RFC: Initial ROM vendor hooks implementation #25642
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The ROM state API allows for defining a set of ROM states and their associated hooks and callback. Each state is defined by its run callback, and two hooks: the pre-run hook is executed prior to the run callback while the post-run one runs after. The rom_state_fsm() function walks through the ROM states, as each state run callback returns the next ROM state to transition to. ROM state hooks can be overridden by silicon creator implementations, through an external, potentially closed source, code repository. Signed-off-by: Samuel Ortiz <[email protected]>
And define the hooks setup bazel rules for silicon creators to provide their own ROM state hooks implementations. Signed-off-by: Samuel Ortiz <[email protected]>
Signed-off-by: Samuel Ortiz <[email protected]>
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This PR implements an initial framework for allowing vendors to customize OpenTitan ROMs with external , potentially closed-source hooks. See #25633 for more details on the problem statement and the proposed solution.
This pull request is made of three commits:
[sw,silicon_creator,rom] Add a ROM state APIis the main ROM vendor hooks implementation. It provides a set of C macros for defining ROM states and binding them with a run callback implementation. It also provides a simple API for walking through all defined states.[sw,silicon_creator,rom] Add dummy ROM state hooksexpands thehooks_setupbazel rules for supporting external ROM hooks repository. It also provides a dummy example of such a repository, with basic documentation on how to replicate that setup to actually implement custom ROM hooks[sw,silicon_creator,rom] Convert the OpenTitan ROM to the ROM state APIis really just a PoC as it converts the existing Earlgrey ROM to this new framework. In this commit, the ROM state definitions are wrapper around the existing high level functions of the Earlgrey ROM. A real conversion would split those functions into more granular ones and map those to a finer ROM state machine. This is not done in this commit to keep it as little intrusive as possible, mostly for readability purposes.Fixes #25633