U-boot build error

If i add WATCHDOG DRIVER SUPPORT is the error output:
u-boot/lib/time.c:192: undefined reference to watchdog_reset' u-boot/lib/time.c:192:(.text.udelay+0x1c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol watchdog_reset’
u-boot/drivers/serial/ns16550.c:393: undefined reference to watchdog_reset' u-boot/drivers/serial/ns16550.c:393:(.text.ns16550_serial_putc+0x6c): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol watchdog_reset’