1. 根目录:
2. drivers
3. ide
4. ide-park.c

#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/ide.h>
#include <linux/jiffies.h>
#include <linux/blkdev.h>

DECLARE_WAIT_QUEUE_HEAD(ide_park_wq);

static void issue_park_cmd(ide_drive_t *drive, unsigned long timeout)
{
	ide_hwif_t *hwif = drive->hwif;
	struct request_queue *q = drive->queue;
	struct request *rq;
	int rc;

	timeout += jiffies;
	spin_lock_irq(&hwif->lock);
	if (drive->dev_flags & IDE_DFLAG_PARKED) {
		int reset_timer = time_before(timeout, drive->sleep);
		int start_queue = 0;

		drive->sleep = timeout;
		wake_up_all(&ide_park_wq);
		if (reset_timer && del_timer(&hwif->timer))
			start_queue = 1;
		spin_unlock_irq(&hwif->lock);

		if (start_queue)
			blk_run_queue(q);
		return;
	}
	spin_unlock_irq(&hwif->lock);

	rq = blk_get_request(q, READ, __GFP_WAIT);
	rq->cmd[0] = REQ_PARK_HEADS;
	rq->cmd_len = 1;
	rq->cmd_type = REQ_TYPE_SPECIAL;
	rq->special = &timeout;
	rc = blk_execute_rq(q, NULL, rq, 1);
	blk_put_request(rq);
	if (rc)
		goto out;

	/*
	 * Make sure that *some* command is sent to the drive after the
	 * timeout has expired, so power management will be reenabled.
	 */
	rq = blk_get_request(q, READ, GFP_NOWAIT);
	if (unlikely(!rq))
		goto out;

	rq->cmd[0] = REQ_UNPARK_HEADS;
	rq->cmd_len = 1;
	rq->cmd_type = REQ_TYPE_SPECIAL;
	elv_add_request(q, rq, ELEVATOR_INSERT_FRONT);

out:
	return;
}

ide_startstop_t ide_do_park_unpark(ide_drive_t *drive, struct request *rq)
{
	struct ide_cmd cmd;
	struct ide_taskfile *tf = &cmd.tf;

	memset(&cmd, 0, sizeof(cmd));
	if (rq->cmd[0] == 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;
		cmd.valid.out.tf = IDE_VALID_OUT_TF | IDE_VALID_DEVICE;
		cmd.valid.in.tf  = IDE_VALID_IN_TF  | IDE_VALID_DEVICE;
	} else		/* cmd == REQ_UNPARK_HEADS */
		tf->command = ATA_CMD_CHK_POWER;

	cmd.tf_flags |= IDE_TFLAG_CUSTOM_HANDLER;
	cmd.protocol = ATA_PROT_NODATA;

	cmd.rq = rq;

	return do_rw_taskfile(drive, &cmd);
}

ssize_t ide_park_show(struct device *dev, struct device_attribute *attr,
		      char *buf)
{
	ide_drive_t *drive = to_ide_device(dev);
	ide_hwif_t *hwif = drive->hwif;
	unsigned long now;
	unsigned int msecs;

	if (drive->dev_flags & IDE_DFLAG_NO_UNLOAD)
		return -EOPNOTSUPP;

	spin_lock_irq(&hwif->lock);
	now = jiffies;
	if (drive->dev_flags & IDE_DFLAG_PARKED &&
	    time_after(drive->sleep, now))
		msecs = jiffies_to_msecs(drive->sleep - now);
	else
		msecs = 0;
	spin_unlock_irq(&hwif->lock);

	return snprintf(buf, 20, "%u\n", msecs);
}

ssize_t ide_park_store(struct device *dev, struct device_attribute *attr,
		       const char *buf, size_t len)
{
#define MAX_PARK_TIMEOUT 30000
	ide_drive_t *drive = to_ide_device(dev);
	long int input;
	int rc;

	rc = kstrtol(buf, 10, &input);
	if (rc)
		return rc;
	if (input < -2)
		return -EINVAL;
	if (input > MAX_PARK_TIMEOUT) {
		input = MAX_PARK_TIMEOUT;
		rc = -EOVERFLOW;
	}

	mutex_lock(&ide_setting_mtx);
	if (input >= 0) {
		if (drive->dev_flags & IDE_DFLAG_NO_UNLOAD)
			rc = -EOPNOTSUPP;
		else if (input || drive->dev_flags & IDE_DFLAG_PARKED)
			issue_park_cmd(drive, msecs_to_jiffies(input));
	} else {
		if (drive->media == ide_disk)
			switch (input) {
			case -1:
				drive->dev_flags &= ~IDE_DFLAG_NO_UNLOAD;
				break;
			case -2:
				drive->dev_flags |= IDE_DFLAG_NO_UNLOAD;
				break;
			}
		else
			rc = -EOPNOTSUPP;
	}
	mutex_unlock(&ide_setting_mtx);

	return rc ? rc : len;
}