A description of the options accepted by spatch is available here.

A grammar of the SmPL language is available in pdf or html. This document also contains some annotated examples.

More examples are available here.

The Wiki contains more hints about using Coccinelle.

The LWN articles about Coccinelle may provide a useful introduction: Semantic patching with Coccinelle by Valerie Aurora, and Evolutionary development of a semantic patch using Coccinelle by Wolfram Sang. Eric Leblond has also written an article about his experiences.

An introductory lecture is available here.