wiki:newport/PCIe

Version 9 (modified by Tim Harvey, 3 months ago) (diff)

updated notes about PCIe gen2/3

Newport PCI/PCIe Support

The CN80XX/CN81XX has three PEM's (PCI Express Interface) internally which are routed to MiniPCIe socket's depending on board and Bootloader configuration (see hwconfig).

CN80XX/CN81XX PEM Features:

  • PCIe root complex (RC) support
  • PCIe Specification v3.0 compliant
  • dedicated reset pin per port/controller
  • PCIe memory-space master support:
    • 256 separate 32bit windows available for direct core access to PCIe memory space in Switch Logic Interface Unit (SLI)
      • Programmable store merging
      • Regions can be combined to form up to a 40bit window
    • Direct core PCIe I/O space and configuration space request generation windows in SLI
    • ECAM support
  • Dected PCIe support summary:
    • Max_Payload_Size up to 256 bytes
    • Readcompletion boundary of 128 bytes
    • ECRC implemented
    • MSI-X implemented for both SR-IOV and non-SR-IOV configurations
    • ASPM support for both L0s and L1 (DLM/PHY power might not be reduced in these states but the power consumed by the link partner may be)
    • Extended tag supported
    • Atomic operations (both 32bit and 64bit CAS, FADD and SWAP)

Mini-PCIe Routing Configuration

Each slot can be configured to be either PCIe, SATA, or USB3. To configure the slots, read about hwconfig

PCIe Pinout

Please see the user manuals here

PCIe Throughput

The CN80XX/CN81XX PCIe host supports up to PCI Gen3 (8.0GT/sec or 6.4Gbps) however this requires a higher co-processor (SCLK) speed (550MHz) than is configured by default (350MHz) on some standard Newport boards. This is a resistor loading option thus can't be changed by software. The decision to default to 350MHz supporting Gen2 (5.0GT/sec or 4Gbps) was made because it saves approximately 500mW of power consumption and the lack of Gen3 miniPCIe card availability.

By default Newport boards support PCI Gen2 (5.0GHz/sec or 4Gbps) which is backwards compatible with PCI Gen1 (2.5GT/sec or 2Gbps).

If you are interested in utilizing PCIe cards up to Gen3 performance (8.0GGT/sec or 6.4Gbps) please contact sales@…. A resistor modification is required on the board to do move SCLK from 350MHz to 550Mhz.

Note that the GW640x boards have a coprocessor clock running at 550MHz required for the QSGMII phy and as such the GW640x will configure the PCIe host controllers for 8.0GT/sec for Gen3 rates.

The bus speed represents a theoretical maximum throughput and does not account for host processing speed or bus contention from multiple masters.

PCIe Reset

PCI Reset signals (PERST#) are routed to the Mini-PCIe slots. On the Newport boards each Mini-PCIe socket has its own dedicated PCI Reset (PERST#) signal. These signals are managed during PCI enumeration by the software drivers in the BDK (Boot firmware) and the Linux kernel.

If you wish to manually assert these signals (which should never be done for an actual PCIe device as it would likely require re-enumeration but may be useful for a non-PCIe device in a miniPCIe socket like a modem) you can use the RST_SOFT_PRST register.

You can use the following script to assert PERST# for PEM0, PEM1, or PEM2 on a Newport board:

#/bin/sh
PEM=$1

[ "$PEM" -ge 0 -a "$PEM" -le 2 ] || {
   echo "Error: $0 [0|1|2]"
   exit 1
}
RST_SOFT_PRST=$((0x87e0060016c0 + $((1*8)) ))
printf "PEM%d 0x%x\n" $PEM $RST_SOFT_PRST

devmem2 $RST_SOFT_PRST b 1 # assert low
sleep 1
devmem2 $RST_SOFT_PRST b 0 # assert high

The following table shows the mapping of the three CN80XX PEM's to miniPCIe socket:

Board PEM miniPCIe Socket Notes
GW610x PEM2 J6 Provides USB2 as well as PCIe, mSATA, or USB3 (see hwconfig)
GW620x PEM0 J6 Provides USB2 as well as PCIe, mSATA, or USB3 (see hwconfig)
PEM2 J8 Provides USB2 and PCIe
GW630x PEM0 J9 Provides USB2 and PCIe
PEM1 J11 Provides USB2 as well as PCIe or USB3 (see hwconfig)
PEM2 J10 Provides USB2 and PCIe or mSATA (see hwconfig)
GW640x PEM0 J9 Provides USB2 and PCIe
PEM1 J11 Provides USB2 and PCIe
PEM2 J10 Provides USB2 and PCIe or mSATA (see hwconfig)
N/A J12 Provides USB2 and USB3 (PERST# is floating and not driven - no way to reset)

Mini-PCIe Mechanical Specification

Please see here: Mini-PCIe Mechanical

See also