UPD: with another chip of the same model RTC works just fine, presumably that the chip was broken/damaged.
I installed DS3231 RTC clock ( which is detected as DS1307 for some reason). My config.txt looks like
gpu_mem=64 dtoverlay=dwc2 dtoverlay=i2c-rtc,ds3231 dtparam=i2c_arm=on dtparam=i2c_arm_baudrate=1000000 dtparam=spi=on enable_uart=1
The clock is detected by
i2cdetect and I can see that
dmesg | grep rtc shows
dmesg | grep rtc [ 4.021947] rtc-ds1307 1-0068: registered as rtc0
The problem is -
hwclock -r always returns the same time. I can set it with
hwclock -w and it will keep that very time for weeks.
Am I missing something there? Isn't it supposed to tick?