google/reef: Add mainboard handler function for gpio SMI

This patch adds mainboard_smi_gpi_handler which handles the
SMI event. This can happen in situations like lidclose and
system goes to shutdown.

BUG=chrome-os-partner:54977
TEST=When system is in firmware mode executing the command
     lidclose from ec console shuts down the system.

Change-Id: I8ff6001e48dcbbd4cee5097e759352d8fea6189b
Signed-off-by: Shaunak Saha <shaunak.saha@intel.com>
Reviewed-on: https://review.coreboot.org/15834
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/google/reef/ec.h

@@ -24,6 +24,9 @@
  */
 #define EC_SCI_GPI	GPE0_DW1_11
 
+/* EC SMI */
+#define EC_SMI_GPI	GPIO_49
+
 /*
  * On lidopen/lidclose GPIO_22 from North Community gets toggled and
  * is used in _PRW to wake up device from sleep. GPIO_22 maps to

src/mainboard/google/reef/smihandler.c

@@ -18,8 +18,15 @@
 #include <cpu/x86/smm.h>
 #include <ec/google/chromeec/smm.h>
 #include <soc/pm.h>
+#include <soc/smm.h>
 #include "ec.h"
 
+void mainboard_smi_gpi_handler(const struct gpi_status *sts)
+{
+	if (gpi_status_get(sts, EC_SMI_GPI))
+		chromeec_smi_process_events();
+}
+
 void mainboard_smi_sleep(u8 slp_typ)
 {
 	if (slp_typ == ACPI_S3)