BB-I2C2-PCF8523-00A0.dtsi (for overlay-utils)

// make the pcf8523 rtc0 (the primary rtc), renumber the internal rtc to rtc1
&{/aliases} {
#if 0
    // this is what we want:
    rtc0 = &extrtc;
    rtc1 = &rtc;
    // and this would work in a base dts, but path references are not
    // supported in overlay properties.  as workaround you need to hardcode
    // the paths, which unfortunately are kernel version dependent:
#elif 0
    // kernel 4.19
    rtc0 = "/ocp/i2c@4819c000/pcf8523@68";
    rtc1 = "/ocp/rtc@44e3e000";
#elif 1
    // kernel 5.10
    rtc0 = "/ocp/interconnect@48000000/segment@100000/target-module@9c000/i2c@0/pcf8523@68";
    rtc1 = "/ocp/interconnect@44c00000/segment@200000/target-module@3e000/rtc@0";
#endif
};

&i2c2 {
    extrtc: pcf8523@68 {
        compatible = "nxp,pcf8523";
        reg = <0x68>;
    };
};