OpenThread platform integration in BPI R4 with silabs

Scope

Goal is to understand and bringup required platform for supporting thread in RDK-B Bananapi R4 with silabs module

Hardware used

•  Silabs xG24 Explorer Kit (brd2703a)

Where to purchase hardware

• https://www.silabs.com/development-tools/wireless/efr32xg24-explorer-kit?tab=overview

Highlevel block

• otbr

Kernel side changes

• Minimal kernel changes

  • CONFIG_USB_ACM=y

    • drivers/usb/class/Makefile

    • Description - ACM support for UART communication

  • CONFIG_TUN=y

    • drivers/net/tap.c

    • Description - TUN generic  support 

  • CONFIG_IEEE802154=y

    • net/ieee802154

    • Description - Generic IEEE802154

  • CONFIG_MAC802154=y

    • net/mac802154

    • Description - Generic MAC layer for IEEE802154

User space code changes

• cpcd

  • https://gerrit.teamccp.com/plugins/gitiles/rdk/yocto_oe/layers/meta-rdk-comcast-broadband/+/refs/heads/25Q1_sprint/recipes-connectivity/cpcd

• otbr-agent

  • https://gerrit.teamccp.com/#/c/887931/

Yocto changes

• Image install changes in BPI

  • otbrinstall11

Runtime changes

• cpcd.conf

  • set disable_encryption to true

• cpcd.service

  • Remove ExecStartPre=/usr/bin/init-iot-radio.sh

• Directory creation

  • mkdir /nvram/icontrol/etc/thread

• otbr-agent.service

  • update debug level to 7 from 5 

Testing

• cpcd service should be up and running
• otbr-agent service should be up and running
• ot-ctl shoule be accessible and get state

  • W:~# ot-ctl 
    > state
    disabled
    Done
    > 

Firmware upgrade of BRD module

• Use simplicity studio
  • Use commander tool 
  • Installed software in ubuntu and connected module with USB Type C
• Get Approval from Thomas Lea to get access to the firmware - rcp-multi-all-4.4.5-2-brd2703a.hex

Documentation

• https://docs.silabs.com/multiprotocol/latest/multiprotocol-solution-linux/

Key check points when we land in issues

• Make sure we have wpan0 interface up
• brlan0 should be up and running
• who creates wpan0
  • otbr-agent
  • More technical explanation
    • Initial OTBR-agent startup:
      • OTBR-agent process starts
      • At this point, no wpan0 interface exists yet
      • No socket exists yet at /run/openthread-wpan0.sock
    • OTBR-agent creates socket:
      • Creates Unix domain socket at /run/openthread-wpan0.sock
      • This socket will be used for IPC/control operations
    • OTBR-agent creates network interface:
      • Creates the wpan0 network interface
      • Takes ownership of managing this interface
    • Runtime dependencies:
      • The wpan0 interface is ONLY available while OTBR-agent is running
      • If OTBR-agent stops, the wpan0 interface goes away
      • Other services/processes should not expect wpan0 to exist without OTBR-agent running
    • Communication flow:
      • Other processes can communicate with OTBR-agent through the socket at /run/openthread-wpan0.sock
      • Network traffic goes through the wpan0 interface managed by OTBR-agent