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5.7. 64- or 128-Bit Avalon-MM Bridge Register Descriptions
The CRA Avalon-MM slave module provides access control and status registers in the PCI Express Avalon-MM bridge. In addition, it provides access to selected Configuration Space registers and link status registers in read-only mode. This module is optional. However, you must include it to access the registers.
The control and status register address space is 16 KB. Each 4 KB sub-region contains a set of functions, which may be specific to accesses from the PCI Express Root Complex only, from Avalon‑MM processors only, or from both types of processors. Because all accesses come across the interconnect fabric—requests from the Avalon‑MM Arria® V GZ Hard IP for PCI Express are routed through the interconnect fabric—hardware does not enforce restrictions to limit individual processor access to specific regions. However, the regions are designed to enable straight-forward enforcement by processor software. The following figure illustrates accesses to the Avalon‑MM control and status registers from the Host CPU and PCI Express link.
The following table describes the four subregions.
Address Range |
Address Space Usage |
---|---|
0x0000-0x0FFF |
Registers typically intended for access by PCI Express link partner only. This includes PCI Express interrupt enable controls, write access to the PCI Express Avalon-MM bridge mailbox registers, and read access to Avalon-MM-to-PCI Express mailbox registers. |
0x1000-0x1FFF |
Avalon-MM-to-PCI Express address translation tables. Depending on the system design these may be accessed by the PCI Express link partner, Avalon-MM processors, or both. |
0x2000-0x2FFF |
Root Port request registers. An embedded processor, such as the Nios II processor, programs these registers to send the data for Configuration TLPs, I/O TLPs, single dword Memory Read and Write requests, and receive interrupts from an Endpoint. |
0x3000-0x3FFF |
Registers typically intended for access by Avalon-MM processors only. Provides host access to selected Configuration Space and status registers. |
The following table lists the complete address map for the PCI Express Avalon-MM bridge registers.
Address Range |
Register |
---|---|
0x0040 |
Avalon-MM to PCI Express Interrupt Status Register |
0x0050 |
Avalon-MM to PCI Express Interrupt Status Enable Register |
0x0800–0x081F |
PCI Express-to-Avalon-MM Mailbox Registers |
0x0900–x091F |
Avalon-MM to PCI Express Mailbox Registers |
0x1000–0x1FFF |
Avalon-MM to PCI Express Address Translation Table |
0x2000–0x2FFF |
Root Port TLP Data Registers |
0x3060 |
Avalon-MM to PCI Express Interrupt Status Registers for Root Ports |
0x3060 |
PCI Express to Avalon-MM Interrupt Status Register for Endpoints |
0x3070 |
INT-X Interrupt Enable Register for Root Ports |
0x3070 |
INT-X Interrupt Enable Register for Endpoints |
0x3A00-0x3A1F |
Avalon-MM to PCI Express Mailbox Registers |
0x3B00-0x3B1F |
PCI Express to Avalon-MM Mailbox Registers |
0x3C00-0x3C6C |
Host (Avalon-MM master) access to selected Configuration Space and status registers. |