User guide

Table Of Contents
Chapter 10: Transaction Layer Protocol (TLP) Details 10–3
Transaction Layer Routing Rules
December 2013 Altera Corporation Cyclone V Hard IP for PCI Express
User Guide
Transaction Layer Routing Rules
Transactions adhere to the following routing rules:
In the receive direction (from the PCI Express link), memory and I/O requests that
match the defined base address register (BAR) contents and vendor-defined
messages with or without data route to the receive interface. The Application
Layer logic processes the requests and generates the read completions, if needed.
In Endpoint mode, received Type 0 Configuration requests from the PCI Express
upstream port route to the internal Configuration Space and the Cyclone V Hard
IP for PCI Express generates and transmits the completion.
The Hard IP handles supported received message transactions (Power
Management and Slot Power Limit) internally. The Endpoint also supports the
Unlock and Type 1 Messages. The Root Port supports Interrupt, Type 1 and error
Messages.
Vendor-defined Type 0 Message TLPs are passed to the Application Layer.
The Transaction Layer treats all other received transactions (including memory or
I/O requests that do not match a defined BAR) as Unsupported Requests. The
Transaction Layer sets the appropriate error bits and transmits a completion, if
needed. These Unsupported Requests are not made visible to the Application
Layer; the header and data is dropped.
Hot Plug Messages
Attention_indicator On Transmit Receive No Yes No
As per the recommendations in the
PCI
Express Base Specification Revision 2.1
,
these messages are not transmitted to the
Application Layer.
Attention_Indicator
Blink
Transmit Receive No Yes No
Attention_indicator_
Off
Transmit Receive No Yes No
Power_Indicator On Transmit Receive No Yes No
Power_Indicator Blink Transmit Receive No Yes No
Power_Indicator Off Transmit Receive No Yes No
Attention
Button_Pressed
(1)
Receive Transmit No No Yes
Notes to Table 10–1:
(1) In Endpoint mode.
(2) In the PCI Express Base Specification Revision 2.1, this message is no longer mandatory after link training.
Table 10–1. Supported Message Types
(2)
(Part 3 of 3)
Message
Root
Port
Endpoint
Generated by
Comments
App
Layer
Core
Core (with
App Layer
input)