[util] Add missing file

Signed-off-by: Timothy Chen <timothytim@google.com>
diff --git a/util/design/gen-mubi.py b/util/design/gen-mubi.py
new file mode 100755
index 0000000..6f2cfa1
--- /dev/null
+++ b/util/design/gen-mubi.py
@@ -0,0 +1,17 @@
+#!/usr/bin/env python3
+# Copyright lowRISC contributors.
+# Licensed under the Apache License, Version 2.0, see LICENSE for details.
+# SPDX-License-Identifier: Apache-2.0
+r"""Converts mubi mako templates
+"""
+from mubi import prim_mubi
+from secded_gen import format_c_files
+
+def main():
+    prim_mubi.gen()
+    c_path = prim_mubi.get_c_path()
+
+    format_c_files(c_path, c_path)
+
+if __name__ == "__main__":
+    main()