SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Legacy INTx (with x= A/B/C/D) are interrupt events inherited from PCI, where each was implemented on a physical bus wire. The RC can allocate each line to a given EP function, which is then allowed to assert/deassert that line (and only that line). PCI legacy interrupt events are mapped on the MSI interrupt line of PCIe controller. For more details, refer to Section 24.9.4.6.2.1.2 and Section 24.9.4.6.2.1.3.
The controller HW shall both set and clear the IRQ status bit according to the assert and deassert messages received over the PCIe wire, respectively. In other words, the legacy interrupt status bit do not need to be cleared by the local software after processing.
Typical legacy interrupt service routine (ISR) on the RC-configured PCIe controller is: