PATCH: ide: ide-disk freeze support for hdaps

Hi all,

Attached below is a patch heavily based on Jon Escombe's patch, but
implemented as a sysfs attribute as Jens described, with a timeout
(configurable by module/kernel parameter) to ensure the queue isn't
stopped forever.

The driver creates a sysfs attribute "/sys/block/hdX/device/freeze",
which when set (echo 1 >
/sys/block/hda/device/freeze/sys/block/hda/device/freeze) freezes the
queue and parks the head on the drive, protecting the drive
(theoretically) from severe damage, until the drive is thawed (echo 0

/sys/block/hda/device/freeze) or a timeout is reached (default 10s).

The patch is meant for usage with the hdaps (hard drive active
protection system) for Thinkpads, however would also be useful for
similair systems implemented on powerbooks, and other laptops out
there.

I've tested it out on my T42p and it seems to work well, but as Jon
warns this is experimental...

Thanks,
Yani

Signed-off-by: Yani Ioannou <redacted>