...
- Factory (STATE_FACTORY) – Factory state is intended to be accessible only accessed by Renesas only. In this state, MCU runs the factory bootloader in secure (S) mode. Both secure and non-secure code/data can be read and written. Factory mode state can only be entered from unsealed state with factory command and factory password known only to Renesas. Factory state is always exits to seal Sealed state with a self-reset.
- Sealed (STATE_SEALED) – Sealed state is where the application runs. After reset , the factory bootloader runs, and it quickly check checks if it should enter the factory state; if not it will immediately transition to sealed state and jumps to the application.
- Unsealed (STATE_UNSEALED) – Unsealed state is only entered from the sealed Sealed state with unsealed CMD_UNSEAL command and the correct customer password. Unsealed state runs in NS mode and supports additional commands.
...
Figure 2. Privilege states of MCU with TZ support.
The benefit of having a TZ is to enable OEM/ODM to customize the device with Renesas "secret sauce" pre-programmed into the device. For MCU without TZ support, such as CM0+ and RL78, only OEM/ODM role is supported. The booting state transitions look like the below:
- Sealed (STATE_SEALED) – Sealed state is entered right after reset. This state support basic command set required by the application.
- Unsealed (STATE_UNSEALED) – Unsealed state is only entered from the sealed state with unsealed command and customer password. Unsealed state supports additional commands beyond the basic set.
there will be no Factory state, and therefore the Factory State will be bypassed resulting in the below state transition diagram:
Figure 3. Privilege states of MCU without TZ support.
Note that, in this case, Note that since there is no TZ support, therefore "secret sauce" code/data hiding is not possible, for IP protection . Renesas must be the one doing any required the firmware customization , and deliver just only the compiled executable binary.
...
3.4.1 Top-level pseudo code
...