It’s been surprisingly difficult to find consensus on how to set up the Debian SPI interface on the Beaglebone Black. Fortunately, Maniacal Labs has posted a nice easy approach that can be easily modified for Debian.
Load uEnv.txt either by plugging the BBB into your computer via USB or via:
sudo nano /boot/uEnv.txt
Paste the following line at the end of the file:
optargs=quiet drm.debug=7 capemgr.enable_partno=BB-SPIDEV0
Save the file and reboot your beaglebone black:
Make sure it is enabled:
ls -al /dev/spidev*
You should see the following:
crw-rw---T 1 root spi 153, 1 May 15 02:22 /dev/spidev1.0 crw-rw---T 1 root spi 153, 0 May 15 02:22 /dev/spidev1.1
Most of this was copied from the instructions on https://github.com/ManiacalLabs/BiblioPixel/wiki/SPI-Setup.