MSI-X Interrupt External Interface - 1.0 English

Versal Adaptive SoC Integrated Block for PCI Express LogiCORE IP Product Guide (PG343)

Document ID
PG343
Release Date
2024-05-30
Version
1.0 English
Table 1. MSI-X Interrupt External Interface Port Descriptions
Name I/O Width Description
cfg_interrupt_msix_enable O

4 in PL-PCIE4

1 in PL-PCIE5

Configuration Interrupt MSI-X Function Enabled

These outputs reflect the setting of the MSI-X Enable bits of the MSI-X Control Register of Physical Functions 0 – 3.

Note: In PL-PCIE5, only the Function 0 setting is indicated. For subsequent functions, the wrreq interface is used.
cfg_interrupt_msix_mask O

4 in PL-PCIE4

1 in PL-PCIE5

Configuration Interrupt MSI-X Function Mask

These outputs reflect the setting of the MSI-X Function Mask bits of the MSI-X Control Register of Physical Functions 0 – 3.

Note: In PL-PCIE5, only the Function 0 setting is indicated. For subsequent functions, the wrreq interface is used.
cfg_interrupt_msix_vf_enable O 252 Configuration Interrupt MSI-X Enable from VFs

These outputs reflect the setting of the MSI-X Enable bits of the MSI-X Control Register of Virtual Functions 0 – 251.

cfg_interrupt_msix_vf_mask O 252 Configuration Interrupt MSI-X VF Mask

These outputs reflect the setting of the MSI-X Function Mask bits of the MSI-X Control Register of Virtual Functions 0 – 251.

cfg_interrupt_msix_address I 64 Configuration Interrupt MSI-X Address

When the core is configured to support MSI-X interrupts and when the MSI-X Table is implemented in user memory, this bus is used by the user logic to communicate the address to be used to generate an MSI-X interrupt.

cfg_interrupt_msix_data I 32 Configuration Interrupt MSI-X Data

When the core is configured to support MSI-X interrupts and when the MSI-X Table is implemented in user memory, this bus is used by the user logic to communicate the data to be used to generate an MSI-X interrupt.

cfg_interrupt_msix_int I 1 Configuration Interrupt MSI-X Data Valid

The assertion of this signal by the user indicates a request from the user to send an MSI-X interrupt. The user must place the identifying information on the designated inputs before asserting this interrupt.

When the MSI-X Table and Pending Bit Array are implemented in user memory, the identifying information consists of the memory address, data, and the originating Function number for the interrupt.

These must be placed on the cfg_interrupt_msix_address[63:0], cfg_interrupt_msix_data[31:0], and cfg_interrupt_msi_function_number[7:0], respectively. The core internally registers these parameters on the 0-to-1 transition of cfg_interrupt_msix_int.

When the MSI-X Table and Pending Bit Array are implemented by the core, the identifying information consists o the originating Function number for the interrupt and the interrupt vector.

These must be placed on cfg_interrupt_msi_function_number[7:0] and cfg_interrupt_msi_int[31:0], respectively.

Bit i of cfg_interrupt_msi_int[31:0] represents interrupt vector i, and only one of the bits of this bus can be set to 1 when asserting cfg_interrupt_msix_int.

After asserting an interrupt, the user logic must wait for the cfg_interrupt_msi_sent or cfg_interrupt_msi_fail indication from the core before asserting a new interrupt.

cfg_interrupt_msix_vec_pending I 2 Configuration Interrupt MSI-X Pending Bit Query/Clear

These mode bits are used only when the core is configured to include the MSI-X Table and Pending Bit Array. These two bits are set when asserting cfg_interrupt_msix_int to send an MSI-X interrupt, to perform certain actions on the MSI-X Pending Bit associated with the selected Function and interrupt vector. The various modes are:

  • 00b: Normal interrupt generation. If the Mask bit associated with the vector was 0 when cfg_interrupt_msix_int was asserted, the core transmits the MSI-X request TLP on the link. If the Mask bit was 1, the core does not immediately send the interrupt, but instead sets the Pending Bit associated with the interrupt vector in its MSI-X Pending Bit Array (and subsequently transmits the MSI-X request TLP when the Mask clears). In both cases, the core asserts cfg_interrupt_msi_sent for one cycle to indicate that the interrupt request was accepted. The user can distinguish these two cases by sampling the cfg_interrupt_msix_vec_pending_status output, which reflects the current setting of the MSI-X Pending Bit corresponding to the interrupt vector.
  • 01b: Pending Bit Query. In this mode, the core treats the assertion of one of the bits of cfg_interrupt_msix_int as a query for the status of its Pending Bit. The user must also place the Function number of the Pending Bit being queried on the cfg_interrupt_msi_function_number input. The core does not transmit a MSI-X request in response, but asserts cfg_interrupt_msi_sent for one cycle, along with the status of the MSI-X Pending Bit on the cfg_interrupt_msix_vec_pending_status output.
  • 10b: Pending Bit Clear. In this mode, the core treats the assertion of one of the bits of cfg_interrupt_msix_int as a request to clear its Pending Bit. The user must also place the Function number of the Pending Bit being queried on the cfg_interrupt_msi_function_number input. The core does not transmit a MSI-X request in response, but clears he MSI-X Pending Bit of the vector (if it is set), and activates cfg_interrupt_msi_sent for one cycle as the acknowledgment. The core also provides the previous state of the MSI-X Pending Bit on the cfg_interrupt_msix_vec_pending_status output, which can be sampled by the user to determine if the Pending Bit was cleared by the core before the user request (because the pending interrupt was actually transmitted). This mode can be used to implement a “polling mode” for MSI-X interrupts, where the interrupt is permanently masked and the software polls the Pending Bit to detect and service the interrupt. After each interrupt is serviced, the Pending Bit can be cleared through this interface.
cfg_interrupt_msix_vec_pending_status O 1 Configuration Interrupt MSI-X Pending Bit Status

This output provides the status of the Pending Bit associated with an MSI-X interrupt, in response to query using the cfg_interrupt_msix_vec_pending input.

It is active only when the core is configured to include the MSI-X Table and Pending Bit Array.