User guide

6–12 Chapter 6: IP Core Architecture
Multi-Function Support
Cyclone V Hard IP for PCI Express December 2013 Altera Corporation
User Guide
Multi-Function Support
The Cyclone V Hard IP for PCI Express supports up to eight functions for Endpoints.
You set up the each function under the Port Functions heading in the parameter
editor. You can configure Cyclone V devices to include both Native and Legacy
Endpoints. Each function replicates the Configuration Space Registers, including logic
for Tag Tracking and Error detection.
Because the Configuration Space is replicated for each function, some Configuration
Space Register settings may conflict. Arbitration logic resolves differences when
settings contain different values across multiple functions. The arbitration logic
implements the rules for resolving conflicts as specified in the PCI Express Base
Specification 2.1. Examples of settings that require arbitration include the following
features:
■ Link Control settings
■ Error detection and logging for non-function-specific errors
■ Error message collapsing
■ Maximum payload size (All functions use the largest specified maximum payload
setting.)
1 Altera strongly recommends that your software configure the Maximum payload size
(in the
Device Control register) with the same value across all functions.
■ Interrupt message collapsing
You can access the Configuration Space Registers for the active function using the
LMI interface. In Root Port mode, you can also access the Configuration Space
Registers using a Configuration Type TLP. Refer to “Configuration Space Register
Content” on page 8–1 for more information about the Configuration Space Registers.
PCI Express Avalon-MM Bridge
In Qsys, the Cyclone V Hard IP for PCI Express is available with either an Avalon-ST
or an Avalon-MM interface to the Application Layer. When you select the Avalon-MM
Cyclone V Hard IP for PCI Express, an Avalon-MM bridge module connects the PCI
Express link to the interconnect fabric. The bridge facilitates the design of Root Ports
or Endpoints that include Qsys components.
The full-featured Avalon-MM bridge provides three possible Avalon-MM ports: a
bursting master, an optional bursting slave, and an optional non-bursting slave. The
Avalon-MM bridge comprises the following three modules:
■ TX Slave Module—This optional 64- or 128-bit bursting, Avalon-MM dynamic
addressing slave port propagates read and write requests of up to 4 KBytes in size
from the interconnect fabric to the PCI Express link. The bridge translates requests
from the interconnect fabric to PCI Express request packets.
■ RX Master Module—This 64- or 128-bit bursting Avalon-MM master port
propagates PCI Express requests, converting them to bursting read or write
requests to the interconnect fabric. If you select the Single dword variant, this is a
32-bit non-bursting master port.