Make scrubber work with CVA6

[NickLohr]

Tried to keep implementation as similar as before, major change is that is uses byte enabled and associativity.

[micprog]

I added a few comments with a few tricks and nitpicks in an attempt to make this compatible with the existing wrapper, but upon further inspection, this does not seem reasonable.

[micprog]

Do you think there is a way to alter the parametrization to remain backward-compatible? E.g.:

Suggested change

	//parameter int unsigned DataWidth = 39,
	parameter int unsigned BlockWidth = 32,
	parameter int unsigned BlockWidthECC = 39,
	parameter int unsigned DataDivisions = 1,
	parameter int unsigned TagWidth = 1,
	//parameter int unsigned ProtWidth = 7,
	parameter int unsigned Assoc = 2,
	parameter type be_t = logic, // need to have a data and tag element
	parameter type line_t = logic // need to have a data and tag element
	parameter int unsigned DataWidth = 39,
	parameter int unsigned ProtWidth = 7,
	parameter int unsigned BlockWidth = DataWidth-ProtWidth,
	parameter int unsigned BlockWidthECC = DataWidth,
	parameter int unsigned DataDivisions = DataWidth/BlockWidthECC,
	parameter int unsigned TagWidth = 1,
	parameter int unsigned Assoc = 2,
	parameter type be_t = logic [DataDivisions-1:0], // need to have a data and tag element
	parameter type line_t = logic[DataWidth-1:0] // need to have a data and tag element

[micprog]

I see this will have an impact on backward compatibility. Do you think this is necessary, i.e., would re-writing the entire data line impact performance?

[micprog]

Suggested change

	bank_we_o = scrub_we;
	bank_we_o = scrub_we;

[micprog]

Suggested change

[micprog]

I think this may also be a challenge for backward compatibility, as you are making assumptions about the structure of line_t. As far as I understand, you need it, so we may just need to write a separate module for your use case, as integrating with this one will break other parts.

[micprog]

Superseded by #24