When evaluating the security and OTP features for our Linux SC5xx projects, we came to the conclusion that at this time secure boot or most other features of the OTP make no sense with Linux, as it is impossible (and not desirable) to lock down the entire Linux system from the outside world.
This said, we wonder how we can prevent an unauthorized (deliberate or not) access to the OTP write functions in ROM (e.g. adi_rom_otp_pgm_data(...)) from any piece of code that might have been injected maliciously? This OTP write function could potentially trigger a complete lockdown of the processor (e.g., by programming all the "bootModeDisable" bits) resulting in a totally, non-recoverable hardware fault.
We understand, that writing to OTP should be disabled when the processor is locked via adi_rom_otp_lock, but this is not an option for us, since the required secure boot-streams etc. make no sense for Linux based systems. Actually, the "adi_rom_otp_lock" function itself is another potentially disastrous candidate to render the device unusable.
what can be done?