There was a Radare2 workshop at HACK.LU 2015, which included firmware targets. Check out the github’s top-level readme, Chapter 2 on Firmware. There are some UEFI-based demos in the Github project, as well.
https://github.com/XVilka/hacklu
http://archive.hack.lu/2015/
Click to access radare2-workshop-slides.pdf
http://archive.hack.lu/2015/radare2-workshop/
http://2015.hack.lu/archive/2015/radare2-workshop/vm/