Getting started with adding module in b43

Hi all,

I am having a BCM43142 card. For me everything is ok on windows, on 10 I 
can turn on hotspot with built in utility.

However, things are very bad on linux, as only broadcom-wl propriety 
drivers are present without AP mode, and wifi hotspot is very important 
to me in college, I have to use windows just because of that.

Because of this frustration I want to port this device myself. I have 
intermediate programming experience and am willing to do my homework.

I need help and guidance getting started with the process, a case / 
example on how this has been done with a different propriety module in 
the past would be great.

Hoping for a response.

Regards

Varun Garg