Cadence WDT Driver

Introduction

This page gives an overview of the WDT driver which is available as part of the Zynq and ZynqMP Linux distribution and in the mainline.
Paths, files, links and documentation on this page are given relative to the Linux kernel source tree.

HW IP Features

  • Configurable timeout interval in seconds.
  • Reset on timeout can be selected.

Known Issues and Limitations


Kernel Configuration

The following config options should be enabled in order to build the wdt driver:
CONFIG_CADENCE_WATCHDOG
CONFIG_XILINX_WATCHDOG




Devicetree
For more details, please refer "Documentation/devicetree/bindings/watchdog/cadence-wdt.txt"

For Zynq7000:
Example: In <plnx-proj-root>/components/plnx_workspace/device-tree/device-tree-generation/zynq-7000.dtsi
Modify the device tree source in <plnx-proj-root>/project-spec/meta-user/recipes-bsp/device-tree/files/system-user.dtsi as below and rebuild your project.
If you want the watchdog to trigger a software reset/reboot upon time out then add "reset-on-timeout" in device tree node.
For ZynqMP:
Example: In <plnx-proj-root>/components/plnx_workspace/device-tree/device-tree-generation/zynqmp.dtsi
Modify the device tree source in <plnx-proj-root>/project-spec/meta-user/recipes-bsp/device-tree/files/system-user.dtsi as below and rebuild your project.
If user want the watchdog to trigger a software reset/reboot upon time out then add "reset-on-timeout" in device tree node. Software reset is handled in PMU firmware for ZynqMP so you need add PMU firmware in your BOOT.bin
Note: For 2017.1 or later PetaLinux ENABLE_EM needs to be enabled from PMUFW
Reference Link: https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842475/PetaLinux+Yocto+Tips  PMU Firmware#PMUFWBuildFlags

Test procedure

Note:
In case of zynqMP WDT 1 must be enabled at the h/w level.

Start the watchdog timer and see if it runs out without enabling reset.

Expected Output

//after 10 seconds

If reset-on-timeout property is present in the watchdog node
Without reset-on-timeout property in the watchdog node

Mainline Status

  • This driver is currently in sync with the mainline kernel

Change Log

  • 2020.2
    • None
  • 2020.1
    • None
  • 2019.2
    • Summary
      • watchdog: cadence: Changed dev_err to dev_warn
      • watchdog: cadence: Avoid printing pointer value
    • Commits
      • 70685663  watchdog: cadence: Changed dev_err to dev_warn
      • e7ea8156  watchdog: cadence: Avoid printing pointer value
  • 2019.1
    • None
  • 2018.3
    • None
  • 2018.2
    • None
  • 2018.1
    • None
  • 2017.4
    • None
  • 2017.3
    • Summary
      • watchdog: cadence_wdt: Fix issue with timeout-sec dt property
      • watchdog: cadence_wdt: make of_device_ids const.
      • watchdog: cadence_wdt: Enable access to module parameters
      • watchdog: cadence_wdt: Show information when driver is probed
    • Commits
      • 33ca085 watchdog: cadence_wdt: Fix issue with timeout-sec dt property
      • e51604b watchdog: cadence_wdt: make of_device_ids const.
      • 98dde08 watchdog: cadence_wdt: Enable access to module parameters
      • cf698e7 watchdog: cadence_wdt: Show information when driver is probed
  • 2017.2
    • None
  • 2017.1
    • Summary
      • watchdog: cadence_wdt: Fix the suspend resume.
      • watchdog: constify watchdog_ops structures.

    • Commits
      • eadc4fe watchdog: cadence_wdt: Fix the suspend resume.
      • 85f15cf watchdog: constify watchdog_ops structures.

  • 2016.4
    • None
  • 2016.3
    • None

Related Links