soc,southbridge/intel: Control SMI related FADT entries

When no SMI is installed, FADT should not advertise a trigger
mechanism that does not respond.

Change-Id: Ifb4f99c11a72e75ec20b9faaf62aed5546de91fa
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41909
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/southbridge/intel/i82801gx/lpc.c b/src/southbridge/intel/i82801gx/lpc.c
index 7e2b5a7..86c3e58 100644
--- a/src/southbridge/intel/i82801gx/lpc.c
+++ b/src/southbridge/intel/i82801gx/lpc.c
@@ -521,13 +521,15 @@
 
 	fadt->reserved = 0;
 	fadt->sci_int = 0x9;
-	fadt->smi_cmd = APM_CNT;
-	fadt->acpi_enable = APM_CNT_ACPI_ENABLE;
-	fadt->acpi_disable = APM_CNT_ACPI_DISABLE;
-	fadt->s4bios_req = 0x0;
-	fadt->pstate_cnt = APM_CNT_PST_CONTROL;
 
-	fadt->cst_cnt = APM_CNT_CST_CONTROL;
+	if (CONFIG(HAVE_SMI_HANDLER)) {
+		fadt->smi_cmd = APM_CNT;
+		fadt->acpi_enable = APM_CNT_ACPI_ENABLE;
+		fadt->acpi_disable = APM_CNT_ACPI_DISABLE;
+		fadt->pstate_cnt = APM_CNT_PST_CONTROL;
+		fadt->cst_cnt = APM_CNT_CST_CONTROL;
+	}
+
 	fadt->p_lvl2_lat = 1;
 	fadt->p_lvl3_lat = chip->c3_latency;
 	fadt->flush_size = 0;