Add licensing clarification page to docs. #20

docs/index.rst

@@ -94,6 +94,7 @@ Links
     hwif
     api
     limitations
+    licensing
 
 .. toctree::
     :hidden:

docs/licensing.rst

@@ -0,0 +1,39 @@
+Licensing
+=========
+
+Distribution of the PeakRDL-regblock code generator tool shall adhere to the
+terms outlined by the GNU GPL v3 license. For a copy of the license, see:
+https://github.com/SystemRDL/PeakRDL-regblock/blob/main/LICENSE
+
+
+Why GPL?
+--------
+GPL was chosen because my intent is to promote a thriving ecosystem of free and
+open source register automation tools. GPL discourages this tool to be bundled
+into some commercially sold closed-source software, as that would be contrary to
+this project's philosophy.
+
+
+What is covered by the GPL v3 license?
+--------------------------------------
+The GPL license is intended for the code generator itself. This includes all
+Python sources, Jinja demplate files, as well as testcase infrastructure not
+explicitly mentioned in the exemptions below.
+
+
+What is exempt from the GPL v3 license?
+---------------------------------------
+Don't worry. Not everything that the PeakRDL-regblock project touches is
+considered GPL v3 code.
+
+The following are exempt and are free to use with no restrictions:
+
+*   Any code that is generated using PeakRDL-regblock is 100% yours. Since it
+    was derived from your regblock definition, it remains yours. You can
+    distribute it freely, use it in a proprietary ASIC, sell it as part of an
+    IP, whatever.
+*   Any code snippets in this documentation can be freely copy/pasted. These are
+    examples that are intended for this purpose.
+*   The UDP definition SystemRDL file distributed in this documentation, and
+    located in the repository.
+*   Any example snippets within this documentation.