fs: btrfs: Add U-Boot fs handlers.

Signed-off-by: Marek Behun <marek.behun@nic.cz>

 create mode 100644 fs/btrfs/Kconfig
 create mode 100644 fs/btrfs/Makefile
 create mode 100644 fs/btrfs/btrfs.c
 create mode 100644 include/btrfs.h
diff --git a/include/btrfs.h b/include/btrfs.h
new file mode 100644
index 0000000..7390975
--- /dev/null
+++ b/include/btrfs.h
@@ -0,0 +1,21 @@
+/*
+ * BTRFS filesystem implementation for U-Boot
+ *
+ * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __U_BOOT_BTRFS_H__
+#define __U_BOOT_BTRFS_H__
+
+int btrfs_probe(struct blk_desc *, disk_partition_t *);
+int btrfs_ls(const char *);
+int btrfs_exists(const char *);
+int btrfs_size(const char *, loff_t *);
+int btrfs_read(const char *, void *, loff_t, loff_t, loff_t *);
+void btrfs_close(void);
+int btrfs_uuid(char *);
+void btrfs_list_subvols(void);
+
+#endif /* __U_BOOT_BTRFS_H__ */