Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 4/01/2024
Public

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4.1.5.1.6. Distributed I/O Interface (DII)

A DII provides an AXI initiator interface to IO devices for non-coherent requests.

DII0 is mostly used for F2H access to PSS resources because the CPU subsystem uses the peripheral port for device accesses to the PSS NoC. DII1 is used to access MPFE data ports and register space. DII2 is used to access the GIC register space. These ports have exceptionally low bandwidth requirements. DII3 is used to access the OCRAM. This port has low to medium bandwidth requirements.

For each DII, the following counter is implemented:

  • RB message counter

For each DII, the following resources are implemented based on message credits:

  • CMD message skid buffer which is sized based on CMD message credits
  • RB control entries which are sized based on RB message credits

For each DII, the following additional resources are implemented:

  • Read transaction table control entries which limit the number of read transactions each DII can have outstanding on the AXI interface
  • Write transaction table control entries which limit the number of write transactions each DII can have outstanding on the AXI interface