AXI Bridge for PCI Express v2.4
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PG055 June 4, 2014
Chapter 3:
Designing with the Core
• Accessing the Bridge AXIBAR_0 with address
0x12340ABC
on the AXI bus yields
0x56710ABC
on the bus for PCIe.
• Accessing the Bridge AXIBAR_1 with address
0xABCDF123
on the AXI bus yields
0x50000000FEDC1123
on the bus for PCIe.
• Accessing the Bridge AXIBAR_2 with address
0xFFFEDCBA
on the AXI bus yields
0x41FEDCBA
on the bus for PCIe.
• Accessing the AXI M S PCIe Bridge AXIBAR_3 with address
0x00000071
on the AXI bus
yields
0x60000000876543F1
on the bus for PCIe.
Addressing Checks
When setting the following parameters for PCIe address mapping, C_PCIE2AXIBAR_n and
C_PCIEBAR_LEN_n, be sure these are set to allow for the 32-bit addressing space on the AXI
system. For example, the following setting is illegal and results in an invalid AXI address.
C_PCIE2AXIBAR_0 = 0xFFFF_0000
C_PCIEBAR_LEN_0 = 23
Also, check for a larger value on C_PCIEBAR_LEN_n compared to the value assigned to
parameter, C_PCIE2AXIBAR_n. For example, the following parameter settings.
C_PCIE2AXIBAR_0 = 0xFFFF_E000
C_PCIEBAR_LEN_0 = 20
To keep the AXIBAR upper address bits as 0xFFFF_E000 (to reference bits [31:13]), the
C_PCIEBAR_LEN_0 parameter must be set to 13.
Interrupts
This section describes the interrupt pins which include Local, MSI and Legacy Interrupts.
Local Interrupts
The
interrupt_out
pin can be configured to send interrupts based on the settings of the
Interrupt Mask register. The
interrupt_out
pin signals interrupts to devices attached to
the memory mapped AXI4 side of the Bridge. The MSI interrupt defined in the Interrupt
Mask & Interrupt Decode registers is used to indicate the receipt of a Message Signaled
Interrupt only when the bridge is operating in Root Port mode (C_INCLUDE_RC=1).