AGWB output usable for DCA

The output generated by with --ipbus is already very close to what is needed for DCA interfacing. It contains

• instance information (instance name and base address)
• register information

What is missing is

• the VER value of a block. It should have the meaning of the API version, see #2 (closed). Of course this value must be available for software so that consistency checks can be made.
• the size of decoded Wishbone address space. The AGWB generated crossbar decodes only as many bits as needed to accommodate all blocks, the higher bits are ignored, the whole design is therefore mirrored as many times as fit into the BAR size. The number of decoded bits is stated in a VHDL file as C_top_ADDR_BITS. This effective address space size should be known to software to prevent that the mirror aliases are accessed by mistake.

One possibility would be to extend the --ipbus format with additional attributes, like

• <node id="VER" address="0x00000001" value="...." permission="r"/>
• <node id="top" addr_bits="...">

Most likely this should be done via a new output target so that the current --ipbus format stays unchanged.

Of relevance for @w.zabolotny_AT_elka.pw.edu.pl , @mkruszew_AT_mion.elka.pw.edu.pl , @mguminski , @i.froehlich