8.5.3.2 Bus Hosts

The security bits in the TZPM control the security of bus accesses generated by the hosts. For example, if the security bit of a system bus host is set to secure, only secure accesses are performed. It is not possible to have different permission levels on the user interface (client) and on the host interface. Peripherals are either only accessible by Secure world and generate secure host accesses, or are accessible by Non-secure and Secure worlds and generate Non-secure host accesses.

Note:
  1. The TZPM has a dedicated peripheral ID. However, the TZPM is always secure and its security bit cannot be modified.

    The security bit value of peripheral IDs may conflict with the security level of interrupt IDs. In this case, the security level of the peripheral prevails. Interrupt security is controlled by the interrupt controller.