soc/amd/common/block: Add mainboard_handle_smi

The current SMM framework only allows the mainboard code to handle GPEs.
i.e., Events 0 - 23. This change allows the mainboard code to handle any
SMI events not handled by the SoC code. This will allow the mainboard
code to handle `SMITYPE_ESPI_SMI`.

BUG=b:222694093
TEST=Build guybrush

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I81943e8cb31e998f29cc60b565d3ca0a8dfe9cb2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62598
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/soc/amd/common/block/cpu/smm/smi_handler.c

@@ -7,6 +7,11 @@
 #include <cpu/x86/smm.h>
 #include <soc/smi.h>
 
+__weak void mainboard_handle_smi(int event)
+{
+	printk(BIOS_WARNING, "SMI event %d is missing handler\n", event);
+}
+
 static void process_smi_sources(uint32_t reg)
 {
 	const uint32_t status = smi_read32(reg);
@@ -19,6 +24,8 @@ static void process_smi_sources(uint32_t reg)
 			source_handler = get_smi_source_handler(i + bit_zero);
 			if (source_handler)
 				source_handler();
+			else if (reg != SMI_REG_SMISTS0 || (status & GEVENT_MASK) == 0)
+				mainboard_handle_smi(i + bit_zero);
 		}
 	}
 

src/soc/amd/common/block/include/amdblocks/smm.h

@@ -14,3 +14,5 @@ void *get_smi_source_handler(int source);
 void handle_smi_gsmi(void);
 void handle_smi_store(void);
 void clear_tvalid(void);
+/* See SMITYPE_* for list possible of events. GEVENTS are handled with mainboard_smi_gpi. */
+void mainboard_handle_smi(int event);