Clean up IOCell types and parameterization

[jerryz123]

No description provided.

[colinschmidt]

LGTM

[jwright6323]

A little late since this was merged already, but I think this actually regresses on some features and should be partially reverted.

[jwright6323]

I don't think you should have changed this; it was done this way intentionally to allow the user to extend the IOCellBundle with foundry IO cell pins. Can you have multiple IOs in BlackBoxes now?

[jerryz123]

I can add this feature back in

[jwright6323]

Cool, thanks. I think everything else looks good, for the record.

[jerryz123]

Actually, it seems like you can already do this in the current system:

class FancyDigitalGPIOCellBundle extends DigitalGPIOCellBundle {
  val extra = Output(Bool())
}

class FancyDigitalGPIOCell extends GenericIOCell with DigitalGPIOCell {
  override val io = IO(new FancyDigitalGPIOCellBundle)
}

so no changes are necessary?

[jwright6323]

I don't think override works- you'll call IO twice and end up with phantom IOs that are disconnected (also I don't think you can call IO twice in BlackBox anyway)

[jerryz123]

NVM the above doesn't work.