Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Remove remaining 4.x compat shims. No resulting changes (verified by
md5).

Add locking to the twe(4) driver and make it MPSAFE:
- Add per-controller configuration (sx) and I/O (mutex) locks. The
configuration lock protects the relationship of volumes and drives
while the I/O lock protects access to the controller's registers and
the main I/O path.
- Remove some checks for M_WAITOK malloc()'s failing.
- Remove the explicit bus space tag/handle from the softc and use
bus_*() rather than bus_space_*().
- Reuse the existing new-bus sysctl context instead of creating a
new one.
- Remove compat shims for FreeBSD 4.x.
- Use pci_enable_busmaster() rather than doing it by hand, and rely
on bus_alloc_resource() to enable PCI I/O decoding.

Tested by: Mike Tancsa mike sentex net
Reviewed by: scottl (partially)
MFC after: 1 month

Remove bus_{mem,p}io.h and related code for a micro-optimization on i386
and amd64. The optimization is a trivial on recent machines.

Reviewed by: -arch (imp, marcel, dfr)

Do the dreaded s/dev_t/struct cdev */
Bump __FreeBSD_version accordingly.

Add missing <sys/module.h> includes

After extensive QA cycles at 3ware, bring the driver in-line with all the
issues which they found and asked to be changed so 3ware can offcially
support the driver.

Summary of the most significant changes:

- TWE_OVERRIDE is no longer supported
- If twe_getparam failed, bogus data would be returned to the caller
- Cache the device unit in the twe_drive structure to aid debugging
- Add the 3ware driver version.
- Proper return error codes for many functions.
- Track the minimum queue length statistics
- 4.x compat: use the cached unit number from the twe_drive structure
instead of the the cached si_drv2. 3ware found that after many loads
and unloads that si_drv2 became corrupted. This did not happen in
-current.

Submitted by: Vinod Kashyap (with modifications by me)
Approved by: re (rwatson)

Prefer new location of pci include files (which have only been in the
tree for two or more years now), except in a few places where there's
code to be compatible with older versions of FreeBSD.

Fix the busdma support in twe to support EINPROGRESS and enable it for
use with PAE kernels.

Properly support the 3ware generic API.

- Build SGL's for ATA_PASSTHROUGH commands
- Fallback to using the sgl_offset when the opcode is unknown for building
SGL's/
- Add ioctl calls for adding and removing units.
- Define previously undefined AEN's
- Allocate memory for the ioctl payload in multiples of 512bytes.

MFC after: 1 week

Fix a bug I introduced by overlooking the fact that "unit number" can
be one of several things in this driver.

Spotted & Tested by: alfred

Centralize the devstat handling for all GEOM disk device drivers
in geom_disk.c.

As a side effect this makes a lot of #include <sys/devicestat.h>
lines not needed and some biofinish() calls can be reduced to
biodone() again.

NO_GEOM cleanup:

Move to new "struct disk *" centric API.
Retire major #147 (twed)

Fix instances of macros with improperly parenthasized arguments.

Verified by: md5

Minor updates:

- Rework of twe_report_request to use the command status value rather
than the flags register. (Joel Jacobson @ 3ware)
- Update to match some changes in -current vs. stable.

MFC in: 1 week

Major update to the 'twe' driver.

- Layout reorganisation to enhance portability. The driver now has
a relatively MI 'core' and a FreeBSD-specific layer over the top.
Since the NetBSD people have already done their own port, this is
largely just to help me with the BSD/OS port.

- Request ID allocation changed to improve performance (I'd been
considering switching to this approach after having failed to come
up with a better way to dynamically allocate request IDs, and seeing
Andy Doran use it in the NetBSD port of the driver convinced me
that I was wasting my time doing it any other way). Now we just
allocate all the requests up front.

- Maximum request count bumped back to 255 after characterisation
of a firmware issue (off-by-one causing it to crash with 256
outstanding commands).

- Control interface implemented. This allows 3ware's '3dm' utility to
talk to the controller. 3dm will be available from 3ware shortly.

- Controller soft-reset feature added; if the controller signals a
firmware or protocol error, the controller will be reset and all
outstanding commands will be retried.