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