R-tile Avalon® Streaming Intel® FPGA IP for PCI Express* User Guide

ID 683501
Date 12/13/2021
Public

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4.4.3.1. Legacy Interrupts

Legacy interrupts mimic the original PCI level-sensitive interrupts using virtual wire messages. The R-tile IP for PCIe signals legacy interrupts on the PCIe link using Message TLPs. The term INTx refers collectively to the four legacy interrupts, INTA#,INTB#, INTC# and INTD#. The R-tile IP for PCIe asserts app_int_i to cause an Assert_INTx Message TLP to be generated and sent upstream. A deassertion of app_int_i, i.e a transition of this signal from high to low, causes a Deassert_INTx Message TLP to be generated and sent upstream. To use legacy interrupts, you must clear the Interrupt Disable bit, which is bit 10 of the Command Register in the configuration header. Then, you must turn off the MSI Enable bit.

Table 59.  Legacy Interrupts
Signal Name Direction Description EP/RP/BP Clock Domain

pX_app_int_i[7:0]

Input When asserted, these signals indicate an assertion of an INTx message is requested. A transition from high to low indicates a deassertion of the INTx message is requested. This bus is for Endpoints only. Each bit is associated with a corresponding physical function. EP slow_clk
pX_app_int_ready_o[7:0] Output One bit per physical function. The new app_int_i value should be held until app_int_ready_o=1. EP slow_clk
pX_irq_status_o Output

These signals drive legacy interrupts to the Application Layer in Root Port mode. The source of the interrupt is logged in the Root Port Interrupt Status registers in the Port Configuration and Status registers.

RP slow_clk

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