southbridge/amd/agesa/hudson: Add initial support for SMM

This sets up the infrastructure to handle SMIs generated by the Hudson
southbridge. An API for interfacing to mainboard handlers is not
defined at this point. A few functions are defined to allow mainboard
code to enable SMIs from GEVENT pins. These are the only functions which
I expect to be needed anytime in the foreseeable future.

SMIs are always acknowledged and cleared, as not clearing an SMI will
cause us to re-enter the SMI, effectively bricking the machine if a
southbridge-generated SMI without a handler occurs.

Change-Id: Ibceb21ac5423eb134d3eb7d24800280b183f7619
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5494
Reviewed-by: Aaron Durbin <adurbin@gmail.com>
Tested-by: build bot (Jenkins)
southbridge/hudson: Pass GEVENT SMIs to mainboard_smi_gpi()

Change-Id: Ifc368974a7a0dc0756431654fb89668e3846801a
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5502
Reviewed-by: Aaron Durbin <adurbin@gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
southbridge/hudson: Add support for ACPI enable/disable via SMI

This enables the ACPI SMI command port in the FADT table, and sets up
the hardware accordingly. If we have SMI enabled, then we don't set
the SCI_EN bit at boot, causing the OS to send the ACPI_ENABLE
command, as required by the ACPI spec. This gives us a chance to hook
into the mainboard_smi_apmc() handler.

Change-Id: Ib4c63d55b3132578dcae48bfe2092d4ea35821dd
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5511
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@gmail.com>