Revamp the config system for Top/Harness (#347)

* Refactor how Configs parameterize the Top and TestHarnesses

* Bump sha3, testchipip, icenet, firesim

docs/Customization/DMA-Devices.rst

@@ -0,0 +1,39 @@
+.. _dma-devices:
+
+Adding a DMA Device
+===================
+
+DMA devices are Tilelink widgets which act as masters. In other words,
+DMA devices can send their own read and write requests to the chip's memory
+system.
+
+For IO devices or accelerators (like a disk or network driver), instead of
+having the CPU poll data from the device, we may want to have the device write
+directly to the coherent memory system instead. For example, here is a device
+that writes zeros to the memory at a configured address.
+
+.. literalinclude:: ../../generators/example/src/main/scala/InitZero.scala
+    :language: scala
+
+.. literalinclude:: ../../generators/example/src/main/scala/Top.scala
+    :language: scala
+    :start-after: DOC include start: Top
+    :end-before: DOC include end: Top
+
+We use ``TLHelper.makeClientNode`` to create a TileLink client node for us.
+We then connect the client node to the memory system through the front bus (fbus).
+For more info on creating TileLink client nodes, take a look at :ref:`Client Node`.
+
+Once we've created our top-level module including the DMA widget, we can create a configuration for it as we did before.
+
+.. literalinclude:: ../../generators/example/src/main/scala/ConfigMixins.scala
+    :language: scala
+    :start-after: DOC include start: WithInitZero
+    :end-before: DOC include end: WithInitZero
+
+.. literalinclude:: ../../generators/example/src/main/scala/RocketConfigs.scala
+    :language: scala
+    :start-after: DOC include start: InitZeroRocketConfig
+    :end-before: DOC include end: InitZeroRocketConfig
+
+