x86: Add DSDT table for supporting ACPI on QEMU

The DSDT table contains a bytecode that is executed by a driver in the kernel.

Signed-off-by: Saket Sinha <saket.sinha89@gmail.com>
Tested with QEMU '-M q35'
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/qemu/acpi/hpet.asl b/arch/x86/cpu/qemu/acpi/hpet.asl
new file mode 100644
index 0000000..983151e
--- /dev/null
+++ b/arch/x86/cpu/qemu/acpi/hpet.asl
@@ -0,0 +1,31 @@
+/* HPET */
+
+Scope(\_SB) {
+    Device(HPET) {
+        Name(_HID, EISAID("PNP0103"))
+        Name(_UID, 0)
+        OperationRegion(HPTM, SystemMemory, 0xfed00000, 0x400)
+        Field(HPTM, DWordAcc, Lock, Preserve) {
+            VEND, 32,
+            PRD, 32,
+        }
+        Method(_STA, 0, NotSerialized) {
+            Store(VEND, Local0)
+            Store(PRD, Local1)
+            ShiftRight(Local0, 16, Local0)
+            If (LOr(LEqual(Local0, 0), LEqual(Local0, 0xffff))) {
+                Return (0x0)
+            }
+            If (LOr(LEqual(Local1, 0), LGreater(Local1, 100000000))) {
+                Return (0x0)
+            }
+            Return (0x0f)
+        }
+        Name(_CRS, ResourceTemplate() {
+            Memory32Fixed(ReadOnly,
+                0xfed00000,         /* Address Base */
+                0x00000400,         /* Address Length */
+                )
+        })
+    }
+}