If someone is interested I found the way to have BT working on orange pi Prime.
Unfortunately default kernel config is missing the following options and need to be manually recompiled:
With these changes and adding "uart1" to the overlays in armbianEnv.txt it's possible to use the driver in:
and start manually with:
./rtk_hciattach -n -s 115200 /dev/ttyS1 rtk_h5
to have bluetooth working.
Alternatively it's possible to use a modified driver and some startup scripts originally developed by NextThings C.H.I.P. that i have modified to run on Orange pi Prime board.
What about to add these kernel options to default next sunxi64 kernel config ?