efi_loader: add RuntimeServicesSupported variable

This variable is defined in UEFI specification 2.8, section 8.1.
Its value should be updated whenever we add any usable runtime services
function.

Currently we only support SetVirtualAddress() for all systems and
ResetSystem() for some.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

lib/efi_loader/efi_runtime.c

@@ -89,6 +89,30 @@ struct elf_rela {
  * handle a good number of runtime callbacks
  */
 
+efi_status_t efi_init_runtime_supported(void)
+{
+	u16 efi_runtime_services_supported = 0;
+
+	/*
+	 * This value must be synced with efi_runtime_detach_list
+	 * as well as efi_runtime_services.
+	 */
+#if CONFIG_IS_ENABLED(ARCH_BCM283X) || \
+    CONFIG_IS_ENABLED(FSL_LAYERSCAPE) || \
+    CONFIG_IS_ENABLED(SYSRESET_X86) || \
+    CONFIG_IS_ENABLED(PSCI_RESET)
+	efi_runtime_services_supported |= EFI_RT_SUPPORTED_RESET_SYSTEM;
+#endif
+	efi_runtime_services_supported |=
+				EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP;
+	return EFI_CALL(efi_set_variable(L"RuntimeServicesSupported",
+					 &efi_global_variable_guid,
+					 EFI_VARIABLE_BOOTSERVICE_ACCESS |
+					 EFI_VARIABLE_RUNTIME_ACCESS,
+					 sizeof(efi_runtime_services_supported),
+					 &efi_runtime_services_supported));
+}
+
 /**
  * efi_update_table_header_crc32() - Update crc32 in table header
  *