Watchdog Integration
The Infuse-IoT watchdog wrapper integrates the Zephyr watchdog API into other Infuse-IoT subsystems, normalises hardware capabilities, and adds new features.
The wrapper automatically uses the watchdog device from the watchdog0 alias:
aliases {
watchdog0 = &wdog0;
};
Integrated Subsystems
Several Infuse-IoT subsystems automatically claim watchdog channels to ensure that critical system threads are operating normally:
Remote Procedure Calls (RPC): Command processing thread
ePacket: Packet processing thread
Task Runner: Infuse Workqueue thread
Software Pre-Warning
For use cases where large amounts of work need to be performed on watchdog expiry, and the hardware
automatically reboots the device too quickly, the wrapper implements a software pre-warning feature,
CONFIG_INFUSE_WATCHDOG_SOFTWARE_WARNING. This warning is implemented on top of standard
Zephyr kernel timers, and calls infuse_watchdog_warning() a configurable time before the
hardware watchdog would expire.
The default behaviour of this warning is to immediately reboot the device after storing reboot reason information.
Note
This feature does not replace the hardware channels, which will still expire normally if the software warning callback fails to run or blocks.
Software Multi-channel Emulation
When the underlying watchdog only implements a single hardware watchdog channel, the Infuse-IoT
integration can simulate multiple hardware channels in software, enabled by
CONFIG_INFUSE_WATCHDOG_SW_MULTICHANNEL. This is achieved by only feeding the hardware
channel once every allocated software channel has fed the watchdog, and is transparent to watchdog
users.