                 return ide_stopped;
 207         }
 208
 209         memset(&cmd, 0, sizeof(cmd));
 210         cmd.protocol = ATA_PROT_NODATA;
 211
 212         if (drive->special_flags & IDE_SFLAG_SET_GEOMETRY) {
 213                 drive->special_flags &= ~IDE_SFLAG_SET_GEOMETRY;
 214                 ide_tf_set_specify_cmd(drive, &cmd.tf);
 215         } else if (drive->special_flags & IDE_SFLAG_RECALIBRATE) {
 216                 drive->special_flags &= ~IDE_SFLAG_RECALIBRATE;
 217                 ide_tf_set_restore_cmd(drive, &cmd.tf);
 218         } else if (drive->special_flags & IDE_SFLAG_SET_MULTMODE) {
 219                 drive->special_flags &= ~IDE_SFLAG_SET_MULTMODE;
 220                 ide_tf_set_setmult_cmd(drive, &cmd.tf);
 221         } else
 222                 BUG();
 223
 224         cmd.valid.out.tf = IDE_VALID_OUT_TF | IDE_VALID_DEVICE;
 225         cmd.valid.in.tf  = IDE_VALID_IN_TF  | IDE_VALID_DEVICE;
 226         cmd.tf_flags = IDE_TFLAG_CUSTOM_HANDLER;
 227
 228         do_rw_taskfile(drive, &cmd);
 229
 230         return ide_started;
 231 }
 232
 233 void ide_map_sg(ide_drive_t *drive, struct ide_cmd *cmd)
 234 {
 235         ide_hwif_t *hwif = drive->hwif;
 236         struct scatterlist *sg = hwif->sg_table;
 237         struct request *rq = cmd->rq;
 238
 239         cmd->sg_nents = blk_rq_map_sg(drive->queue, rq, sg);
 240 }
 241 EXPORT_SYMBOL_GPL(ide_map_sg);
 242
 243 void ide_init_sg_cmd(struct ide_cmd *cmd, unsigned int nr_bytes)
 244 {
 245         cmd->nbytes = cmd->nleft = nr_bytes;
 246         cmd->cursg_ofs = 0;
 247         cmd->cursg = NULL;
 248 }
 249 EXPORT_SYMBOL_GPL(ide_init_sg_cmd);
 250
 251 /**
 252  *      execute_drive_command   -       issue special drive command
 253  *      @drive: the drive to issue the command on
 254  *      @rq: the request structure holding the command
 255  *
 256  *      execute_drive_cmd() issues a special drive command,  usually
 257  *      initiated by ioctl() from the external hdparm program. The
 258  *      command can be a drive command, drive task or taskfile
 259  *      operation. Weirdly you can call it with NULL to wait for
 260  *      all commands to finish. Don't do this as that is due to change
 261  */
 262
 263 static ide_startstop_t execute_drive_cmd (ide_drive_t *drive,
 264                 struct request *rq)
 265 {
 266         struct ide_cmd *cmd = rq->special;
 267
 268         if (cmd) {
 269                 if (cmd->protocol == ATA_PROT_PIO) {
 270                         ide_init_sg_cmd(cmd, blk_rq_sectors(rq) << 9);
 271                         ide_map_sg(drive, cmd);
 272                 }
 273
 274                 return do_rw_taskfile(drive, cmd);
 275         }
 276
 277         /*
 278          * NULL is actually a valid way of waiting for
 279          * all current requests to be flushed from the queue.
 280          */
 281 #ifdef DEBUG
 282         printk("%s: DRIVE_CMD (null)\n", drive->name);
 283 #endif
 284         rq->errors = 0;
 285         ide_complete_rq(drive, 0, blk_rq_bytes(rq));
 286
 287         return ide_stopped;
 288 }
 289
 290 static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
 291 {
 292         u8 cmd = rq->cmd[0];
 293
 294         switch (cmd) {
 295         case REQ_PARK_HEADS:
 296         case REQ_UNPARK_HEADS:
 297                 return ide_do_park_unpark(drive, rq);
 298         case REQ_DEVSET_EXEC:
 299                 return ide_do_devset(drive, rq);
 300         case REQ_DRIVE_RESET:
 301                 return ide_do_reset(drive);
 302         default:
 303                 BUG();
 304         }
 305 }
 306
 307 /**
 308  *      start_request   -       start of I/O and command issuing for IDE
 309  *
 310  *      start_request() initiates handling of a new I/O request. It
 311  *      accepts commands and I/O (read/write) requests.
 312  *
 313  *      FIXME: this function needs a rename
 314  */
 315
 316 static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
 317 {
 318         ide_startstop_t startstop;
 319
 320         BUG_ON(!blk_rq_started(rq));
 321
 322 #ifdef DEBUG
 323         printk("%s: start_request: current=0x%08lx\n",
 324                 drive->hwif->name, (unsigned long) rq);
 325 #endif
 326
 327         /* bail early if we've exceeded max_failures */
 328         if (drive->max_failures && (drive->failures > drive->max_failures)) {
 329                 rq->cmd_flags |= REQ_FAILED;
 330                 goto kill_rq;
 331         }
 332
 333         if (blk_pm_request(rq))
 334                 ide_check_pm_state(drive, rq);
 335
 336         drive->hwif->tp_ops->dev_select(drive);
 337         if (ide_wait_stat(&startstop, drive, drive->ready_stat,
 338                           ATA_BUSY | ATA_DRQ, WAIT_READY)) {
 339                 printk(KERN_ERR "%s: drive not ready for command\n", drive->name);
 340                 return startstop;
 341         }
 342
 343         if (drive->special_flags == 0) {
 344                 struct ide_driver *drv;
 345
 346                 /*
 347                  * We reset the drive so we need to issue a SETFEATURES.
 348                  * Do it _after_ do_special() restored device parameters.
 349                  */
 350                 if (drive->current_speed == 0xff)
 351                         ide_config_drive_speed(drive, drive->desired_speed);
 352
 353                 if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE)
 354                         return execute_drive_cmd(drive, rq);
 355                 else if (blk_pm_request(rq)) {
 356                         struct request_pm_state *pm = rq->special;
 357 #ifdef DEBUG_PM
 358                         printk("%s: start_power_step(step: %d)\n",
 359                                 drive->name, pm->pm_step);
 360 #endif
 361                         startstop = ide_start_power_step(drive, rq);
 362                         if (startstop == ide_stopped &&
 363                             pm->pm_step == IDE_PM_COMPLETED)
 364                                 ide_complete_pm_rq(drive, rq);
 365                         return startstop;
 366                 } else if (!rq->rq_disk && blk_special_request(rq))
 367                         /*
 368                          * TODO: Once all ULDs have been modified to
 369                          * check for specific op codes rather than
 370                          * blindly accepting any special request, the
 371                          * check for ->rq_disk above may be replaced
 372                          * by a more suitable mechanism or even
 373                          * dropped entirely.
 374                          */
 375                         return ide_special_rq(drive, rq);
 376
 377                 drv = *(struct ide_driver **)rq->rq_disk->private_data;
 378
 379                 return drv->do_request(drive, rq, blk_rq_pos(rq));
 380         }
 381         return do_special(drive);
 382 kill_rq:
 383         ide_kill_rq(drive, rq);
 384         return ide_stopped;
 385 }
 386
 387 /**
 388  *      ide_stall_queue         -       pause an IDE device
 389  *      @drive: drive to stall
 390  *      @timeout: time to stall for (jiffies)
 391  *
 392  *      ide_stall_queue() can be used by a drive to give excess bandwidth back
 393  *      to the port by sleeping for timeout jiffies.
 394  */
 395
 396 void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
 397 {
 398         if (timeout > WAIT_WORSTCASE)
 399                 timeout = WAIT_WORSTCASE;
 400         drive->sleep = timeout + jiffies;
 401         drive->dev_flags |= IDE_DFLAG_SLEEPING;
 402 }
 403 EXPORT_SYMBOL(ide_stall_queue);
 404
 405 static inline int ide_lock_port(ide_hwif_t *hwif)
 406 {
 407         if (hwif->busy)
 408                 return 1;
 409
 410         hwif->busy = 1;
 411
 412         return 0;
 413 }
 414
 415 static inline void ide_unlock_port(ide_hwif_t *hwif)
 416 {
 417         hwif->busy = 0;
 418 }
 419
 420 static inline int ide_lock_host(struct ide_host *host, ide_hwif_t *hwif)
 421 {
 422         int rc = 0;
 423
 424         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
 425                 rc = test_and_set_bit_lock(IDE_HOST_BUSY, &host->host_busy);
 426                 if (rc == 0) {
 427                         if (host->get_lock)
 428                                 host->get_lock(ide_intr, hwif);
 429                 }
 430         }
 431         return rc;
 432 }
 433
 434 static inline void ide_unlock_host(struct ide_host *host)
 435 {
 436         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
 437                 if (host->release_lock)
 438                         host->release_lock();
 439                 clear_bit_unlock(IDE_HOST_BUSY, &host->host_busy);
 440         }
 441 }
 442
 443 /*
 444  * Issue a new request to a device.
 445  */
 446 void do_ide_request(struct request_queue *q)
 447 {
 448         ide_drive_t     *drive = q->queuedata;
 449         ide_hwif_t      *hwif = drive->hwif;
 450         struct ide_host *host = hwif->host;
 451         struct request  *rq = NULL;
 452         ide_startstop_t startstop;
 453
 454         /*
 455          * drive is doing pre-flush, ordered write, post-flush sequence. even
 456          * though that is 3 requests, it must be seen as a single transaction.
 457          * we must not preempt this drive until that is complete
 458          */
 459         if (blk_queue_flushing(q))
 460                 /*
 461                  * small race where queue could get replugged during
 462                  * the 3-request flush cycle, just yank the plug since
 463                  * we want it to finish asap
 464                  */
 465                 blk_remove_plug(q);
 466
 467         spin_unlock_irq(q->queue_lock);
 468
 469         /* HLD do_request() callback might sleep, make sure it's okay */
 470         might_sleep();
 471
 472         if (ide_lock_host(host, hwif))
 473                 goto plug_device_2;
 474
 475         spin_lock_irq(&hwif->lock);
 476
 477         if (!ide_lock_port(hwif)) {
 478                 ide_hwif_t *prev_port;
 479
 480                 WARN_ON_ONCE(hwif->rq);
 481 repeat:
 482                 prev_port = hwif->host->cur_port;
 483                 if (drive->dev_flags & IDE_DFLAG_SLEEPING &&
 484                     time_after(drive->sleep, jiffies)) {
 485                         ide_unlock_port(hwif);
 486                         goto plug_device;
 487                 }
 488
 489                 if ((hwif->host->host_flags & IDE_HFLAG_SERIALIZE) &&
 490                     hwif != prev_port) {
 491                         ide_drive_t *cur_dev =
 492                                 prev_port ? prev_port->cur_dev : NULL;
 493
 494                         /*
 495                          * set nIEN for previous port, drives in the
 496                          * quirk list may not like intr setups/cleanups
 497                          */
 498                         if (cur_dev &&
 499                             (cur_dev->dev_flags & IDE_DFLAG_NIEN_QUIRK) == 0)
 500                                 prev_port->tp_ops->write_devctl(prev_port,
 501                                                                 ATA_NIEN |
 502                                                                 ATA_DEVCTL_OBS);
 503
 504                         hwif->host->cur_port = hwif;
 505                 }
 506                 hwif->cur_dev = drive;
 507                 drive->dev_flags &= ~(IDE_DFLAG_SLEEPING | IDE_DFLAG_PARKED);
 508
 509                 spin_unlock_irq(&hwif->lock);
 510                 spin_lock_irq(q->queue_lock);
 511                 /*
 512                  * we know that the queue isn't empty, but this can happen
 513                  * if the q->prep_rq_fn() decides to kill a request
 514                  */
 515                 if (!rq)
 516                         rq = blk_fetch_request(drive->queue);
 517
 518                 spin_unlock_irq(q->queue_lock);
 519                 spin_lock_irq(&hwif->lock);
 520
 521                 if (!rq) {
 522                         ide_unlock_port(hwif);
 523                         goto out;
 524                 }
 525
 526                 /*
 527                  * Sanity: don't accept a request that isn't a PM request
 528                  * if we are currently power managed. This is very important as
 529                  * blk_stop_queue() doesn't prevent the blk_fetch_request()
 530                  * above to return us whatever is in the queue. Since we call
 531                  * ide_do_request() ourselves, we end up taking requests while
 532                  * the queue is blocked...
 533                  *
 534                  * We let requests forced at head of queue with ide-preempt
 535                  * though. I hope that doesn't happen too much, hopefully not
 536                  * unless the subdriver triggers such a thing in its own PM
 537                  * state machine.
 538                  */
 539                 if ((drive->dev_flags & IDE_DFLAG_BLOCKED) &&
 540                     blk_pm_request(rq) == 0 &&
 541                     (rq->cmd_flags & REQ_PREEMPT) == 0) {
 542                         /* there should be no pending command at this point */
 543                         ide_unlock_port(hwif);
 544                         goto plug_device;
 545                 }
 546
 547                 hwif->rq = rq;
 548
 549                 spin_unlock_irq(&hwif->lock);
 550                 startstop = start_request(drive, rq);
 551                 spin_lock_irq(&hwif->lock);
 552
 553                 if (startstop == ide_stopped) {
 554                         rq = hwif->rq;
 555                         hwif->rq = NULL;
 556                         goto repeat;
 557                 }
 558         } else
 559                 goto plug_device;
 560 out:
 561         spin_unlock_irq(&hwif->lock);
 562         if (rq == NULL)
 563                 ide_unlock_host(host);
 564         spin_lock_irq(q->queue_lock);
 565         return;
 566
 567 plug_device:
 568         spin_unlock_irq(&hwif->lock);
 569         ide_unlock_host(host);
 570 plug_device_2:
 571         spin_lock_irq(q->queue_lock);
 572
 573         if (rq)
 574                 blk_requeue_request(q, rq);
 575         if (!elv_queue_empty(q))
 576                 blk_plug_device(q);
 577 }
 578
 579 static void ide_requeue_and_plug(ide_drive_t *drive, struct request *rq)
 580 {
 581         struct request_queue *q = drive->queue;
 582         unsigned long flags;
 583
 584         spin_lock_irqsave(q->queue_lock, flags);
 585
 586         if (rq)
 587                 blk_requeue_request(q, rq);
 588         if (!elv_queue_empty(q))
 589                 blk_plug_device(q);
 590
 591         spin_unlock_irqrestore(q->queue_lock, flags);
 592 }
 593
 594 static int drive_is_ready(ide_drive_t *drive)
 595 {
 596         ide_hwif_t *hwif = drive->hwif;
 597         u8 stat = 0;
 598
 599         if (drive->waiting_for_dma)
 600                 return hwif->dma_ops->dma_test_irq(drive);
 601
 602         if (hwif->io_ports.ctl_addr &&
 603             (hwif->host_flags & IDE_HFLAG_BROKEN_ALTSTATUS) == 0)
 604                 stat = hwif->tp_ops->read_altstatus(hwif);
 605         else
 606                 /* Note: this may clear a pending IRQ!! */
 607                 stat = hwif->tp_ops->read_status(hwif);
 608
 609         if (stat & ATA_BUSY)
 610                 /* drive busy: definitely not interrupting */
 611                 return 0;
 612
 613         /* drive ready: *might* be interrupting */
 614         return 1;
 615 }
 616
 617 /**
 618  *      ide_timer_expiry        -       handle lack of an IDE interrupt
 619  *      @data: timer callback magic (hwif)
 620  *
 621  *      An IDE command has timed out before the expected drive return
 622  *      occurred. At this point we attempt to clean up the current
 623  *      mess. If the current handler includes an expiry handler then
 624  *      we invoke the expiry handler, and providing it is happy the
 625  *      work is done. If that fails we apply generic recovery rules
 626  *      invoking the handler and checking the drive DMA status. We
 627  *      have an excessively incestuous relationship with the DMA
 628  *      logic that wants cleaning up.
 629  */
 630
 631 void ide_timer_expiry (unsigned long data)
 632 {
 633         ide_hwif_t      *hwif = (ide_hwif_t *)data;
 634         ide_drive_t     *uninitialized_var(drive);
 635         ide_handler_t   *handler;
 636         unsigned long   flags;
 637         int             wait = -1;
 638         int             plug_device = 0;
 639         struct request  *uninitialized_var(rq_in_flight);
 640
 641         spin_lock_irqsave(&hwif->lock, flags);
 642
 643         handler = hwif->handler;
 644
 645         if (handler == NULL || hwif->req_gen != hwif->req_gen_timer) {
 646                 /*
 647                  * Either a marginal timeout occurred
 648                  * (got the interrupt just as timer expired),
 649                  * or we were "sleeping" to give other devices a chance.
 650                  * Either way, we don't really want to complain about anything.
 651                  */
 652         } else {
 653                 ide_expiry_t *expiry = hwif->expiry;
 654                 ide_startstop_t startstop = ide_stopped;
 655
 656                 drive = hwif->cur_dev;
 657
 658                 if (expiry) {
 659                         wait = expiry(drive);
 660                         if (wait > 0) { /* continue */
 661                                 /* reset timer */
 662                                 hwif->timer.expires = jiffies + wait;
 663                                 hwif->req_gen_timer = hwif->req_gen;
 664                                 add_timer(&hwif->timer);
 665                                 spin_unlock_irqrestore(&hwif->lock, flags);
 666                                 return;
 667                         }
 668                 }
 669                 hwif->handler = NULL;
 670                 hwif->expiry = NULL;
 671                 /*
 672                  * We need to simulate a real interrupt when invoking
 673                  * the handler() function, which means we need to
 674                  * globally mask the specific IRQ:
 675                  */
 676                 spin_unlock(&hwif->lock);
 677                 /* disable_irq_nosync ?? */
 678                 disable_irq(hwif->irq);
 679                 /* local CPU only, as if we were handling an interrupt */
 680                 local_irq_disable();
 681                 if (hwif->polling) {
 682                         startstop = handler(drive);
 683                 } else if (drive_is_ready(drive)) {
 684                         if (drive->waiting_for_dma)
 685                                 hwif->dma_ops->dma_lost_irq(drive);
 686                         if (hwif->port_ops && hwif->port_ops->clear_irq)
 687                                 hwif->port_ops->clear_irq(drive);
 688
 689                         printk(KERN_WARNING "%s: lost interrupt\n",
 690                                 drive->name);
 691                         startstop = handler(drive);
 692                 } else {
 693                         if (drive->waiting_for_dma)
 694                                 startstop = ide_dma_timeout_retry(drive, wait);
 695                         else
 696                                 startstop = ide_error(drive, "irq timeout",
 697                                         hwif->tp_ops->read_status(hwif));
 698                 }
 699                 spin_lock_irq(&hwif->lock);
 700                 enable_irq(hwif->irq);
 701                 if (startstop == ide_stopped && hwif->polling == 0) {
 702                         rq_in_flight = hwif->rq;
 703                         hwif->rq = NULL;
 704                         ide_unlock_port(hwif);
 705                         plug_device = 1;
 706                 }
 707         }
 708         spin_unlock_irqrestore(&hwif->lock, flags);
 709
 710         if (plug_device) {
 711                 ide_unlock_host(hwif->host);
 712                 ide_requeue_and_plug(drive, rq_in_flight);
 713         }
 714 }
 715
 716 /**
 717  *      unexpected_intr         -       handle an unexpected IDE interrupt
 718  *      @irq: interrupt line
 719  *      @hwif: port being processed
 720  *
 721  *      There's nothing really useful we can do with an unexpected interrupt,
 722  *      other than reading the status register (to clear it), and logging it.
 723  *      There should be no way that an irq can happen before we're ready for it,
 724  *      so we needn't worry much about losing an "important" interrupt here.
 725  *
 726  *      On laptops (and "green" PCs), an unexpected interrupt occurs whenever
 727  *      the drive enters "idle", "standby", or "sleep" mode, so if the status
 728  *      looks "good", we just ignore the interrupt completely.
 729  *
 730  *      This routine assumes __cli() is in effect when called.
 731  *
 732  *      If an unexpected interrupt happens on irq15 while we are handling irq14
 733  *      and if the two interfaces are "serialized" (CMD640), then it looks like
 734  *      we could screw up by interfering with a new request being set up for
 735  *      irq15.
 736  *
 737  *      In reality, this is a non-issue.  The new command is not sent unless
 738  *      the drive is ready to accept one, in which case we know the drive is
 739  *      not trying to interrupt us.  And ide_set_handler() is always invoked
 740  *      before completing the issuance of any new drive command, so we will not
 741  *      be accidentally invoked as a result of any valid command completion
 742  *      interrupt.
 743  */
 744
 745 static void unexpected_intr(int irq, ide_hwif_t *hwif)
 746 {
 747         u8 stat = hwif->tp_ops->read_status(hwif);
 748
 749         if (!OK_STAT(stat, ATA_DRDY, BAD_STAT)) {
 750                 /* Try to not flood the console with msgs */
 751                 static unsigned long last_msgtime, count;
 752                 ++count;
 753
 754                 if (time_after(jiffies, last_msgtime + HZ)) {
 755                         last_msgtime = jiffies;
 756                         printk(KERN_ERR "%s: unexpected interrupt, "
 757                                 "status=0x%02x, count=%ld\n",
 758                                 hwif->name, stat, count);
 759                 }
 760         }
 761 }
 762
 763 /**
 764  *      ide_intr        -       default IDE interrupt handler
 765  *      @irq: interrupt number
 766  *      @dev_id: hwif
 767  *      @regs: unused weirdness from the kernel irq layer
 768  *
 769  *      This is the default IRQ handler for the IDE layer. You should
 770  *      not need to override it. If you do be aware it is subtle in
 771  *      places
 772  *
 773  *      hwif is the interface in the group currently performing
 774  *      a command. hwif->cur_dev is the drive and hwif->handler is
 775  *      the IRQ handler to call. As we issue a command the handlers
 776  *      step through multiple states, reassigning the handler to the
 777  *      next step in the process. Unlike a smart SCSI controller IDE
 778  *      expects the main processor to sequence the various transfer
 779  *      stages. We also manage a poll timer to catch up with most
 780  *      timeout situations. There are still a few where the handlers
 781  *      don't ever decide to give up.
 782  *
 783  *      The handler eventually returns ide_stopped to indicate the
 784  *      request completed. At this point we issue the next request
 785  *      on the port and the process begins again.
 786  */
 787
 788 irqreturn_t ide_intr (int irq, void *dev_id)
 789 {
 790         ide_hwif_t *hwif = (ide_hwif_t *)dev_id;
 791         struct ide_host *host = hwif->host;
 792         ide_drive_t *uninitialized_var(drive);
 793         ide_handler_t *handler;
 794         unsigned long flags;
 795         ide_startstop_t startstop;
 796         irqreturn_t irq_ret = IRQ_NONE;
 797         int plug_device = 0;
 798         struct request *uninitialized_var(rq_in_flight);
 799
 800         if (host->host_flags & IDE_HFLAG_SERIALIZE) {
 801                 if (hwif != host->cur_port)
 802                         goto out_early;
 803         }
 804
 805         spin_lock_irqsave(&hwif->lock, flags);
 806
 807         if (hwif->port_ops && hwif->port_ops->test_irq &&
 808             hwif->port_ops->test_irq(hwif) == 0)
 809                 goto out;
 810
 811         handler = hwif->handler;
 812
 813         if (handler == NULL || hwif->polling) {
 814                 /*
 815                  * Not expecting an interrupt from this drive.
 816                  * That means this could be:
 817                  *      (1) an interrupt from another PCI device
 818                  *      sharing the same PCI INT# as us.
 819                  * or   (2) a drive just entered sleep or standby mode,
 820                  *      and is interrupting to let us know.
 821                  * or   (3) a spurious interrupt of unknown origin.
 822                  *
 823                  * For PCI, we cannot tell the difference,
 824                  * so in that case we just ignore it and hope it goes away.
 825                  */
 826                 if ((host->irq_flags & IRQF_SHARED) == 0) {
 827                         /*
 828                          * Probably not a shared PCI interrupt,
 829                          * so we can safely try to do something about it:
 830                          */
 831                         unexpected_intr(irq, hwif);
 832                 } else {
 833                         /*
 834                          * Whack the status register, just in case
 835                          * we have a leftover pending IRQ.
 836                          */
 837                         (void)hwif->tp_ops->read_status(hwif);
 838                 }
 839                 goto out;
 840         }
 841
 842         drive = hwif->cur_dev;
 843
 844         if (!drive_is_ready(drive))
 845                 /*
 846                  * This happens regularly when we share a PCI IRQ with
 847                  * another device.  Unfortunately, it can also happen
 848                  * with some buggy drives that trigger the IRQ before
 849                  * their status register is up to date.  Hopefully we have
 850                  * enough advance overhead that the latter isn't a problem.
 851                  */
 852                 goto out;
 853
 854         hwif->handler = NULL;
 855         hwif->expiry = NULL;
 856         hwif->req_gen++;
 857         del_timer(&hwif->timer);
 858         spin_unlock(&hwif->lock);
 859
 860         if (hwif->port_ops && hwif->port_ops->clear_irq)
 861                 hwif->port_ops->clear_irq(drive);
 862
 863         if (drive->dev_flags & IDE_DFLAG_UNMASK)
 864                 local_irq_enable_in_hardirq();
 865
 866         /* service this interrupt, may set handler for next interrupt */
 867         startstop = handler(drive);
 868
 869         spin_lock_irq(&hwif->lock);
 870         /*
 871          * Note that handler() may have set things up for another
 872          * interrupt to occur soon, but it cannot happen until
 873          * we exit from this routine, because it will be the
 874          * same irq as is currently being serviced here, and Linux
 875          * won't allow another of the same (on any CPU) until we return.
 876          */
 877         if (startstop == ide_stopped && hwif->polling == 0) {
 878                 BUG_ON(hwif->handler);
 879                 rq_in_flight = hwif->rq;
 880                 hwif->rq = NULL;
 881                 ide_unlock_port(hwif);
 882                 plug_device = 1;
 883         }
 884         irq_ret = IRQ_HANDLED;
 885 out:
 886         spin_unlock_irqrestore(&hwif->lock, flags);
 887 out_early:
 888         if (plug_device) {
 889                 ide_unlock_host(hwif->host);
 890                 ide_requeue_and_plug(drive, rq_in_flight);
 891         }
 892
 893         return irq_ret;
 894 }
 895 EXPORT_SYMBOL_GPL(ide_intr);
 896
 897 void ide_pad_transfer(ide_drive_t *drive, int write, int len)
 898 {
 899         ide_hwif_t *hwif = drive->hwif;
 900         u8 buf[4] = { 0 };
 901
 902         while (len > 0) {
 903                 if (write)
 904                         hwif->tp_ops->output_data(drive, NULL, buf, min(4, len));
 905                 else
 906                         hwif->tp_ops->input_data(drive, NULL, buf, min(4, len));
 907                 len -= 4;
 908         }
 909 }
 910 EXPORT_SYMBOL_GPL(ide_pad_transfer);