[sw,silicon_creator] Make Silicon Creator code top agnostic

[sameo]

Some silicon creator libraries (e.g. the otbn_boot_services library) have hard coded dependencies on specific tops.

In order for those libraries to be shared between top's ROMs and ROM_EXT implementation, we should have a generic framework to allow top software definitions/hooks that could be called from the shared libraries.

cc @luismarques @pamaury

[moidx]

Hi @sameo, if I remember correctly, the seeds fetched from flash are equivalent to factory entropy and are used to maintain FIPS compliance. If we keep this approach, I think it would make sense to move these bits to OTP, allowing us to unify DJ and EG.

Otherwise, would it make sense to have a weak function or other dependency injection mechanism to provide the factory entropy for each top level?

CC @timothytrippel

[sameo]

Hey @moidx

Otherwise, would it make sense to have a weak function or other dependency injection mechanism to provide the factory entropy for each top level?

That's pretty close to what I'm trying to do here: #28439

Basically letting each top define how and where to get that seed from. I did not define it as a weak symbol, as I don't think we should provide a default implementation for it but rather generate a build failure if a top does not explicitly provide an implementation for it.