soc/amd/common/acpi: Create platform.asl to define acpi transitions

Define device _WAK, _PTS, and _INI acpi methods with callbacks into
mainboard methods if provided.

BUG=b:158087989
BRANCH=Zork
TEST=tested backlight during reboot and suspend

Signed-off-by: Josie Nordrum <josienordrum@google.com>
Change-Id: I8020173a15db1d310459d5c1de3600949b173b00
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46669
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/common/acpi/platform.asl

@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/* Callback methods to be implemented by mainboard */
+External(\_SB.MPTS, MethodObj)
+External(\_SB.MWAK, MethodObj)
+External(\_SB.MINI, MethodObj)
+
+Scope (\_SB){
+	/* Platform initialization methods */
+	Method (_INI, 0, NotSerialized)
+	{
+		If (CondRefOf (\_SB.MINI)) {
+			\_SB.MINI()
+		}
+	}
+}
+
+/* Platform-wide wake methods */
+Method (\_WAK, 1, NotSerialized)
+{
+	If (CondRefOf (\_SB.MWAK)) {
+		\_SB.MWAK()
+	}
+	Return (Package (){ 0, 0 })
+}
+
+/* Platform-wide Put To Sleep (suspend) methods */
+Method (\_PTS, 1, NotSerialized)
+{
+	If (CondRefOf (\_SB.MPTS)) {
+		\_SB.MPTS()
+	}
+}