diff --git a/src/soc/sifive/fu540/cbmem.c b/src/soc/sifive/fu540/cbmem.c
new file mode 100644
index 0000000..8648370
--- /dev/null
+++ b/src/soc/sifive/fu540/cbmem.c
@@ -0,0 +1,22 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 Jonathan Neuschäfer
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <cbmem.h>
+
+void *cbmem_top(void)
+{
+	/* dummy value */
+	return (void *)(4ULL * GiB);
+}