The dts file for bpi-m1-plus is here
https://github.com/BPI-SINOVOIP/BPI-Mainline-uboot/tree/master/arch/arm/dts
The diff against mainline uboot is here.
http://users.utu.fi/jmjmak/tmp/uboot-bananapi.patch
This 4.2 kernel also works, but it's quite bloated with extra config:
https://github.com/BPI-SINOVOIP/BPI-Mainline-kernel