hd dance around local irq and HD_IRQ enable without achieving much.
It ends up transferring data from irq handler with both local irq and
HD_IRQ disabled.  The only place it actually does something is while
transferring the first block of a request which it does with HD_IRQ
disabled but local irq enabled.

Unfortunately, the dancing is horribly broken from locking POV.  IRQ
and timeout handlers access block queue without grabbing the queue
lock and running the driver in SMP configuration crashes the whole
machine pretty quickly.

Remove meaningless irq enable/disable dancing and add proper locking
in issue, irq and timeout paths.

Signed-off-by: Tejun Heo <tj@kernel.org>

* Move HD_IRQ define to drivers/block/hd.c (only user).

* Remove unused *_STAT, *_ERR, HD_*, CD, IO, REL and TAG_MASK defines.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

* Use ATA_CMD_* defines instead of WIN_* ones.

* Include <linux/ata.h> directly instead of through <linux/hdreg.h>.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

The code that needed this #include was removed one year ago.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Cc: rmk@arm.linux.org.uk
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

This patch moves hd.c to drivers/block/

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Cc: rmk@arm.linux.org.uk
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>