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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/drivers/ide/ide-io.c

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43 KiB
C
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/*
* 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/hdreg.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;
int error = 0;
if (uptodate <= 0)
error = uptodate ? uptodate : -EIO;
/*
* if failfast is set on a request, override number of sectors and
* complete the whole request right now
*/
if (blk_noretry_request(rq) && error)
nr_bytes = rq->hard_nr_sectors << 9;
if (!blk_fs_request(rq) && error && !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->dev_flags & IDE_DFLAG_DMA_PIO_RETRY) &&
drive->retry_pio <= 3) {
drive->dev_flags &= ~IDE_DFLAG_DMA_PIO_RETRY;
ide_dma_on(drive);
}
if (!__blk_end_request(rq, error, nr_bytes)) {
if (dequeue)
HWGROUP(drive)->rq = NULL;
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);
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) */
if (pm->pm_state == PM_EVENT_FREEZE)
pm->pm_step = IDE_PM_COMPLETED;
else
pm->pm_step = IDE_PM_STANDBY;
break;
case IDE_PM_STANDBY: /* Suspend step 2 (standby) */
pm->pm_step = IDE_PM_COMPLETED;
break;
case IDE_PM_RESTORE_PIO: /* Resume step 1 (restore PIO) */
pm->pm_step = IDE_PM_IDLE;
break;
case IDE_PM_IDLE: /* Resume step 2 (idle)*/
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 (ata_id_flush_enabled(drive->id) == 0 ||
(drive->dev_flags & IDE_DFLAG_WCACHE) == 0) {
ide_complete_power_step(drive, rq, 0, 0);
return ide_stopped;
}
if (ata_id_flush_ext_enabled(drive->id))
args->tf.command = ATA_CMD_FLUSH_EXT;
else
args->tf.command = ATA_CMD_FLUSH;
goto out_do_tf;
case IDE_PM_STANDBY: /* Suspend step 2 (standby) */
args->tf.command = ATA_CMD_STANDBYNOW1;
goto out_do_tf;
case IDE_PM_RESTORE_PIO: /* Resume step 1 (restore PIO) */
ide_set_max_pio(drive);
/*
* skip IDE_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 IDE_PM_IDLE: /* Resume step 2 (idle) */
args->tf.command = ATA_CMD_IDLEIMMEDIATE;
goto out_do_tf;
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->dma_ops == NULL)
break;
/*
* TODO: respect IDE_DFLAG_USING_DMA
*/
ide_set_dma(drive);
break;
}
pm->pm_step = IDE_PM_COMPLETED;
return ide_stopped;
out_do_tf:
args->tf_flags = IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
args->data_phase = TASKFILE_NO_DATA;
return do_rw_taskfile(drive, args);
}
/**
* 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->dev_flags &= ~IDE_DFLAG_BLOCKED;
blk_start_queue(drive->queue);
}
HWGROUP(drive)->rq = NULL;
if (__blk_end_request(rq, 0, 0))
BUG();
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)
{
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_TASKFILE) {
ide_task_t *task = (ide_task_t *)rq->special;
if (rq->errors == 0)
rq->errors = !OK_STAT(stat, ATA_DRDY, BAD_STAT);
if (task) {
struct ide_taskfile *tf = &task->tf;
tf->error = err;
tf->status = stat;
drive->hwif->tp_ops->tf_read(drive, task);
if (task->tf_flags & IDE_TFLAG_DYN)
kfree(task);
}
} 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_COMPLETED)
ide_complete_pm_request(drive, rq);
return;
}
spin_lock_irqsave(&ide_lock, flags);
HWGROUP(drive)->rq = NULL;
rq->errors = err;
if (unlikely(__blk_end_request(rq, (rq->errors ? -EIO : 0),
blk_rq_bytes(rq))))
BUG();
spin_unlock_irqrestore(&ide_lock, flags);
}
EXPORT_SYMBOL(ide_end_drive_cmd);
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 & ATA_BUSY) ||
((stat & ATA_DF) && (drive->dev_flags & IDE_DFLAG_NOWERR) == 0)) {
/* other bits are useless when BUSY */
rq->errors |= ERROR_RESET;
} else if (stat & ATA_ERR) {
/* err has different meaning on cdrom and tape */
if (err == ATA_ABORTED) {
if ((drive->dev_flags & IDE_DFLAG_LBA) &&
/* some newer drives don't support ATA_CMD_INIT_DEV_PARAMS */
hwif->tp_ops->read_status(hwif) == ATA_CMD_INIT_DEV_PARAMS)
return ide_stopped;
} else if ((err & BAD_CRC) == BAD_CRC) {
/* UDMA crc error, just retry the operation */
drive->crc_count++;
} else if (err & (ATA_BBK | ATA_UNC)) {
/* retries won't help these */
rq->errors = ERROR_MAX;
} else if (err & ATA_TRK0NF) {
/* help it find track zero */
rq->errors |= ERROR_RECAL;
}
}
if ((stat & ATA_DRQ) && rq_data_dir(rq) == READ &&
(hwif->host_flags & IDE_HFLAG_ERROR_STOPS_FIFO) == 0) {
int nsect = drive->mult_count ? drive->mult_count : 1;
ide_pad_transfer(drive, READ, nsect * SECTOR_SIZE);
}
if (rq->errors >= ERROR_MAX || blk_noretry_request(rq)) {
ide_kill_rq(drive, rq);
return ide_stopped;
}
if (hwif->tp_ops->read_status(hwif) & (ATA_BUSY | ATA_DRQ))
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 & ATA_BUSY) ||
((stat & ATA_DF) && (drive->dev_flags & IDE_DFLAG_NOWERR) == 0)) {
/* other bits are useless when BUSY */
rq->errors |= ERROR_RESET;
} else {
/* add decoding error stuff */
}
if (hwif->tp_ops->read_status(hwif) & (ATA_BUSY | ATA_DRQ))
/* force an abort */
hwif->tp_ops->exec_command(hwif, ATA_CMD_IDLEIMMEDIATE);
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);
static void ide_tf_set_specify_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
{
tf->nsect = drive->sect;
tf->lbal = drive->sect;
tf->lbam = drive->cyl;
tf->lbah = drive->cyl >> 8;
tf->device = (drive->head - 1) | drive->select;
tf->command = ATA_CMD_INIT_DEV_PARAMS;
}
static void ide_tf_set_restore_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
{
tf->nsect = drive->sect;
tf->command = ATA_CMD_RESTORE;
}
static void ide_tf_set_setmult_cmd(ide_drive_t *drive, struct ide_taskfile *tf)
{
tf->nsect = drive->mult_req;
tf->command = ATA_CMD_SET_MULTI;
}
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.data_phase = TASKFILE_NO_DATA;
if (s->b.set_geometry) {
s->b.set_geometry = 0;
ide_tf_set_specify_cmd(drive, &args.tf);
} else if (s->b.recalibrate) {
s->b.recalibrate = 0;
ide_tf_set_restore_cmd(drive, &args.tf);
} else if (s->b.set_multmode) {
s->b.set_multmode = 0;
ide_tf_set_setmult_cmd(drive, &args.tf);
} 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;
}
args.tf_flags = IDE_TFLAG_TF | IDE_TFLAG_DEVICE |
IDE_TFLAG_CUSTOM_HANDLER;
do_rw_taskfile(drive, &args);
return ide_started;
}
/**
* do_special - issue some special commands
* @drive: drive the command is for
*
* do_special() is used to issue ATA_CMD_INIT_DEV_PARAMS,
* ATA_CMD_RESTORE and ATA_CMD_SET_MULTI 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 (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);
ide_task_t *task = rq->special;
if (task) {
hwif->data_phase = task->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;
}
return do_rw_taskfile(drive, task);
}
/*
* 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->tp_ops->read_status(hwif),
ide_read_error(drive));
return ide_stopped;
}
int ide_devset_execute(ide_drive_t *drive, const struct ide_devset *setting,
int arg)
{
struct request_queue *q = drive->queue;
struct request *rq;
int ret = 0;
if (!(setting->flags & DS_SYNC))
return setting->set(drive, arg);
rq = blk_get_request(q, READ, __GFP_WAIT);
rq->cmd_type = REQ_TYPE_SPECIAL;
rq->cmd_len = 5;
rq->cmd[0] = REQ_DEVSET_EXEC;
*(int *)&rq->cmd[1] = arg;
rq->special = setting->set;
if (blk_execute_rq(q, NULL, rq, 0))
ret = rq->errors;
blk_put_request(rq);
return ret;
}
EXPORT_SYMBOL_GPL(ide_devset_execute);
static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
{
u8 cmd = rq->cmd[0];
if (cmd == REQ_PARK_HEADS || cmd == REQ_UNPARK_HEADS) {
ide_task_t task;
struct ide_taskfile *tf = &task.tf;
memset(&task, 0, sizeof(task));
if (cmd == REQ_PARK_HEADS) {
drive->sleep = *(unsigned long *)rq->special;
drive->dev_flags |= IDE_DFLAG_SLEEPING;
tf->command = ATA_CMD_IDLEIMMEDIATE;
tf->feature = 0x44;
tf->lbal = 0x4c;
tf->lbam = 0x4e;
tf->lbah = 0x55;
task.tf_flags |= IDE_TFLAG_CUSTOM_HANDLER;
} else /* cmd == REQ_UNPARK_HEADS */
tf->command = ATA_CMD_CHK_POWER;
task.tf_flags |= IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
task.rq = rq;
drive->hwif->data_phase = task.data_phase = TASKFILE_NO_DATA;
return do_rw_taskfile(drive, &task);
}
switch (cmd) {
case REQ_DEVSET_EXEC:
{
int err, (*setfunc)(ide_drive_t *, int) = rq->special;
err = setfunc(drive, *(int *)&rq->cmd[1]);
if (err)
rq->errors = err;
else
err = 1;
ide_end_request(drive, err, 0);
return ide_stopped;
}
case REQ_DRIVE_RESET:
return ide_do_reset(drive);
default:
blk_dump_rq_flags(rq, "ide_special_rq - bad request");
ide_end_request(drive, 0, 0);
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_START_SUSPEND)
/* Mark drive blocked when starting the suspend sequence. */
drive->dev_flags |= IDE_DFLAG_BLOCKED;
else if (blk_pm_resume_request(rq) &&
pm->pm_step == IDE_PM_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.
*/
ide_hwif_t *hwif = drive->hwif;
int rc;
#ifdef DEBUG_PM
printk("%s: Wakeup request inited, waiting for !BSY...\n", drive->name);
#endif
rc = ide_wait_not_busy(hwif, 35000);
if (rc)
printk(KERN_WARNING "%s: bus not ready on wakeup\n", drive->name);
SELECT_DRIVE(drive);
hwif->tp_ops->set_irq(hwif, 1);
rc = ide_wait_not_busy(hwif, 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.
*
* FIXME: this function needs a rename
*/
static ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
{
ide_startstop_t startstop;
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)) {
rq->cmd_flags |= REQ_FAILED;
goto kill_rq;
}
if (blk_pm_request(rq))
ide_check_pm_state(drive, rq);
SELECT_DRIVE(drive);
if (ide_wait_stat(&startstop, drive, drive->ready_stat,
ATA_BUSY | ATA_DRQ, 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_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_COMPLETED)
ide_complete_pm_request(drive, rq);
return startstop;
} else if (!rq->rq_disk && blk_special_request(rq))
/*
* TODO: Once all ULDs have been modified to
* check for specific op codes rather than
* blindly accepting any special request, the
* check for ->rq_disk above may be replaced
* by a more suitable mechanism or even
* dropped entirely.
*/
return ide_special_rq(drive, rq);
drv = *(ide_driver_t **)rq->rq_disk->private_data;
return drv->do_request(drive, rq, rq->sector);
}
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->dev_flags |= IDE_DFLAG_SLEEPING;
}
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 {
u8 dev_s = !!(drive->dev_flags & IDE_DFLAG_SLEEPING);
u8 best_s = (best && !!(best->dev_flags & IDE_DFLAG_SLEEPING));
if ((dev_s == 0 || time_after_eq(jiffies, drive->sleep)) &&
!elv_queue_empty(drive->queue)) {
if (best == NULL ||
(dev_s && (best_s == 0 || time_before(drive->sleep, best->sleep))) ||
(best_s == 0 && time_before(WAKEUP(drive), WAKEUP(best)))) {
if (!blk_queue_plugged(drive->queue))
best = drive;
}
}
} while ((drive = drive->next) != hwgroup->drive);
if (best && (best->dev_flags & IDE_DFLAG_NICE1) &&
(best->dev_flags & IDE_DFLAG_SLEEPING) == 0 &&
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->dev_flags & IDE_DFLAG_SLEEPING) == 0
&& 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->dev_flags & IDE_DFLAG_SLEEPING) &&
(sleeping == 0 ||
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) {
/*
* set nIEN for previous hwif, drives in the
* quirk_list may not like intr setups/cleanups
*/
if (drive->quirk_list != 1)
hwif->tp_ops->set_irq(hwif, 0);
}
hwgroup->hwif = hwif;
hwgroup->drive = drive;
drive->dev_flags &= ~(IDE_DFLAG_SLEEPING | IDE_DFLAG_PARKED);
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->dev_flags & IDE_DFLAG_BLOCKED) &&
blk_pm_request(rq) == 0 &&
(rq->cmd_flags & REQ_PREEMPT) == 0) {
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->dma_ops->dma_end(drive);
ret = ide_error(drive, "dma timeout error",
hwif->tp_ops->read_status(hwif));
} else {
printk(KERN_WARNING "%s: DMA timeout retry\n", drive->name);
hwif->dma_ops->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->dev_flags |= IDE_DFLAG_DMA_PIO_RETRY;
drive->retry_pio++;
ide_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);
/* disable_irq_nosync ?? */
disable_irq(hwif->irq);
/* 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)
hwif->dma_ops->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->tp_ops->read_status(hwif));
}
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->tp_ops->read_status(hwif);
if (!OK_STAT(stat, ATA_DRDY, 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->chipset != ide_pci)
#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->tp_ops->read_status(hwif);
#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);
if (hwif->port_ops && hwif->port_ops->clear_irq)
hwif->port_ops->clear_irq(drive);
if (drive->dev_flags & IDE_DFLAG_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_do_drive_cmd - issue IDE special command
* @drive: device to issue command
* @rq: request to issue
*
* This function issues a special IDE device request
* onto the request queue.
*
* 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.
*/
void ide_do_drive_cmd(ide_drive_t *drive, struct request *rq)
{
unsigned long flags;
ide_hwgroup_t *hwgroup = HWGROUP(drive);
spin_lock_irqsave(&ide_lock, flags);
hwgroup->rq = NULL;
__elv_add_request(drive->queue, rq, ELEVATOR_INSERT_FRONT, 0);
blk_start_queueing(drive->queue);
spin_unlock_irqrestore(&ide_lock, flags);
}
EXPORT_SYMBOL(ide_do_drive_cmd);
void ide_pktcmd_tf_load(ide_drive_t *drive, u32 tf_flags, u16 bcount, u8 dma)
{
ide_hwif_t *hwif = drive->hwif;
ide_task_t task;
memset(&task, 0, sizeof(task));
task.tf_flags = IDE_TFLAG_OUT_LBAH | IDE_TFLAG_OUT_LBAM |
IDE_TFLAG_OUT_FEATURE | tf_flags;
task.tf.feature = dma; /* Use PIO/DMA */
task.tf.lbam = bcount & 0xff;
task.tf.lbah = (bcount >> 8) & 0xff;
ide_tf_dump(drive->name, &task.tf);
hwif->tp_ops->set_irq(hwif, 1);
SELECT_MASK(drive, 0);
hwif->tp_ops->tf_load(drive, &task);
}
EXPORT_SYMBOL_GPL(ide_pktcmd_tf_load);
void ide_pad_transfer(ide_drive_t *drive, int write, int len)
{
ide_hwif_t *hwif = drive->hwif;
u8 buf[4] = { 0 };
while (len > 0) {
if (write)
hwif->tp_ops->output_data(drive, NULL, buf, min(4, len));
else
hwif->tp_ops->input_data(drive, NULL, buf, min(4, len));
len -= 4;
}
}
EXPORT_SYMBOL_GPL(ide_pad_transfer);
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