Extend new APB defines in integration document

[steven-bellock]

Follow-up to #279.

Signed-off-by: Steven Bellock [email protected]

[steven-bellock]

@Nitsirks now that I look at this, why is CALIPTRA_APB_DATA_WIDTH configurable by the Integrator? This should be an unconfigurable 32-bits.

[Nitsirks]

You are right - it's probably best if none of the APB parameters are configurable. I think early on these got put in this list, but we never tested them and there is no reason for them to be configurable. Integrators should put a gasket here to comply with the caliptra settings. Can/should we update the integration spec again to remove all of these APB defines as integration defines?

[calebofearth]

As-is, this PR still suggests that the APB interface signals are integrator configurable.
To implement changes from the discussion above, we should actually be defining all of the APB signals in Table 5 using a hardcoded width (so, APB_USER_REQ_WIDTH is replaced by 32) and removing APB interface defines from Table 3.

EDIT: This recommendation is only for edits to the specification (Tables 3 and 5); I do not suggest any RTL modifications at this stage.

[andreslagarcavilla]

Unclear if this is ready for merge

[steven-bellock]

Unclear if this is ready for merge

No, I'll need to revise it.

[steven-bellock]

@calebofearth @Nitsirks I deleted APB from Table 3 but I think it's fine to have the macro name in the Width column, especially since Table 8 uses them.