Help: using the scull driver

Hi, I'd like to ask how can I use the scull driver today? The scull driver appears in the book "Linux Device Drivers, Third Edition". I am using linux vesion 5.1.6 I found the code of scull here: https://github.com/starpos/scull But, it says there that the code is compatible with linux version 2.6.35. I've tried to port the code to run with my linux version, but I got stuck when it comes to exchange the old semaphores with the newly introduced mutexes. I also tried to install linux version 2.6.35 on my machine, but I could compile the code. I assume it's related to the gcc version, but I don't know how to handle this. Can you give me some advice here? Thanks, Yacov