3.1 About this programmers model

This section provides general information about the CCI-550 register properties.

The following information applies to the CCI-550 registers:
  • The base address is not fixed, and can be different for any particular system implementation. The offset of each register from the base address is fixed.
  • Do not attempt to access reserved or unused address locations. Attempting to access these locations can result in UNPREDICTABLE behavior.
  • Unless otherwise stated in the accompanying text:
    • Do not modify undefined register bits.
    • Ignore undefined register bits on reads.
    • All register bits are reset to 0 by a system or powerup reset.
  • Access type is described as follows:
    RWRead and write.
    RORead only.
    WOWrite only.
    RAZRead as zero.
    WIWrite ignored.
  • Bit positions described as reserved are:
    • In an RW register, RAZ/WI
    • In an RO register, RAZ
    • In a WO register, WI.
The CCI-550 registers are accessed using the APB4 slave interface and cannot be accessed directly through the ACE or ACE-Lite slave interfaces.
The programmers model contains regions for control, slave interface, and performance counter registers. Accesses to unmapped or reserved registers are WI/RAZ. Non-secure accesses to Secure registers are WI/RAZ.
The programmers model is not affected by the number of interfaces on a specific CCI-550 configuration. Writing to registers pertaining to interfaces that are not present on your specific implementation has no effect.
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