Can I use an optimisation solver in a Matlab embedded functions for a real time application?

I was wondering if I can use an Embedded MATLAB function in Simulink to call an optimisation solver, say fmincon, so that I can implement an MPC controller in real time. Or using the C-MEX function is the only way possible? I'm fairly new to Simulink, and the RT workshop and all the available info seems a bit confusing.