BootstrapProtocol describes the supported types of bootstrap.
The Primitive SPI protocol is used by OpenTitan during development.
The Legacy SPI protocol is used by previous generations of Google Titan-class chips.
The LegacyRescue UART protocol is used by previous generations of Google Titan-class chips.
The Eeprom SPI protocol is planned to be implemented for OpenTitan.
The Jtag protocol is used for integrated IP during development.
The ‘Emulator’ value indicates that this tool has a direct way
of communicating with the OpenTitan emulator, to replace the
contents of the emulated flash storage.