ICAP Arbitration Interface - 3.1 English

This interface is provided as a convenience for use in systems where the ICAP primitive is shared between multiple functions or when there is a need to manage the SEM controller access to the ICAP. Ideally, this interface should be driven by a user-defined ICAP arbiter that controls when the different functions have ICAP control and when the SEM controller has access to the ICAP. For more information of the mechanism to sharing the ICAP with the SEM controller, contact AMD.

The following figure shows how the SEM controller behaves when the ICAP arbitration signals are manipulated. There are two potential starting points:

• Controller is in an Observation, Detect only, or Diagnostic Scan state (Starting point 1 in the diagram)
• Controller is being brought up the first time after configuration (Starting point 2 in the diagram)

The white blocks indicates states in which the IP expects to have sole access to the ICAP. The shaded blocks indicates the states in which the IP is not accessing the ICAP.

When using the ICAP Arbitration Interface to relinquish the IP control of its ICAP access (by manipulating the cap_rel and cap_gnt signals), the IP reboots and reinitializes (identical to performing software reset) after the accessed is granted again. Because the IP has no knowledge of whether the configuration memory or settings was manipulated while its access to ICAP was halted, this is the safest method to ensure that the controller functions correctly after ICAP access is granted back to the IP.

If this behavior is undesirable, you can alternatively perform the following manual steps to halt the IP access to the ICAP:

1. Command controller to Idle state.
2. Take over the ICAP access and perform the desired operation(s).
3. After you have completed the desired operation and relinquished access to ICAP, command the controller back to the state you desire (Observation, Detect only, etc.).
4. Using these steps does not cause the IP to reboot and initialize but you are responsible to ensure that the configuration memory and setting have not been manipulated while performing your own operations on the ICAP. This is critical to ensure that the SEM controller continues to function correctly.

If the ICAP sharing function is not used, tie off the interface inputs in the following method:

• cap_gnt = High
• cap_rel = Low