How to fast master kernel

Hi all, I buy many boards, already on my hands boards: S3C6410, AR9331,AllWinner A20, H3. But for each board, it have dedicated kernel code package. For example, what I want to do first, it I can write kernel drivers and kernel code freely. I can easily add a I2C (AT24C02) device and finished its driver in a short time. Any good tutorial or good practise to guide me, make me easily to do that? If we have more small code example it will help? Sorry all for my stupid questions. /BRs