SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
As part of the standard enumeration process, the RC maps all the I/O BARs it finds (while discovering the connected EP functions) into the 4 GiB I/O address space (32-bit address).
An ATU outbound region shall then be programmed to map a zone of the I/O space into the controller target’s outbound window, accessed through the slave port.
Initiators in the RC host (typically a local CPU) can then access I/O space by initiating (1 DWORD) read/write accesses to the ATU region’s range on the controller’s slave port on L3_MAIN.
There is NO specific hardware mechanism to notify the RC that it is allowed to issue I/O requests, since that configuration decision comes from the RC in the first place.