Theory Of Operation; Introduction; Transaction Routing; Interrupts - Renesas IDT 89HPES48H12G2 User Manual

Notes
PES48H12G2 User Manual
®

Introduction

Each PES48H12G2 partition operates logically as a completely independent PCI Express switch that
implements the behavior and capabilities required of a switch by the PCI Express Base 2.0 specification.
This chapter describes the PES48H12G2-specific architectural behavior for the PCI Express switch associ-
ated with each partition.

Transaction Routing

The switch supports routing of all transaction types defined in PCI Express Base Specification Revision
2.0. This includes routing of specification defined transactions as well as those that may be used in vendor
defined messages and in future revisions of the PCI Express specification. Specifically, the PES48H12G2
supports the following type of routing:
– Address routing with 32-bit or 64-bit format
– ID based routing using bus, device and function numbers.
– Implicit routing utilizing
• Route to root
• Broadcast from root
• Local - terminate at receiver
• Gathered and routed to root
A summary of TLP types that use the above routing methods is provided in Table 9.1.
Routing Method
Route by Address
ID Based Routing
Imlicit Routing - Route to Root
Implicit Routing - Broadcast from Root
Implicit Routing - Local
Implicit Routing - Gathered and Routed to
1
Root
1.
The only Gathered and Routed to Root message supported is a PME_TO_Ack message received on a downstream
port.

Interrupts

When an unmasked interrupt condition occurs, an MSI or interrupt message is generated by the corre-
sponding port as described in Table 9.2. The removal of the interrupt condition occurs when unmasked
status bit(s) causing the interrupt are masked or cleared. The PES48H12G2 assumes that all generated
MSIs target the root and routes these transactions to the upstream port. Configuring the address contained
in a downstream port's MSIADDR and MSIADDRU registers to an address that does not route to the
upstream port and generating an MSI produces undefined results.

Theory of Operation

TLP Type Using Routing Method
MRd, MrdLk, MWr, IORd, IOWr, Msg, MsgD
CfgRd0, CfgWr0, CfgRd1, CfgWr1, TCfgRd, TCfgWr, Cpl,
CpdD, CplLk, CplDLk, Msg, MsgD
Msg, MsgD
Msg, MsgD
Msg, MsgD
Only supported for PME_TO_Ack messages in response to a
root initiated PME_Turn_Off message.

Table 9.1 Switch Routing Methods

9 - 1
Chapter 9
April 5, 2013