Hi Ken Green ,
You can follow the i.MX Reference manual of the linux version that you are using. It will have the information regarding the files that you are looking for. Moreover, you can also have a look at i.MX Reference manual for particular board for more registers information. Below is the screenshot of the i.MX Reference Manual for linux version L4.14.98:

Let us know if you have any concerns.
Regards,
Karan Gajjar