v4.19.13 snapshot.
diff --git a/include/linux/bcd.h b/include/linux/bcd.h
new file mode 100644
index 0000000..118bea3
--- /dev/null
+++ b/include/linux/bcd.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCD_H
+#define _BCD_H
+
+#include <linux/compiler.h>
+
+#define bcd2bin(x) \
+ (__builtin_constant_p((u8 )(x)) ? \
+ const_bcd2bin(x) : \
+ _bcd2bin(x))
+
+#define bin2bcd(x) \
+ (__builtin_constant_p((u8 )(x)) ? \
+ const_bin2bcd(x) : \
+ _bin2bcd(x))
+
+#define const_bcd2bin(x) (((x) & 0x0f) + ((x) >> 4) * 10)
+#define const_bin2bcd(x) ((((x) / 10) << 4) + (x) % 10)
+
+unsigned _bcd2bin(unsigned char val) __attribute_const__;
+unsigned char _bin2bcd(unsigned val) __attribute_const__;
+
+#endif /* _BCD_H */