Initial Commit - Forked from PeakRDL-regblock @ a440cc19769069be831d267505da4f3789a26695

docs/cpuif/apb.rst

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+AMBA APB
+========
+
+Both APB3 and APB4 standards are supported.
+
+.. warning::
+    Some IP vendors will incorrectly implement the address signalling
+    assuming word-addresses. (that each increment of ``PADDR`` is the next word)
+
+    For this exporter, values on the interface's ``PADDR`` input are interpreted
+    as byte-addresses. (an APB interface with 32-bit wide data increments
+    ``PADDR`` in steps of 4 for every word). Even though APB protocol does not
+    allow for unaligned transfers, this is in accordance to the official AMBA
+    specification.
+
+    Be sure to double-check the interpretation of your interconnect IP. A simple
+    bit-shift operation can be used to correct this if necessary.
+
+
+APB3
+----
+
+Implements the register block using an
+`AMBA 3 APB <https://developer.arm.com/documentation/ihi0024/b/Introduction/About-the-AMBA-3-APB>`_
+CPU interface.
+
+The APB3 CPU interface comes in two i/o port flavors:
+
+SystemVerilog Interface
+    * Command line: ``--cpuif apb3``
+    * Interface Definition: :download:`apb3_intf.sv <../../hdl-src/apb3_intf.sv>`
+    * Class: :class:`peakrdl_regblock.cpuif.apb3.APB3_Cpuif`
+
+Flattened inputs/outputs
+    Flattens the interface into discrete input and output ports.
+
+    * Command line: ``--cpuif apb3-flat``
+    * Class: :class:`peakrdl_regblock.cpuif.apb3.APB3_Cpuif_flattened`
+
+
+APB4
+----
+
+Implements the register block using an
+`AMBA 4 APB <https://developer.arm.com/documentation/ihi0024/d/?lang=en>`_
+CPU interface.
+
+The APB4 CPU interface comes in two i/o port flavors:
+
+SystemVerilog Interface
+    * Command line: ``--cpuif apb4``
+    * Interface Definition: :download:`apb4_intf.sv <../../hdl-src/apb4_intf.sv>`
+    * Class: :class:`peakrdl_regblock.cpuif.apb4.APB4_Cpuif`
+
+Flattened inputs/outputs
+    Flattens the interface into discrete input and output ports.
+
+    * Command line: ``--cpuif apb4-flat``
+    * Class: :class:`peakrdl_regblock.cpuif.apb4.APB4_Cpuif_flattened`