Hi Amir,
It has been a while since your post, but anyway here are some pointers:
The SPI master bus is enabled by default on the nanopi neo3, see e.g.:
ls /sys/firmware/devicetree/base/spi@ff190000
You can use the bus by attaching an SPI device to the bus and use it either via userland using the general purpose spidev kernel driver or load/write the appropriate driver kernel module and/or trigger driver loading via a device tree overlay.
We use our own driver and device tree overlay for SPI with an ADC on the neo3, we see sporadic loss of SPI interrupts at 4KHz sampling and more at higher sampling rates, especially when there is high CPU load on the neo3.
Kind regards,
Dennis
