hp/pavilion_m6_1035dx: Add SMI handler and handle EC requests

The EC may disable some functionality, such as Caps Lock LED and
battery charging if it never receives a command to go in APM mode. If
we start it in APM mode, then immediately switch to ACPI mode, it will
not get its SCIs serviced until an ACPI OS boots. If its SCIs are not
serviced, it may assume the OS has hung.

The way we solve this is to initalize the EC in APM mode, and only
switch it to ACPI when an ACPI-capable OS issues the ACPI_ENABLE
command. The switch has to be handled in SMM.

Although we aren't yet processing SMIs from the EC, we are reading the
status in order to satisfy the EC that the event is handled.

Change-Id: Iffaeb9a6f57841f456c4bce8337dc09b287f8758
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/5512
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Aaron Durbin <adurbin@gmail.com>
diff --git a/src/mainboard/hp/pavilion_m6_1035dx/Makefile.inc b/src/mainboard/hp/pavilion_m6_1035dx/Makefile.inc
index 07ea765..7039c72 100644
--- a/src/mainboard/hp/pavilion_m6_1035dx/Makefile.inc
+++ b/src/mainboard/hp/pavilion_m6_1035dx/Makefile.inc
@@ -27,3 +27,5 @@
 ramstage-y += BiosCallOuts.c
 ramstage-y += PlatformGnbPcie.c
 ramstage-y += ec.c
+
+smm-y += mainboard_smi.c