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

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

DEFINE_MUTEX(ide_setting_mtx);

ide_devset_get(io_32bit, io_32bit);

static int set_io_32bit(ide_drive_t *drive, int arg)
{
	if (drive->dev_flags & IDE_DFLAG_NO_IO_32BIT)
		return -EPERM;

	if (arg < 0 || arg > 1 + (SUPPORT_VLB_SYNC << 1))
		return -EINVAL;

	drive->io_32bit = arg;

	return 0;
}

ide_devset_get_flag(ksettings, IDE_DFLAG_KEEP_SETTINGS);

static int set_ksettings(ide_drive_t *drive, int arg)
{
	if (arg < 0 || arg > 1)
		return -EINVAL;

	if (arg)
		drive->dev_flags |= IDE_DFLAG_KEEP_SETTINGS;
	else
		drive->dev_flags &= ~IDE_DFLAG_KEEP_SETTINGS;

	return 0;
}

ide_devset_get_flag(using_dma, IDE_DFLAG_USING_DMA);

static int set_using_dma(ide_drive_t *drive, int arg)
{
#ifdef CONFIG_BLK_DEV_IDEDMA
	int err = -EPERM;

	if (arg < 0 || arg > 1)
		return -EINVAL;

	if (ata_id_has_dma(drive->id) == 0)
		goto out;

	if (drive->hwif->dma_ops == NULL)
		goto out;

	err = 0;

	if (arg) {
		if (ide_set_dma(drive))
			err = -EIO;
	} else
		ide_dma_off(drive);

out:
	return err;
#else
	if (arg < 0 || arg > 1)
		return -EINVAL;

	return -EPERM;
#endif
}

/*
 * 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;
	}
}

static int set_pio_mode(ide_drive_t *drive, int arg)
{
	ide_hwif_t *hwif = drive->hwif;
	const struct ide_port_ops *port_ops = hwif->port_ops;

	if (arg < 0 || arg > 255)
		return -EINVAL;

	if (port_ops == NULL || port_ops->set_pio_mode == NULL ||
	    (hwif->host_flags & IDE_HFLAG_NO_SET_MODE))
		return -ENOSYS;

	if (set_pio_mode_abuse(drive->hwif, arg)) {
		drive->pio_mode = arg + XFER_PIO_0;

		if (arg == 8 || arg == 9) {
			unsigned long flags;

			/* take lock for IDE_DFLAG_[NO_]UNMASK/[NO_]IO_32BIT */
			spin_lock_irqsave(&hwif->lock, flags);
			port_ops->set_pio_mode(hwif, drive);
			spin_unlock_irqrestore(&hwif->lock, flags);
		} else
			port_ops->set_pio_mode(hwif, drive);
	} else {
		int keep_dma = !!(drive->dev_flags & IDE_DFLAG_USING_DMA);

		ide_set_pio(drive, arg);

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

	return 0;
}

ide_devset_get_flag(unmaskirq, IDE_DFLAG_UNMASK);

static int set_unmaskirq(ide_drive_t *drive, int arg)
{
	if (drive->dev_flags & IDE_DFLAG_NO_UNMASK)
		return -EPERM;

	if (arg < 0 || arg > 1)
		return -EINVAL;

	if (arg)
		drive->dev_flags |= IDE_DFLAG_UNMASK;
	else
		drive->dev_flags &= ~IDE_DFLAG_UNMASK;

	return 0;
}

ide_ext_devset_rw_sync(io_32bit, io_32bit);
ide_ext_devset_rw_sync(keepsettings, ksettings);
ide_ext_devset_rw_sync(unmaskirq, unmaskirq);
ide_ext_devset_rw_sync(using_dma, using_dma);
__IDE_DEVSET(pio_mode, DS_SYNC, NULL, set_pio_mode);

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;
}

ide_startstop_t ide_do_devset(ide_drive_t *drive, struct request *rq)
{
	int err, (*setfunc)(ide_drive_t *, int) = rq->special;

	err = setfunc(drive, *(int *)&rq->cmd[1]);
	if (err)
		rq->errors = err;
	ide_complete_rq(drive, err, blk_rq_bytes(rq));
	return ide_stopped;
}