如何在BeagleBoneBlack上启用和使用SPI

I have a BeagleBoneBlack Wireless and I would like to use SPI (and I2C). I am finding it very difficult to get definitive instructions on how to set up and use SPI on the BBB. Firstly, it is not clear to me what the default configuration of the BBB is. I appear to have two SPI devices:I have a BeagleBoneBlack Wireless and I would l