regview is a gdb based utility for viewing control register state. ADC, DMA, RCC,… I use it to view STM32 registers
I am not the original author, but I needed some additional features. In particular, the ability to save and compare states from two sessions. I had a reference prototype that worked and some code of my own that didn’t. Compare register states between the two helped me move forward.
 

 
The enhancement I talk about are here:
https://github.com/mmccoo/gdb-regview
It is a fork of this original:
https://github.com/fnoble/gdb-regview
It uses register definitions from here:
https://sourceforge.net/p/embsysregview/code/HEAD/tree/trunk/org.eclipse.cdt.embsysregview.data/data/cortex-m3/STMicro/
gdb python is documented here:
https://sourceware.org/gdb/onlinedocs/gdb/Python-API.html