ata_get_mode_mask() uses bits 3 and 4 in the pio_mask to represent PIO
modes 3 and 4.  The value read from the drive, which reports support
for PIO3 and PIO4 in bits 0 and 1, is shifted left by 3 bits and OR'd
with 0x7 (which then corresponds to PIO 2-0 in libata).  Thus, the
drivers below need adjustments to comply with the way pio_mask is
used.  I changed the masks from the commented values to all support
PIO4-0, since the spec mandates that PIO0-2 are supported and there's
no reason not to support PIO3 IMO.
Signed-off-by: NBrett Russ <russb@emc.com>
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>

- changes license of all code from OSL+GPL to plain ole GPL
  - except for NVIDIA, who hasn't yet responded about sata_nv
  - copyright holders were already contacted privately

- adds info in each driver about where hardware/protocol docs may be
  obtained

- where I have made major contributions, updated copyright dates

Also, fixup a tabs-to-spaces block of code in ata_piix.

Jens Axboe pointed out that the iounmap() call in libata was occurring
too early, and some drivers (ahci, probably others) were using ioremap'd
memory after it had been unmapped.

The patch should address that problem by way of improving the libata
driver API:

* move ->host_stop() call after all ->port_stop() calls have occurred.

* create default helper function ata_host_stop(), and move iounmap()
call there.

* add ->host_stop_prewalk() hook, use it in sata_qstor.c (hi Mark).
sata_qstor appears to require the host-stop-before-port-stop ordering
that existed prior to applying the attached patch.

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!