PINE64 - Arch Linux Arm - external RTC problem

I have connected an external RTC module (ds3231) to a Rock 64/4g.

I've loaded i2c-dev modules and rtc-ds1307 modules but my rtc mod is not detected by i2c (i2cdetect shows nothing connected at address 68)

Hardware is ok (if I boot with ayurfan distro I can see the external RTC module).

Could it be a kernel configuration problem? Has anyone had similar experience?

My Linux distro is Arch Linux Arm.

Regards

Max

if anyone would be interested I managed to make it all work.

- i've modified, recompiled and overwrite to original one (in /boot/dtb) rk3328-rock64.dts, adding this fragment of code

Code:
  &i2c0 {

      status = "okay";

      ds1307: ds1307@68 {

        compatible = "maxim,ds1307";

        reg = <0x68>;

        status = "okay";

      };

      ds3231: ds3231@68 {

        compatible = "maxim,ds3231";

        reg = <0x68>;

        status = "okay";

      };

};

to enable i2c0 bus and to let automatically discovered the rtc device by the kernel at boot time.

- blacklisted rock64 rtc module (rtc_rk808)

- added rtc_ds1307 module to automatic module loading system

After reboot rtc device will be created and the rtc module enabled