diff --git a/realm/include/platform.h b/realm/include/platform.h
new file mode 100644
index 0000000..de91c16
--- /dev/null
+++ b/realm/include/platform.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2022-2023, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef PLATFORM_H
+#define PLATFORM_H
+
+/*
+ * Helper that returns a linear core ID from a MPID
+ * Need to provide a RSI_HOST_CALL to request this from Host platform.
+ */
+unsigned int platform_get_core_pos(u_register_t mpid)
+{
+	return 0U;
+}
+
+#endif /* PLATFORM_H */