What could be the cause for that error message, IRQ problem? The device is based on imx6ulz-14x14-evk, the rtc is defined in imx6ull.dtsi, it is running on kernel 4.19, the driver looks good, the clock seems fine.
# ls /dev/rtc*
# ls -l /dev/rtc0
crw------- 1 root root 253, 0 Mar 31 07:44 /dev/rtc0