AXI Slave Interface

The AXI slave interface enables a client endpoint to initiate PCI transactions as a bus master across the PCIe link to the host memory. For root ports, this interface initiates I/O and configuration requests. For endpoints, this interface must be connected to client logic only when the client has bus master capability. Endpoints and root ports can also use the slave interface to send messages on the PCIe link. The transactions on this bus are similar to those on the AXI master bus, except that the roles of the PCIe Controller and the client are reversed.

The client must check the following conditions before making a request on the AXI slave interface:

  • Only root ports can initiate I/O or configuration requests.
  • An endpoint can initiate a memory read or write request only when the Bus Master Enable bit of the PCI Command Register associated with the requesting function is set. These bits are accessible on the PCIe Controller's FUNCTION_STATUS output (see Status and Error Indicator Signals).
  • An endpoint can only send requests when the originating function's power state is D0-Active. The function power state is available on the FUNCTION_POWER_STATE output (see Status and Error Indicator Signals).
  • The originating function is not currently processing a function-level reset (FLR).
Note: All AXI slave interface signals have the prefix MASTER_AXI (see AXI Slave Interface Signals).