more stuff in the README

README.md

@@ -23,3 +23,54 @@ MMIO register definition files.
 * DSLite → SVD [*planned*]
 * SVD → DTS/DTB (peripherals only) [*planned*]
 * DTS/DTB → SVD (peripherals only) [*planned*]
+
+## Usage
+
+#### Libraries
+
+* `dvf/dvfparse.py` is able to parse DVF files
+* `svd/svd.py`, `svd/svdparse.py`, `svd/svdgen.py` handle SVD files
+
+#### Utilities
+
+* `dvf/dvf2h.py` is a quick DVF-to-headerfile converter
+* `dvf2svd.py` converts DVF to SVD files using the above libraries
+
+## Dependencies
+
+Python stdlib only, though I've been using 3.10, it might be the case that some
+things aren't in eg. 3.6.
+
+## FAQ etc
+
+#### Why is it Python? Why is the Python code so hacky?
+
+I quickly wanted to get something to work so that I could import MMIO stuff in
+Ghidra. Yes the code could be cleaner/faster (especially with a resp. Racket or
+Rust rewrite), but I just wanted to Get Things Done.
+
+#### Why is it not a proper Python module?
+
+I started from a script and things evolved from there. I should probably
+restructure the codebase a bit, the current method of importing stuff (by
+adding things to the Python module path...) is, not a good idea.
+
+#### Why are the converters inaccurate?
+
+For DVF, the main problem lies in the file format: all registers are laid out
+without peripheral associations, so no peripheral information (and peripheral ↔
+interrupt) mapping is available. Furthermore, the file format is binary, so
+figuring out which exact bits correspond to which register properties (eg.
+'write-to-clear') is pretty hard. The basics are still there, though. The code
+is currently untested for V830 and RX DVF files, which might differ in some
+ways.
+
+For TRACE32 PER, a large problem is that these files mix UI elements,
+conditionals and loops, and actual peripheral and register definitions, in a
+quite shitty to parse text-based format, making things quite complicated. The
+conditionals depend on outside knowledge (eg. exact chip names, Xtensa TRAX
+register bases, ...) which I don't have, so those are currently left ignored.
+
+## License
+
+Eh, idk yet.