soc/intel/common/block/smm: Keep selected wake sources enabled in S5

The generic Intel SMM S5 entry path disables all GPEs before asserting
SLP_EN, which clears OS-armed wake enables (e.g. LAN_WAKE) and prevents
Wake-on-LAN from S5.

Add a mainboard override hook, mainboard_smi_sleep_finalize(), called
after the S5 teardown but before SLP_EN is asserted, allowing boards to
restore required wake sources.

Change-Id: I9e97308ed94961fc4c08a10714b1b53f198bb593
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90792
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>

src/cpu/x86/smm/smm_module_handler.c

@@ -226,6 +226,7 @@ void __weak southbridge_smi_handler(void) {}
 void __weak mainboard_smi_gpi(u32 gpi_sts) {}
 int __weak mainboard_smi_apmc(u8 data) { return 0; }
 void __weak mainboard_smi_sleep(u8 slp_typ) {}
+void __weak mainboard_smi_sleep_finalize(u8 slp_typ) {}
 void __weak mainboard_smi_finalize(void) {}
 
 void __weak smm_soc_early_init(void) {}

src/include/cpu/x86/smm.h

@@ -61,6 +61,7 @@ void southbridge_smi_handler(void);
 void mainboard_smi_gpi(u32 gpi_sts);
 int  mainboard_smi_apmc(u8 data);
 void mainboard_smi_sleep(u8 slp_typ);
+void mainboard_smi_sleep_finalize(u8 slp_typ);
 void mainboard_smi_finalize(void);
 int mainboard_set_smm_log_level(void);
 

src/soc/intel/common/block/smm/smihandler.c

@@ -220,6 +220,9 @@ void smihandler_southbridge_sleep(
 		break;
 	}
 
+	/* Allow mainboard to restore wake sources (e.g. for S5 WOL). */
+	mainboard_smi_sleep_finalize(slp_typ);
+
 	/*
 	 * Write back to the SLP register to cause the originally intended
 	 * event again. We need to set BIT13 (SLP_EN) though to make the