In some cases limits are just not needed, in others -- DFLTPHYS is the
right constant to use instead.

md5).

  twe_start() to simulate the behavior on 4.x where the driver dropped
  spl to allow interrupts to run to free up space in the command
  queue.  Be careful to only poll if we are going to make at least
  one more attempt to queue the current command.  Also, when polling,
  be careful to not call twe_startio() to queue more commands to avoid
  recursion.
- Move the buffer for formatting AEN messages into the softc instead of
  using a single driver-wide static buffer.

Requested by:	scottl (1)
Tested by:	Mike Tancsa @ Sentex

- 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

PCI device attachment.

  one. Interestingly, these are actually the default for quite some time
  (bus_generic_driver_added(9) since r52045 and bus_generic_print_child(9)
  since r52045) but even recently added device drivers do this unnecessarily.
  Discussed with: jhb, marcel
- While at it, use DEVMETHOD_END.
  Discussed with: jhb
- Also while at it, use __FBSDID.

This means that their use is restricted to a single C file.

truncating the command to 32bit on 64bit archs where int is 32bit
(ie. amd64).

Approved by:	scottl
Approved by:	ed (mentor, implicit)

reintroduced after HEAD is reopened for commits by re@.

Approved by:	re (kib), attilio