--- linux-4.9.37/fs/yaffs2/yaffs_mtdif.h	1970-01-01 03:00:00.000000000 +0300
+++ linux-4.9.y/fs/yaffs2/yaffs_mtdif.h	2021-06-07 13:01:34.000000000 +0300
@@ -0,0 +1,25 @@
+/*
+ * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
+ *
+ * Copyright (C) 2002-2011 Aleph One Ltd.
+ *   for Toby Churchill Ltd and Brightstar Engineering
+ *
+ * Created by Charles Manning <charles@aleph1.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1 as
+ * published by the Free Software Foundation.
+ *
+ * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
+ */
+
+#ifndef __YAFFS_MTDIF_H__
+#define __YAFFS_MTDIF_H__
+
+#include "yaffs_guts.h"
+
+void yaffs_mtd_drv_install(struct yaffs_dev *dev);
+struct mtd_info * yaffs_get_mtd_device(dev_t sdev);
+void yaffs_put_mtd_device(struct mtd_info *mtd);
+int yaffs_verify_mtd(struct mtd_info *mtd, int yaffs_version, int inband_tags);
+#endif