feat(devkit): add watchdog timer 30 second (Devkit)

[harshithsunku]

• Add wdog_facade module (30s timeout, SoC reset on expiry)

• Initialize watchdog in main.c at boot

• Integrate task-level watchdog: only feed if pusher thread is alive

• Add pusher_check_and_reset_alive() to transport.c for thread monitoring

• Disable watchdog before system power-off in button.c

• Enable CONFIG_WATCHDOG in devkit v2 config
  [devkit2] - watchdog timer with a 30s timeout #3434

[gemini-code-assist]

Code Review

This pull request introduces a watchdog timer with a 30-second timeout, significantly enhancing system robustness. The implementation correctly includes early initialization during boot, task-level monitoring of the pusher thread, and proper deinitialization before system power-off. The use of atomic operations for thread liveness checks is an appropriate and thread-safe approach.

[gemini-code-assist]

The watchdog_deinit function does not check if wdt_dev is NULL before calling wdt_disable. If watchdog_init fails (e.g., the watchdog device is not ready), wdt_dev might remain NULL. Calling wdt_disable with a NULL device pointer could lead to a system crash. It's important to ensure wdt_dev is valid before attempting to disable the watchdog.

    if (wdt_dev) {
        return wdt_disable(wdt_dev);
    }
    return 0;

[harshithsunku]

Hi @TuEmb ,

Ported watchdog support to devkit. The original implementation only feeds the watchdog from the main loop. I've added task-level monitoring for the pusher thread as a sample. Should I extend this to other threads, or should we keep the watchdog feed only in main like the original?

My recommendation: Extending to other threads would be better since any hung thread can cause the device to become unresponsive, not just main. The main loop running doesn't guarantee the whole system is healthy.