what are the prerequisites for studying embedded system software development?
Basic knowledge in C, C++ and a basic understanding of Linux OS, I'd say. It really depends if the course you're enrolling in assumes prior knowledge or not, but if it does, I imagine these three would be there.
Going along with Hatsy Rei and Ace there is a good reference to read on Quora which may help as well https://www.quora.com/What-are-the-prerequisites-for-learning-embedded-systems
A one stop channel for the aforementioned https://m.youtube.com/user/nesoacademy?itct=CCMQoTAYACITCKKVlbiRoOQCFTnIwQodh9AMuQ%3D%3D