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ide-io.c

/*
 *    IDE I/O functions
 *
 *    Basic PIO and command management functionality.
 *
 * This code was split off from ide.c. See ide.c for history and original
 * copyrights.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * For the avoidance of doubt the "preferred form" of this code is one which
 * is in an open non patent encumbered format. Where cryptographic key signing
 * forms part of the process of creating an executable the information
 * including keys needed to generate an equivalently functional executable
 * are deemed to be part of the source code.
 */
 
 
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/genhd.h>
#include <linux/blkpg.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/completion.h>
#include <linux/reboot.h>
#include <linux/cdrom.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/kmod.h>
#include <linux/scatterlist.h>
#include <linux/bitops.h>

#include <asm/byteorder.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/io.h>

static int __ide_end_request(ide_drive_t *drive, struct request *rq,
                       int uptodate, unsigned int nr_bytes, int dequeue)
{
      int ret = 1;

      /*
       * if failfast is set on a request, override number of sectors and
       * complete the whole request right now
       */
      if (blk_noretry_request(rq) && end_io_error(uptodate))
            nr_bytes = rq->hard_nr_sectors << 9;

      if (!blk_fs_request(rq) && end_io_error(uptodate) && !rq->errors)
            rq->errors = -EIO;

      /*
       * decide whether to reenable DMA -- 3 is a random magic for now,
       * if we DMA timeout more than 3 times, just stay in PIO
       */
      if (drive->state == DMA_PIO_RETRY && drive->retry_pio <= 3) {
            drive->state = 0;
            HWGROUP(drive)->hwif->ide_dma_on(drive);
      }

      if (!end_that_request_chunk(rq, uptodate, nr_bytes)) {
            add_disk_randomness(rq->rq_disk);
            if (dequeue) {
                  if (!list_empty(&rq->queuelist))
                        blkdev_dequeue_request(rq);
                  HWGROUP(drive)->rq = NULL;
            }
            end_that_request_last(rq, uptodate);
            ret = 0;
      }

      return ret;
}

/**
 *    ide_end_request         -     complete an IDE I/O
 *    @drive: IDE device for the I/O
 *    @uptodate:
 *    @nr_sectors: number of sectors completed
 *
 *    This is our end_request wrapper function. We complete the I/O
 *    update random number input and dequeue the request, which if
 *    it was tagged may be out of order.
 */

int ide_end_request (ide_drive_t *drive, int uptodate, int nr_sectors)
{
      unsigned int nr_bytes = nr_sectors << 9;
      struct request *rq;
      unsigned long flags;
      int ret = 1;

      /*
       * room for locking improvements here, the calls below don't
       * need the queue lock held at all
       */
      spin_lock_irqsave(&ide_lock, flags);
      rq = HWGROUP(drive)->rq;

      if (!nr_bytes) {
            if (blk_pc_request(rq))
                  nr_bytes = rq->data_len;
            else
                  nr_bytes = rq->hard_cur_sectors << 9;
      }

      ret = __ide_end_request(drive, rq, uptodate, nr_bytes, 1);

      spin_unlock_irqrestore(&ide_lock, flags);
      return ret;
}
EXPORT_SYMBOL(ide_end_request);

/*
 * Power Management state machine. This one is rather trivial for now,
 * we should probably add more, like switching back to PIO on suspend
 * to help some BIOSes, re-do the door locking on resume, etc...
 */

enum {
      ide_pm_flush_cache      = ide_pm_state_start_suspend,
      idedisk_pm_standby,

      idedisk_pm_restore_pio  = ide_pm_state_start_resume,
      idedisk_pm_idle,
      ide_pm_restore_dma,
};

static void ide_complete_power_step(ide_drive_t *drive, struct request *rq, u8 stat, u8 error)
{
      struct request_pm_state *pm = rq->data;

      if (drive->media != ide_disk)
            return;

      switch (pm->pm_step) {
      case ide_pm_flush_cache:      /* Suspend step 1 (flush cache) complete */
            if (pm->pm_state == PM_EVENT_FREEZE)
                  pm->pm_step = ide_pm_state_completed;
            else
                  pm->pm_step = idedisk_pm_standby;
            break;
      case idedisk_pm_standby:      /* Suspend step 2 (standby) complete */
            pm->pm_step = ide_pm_state_completed;
            break;
      case idedisk_pm_restore_pio:  /* Resume step 1 complete */
            pm->pm_step = idedisk_pm_idle;
            break;
      case idedisk_pm_idle:         /* Resume step 2 (idle) complete */
            pm->pm_step = ide_pm_restore_dma;
            break;
      }
}

static ide_startstop_t ide_start_power_step(ide_drive_t *drive, struct request *rq)
{
      struct request_pm_state *pm = rq->data;
      ide_task_t *args = rq->special;

      memset(args, 0, sizeof(*args));

      switch (pm->pm_step) {
      case ide_pm_flush_cache:      /* Suspend step 1 (flush cache) */
            if (drive->media != ide_disk)
                  break;
            /* Not supported? Switch to next step now. */
            if (!drive->wcache || !ide_id_has_flush_cache(drive->id)) {
                  ide_complete_power_step(drive, rq, 0, 0);
                  return ide_stopped;
            }
            if (ide_id_has_flush_cache_ext(drive->id))
                  args->tfRegister[IDE_COMMAND_OFFSET] = WIN_FLUSH_CACHE_EXT;
            else
                  args->tfRegister[IDE_COMMAND_OFFSET] = WIN_FLUSH_CACHE;
            args->command_type = IDE_DRIVE_TASK_NO_DATA;
            args->handler        = &task_no_data_intr;
            return do_rw_taskfile(drive, args);

      case idedisk_pm_standby:      /* Suspend step 2 (standby) */
            args->tfRegister[IDE_COMMAND_OFFSET] = WIN_STANDBYNOW1;
            args->command_type = IDE_DRIVE_TASK_NO_DATA;
            args->handler        = &task_no_data_intr;
            return do_rw_taskfile(drive, args);

      case idedisk_pm_restore_pio:  /* Resume step 1 (restore PIO) */
            ide_set_max_pio(drive);
            /*
             * skip idedisk_pm_idle for ATAPI devices
             */
            if (drive->media != ide_disk)
                  pm->pm_step = ide_pm_restore_dma;
            else
                  ide_complete_power_step(drive, rq, 0, 0);
            return ide_stopped;

      case idedisk_pm_idle:         /* Resume step 2 (idle) */
            args->tfRegister[IDE_COMMAND_OFFSET] = WIN_IDLEIMMEDIATE;
            args->command_type = IDE_DRIVE_TASK_NO_DATA;
            args->handler = task_no_data_intr;
            return do_rw_taskfile(drive, args);

      case ide_pm_restore_dma:      /* Resume step 3 (restore DMA) */
            /*
             * Right now, all we do is call ide_set_dma(drive),
             * we could be smarter and check for current xfer_speed
             * in struct drive etc...
             */
            if (drive->hwif->ide_dma_on == NULL)
                  break;
            drive->hwif->dma_off_quietly(drive);
            /*
             * TODO: respect ->using_dma setting
             */
            ide_set_dma(drive);
            break;
      }
      pm->pm_step = ide_pm_state_completed;
      return ide_stopped;
}

/**
 *    ide_end_dequeued_request      -     complete an IDE I/O
 *    @drive: IDE device for the I/O
 *    @uptodate:
 *    @nr_sectors: number of sectors completed
 *
 *    Complete an I/O that is no longer on the request queue. This
 *    typically occurs when we pull the request and issue a REQUEST_SENSE.
 *    We must still finish the old request but we must not tamper with the
 *    queue in the meantime.
 *
 *    NOTE: This path does not handle barrier, but barrier is not supported
 *    on ide-cd anyway.
 */

int ide_end_dequeued_request(ide_drive_t *drive, struct request *rq,
                       int uptodate, int nr_sectors)
{
      unsigned long flags;
      int ret;

      spin_lock_irqsave(&ide_lock, flags);
      BUG_ON(!blk_rq_started(rq));
      ret = __ide_end_request(drive, rq, uptodate, nr_sectors << 9, 0);
      spin_unlock_irqrestore(&ide_lock, flags);

      return ret;
}
EXPORT_SYMBOL_GPL(ide_end_dequeued_request);


/**
 *    ide_complete_pm_request - end the current Power Management request
 *    @drive: target drive
 *    @rq: request
 *
 *    This function cleans up the current PM request and stops the queue
 *    if necessary.
 */
static void ide_complete_pm_request (ide_drive_t *drive, struct request *rq)
{
      unsigned long flags;

#ifdef DEBUG_PM
      printk("%s: completing PM request, %s\n", drive->name,
             blk_pm_suspend_request(rq) ? "suspend" : "resume");
#endif
      spin_lock_irqsave(&ide_lock, flags);
      if (blk_pm_suspend_request(rq)) {
            blk_stop_queue(drive->queue);
      } else {
            drive->blocked = 0;
            blk_start_queue(drive->queue);
      }
      blkdev_dequeue_request(rq);
      HWGROUP(drive)->rq = NULL;
      end_that_request_last(rq, 1);
      spin_unlock_irqrestore(&ide_lock, flags);
}

/**
 *    ide_end_drive_cmd -     end an explicit drive command
 *    @drive: command 
 *    @stat: status bits
 *    @err: error bits
 *
 *    Clean up after success/failure of an explicit drive command.
 *    These get thrown onto the queue so they are synchronized with
 *    real I/O operations on the drive.
 *
 *    In LBA48 mode we have to read the register set twice to get
 *    all the extra information out.
 */
 
void ide_end_drive_cmd (ide_drive_t *drive, u8 stat, u8 err)
{
      ide_hwif_t *hwif = HWIF(drive);
      unsigned long flags;
      struct request *rq;

      spin_lock_irqsave(&ide_lock, flags);
      rq = HWGROUP(drive)->rq;
      spin_unlock_irqrestore(&ide_lock, flags);

      if (rq->cmd_type == REQ_TYPE_ATA_CMD) {
            u8 *args = (u8 *) rq->buffer;
            if (rq->errors == 0)
                  rq->errors = !OK_STAT(stat,READY_STAT,BAD_STAT);

            if (args) {
                  args[0] = stat;
                  args[1] = err;
                  args[2] = hwif->INB(IDE_NSECTOR_REG);
            }
      } else if (rq->cmd_type == REQ_TYPE_ATA_TASK) {
            u8 *args = (u8 *) rq->buffer;
            if (rq->errors == 0)
                  rq->errors = !OK_STAT(stat,READY_STAT,BAD_STAT);

            if (args) {
                  args[0] = stat;
                  args[1] = err;
                  /* be sure we're looking at the low order bits */
                  hwif->OUTB(drive->ctl & ~0x80, IDE_CONTROL_REG);
                  args[2] = hwif->INB(IDE_NSECTOR_REG);
                  args[3] = hwif->INB(IDE_SECTOR_REG);
                  args[4] = hwif->INB(IDE_LCYL_REG);
                  args[5] = hwif->INB(IDE_HCYL_REG);
                  args[6] = hwif->INB(IDE_SELECT_REG);
            }
      } else if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
            ide_task_t *args = (ide_task_t *) rq->special;
            if (rq->errors == 0)
                  rq->errors = !OK_STAT(stat,READY_STAT,BAD_STAT);
                  
            if (args) {
                  if (args->tf_in_flags.b.data) {
                        u16 data                      = hwif->INW(IDE_DATA_REG);
                        args->tfRegister[IDE_DATA_OFFSET]   = (data) & 0xFF;
                        args->hobRegister[IDE_DATA_OFFSET]  = (data >> 8) & 0xFF;
                  }
                  args->tfRegister[IDE_ERROR_OFFSET]   = err;
                  /* be sure we're looking at the low order bits */
                  hwif->OUTB(drive->ctl & ~0x80, IDE_CONTROL_REG);
                  args->tfRegister[IDE_NSECTOR_OFFSET] = hwif->INB(IDE_NSECTOR_REG);
                  args->tfRegister[IDE_SECTOR_OFFSET]  = hwif->INB(IDE_SECTOR_REG);
                  args->tfRegister[IDE_LCYL_OFFSET]    = hwif->INB(IDE_LCYL_REG);
                  args->tfRegister[IDE_HCYL_OFFSET]    = hwif->INB(IDE_HCYL_REG);
                  args->tfRegister[IDE_SELECT_OFFSET]  = hwif->INB(IDE_SELECT_REG);
                  args->tfRegister[IDE_STATUS_OFFSET]  = stat;

                  if (drive->addressing == 1) {
                        hwif->OUTB(drive->ctl|0x80, IDE_CONTROL_REG);
                        args->hobRegister[IDE_FEATURE_OFFSET]     = hwif->INB(IDE_FEATURE_REG);
                        args->hobRegister[IDE_NSECTOR_OFFSET]     = hwif->INB(IDE_NSECTOR_REG);
                        args->hobRegister[IDE_SECTOR_OFFSET]      = hwif->INB(IDE_SECTOR_REG);
                        args->hobRegister[IDE_LCYL_OFFSET]  = hwif->INB(IDE_LCYL_REG);
                        args->hobRegister[IDE_HCYL_OFFSET]  = hwif->INB(IDE_HCYL_REG);
                  }
            }
      } else if (blk_pm_request(rq)) {
            struct request_pm_state *pm = rq->data;
#ifdef DEBUG_PM
            printk("%s: complete_power_step(step: %d, stat: %x, err: %x)\n",
                  drive->name, rq->pm->pm_step, stat, err);
#endif
            ide_complete_power_step(drive, rq, stat, err);
            if (pm->pm_step == ide_pm_state_completed)
                  ide_complete_pm_request(drive, rq);
            return;
      }

      spin_lock_irqsave(&ide_lock, flags);
      blkdev_dequeue_request(rq);
      HWGROUP(drive)->rq = NULL;
      rq->errors = err;
      end_that_request_last(rq, !rq->errors);
      spin_unlock_irqrestore(&ide_lock, flags);
}

EXPORT_SYMBOL(ide_end_drive_cmd);

/**
 *    try_to_flush_leftover_data    -     flush junk
 *    @drive: drive to flush
 *
 *    try_to_flush_leftover_data() is invoked in response to a drive
 *    unexpectedly having its DRQ_STAT bit set.  As an alternative to
 *    resetting the drive, this routine tries to clear the condition
 *    by read a sector's worth of data from the drive.  Of course,
 *    this may not help if the drive is *waiting* for data from *us*.
 */
static void try_to_flush_leftover_data (ide_drive_t *drive)
{
      int i = (drive->mult_count ? drive->mult_count : 1) * SECTOR_WORDS;

      if (drive->media != ide_disk)
            return;
      while (i > 0) {
            u32 buffer[16];
            u32 wcount = (i > 16) ? 16 : i;

            i -= wcount;
            HWIF(drive)->ata_input_data(drive, buffer, wcount);
      }
}

static void ide_kill_rq(ide_drive_t *drive, struct request *rq)
{
      if (rq->rq_disk) {
            ide_driver_t *drv;

            drv = *(ide_driver_t **)rq->rq_disk->private_data;
            drv->end_request(drive, 0, 0);
      } else
            ide_end_request(drive, 0, 0);
}

static ide_startstop_t ide_ata_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
{
      ide_hwif_t *hwif = drive->hwif;

      if (stat & BUSY_STAT || ((stat & WRERR_STAT) && !drive->nowerr)) {
            /* other bits are useless when BUSY */
            rq->errors |= ERROR_RESET;
      } else if (stat & ERR_STAT) {
            /* err has different meaning on cdrom and tape */
            if (err == ABRT_ERR) {
                  if (drive->select.b.lba &&
                      /* some newer drives don't support WIN_SPECIFY */
                      hwif->INB(IDE_COMMAND_REG) == WIN_SPECIFY)
                        return ide_stopped;
            } else if ((err & BAD_CRC) == BAD_CRC) {
                  /* UDMA crc error, just retry the operation */
                  drive->crc_count++;
            } else if (err & (BBD_ERR | ECC_ERR)) {
                  /* retries won't help these */
                  rq->errors = ERROR_MAX;
            } else if (err & TRK0_ERR) {
                  /* help it find track zero */
                  rq->errors |= ERROR_RECAL;
            }
      }

      if ((stat & DRQ_STAT) && rq_data_dir(rq) == READ &&
          (hwif->host_flags & IDE_HFLAG_ERROR_STOPS_FIFO) == 0)
            try_to_flush_leftover_data(drive);

      if (rq->errors >= ERROR_MAX || blk_noretry_request(rq)) {
            ide_kill_rq(drive, rq);
            return ide_stopped;
      }

      if (hwif->INB(IDE_STATUS_REG) & (BUSY_STAT|DRQ_STAT))
            rq->errors |= ERROR_RESET;

      if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
            ++rq->errors;
            return ide_do_reset(drive);
      }

      if ((rq->errors & ERROR_RECAL) == ERROR_RECAL)
            drive->special.b.recalibrate = 1;

      ++rq->errors;

      return ide_stopped;
}

static ide_startstop_t ide_atapi_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
{
      ide_hwif_t *hwif = drive->hwif;

      if (stat & BUSY_STAT || ((stat & WRERR_STAT) && !drive->nowerr)) {
            /* other bits are useless when BUSY */
            rq->errors |= ERROR_RESET;
      } else {
            /* add decoding error stuff */
      }

      if (hwif->INB(IDE_STATUS_REG) & (BUSY_STAT|DRQ_STAT))
            /* force an abort */
            hwif->OUTB(WIN_IDLEIMMEDIATE, IDE_COMMAND_REG);

      if (rq->errors >= ERROR_MAX) {
            ide_kill_rq(drive, rq);
      } else {
            if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
                  ++rq->errors;
                  return ide_do_reset(drive);
            }
            ++rq->errors;
      }

      return ide_stopped;
}

ide_startstop_t
__ide_error(ide_drive_t *drive, struct request *rq, u8 stat, u8 err)
{
      if (drive->media == ide_disk)
            return ide_ata_error(drive, rq, stat, err);
      return ide_atapi_error(drive, rq, stat, err);
}

EXPORT_SYMBOL_GPL(__ide_error);

/**
 *    ide_error   -     handle an error on the IDE
 *    @drive: drive the error occurred on
 *    @msg: message to report
 *    @stat: status bits
 *
 *    ide_error() takes action based on the error returned by the drive.
 *    For normal I/O that may well include retries. We deal with
 *    both new-style (taskfile) and old style command handling here.
 *    In the case of taskfile command handling there is work left to
 *    do
 */
 
ide_startstop_t ide_error (ide_drive_t *drive, const char *msg, u8 stat)
{
      struct request *rq;
      u8 err;

      err = ide_dump_status(drive, msg, stat);

      if ((rq = HWGROUP(drive)->rq) == NULL)
            return ide_stopped;

      /* retry only "normal" I/O: */
      if (!blk_fs_request(rq)) {
            rq->errors = 1;
            ide_end_drive_cmd(drive, stat, err);
            return ide_stopped;
      }

      if (rq->rq_disk) {
            ide_driver_t *drv;

            drv = *(ide_driver_t **)rq->rq_disk->private_data;
            return drv->error(drive, rq, stat, err);
      } else
            return __ide_error(drive, rq, stat, err);
}

EXPORT_SYMBOL_GPL(ide_error);

ide_startstop_t __ide_abort(ide_drive_t *drive, struct request *rq)
{
      if (drive->media != ide_disk)
            rq->errors |= ERROR_RESET;

      ide_kill_rq(drive, rq);

      return ide_stopped;
}

EXPORT_SYMBOL_GPL(__ide_abort);

/**
 *    ide_abort   -     abort pending IDE operations
 *    @drive: drive the error occurred on
 *    @msg: message to report
 *
 *    ide_abort kills and cleans up when we are about to do a 
 *    host initiated reset on active commands. Longer term we
 *    want handlers to have sensible abort handling themselves
 *
 *    This differs fundamentally from ide_error because in 
 *    this case the command is doing just fine when we
 *    blow it away.
 */
 
ide_startstop_t ide_abort(ide_drive_t *drive, const char *msg)
{
      struct request *rq;

      if (drive == NULL || (rq = HWGROUP(drive)->rq) == NULL)
            return ide_stopped;

      /* retry only "normal" I/O: */
      if (!blk_fs_request(rq)) {
            rq->errors = 1;
            ide_end_drive_cmd(drive, BUSY_STAT, 0);
            return ide_stopped;
      }

      if (rq->rq_disk) {
            ide_driver_t *drv;

            drv = *(ide_driver_t **)rq->rq_disk->private_data;
            return drv->abort(drive, rq);
      } else
            return __ide_abort(drive, rq);
}

/**
 *    ide_cmd           -     issue a simple drive command
 *    @drive: drive the command is for
 *    @cmd: command byte
 *    @nsect: sector byte
 *    @handler: handler for the command completion
 *
 *    Issue a simple drive command with interrupts.
 *    The drive must be selected beforehand.
 */

static void ide_cmd (ide_drive_t *drive, u8 cmd, u8 nsect,
            ide_handler_t *handler)
{
      ide_hwif_t *hwif = HWIF(drive);
      if (IDE_CONTROL_REG)
            hwif->OUTB(drive->ctl,IDE_CONTROL_REG);   /* clear nIEN */
      SELECT_MASK(drive,0);
      hwif->OUTB(nsect,IDE_NSECTOR_REG);
      ide_execute_command(drive, cmd, handler, WAIT_CMD, NULL);
}

/**
 *    drive_cmd_intr          -     drive command completion interrupt
 *    @drive: drive the completion interrupt occurred on
 *
 *    drive_cmd_intr() is invoked on completion of a special DRIVE_CMD.
 *    We do any necessary data reading and then wait for the drive to
 *    go non busy. At that point we may read the error data and complete
 *    the request
 */
 
static ide_startstop_t drive_cmd_intr (ide_drive_t *drive)
{
      struct request *rq = HWGROUP(drive)->rq;
      ide_hwif_t *hwif = HWIF(drive);
      u8 *args = (u8 *) rq->buffer;
      u8 stat = hwif->INB(IDE_STATUS_REG);
      int retries = 10;

      local_irq_enable_in_hardirq();
      if (rq->cmd_type == REQ_TYPE_ATA_CMD &&
          (stat & DRQ_STAT) && args && args[3]) {
            u8 io_32bit = drive->io_32bit;
            drive->io_32bit = 0;
            hwif->ata_input_data(drive, &args[4], args[3] * SECTOR_WORDS);
            drive->io_32bit = io_32bit;
            while (((stat = hwif->INB(IDE_STATUS_REG)) & BUSY_STAT) && retries--)
                  udelay(100);
      }

      if (!OK_STAT(stat, READY_STAT, BAD_STAT))
            return ide_error(drive, "drive_cmd", stat);
            /* calls ide_end_drive_cmd */
      ide_end_drive_cmd(drive, stat, hwif->INB(IDE_ERROR_REG));
      return ide_stopped;
}

static void ide_init_specify_cmd(ide_drive_t *drive, ide_task_t *task)
{
      task->tfRegister[IDE_NSECTOR_OFFSET] = drive->sect;
      task->tfRegister[IDE_SECTOR_OFFSET]  = drive->sect;
      task->tfRegister[IDE_LCYL_OFFSET]    = drive->cyl;
      task->tfRegister[IDE_HCYL_OFFSET]    = drive->cyl>>8;
      task->tfRegister[IDE_SELECT_OFFSET]  = ((drive->head-1)|drive->select.all)&0xBF;
      task->tfRegister[IDE_COMMAND_OFFSET] = WIN_SPECIFY;

      task->handler = &set_geometry_intr;
}

static void ide_init_restore_cmd(ide_drive_t *drive, ide_task_t *task)
{
      task->tfRegister[IDE_NSECTOR_OFFSET] = drive->sect;
      task->tfRegister[IDE_COMMAND_OFFSET] = WIN_RESTORE;

      task->handler = &recal_intr;
}

static void ide_init_setmult_cmd(ide_drive_t *drive, ide_task_t *task)
{
      task->tfRegister[IDE_NSECTOR_OFFSET] = drive->mult_req;
      task->tfRegister[IDE_COMMAND_OFFSET] = WIN_SETMULT;

      task->handler = &set_multmode_intr;
}

static ide_startstop_t ide_disk_special(ide_drive_t *drive)
{
      special_t *s = &drive->special;
      ide_task_t args;

      memset(&args, 0, sizeof(ide_task_t));
      args.command_type = IDE_DRIVE_TASK_NO_DATA;

      if (s->b.set_geometry) {
            s->b.set_geometry = 0;
            ide_init_specify_cmd(drive, &args);
      } else if (s->b.recalibrate) {
            s->b.recalibrate = 0;
            ide_init_restore_cmd(drive, &args);
      } else if (s->b.set_multmode) {
            s->b.set_multmode = 0;
            if (drive->mult_req > drive->id->max_multsect)
                  drive->mult_req = drive->id->max_multsect;
            ide_init_setmult_cmd(drive, &args);
      } else if (s->all) {
            int special = s->all;
            s->all = 0;
            printk(KERN_ERR "%s: bad special flag: 0x%02x\n", drive->name, special);
            return ide_stopped;
      }

      do_rw_taskfile(drive, &args);

      return ide_started;
}

/*
 * handle HDIO_SET_PIO_MODE ioctl abusers here, eventually it will go away
 */
static int set_pio_mode_abuse(ide_hwif_t *hwif, u8 req_pio)
{
      switch (req_pio) {
      case 202:
      case 201:
      case 200:
      case 102:
      case 101:
      case 100:
            return (hwif->host_flags & IDE_HFLAG_ABUSE_DMA_MODES) ? 1 : 0;
      case 9:
      case 8:
            return (hwif->host_flags & IDE_HFLAG_ABUSE_PREFETCH) ? 1 : 0;
      case 7:
      case 6:
            return (hwif->host_flags & IDE_HFLAG_ABUSE_FAST_DEVSEL) ? 1 : 0;
      default:
            return 0;
      }
}

/**
 *    do_special        -     issue some special commands
 *    @drive: drive the command is for
 *
 *    do_special() is used to issue WIN_SPECIFY, WIN_RESTORE, and WIN_SETMULT
 *    commands to a drive.  It used to do much more, but has been scaled
 *    back.
 */

static ide_startstop_t do_special (ide_drive_t *drive)
{
      special_t *s = &drive->special;

#ifdef DEBUG
      printk("%s: do_special: 0x%02x\n", drive->name, s->all);
#endif
      if (s->b.set_tune) {
            ide_hwif_t *hwif = drive->hwif;
            u8 req_pio = drive->tune_req;

            s->b.set_tune = 0;

            if (set_pio_mode_abuse(drive->hwif, req_pio)) {

                  if (hwif->set_pio_mode == NULL)
                        return ide_stopped;

                  /*
                   * take ide_lock for drive->[no_]unmask/[no_]io_32bit
                   */
                  if (req_pio == 8 || req_pio == 9) {
                        unsigned long flags;

                        spin_lock_irqsave(&ide_lock, flags);
                        hwif->set_pio_mode(drive, req_pio);
                        spin_unlock_irqrestore(&ide_lock, flags);
                  } else
                        hwif->set_pio_mode(drive, req_pio);
            } else {
                  int keep_dma = drive->using_dma;

                  ide_set_pio(drive, req_pio);

                  if (hwif->host_flags & IDE_HFLAG_SET_PIO_MODE_KEEP_DMA) {
                        if (keep_dma)
                              hwif->ide_dma_on(drive);
                  }
            }

            return ide_stopped;
      } else {
            if (drive->media == ide_disk)
                  return ide_disk_special(drive);

            s->all = 0;
            drive->mult_req = 0;
            return ide_stopped;
      }
}

void ide_map_sg(ide_drive_t *drive, struct request *rq)
{
      ide_hwif_t *hwif = drive->hwif;
      struct scatterlist *sg = hwif->sg_table;

      if (hwif->sg_mapped)    /* needed by ide-scsi */
            return;

      if (rq->cmd_type != REQ_TYPE_ATA_TASKFILE) {
            hwif->sg_nents = blk_rq_map_sg(drive->queue, rq, sg);
      } else {
            sg_init_one(sg, rq->buffer, rq->nr_sectors * SECTOR_SIZE);
            hwif->sg_nents = 1;
      }
}

EXPORT_SYMBOL_GPL(ide_map_sg);

void ide_init_sg_cmd(ide_drive_t *drive, struct request *rq)
{
      ide_hwif_t *hwif = drive->hwif;

      hwif->nsect = hwif->nleft = rq->nr_sectors;
      hwif->cursg_ofs = 0;
      hwif->cursg = NULL;
}

EXPORT_SYMBOL_GPL(ide_init_sg_cmd);

/**
 *    execute_drive_command   -     issue special drive command
 *    @drive: the drive to issue the command on
 *    @rq: the request structure holding the command
 *
 *    execute_drive_cmd() issues a special drive command,  usually 
 *    initiated by ioctl() from the external hdparm program. The
 *    command can be a drive command, drive task or taskfile 
 *    operation. Weirdly you can call it with NULL to wait for
 *    all commands to finish. Don't do this as that is due to change
 */

static ide_startstop_t execute_drive_cmd (ide_drive_t *drive,
            struct request *rq)
{
      ide_hwif_t *hwif = HWIF(drive);
      if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
            ide_task_t *args = rq->special;
 
            if (!args)
                  goto done;

            hwif->data_phase = args->data_phase;

            switch (hwif->data_phase) {
            case TASKFILE_MULTI_OUT:
            case TASKFILE_OUT:
            case TASKFILE_MULTI_IN:
            case TASKFILE_IN:
                  ide_init_sg_cmd(drive, rq);
                  ide_map_sg(drive, rq);
            default:
                  break;
            }

            if (args->tf_out_flags.all != 0) 
                  return flagged_taskfile(drive, args);
            return do_rw_taskfile(drive, args);
      } else if (rq->cmd_type == REQ_TYPE_ATA_TASK) {
            u8 *args = rq->buffer;
 
            if (!args)
                  goto done;
#ifdef DEBUG
            printk("%s: DRIVE_TASK_CMD ", drive->name);
            printk("cmd=0x%02x ", args[0]);
            printk("fr=0x%02x ", args[1]);
            printk("ns=0x%02x ", args[2]);
            printk("sc=0x%02x ", args[3]);
            printk("lcyl=0x%02x ", args[4]);
            printk("hcyl=0x%02x ", args[5]);
            printk("sel=0x%02x\n", args[6]);
#endif
            hwif->OUTB(args[1], IDE_FEATURE_REG);
            hwif->OUTB(args[3], IDE_SECTOR_REG);
            hwif->OUTB(args[4], IDE_LCYL_REG);
            hwif->OUTB(args[5], IDE_HCYL_REG);
            hwif->OUTB((args[6] & 0xEF)|drive->select.all, IDE_SELECT_REG);
            ide_cmd(drive, args[0], args[2], &drive_cmd_intr);
            return ide_started;
      } else if (rq->cmd_type == REQ_TYPE_ATA_CMD) {
            u8 *args = rq->buffer;

            if (!args)
                  goto done;
#ifdef DEBUG
            printk("%s: DRIVE_CMD ", drive->name);
            printk("cmd=0x%02x ", args[0]);
            printk("sc=0x%02x ", args[1]);
            printk("fr=0x%02x ", args[2]);
            printk("xx=0x%02x\n", args[3]);
#endif
            if (args[0] == WIN_SMART) {
                  hwif->OUTB(0x4f, IDE_LCYL_REG);
                  hwif->OUTB(0xc2, IDE_HCYL_REG);
                  hwif->OUTB(args[2],IDE_FEATURE_REG);
                  hwif->OUTB(args[1],IDE_SECTOR_REG);
                  ide_cmd(drive, args[0], args[3], &drive_cmd_intr);
                  return ide_started;
            }
            hwif->OUTB(args[2],IDE_FEATURE_REG);
            ide_cmd(drive, args[0], args[1], &drive_cmd_intr);
            return ide_started;
      }

done:
      /*
       * NULL is actually a valid way of waiting for
       * all current requests to be flushed from the queue.
       */
#ifdef DEBUG
      printk("%s: DRIVE_CMD (null)\n", drive->name);
#endif
      ide_end_drive_cmd(drive,
                  hwif->INB(IDE_STATUS_REG),
                  hwif->INB(IDE_ERROR_REG));
      return ide_stopped;
}

static void ide_check_pm_state(ide_drive_t *drive, struct request *rq)
{
      struct request_pm_state *pm = rq->data;

      if (blk_pm_suspend_request(rq) &&
          pm->pm_step == ide_pm_state_start_suspend)
            /* Mark drive blocked when starting the suspend sequence. */
            drive->blocked = 1;
      else if (blk_pm_resume_request(rq) &&
             pm->pm_step == ide_pm_state_start_resume) {
            /* 
             * The first thing we do on wakeup is to wait for BSY bit to
             * go away (with a looong timeout) as a drive on this hwif may
             * just be POSTing itself.
             * We do that before even selecting as the "other" device on
             * the bus may be broken enough to walk on our toes at this
             * point.
             */
            int rc;
#ifdef DEBUG_PM
            printk("%s: Wakeup request inited, waiting for !BSY...\n", drive->name);
#endif
            rc = ide_wait_not_busy(HWIF(drive), 35000);
            if (rc)
                  printk(KERN_WARNING "%s: bus not ready on wakeup\n", drive->name);
            SELECT_DRIVE(drive);
            if (IDE_CONTROL_REG)
                  HWIF(drive)->OUTB(drive->ctl, IDE_CONTROL_REG);
            rc = ide_wait_not_busy(HWIF(drive), 100000);
            if (rc)
                  printk(KERN_WARNING "%s: drive not ready on wakeup\n", drive->name);
      }
}

/**
 *    start_request     -     start of I/O and command issuing for IDE
 *
 *    start_request() initiates handling of a new I/O request. It
 *    accepts commands and I/O (read/write) requests. It also does
 *    the final remapping for weird stuff like EZDrive. Once 
 *    device mapper can work sector level the EZDrive stuff can go away
 *
 *    FIXME: this function needs a rename
 */
 
static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
{
      ide_startstop_t startstop;
      sector_t block;

      BUG_ON(!blk_rq_started(rq));

#ifdef DEBUG
      printk("%s: start_request: current=0x%08lx\n",
            HWIF(drive)->name, (unsigned long) rq);
#endif

      /* bail early if we've exceeded max_failures */
      if (drive->max_failures && (drive->failures > drive->max_failures)) {
            goto kill_rq;
      }

      block    = rq->sector;
      if (blk_fs_request(rq) &&
          (drive->media == ide_disk || drive->media == ide_floppy)) {
            block += drive->sect0;
      }
      /* Yecch - this will shift the entire interval,
         possibly killing some innocent following sector */
      if (block == 0 && drive->remap_0_to_1 == 1)
            block = 1;  /* redirect MBR access to EZ-Drive partn table */

      if (blk_pm_request(rq))
            ide_check_pm_state(drive, rq);

      SELECT_DRIVE(drive);
      if (ide_wait_stat(&startstop, drive, drive->ready_stat, BUSY_STAT|DRQ_STAT, WAIT_READY)) {
            printk(KERN_ERR "%s: drive not ready for command\n", drive->name);
            return startstop;
      }
      if (!drive->special.all) {
            ide_driver_t *drv;

            /*
             * We reset the drive so we need to issue a SETFEATURES.
             * Do it _after_ do_special() restored device parameters.
             */
            if (drive->current_speed == 0xff)
                  ide_config_drive_speed(drive, drive->desired_speed);

            if (rq->cmd_type == REQ_TYPE_ATA_CMD ||
                rq->cmd_type == REQ_TYPE_ATA_TASK ||
                rq->cmd_type == REQ_TYPE_ATA_TASKFILE)
                  return execute_drive_cmd(drive, rq);
            else if (blk_pm_request(rq)) {
                  struct request_pm_state *pm = rq->data;
#ifdef DEBUG_PM
                  printk("%s: start_power_step(step: %d)\n",
                        drive->name, rq->pm->pm_step);
#endif
                  startstop = ide_start_power_step(drive, rq);
                  if (startstop == ide_stopped &&
                      pm->pm_step == ide_pm_state_completed)
                        ide_complete_pm_request(drive, rq);
                  return startstop;
            }

            drv = *(ide_driver_t **)rq->rq_disk->private_data;
            return drv->do_request(drive, rq, block);
      }
      return do_special(drive);
kill_rq:
      ide_kill_rq(drive, rq);
      return ide_stopped;
}

/**
 *    ide_stall_queue         -     pause an IDE device
 *    @drive: drive to stall
 *    @timeout: time to stall for (jiffies)
 *
 *    ide_stall_queue() can be used by a drive to give excess bandwidth back
 *    to the hwgroup by sleeping for timeout jiffies.
 */
 
void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
{
      if (timeout > WAIT_WORSTCASE)
            timeout = WAIT_WORSTCASE;
      drive->sleep = timeout + jiffies;
      drive->sleeping = 1;
}

EXPORT_SYMBOL(ide_stall_queue);

#define WAKEUP(drive)   ((drive)->service_start + 2 * (drive)->service_time)

/**
 *    choose_drive            -     select a drive to service
 *    @hwgroup: hardware group to select on
 *
 *    choose_drive() selects the next drive which will be serviced.
 *    This is necessary because the IDE layer can't issue commands
 *    to both drives on the same cable, unlike SCSI.
 */
 
static inline ide_drive_t *choose_drive (ide_hwgroup_t *hwgroup)
{
      ide_drive_t *drive, *best;

repeat:     
      best = NULL;
      drive = hwgroup->drive;

      /*
       * drive is doing pre-flush, ordered write, post-flush sequence. even
       * though that is 3 requests, it must be seen as a single transaction.
       * we must not preempt this drive until that is complete
       */
      if (blk_queue_flushing(drive->queue)) {
            /*
             * small race where queue could get replugged during
             * the 3-request flush cycle, just yank the plug since
             * we want it to finish asap
             */
            blk_remove_plug(drive->queue);
            return drive;
      }

      do {
            if ((!drive->sleeping || time_after_eq(jiffies, drive->sleep))
                && !elv_queue_empty(drive->queue)) {
                  if (!best
                   || (drive->sleeping && (!best->sleeping || time_before(drive->sleep, best->sleep)))
                   || (!best->sleeping && time_before(WAKEUP(drive), WAKEUP(best))))
                  {
                        if (!blk_queue_plugged(drive->queue))
                              best = drive;
                  }
            }
      } while ((drive = drive->next) != hwgroup->drive);
      if (best && best->nice1 && !best->sleeping && best != hwgroup->drive && best->service_time > WAIT_MIN_SLEEP) {
            long t = (signed long)(WAKEUP(best) - jiffies);
            if (t >= WAIT_MIN_SLEEP) {
            /*
             * We *may* have some time to spare, but first let's see if
             * someone can potentially benefit from our nice mood today..
             */
                  drive = best->next;
                  do {
                        if (!drive->sleeping
                         && time_before(jiffies - best->service_time, WAKEUP(drive))
                         && time_before(WAKEUP(drive), jiffies + t))
                        {
                              ide_stall_queue(best, min_t(long, t, 10 * WAIT_MIN_SLEEP));
                              goto repeat;
                        }
                  } while ((drive = drive->next) != best);
            }
      }
      return best;
}

/*
 * Issue a new request to a drive from hwgroup
 * Caller must have already done spin_lock_irqsave(&ide_lock, ..);
 *
 * A hwgroup is a serialized group of IDE interfaces.  Usually there is
 * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
 * may have both interfaces in a single hwgroup to "serialize" access.
 * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
 * together into one hwgroup for serialized access.
 *
 * Note also that several hwgroups can end up sharing a single IRQ,
 * possibly along with many other devices.  This is especially common in
 * PCI-based systems with off-board IDE controller cards.
 *
 * The IDE driver uses the single global ide_lock spinlock to protect
 * access to the request queues, and to protect the hwgroup->busy flag.
 *
 * The first thread into the driver for a particular hwgroup sets the
 * hwgroup->busy flag to indicate that this hwgroup is now active,
 * and then initiates processing of the top request from the request queue.
 *
 * Other threads attempting entry notice the busy setting, and will simply
 * queue their new requests and exit immediately.  Note that hwgroup->busy
 * remains set even when the driver is merely awaiting the next interrupt.
 * Thus, the meaning is "this hwgroup is busy processing a request".
 *
 * When processing of a request completes, the completing thread or IRQ-handler
 * will start the next request from the queue.  If no more work remains,
 * the driver will clear the hwgroup->busy flag and exit.
 *
 * The ide_lock (spinlock) is used to protect all access to the
 * hwgroup->busy flag, but is otherwise not needed for most processing in
 * the driver.  This makes the driver much more friendlier to shared IRQs
 * than previous designs, while remaining 100% (?) SMP safe and capable.
 */
static void ide_do_request (ide_hwgroup_t *hwgroup, int masked_irq)
{
      ide_drive_t *drive;
      ide_hwif_t  *hwif;
      struct request    *rq;
      ide_startstop_t   startstop;
      int             loops = 0;

      /* for atari only: POSSIBLY BROKEN HERE(?) */
      ide_get_lock(ide_intr, hwgroup);

      /* caller must own ide_lock */
      BUG_ON(!irqs_disabled());

      while (!hwgroup->busy) {
            hwgroup->busy = 1;
            drive = choose_drive(hwgroup);
            if (drive == NULL) {
                  int sleeping = 0;
                  unsigned long sleep = 0; /* shut up, gcc */
                  hwgroup->rq = NULL;
                  drive = hwgroup->drive;
                  do {
                        if (drive->sleeping && (!sleeping || time_before(drive->sleep, sleep))) {
                              sleeping = 1;
                              sleep = drive->sleep;
                        }
                  } while ((drive = drive->next) != hwgroup->drive);
                  if (sleeping) {
            /*
             * Take a short snooze, and then wake up this hwgroup again.
             * This gives other hwgroups on the same a chance to
             * play fairly with us, just in case there are big differences
             * in relative throughputs.. don't want to hog the cpu too much.
             */
                        if (time_before(sleep, jiffies + WAIT_MIN_SLEEP))
                              sleep = jiffies + WAIT_MIN_SLEEP;
#if 1
                        if (timer_pending(&hwgroup->timer))
                              printk(KERN_CRIT "ide_set_handler: timer already active\n");
#endif
                        /* so that ide_timer_expiry knows what to do */
                        hwgroup->sleeping = 1;
                        hwgroup->req_gen_timer = hwgroup->req_gen;
                        mod_timer(&hwgroup->timer, sleep);
                        /* we purposely leave hwgroup->busy==1
                         * while sleeping */
                  } else {
                        /* Ugly, but how can we sleep for the lock
                         * otherwise? perhaps from tq_disk?
                         */

                        /* for atari only */
                        ide_release_lock();
                        hwgroup->busy = 0;
                  }

                  /* no more work for this hwgroup (for now) */
                  return;
            }
      again:
            hwif = HWIF(drive);
            if (hwgroup->hwif->sharing_irq &&
                hwif != hwgroup->hwif &&
                hwif->io_ports[IDE_CONTROL_OFFSET]) {
                  /* set nIEN for previous hwif */
                  SELECT_INTERRUPT(drive);
            }
            hwgroup->hwif = hwif;
            hwgroup->drive = drive;
            drive->sleeping = 0;
            drive->service_start = jiffies;

            if (blk_queue_plugged(drive->queue)) {
                  printk(KERN_ERR "ide: huh? queue was plugged!\n");
                  break;
            }

            /*
             * we know that the queue isn't empty, but this can happen
             * if the q->prep_rq_fn() decides to kill a request
             */
            rq = elv_next_request(drive->queue);
            if (!rq) {
                  hwgroup->busy = 0;
                  break;
            }

            /*
             * Sanity: don't accept a request that isn't a PM request
             * if we are currently power managed. This is very important as
             * blk_stop_queue() doesn't prevent the elv_next_request()
             * above to return us whatever is in the queue. Since we call
             * ide_do_request() ourselves, we end up taking requests while
             * the queue is blocked...
             * 
             * We let requests forced at head of queue with ide-preempt
             * though. I hope that doesn't happen too much, hopefully not
             * unless the subdriver triggers such a thing in its own PM
             * state machine.
             *
             * We count how many times we loop here to make sure we service
             * all drives in the hwgroup without looping for ever
             */
            if (drive->blocked && !blk_pm_request(rq) && !(rq->cmd_flags & REQ_PREEMPT)) {
                  drive = drive->next ? drive->next : hwgroup->drive;
                  if (loops++ < 4 && !blk_queue_plugged(drive->queue))
                        goto again;
                  /* We clear busy, there should be no pending ATA command at this point. */
                  hwgroup->busy = 0;
                  break;
            }

            hwgroup->rq = rq;

            /*
             * Some systems have trouble with IDE IRQs arriving while
             * the driver is still setting things up.  So, here we disable
             * the IRQ used by this interface while the request is being started.
             * This may look bad at first, but pretty much the same thing
             * happens anyway when any interrupt comes in, IDE or otherwise
             *  -- the kernel masks the IRQ while it is being handled.
             */
            if (masked_irq != IDE_NO_IRQ && hwif->irq != masked_irq)
                  disable_irq_nosync(hwif->irq);
            spin_unlock(&ide_lock);
            local_irq_enable_in_hardirq();
                  /* allow other IRQs while we start this request */
            startstop = start_request(drive, rq);
            spin_lock_irq(&ide_lock);
            if (masked_irq != IDE_NO_IRQ && hwif->irq != masked_irq)
                  enable_irq(hwif->irq);
            if (startstop == ide_stopped)
                  hwgroup->busy = 0;
      }
}

/*
 * Passes the stuff to ide_do_request
 */
void do_ide_request(struct request_queue *q)
{
      ide_drive_t *drive = q->queuedata;

      ide_do_request(HWGROUP(drive), IDE_NO_IRQ);
}

/*
 * un-busy the hwgroup etc, and clear any pending DMA status. we want to
 * retry the current request in pio mode instead of risking tossing it
 * all away
 */
static ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error)
{
      ide_hwif_t *hwif = HWIF(drive);
      struct request *rq;
      ide_startstop_t ret = ide_stopped;

      /*
       * end current dma transaction
       */

      if (error < 0) {
            printk(KERN_WARNING "%s: DMA timeout error\n", drive->name);
            (void)HWIF(drive)->ide_dma_end(drive);
            ret = ide_error(drive, "dma timeout error",
                                    hwif->INB(IDE_STATUS_REG));
      } else {
            printk(KERN_WARNING "%s: DMA timeout retry\n", drive->name);
            hwif->dma_timeout(drive);
      }

      /*
       * disable dma for now, but remember that we did so because of
       * a timeout -- we'll reenable after we finish this next request
       * (or rather the first chunk of it) in pio.
       */
      drive->retry_pio++;
      drive->state = DMA_PIO_RETRY;
      hwif->dma_off_quietly(drive);

      /*
       * un-busy drive etc (hwgroup->busy is cleared on return) and
       * make sure request is sane
       */
      rq = HWGROUP(drive)->rq;

      if (!rq)
            goto out;

      HWGROUP(drive)->rq = NULL;

      rq->errors = 0;

      if (!rq->bio)
            goto out;

      rq->sector = rq->bio->bi_sector;
      rq->current_nr_sectors = bio_iovec(rq->bio)->bv_len >> 9;
      rq->hard_cur_sectors = rq->current_nr_sectors;
      rq->buffer = bio_data(rq->bio);
out:
      return ret;
}

/**
 *    ide_timer_expiry  -     handle lack of an IDE interrupt
 *    @data: timer callback magic (hwgroup)
 *
 *    An IDE command has timed out before the expected drive return
 *    occurred. At this point we attempt to clean up the current
 *    mess. If the current handler includes an expiry handler then
 *    we invoke the expiry handler, and providing it is happy the
 *    work is done. If that fails we apply generic recovery rules
 *    invoking the handler and checking the drive DMA status. We
 *    have an excessively incestuous relationship with the DMA
 *    logic that wants cleaning up.
 */
 
void ide_timer_expiry (unsigned long data)
{
      ide_hwgroup_t     *hwgroup = (ide_hwgroup_t *) data;
      ide_handler_t     *handler;
      ide_expiry_t      *expiry;
      unsigned long     flags;
      unsigned long     wait = -1;

      spin_lock_irqsave(&ide_lock, flags);

      if (((handler = hwgroup->handler) == NULL) ||
          (hwgroup->req_gen != hwgroup->req_gen_timer)) {
            /*
             * Either a marginal timeout occurred
             * (got the interrupt just as timer expired),
             * or we were "sleeping" to give other devices a chance.
             * Either way, we don't really want to complain about anything.
             */
            if (hwgroup->sleeping) {
                  hwgroup->sleeping = 0;
                  hwgroup->busy = 0;
            }
      } else {
            ide_drive_t *drive = hwgroup->drive;
            if (!drive) {
                  printk(KERN_ERR "ide_timer_expiry: hwgroup->drive was NULL\n");
                  hwgroup->handler = NULL;
            } else {
                  ide_hwif_t *hwif;
                  ide_startstop_t startstop = ide_stopped;
                  if (!hwgroup->busy) {
                        hwgroup->busy = 1;      /* paranoia */
                        printk(KERN_ERR "%s: ide_timer_expiry: hwgroup->busy was 0 ??\n", drive->name);
                  }
                  if ((expiry = hwgroup->expiry) != NULL) {
                        /* continue */
                        if ((wait = expiry(drive)) > 0) {
                              /* reset timer */
                              hwgroup->timer.expires  = jiffies + wait;
                              hwgroup->req_gen_timer = hwgroup->req_gen;
                              add_timer(&hwgroup->timer);
                              spin_unlock_irqrestore(&ide_lock, flags);
                              return;
                        }
                  }
                  hwgroup->handler = NULL;
                  /*
                   * We need to simulate a real interrupt when invoking
                   * the handler() function, which means we need to
                   * globally mask the specific IRQ:
                   */
                  spin_unlock(&ide_lock);
                  hwif  = HWIF(drive);
#if DISABLE_IRQ_NOSYNC
                  disable_irq_nosync(hwif->irq);
#else
                  /* disable_irq_nosync ?? */
                  disable_irq(hwif->irq);
#endif /* DISABLE_IRQ_NOSYNC */
                  /* local CPU only,
                   * as if we were handling an interrupt */
                  local_irq_disable();
                  if (hwgroup->polling) {
                        startstop = handler(drive);
                  } else if (drive_is_ready(drive)) {
                        if (drive->waiting_for_dma)
                              hwgroup->hwif->dma_lost_irq(drive);
                        (void)ide_ack_intr(hwif);
                        printk(KERN_WARNING "%s: lost interrupt\n", drive->name);
                        startstop = handler(drive);
                  } else {
                        if (drive->waiting_for_dma) {
                              startstop = ide_dma_timeout_retry(drive, wait);
                        } else
                              startstop =
                              ide_error(drive, "irq timeout", hwif->INB(IDE_STATUS_REG));
                  }
                  drive->service_time = jiffies - drive->service_start;
                  spin_lock_irq(&ide_lock);
                  enable_irq(hwif->irq);
                  if (startstop == ide_stopped)
                        hwgroup->busy = 0;
            }
      }
      ide_do_request(hwgroup, IDE_NO_IRQ);
      spin_unlock_irqrestore(&ide_lock, flags);
}

/**
 *    unexpected_intr         -     handle an unexpected IDE interrupt
 *    @irq: interrupt line
 *    @hwgroup: hwgroup being processed
 *
 *    There's nothing really useful we can do with an unexpected interrupt,
 *    other than reading the status register (to clear it), and logging it.
 *    There should be no way that an irq can happen before we're ready for it,
 *    so we needn't worry much about losing an "important" interrupt here.
 *
 *    On laptops (and "green" PCs), an unexpected interrupt occurs whenever
 *    the drive enters "idle", "standby", or "sleep" mode, so if the status
 *    looks "good", we just ignore the interrupt completely.
 *
 *    This routine assumes __cli() is in effect when called.
 *
 *    If an unexpected interrupt happens on irq15 while we are handling irq14
 *    and if the two interfaces are "serialized" (CMD640), then it looks like
 *    we could screw up by interfering with a new request being set up for 
 *    irq15.
 *
 *    In reality, this is a non-issue.  The new command is not sent unless 
 *    the drive is ready to accept one, in which case we know the drive is
 *    not trying to interrupt us.  And ide_set_handler() is always invoked
 *    before completing the issuance of any new drive command, so we will not
 *    be accidentally invoked as a result of any valid command completion
 *    interrupt.
 *
 *    Note that we must walk the entire hwgroup here. We know which hwif
 *    is doing the current command, but we don't know which hwif burped
 *    mysteriously.
 */
 
static void unexpected_intr (int irq, ide_hwgroup_t *hwgroup)
{
      u8 stat;
      ide_hwif_t *hwif = hwgroup->hwif;

      /*
       * handle the unexpected interrupt
       */
      do {
            if (hwif->irq == irq) {
                  stat = hwif->INB(hwif->io_ports[IDE_STATUS_OFFSET]);
                  if (!OK_STAT(stat, READY_STAT, BAD_STAT)) {
                        /* Try to not flood the console with msgs */
                        static unsigned long last_msgtime, count;
                        ++count;
                        if (time_after(jiffies, last_msgtime + HZ)) {
                              last_msgtime = jiffies;
                              printk(KERN_ERR "%s%s: unexpected interrupt, "
                                    "status=0x%02x, count=%ld\n",
                                    hwif->name,
                                    (hwif->next==hwgroup->hwif) ? "" : "(?)", stat, count);
                        }
                  }
            }
      } while ((hwif = hwif->next) != hwgroup->hwif);
}

/**
 *    ide_intr    -     default IDE interrupt handler
 *    @irq: interrupt number
 *    @dev_id: hwif group
 *    @regs: unused weirdness from the kernel irq layer
 *
 *    This is the default IRQ handler for the IDE layer. You should
 *    not need to override it. If you do be aware it is subtle in
 *    places
 *
 *    hwgroup->hwif is the interface in the group currently performing
 *    a command. hwgroup->drive is the drive and hwgroup->handler is
 *    the IRQ handler to call. As we issue a command the handlers
 *    step through multiple states, reassigning the handler to the
 *    next step in the process. Unlike a smart SCSI controller IDE
 *    expects the main processor to sequence the various transfer
 *    stages. We also manage a poll timer to catch up with most
 *    timeout situations. There are still a few where the handlers
 *    don't ever decide to give up.
 *
 *    The handler eventually returns ide_stopped to indicate the
 *    request completed. At this point we issue the next request
 *    on the hwgroup and the process begins again.
 */
 
irqreturn_t ide_intr (int irq, void *dev_id)
{
      unsigned long flags;
      ide_hwgroup_t *hwgroup = (ide_hwgroup_t *)dev_id;
      ide_hwif_t *hwif;
      ide_drive_t *drive;
      ide_handler_t *handler;
      ide_startstop_t startstop;

      spin_lock_irqsave(&ide_lock, flags);
      hwif = hwgroup->hwif;

      if (!ide_ack_intr(hwif)) {
            spin_unlock_irqrestore(&ide_lock, flags);
            return IRQ_NONE;
      }

      if ((handler = hwgroup->handler) == NULL || hwgroup->polling) {
            /*
             * Not expecting an interrupt from this drive.
             * That means this could be:
             *    (1) an interrupt from another PCI device
             *    sharing the same PCI INT# as us.
             * or (2) a drive just entered sleep or standby mode,
             *    and is interrupting to let us know.
             * or (3) a spurious interrupt of unknown origin.
             *
             * For PCI, we cannot tell the difference,
             * so in that case we just ignore it and hope it goes away.
             *
             * FIXME: unexpected_intr should be hwif-> then we can
             * remove all the ifdef PCI crap
             */
#ifdef CONFIG_BLK_DEV_IDEPCI
            if (hwif->pci_dev && !hwif->pci_dev->vendor)
#endif      /* CONFIG_BLK_DEV_IDEPCI */
            {
                  /*
                   * Probably not a shared PCI interrupt,
                   * so we can safely try to do something about it:
                   */
                  unexpected_intr(irq, hwgroup);
#ifdef CONFIG_BLK_DEV_IDEPCI
            } else {
                  /*
                   * Whack the status register, just in case
                   * we have a leftover pending IRQ.
                   */
                  (void) hwif->INB(hwif->io_ports[IDE_STATUS_OFFSET]);
#endif /* CONFIG_BLK_DEV_IDEPCI */
            }
            spin_unlock_irqrestore(&ide_lock, flags);
            return IRQ_NONE;
      }
      drive = hwgroup->drive;
      if (!drive) {
            /*
             * This should NEVER happen, and there isn't much
             * we could do about it here.
             *
             * [Note - this can occur if the drive is hot unplugged]
             */
            spin_unlock_irqrestore(&ide_lock, flags);
            return IRQ_HANDLED;
      }
      if (!drive_is_ready(drive)) {
            /*
             * This happens regularly when we share a PCI IRQ with
             * another device.  Unfortunately, it can also happen
             * with some buggy drives that trigger the IRQ before
             * their status register is up to date.  Hopefully we have
             * enough advance overhead that the latter isn't a problem.
             */
            spin_unlock_irqrestore(&ide_lock, flags);
            return IRQ_NONE;
      }
      if (!hwgroup->busy) {
            hwgroup->busy = 1;      /* paranoia */
            printk(KERN_ERR "%s: ide_intr: hwgroup->busy was 0 ??\n", drive->name);
      }
      hwgroup->handler = NULL;
      hwgroup->req_gen++;
      del_timer(&hwgroup->timer);
      spin_unlock(&ide_lock);

      /* Some controllers might set DMA INTR no matter DMA or PIO;
       * bmdma status might need to be cleared even for
       * PIO interrupts to prevent spurious/lost irq.
       */
      if (hwif->ide_dma_clear_irq && !(drive->waiting_for_dma))
            /* ide_dma_end() needs bmdma status for error checking.
             * So, skip clearing bmdma status here and leave it
             * to ide_dma_end() if this is dma interrupt.
             */
            hwif->ide_dma_clear_irq(drive);

      if (drive->unmask)
            local_irq_enable_in_hardirq();
      /* service this interrupt, may set handler for next interrupt */
      startstop = handler(drive);
      spin_lock_irq(&ide_lock);

      /*
       * Note that handler() may have set things up for another
       * interrupt to occur soon, but it cannot happen until
       * we exit from this routine, because it will be the
       * same irq as is currently being serviced here, and Linux
       * won't allow another of the same (on any CPU) until we return.
       */
      drive->service_time = jiffies - drive->service_start;
      if (startstop == ide_stopped) {
            if (hwgroup->handler == NULL) {     /* paranoia */
                  hwgroup->busy = 0;
                  ide_do_request(hwgroup, hwif->irq);
            } else {
                  printk(KERN_ERR "%s: ide_intr: huh? expected NULL handler "
                        "on exit\n", drive->name);
            }
      }
      spin_unlock_irqrestore(&ide_lock, flags);
      return IRQ_HANDLED;
}

/**
 *    ide_init_drive_cmd      -     initialize a drive command request
 *    @rq: request object
 *
 *    Initialize a request before we fill it in and send it down to
 *    ide_do_drive_cmd. Commands must be set up by this function. Right
 *    now it doesn't do a lot, but if that changes abusers will have a
 *    nasty surprise.
 */

void ide_init_drive_cmd (struct request *rq)
{
      memset(rq, 0, sizeof(*rq));
      rq->cmd_type = REQ_TYPE_ATA_CMD;
      rq->ref_count = 1;
}

EXPORT_SYMBOL(ide_init_drive_cmd);

/**
 *    ide_do_drive_cmd  -     issue IDE special command
 *    @drive: device to issue command
 *    @rq: request to issue
 *    @action: action for processing
 *
 *    This function issues a special IDE device request
 *    onto the request queue.
 *
 *    If action is ide_wait, then the rq is queued at the end of the
 *    request queue, and the function sleeps until it has been processed.
 *    This is for use when invoked from an ioctl handler.
 *
 *    If action is ide_preempt, then the rq is queued at the head of
 *    the request queue, displacing the currently-being-processed
 *    request and this function returns immediately without waiting
 *    for the new rq to be completed.  This is VERY DANGEROUS, and is
 *    intended for careful use by the ATAPI tape/cdrom driver code.
 *
 *    If action is ide_end, then the rq is queued at the end of the
 *    request queue, and the function returns immediately without waiting
 *    for the new rq to be completed. This is again intended for careful
 *    use by the ATAPI tape/cdrom driver code.
 */
 
int ide_do_drive_cmd (ide_drive_t *drive, struct request *rq, ide_action_t action)
{
      unsigned long flags;
      ide_hwgroup_t *hwgroup = HWGROUP(drive);
      DECLARE_COMPLETION_ONSTACK(wait);
      int where = ELEVATOR_INSERT_BACK, err;
      int must_wait = (action == ide_wait || action == ide_head_wait);

      rq->errors = 0;

      /*
       * we need to hold an extra reference to request for safe inspection
       * after completion
       */
      if (must_wait) {
            rq->ref_count++;
            rq->end_io_data = &wait;
            rq->end_io = blk_end_sync_rq;
      }

      spin_lock_irqsave(&ide_lock, flags);
      if (action == ide_preempt)
            hwgroup->rq = NULL;
      if (action == ide_preempt || action == ide_head_wait) {
            where = ELEVATOR_INSERT_FRONT;
            rq->cmd_flags |= REQ_PREEMPT;
      }
      __elv_add_request(drive->queue, rq, where, 0);
      ide_do_request(hwgroup, IDE_NO_IRQ);
      spin_unlock_irqrestore(&ide_lock, flags);

      err = 0;
      if (must_wait) {
            wait_for_completion(&wait);
            if (rq->errors)
                  err = -EIO;

            blk_put_request(rq);
      }

      return err;
}

EXPORT_SYMBOL(ide_do_drive_cmd);

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