In addition to UEFI Firmware Parser, and other tools, Teddy Reed *ALSO* has written a fuzzer for Apple SMC firmware:
devnull’s SMC read/write code, along with simple fuzz options. This smc tool uses the AppleSMC IOKit interface and a userland API for interacting with the System Management Controller (Mac embedded controllers). The tool focuses on the SMC key/value API, but could be expanded to more API methods.
Click on the above Twitter URL for the follow-up conversation with some more information about SMC.