To install all necessary packages and synthesize and program ice4pi:

 sudo apt-get install yosys fpga-icestorm arachne-pnr
 make

1. Make sure your Pi has SPI enabled

2. There is a problem in arachne-pnr reporting bogus dependency conflict that can be worked around:

 apt-get source arachne-pnr
 cd arachne-pnr-0.1+20180909git840bdfd-1.1/
 dpkg-buildpackage -us -uc -j2
 sudo dpkg -i ../arachne*.deb