Thanks for your reply. I agree that AUX_ADC will serve my purpose. But according to schematics page 6, in AUX_IN section, the 5 ADC channels(AUXIN0, 1,2,3,4) were not pinned out. So, I believe I cannot use it from processor (MT6797).
Is there any way I can get an ADC from PMIC (MT6351). Where can I download the datasheet for the PMIC (MT6351)?