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Time-Sensitive Networking (TSN) is a set of standards under development by the Time-Sensitive Networking task group of the IEEE 802.1 working group.

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TSN user space utilities and sample configurations are provided to enable TSN functionality. Please refer to the TSN SW user guide and the following sections for more details.

Kernel Configuration

The following config options should be enabled in order to build the TSN Subsystem:

CONFIG_XILINX_TSN

CONFIG_AXIENET_HAS_TADMA

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Please refer to PL Ethernet and DMA documentation for additional information: Documentation/devicetree/bindings/net/xilinx_axienet.txt

For more details on phy bindings please refer "Documentation/devicetree/bindings/net/phy.txt"

TSN System

  • Xilinx’s TSN IP Switch has three ports Endpoint (Port 0), MAC1 (Port 1) and MAC2 (Port 2)
  • Endpoint is connected to MCDMA (Multichannel DMA), each MCDMA channel is a dedicated channel for each type of traffic, i.e. Best Effort, Scheduled Traffic and Reserved. There could be other use cases where there would be separate channels for management traffic
  • MAC1 is connected to external world by PHY1
  • MAC2 is connected to external world by PHY2      

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You would observe that every second 12 ST packets are sent of which 8 packets are sent in the 100us of 10 ms cycle and the rest 4 packets are sent in the next cycle.

As we can see in the above picture, from 4th packet until 11th packet (8 packets) are received sequentially and the next packet starts after 10ms delay (packet no. 12).

Running IPIC:

IP interception translates the transmit packet with the configured source, destination MAC addresses, VLAN ID and PCP values if the packets' IPv4 tuples (source IP, destination IP, DSCP, protocol, source port number and destination port number) match. IPIC module maintains hash entries of IPv4 tuples and if the out-going packets' tuple data match with that of hash entries , translates the IP stream.

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1. Change MAC addresses (if two xilinx boards are used back to back).
2. Launch lldpad daemon.

# lldpad -d

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4. Bring up the network interfaces.
5. Establish PTP sync, run qbv on tx side.
6. Add switch CAM entries as necessary, and send traffic, both ST and BE (express and preemptable) from tx side.
7. Run br_prog <interface name> stats, check if the TX MAC MERGE FRAGMENT COUNT(on tx side), RX MAC MERGE FRAGMENT COUNT(On rx side), are increasing.

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→ TSN PCP values are mandatory and there are no default values for PCP if not chosen as described in the section "PCP and Traffic Class".


Changelog

2022.2

  • Bug fixes.
  • Removed Hard coded interface names for tsn interfaces.
  • Set default PCP to queue mapping, incase its not defined via bootargs.

2022.1

  • TSN kernel driver support added to staging area

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