Kernel Configuration

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

Device tree and Build Configurations

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

Zynq7000

1. Zynq7000 platform device-tree can be found in https://github.com/Xilinx/device-tree-xlnx/blob/xlnx_rel_v2021.2/device_tree/data/kernel_dtsi/2021.2/zynq/zynq-7000.dtsi#L455-L462
   

   zynq-7000.dtsi

   watchdog0: watchdog@f8005000 {
           clocks = <&clkc45>;
           compatible = "cdns,wdt-r1p2";
           interrupt-parent = <&&intc>;
           interrupts = <0 9 1>;
           reg = <0xf8005000 0x1000>;
           timeout-sec = <10>;
   };

2. Modify the device tree in <plnx-proj-root>/project-spec/meta-user/recipes-bsp/device-tree/files/system-user.dtsi as below and rebuild your project. 
   

   system-user.dtsi

   &watchdog0 {
       status = "okay";
   };

   
   

3. If user want the watchdog to trigger a software reset/reboot upon time out then add "reset-on-timeout" in device tree node.

   system-user.dtsi

   &watchdog0 {
       status = "okay";
       reset-on-timeout;
   };

Zynq UltraScale+ MPSoC/RFSoC

1. ZynqMP platform device-tree can be found in https://github.com/Xilinx/device-tree-xlnx/blob/xlnx_rel_v2021.2/device_tree/data/kernel_dtsi/2021.2/zynqmp/zynqmp.dtsi#L1043-L1051
   

   zynqmp.dtsi

   # timeout-sec value is set to 10s in 2018.2 and below release and 60s in 2018.3 and later release.
   watchdog0: watchdog@fd4d0000 {
           compatible = "cdns,wdt-r1p2";
           status = disabled;
           interrupt-parent = <&gic>;
           interrupts = <0 113 1>;
           reg = <0x0 0xfd4d0000 0x1000>;
           timeout-sec = <60>;
   };

2. 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. 
   

   system-user.dtsi

   &watchdog0 {
       status = "okay";
   };

   
   

3. 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 Zynq UltraScale+ MPSoC/RFSoC so you need add PMU firmware elf packaged as part of BOOT.bin

   system-user.dtsi

   &watchdog0 {
       status = "okay";
       reset-on-timeout;
       timeout-sec = <10>;
   };

4.  For 2017.1 or later PetaLinux ENABLE_EM needs to be enabled from PMUFW, For more details refer PetaLinux Yocto Tips and PMU Firmware#PMUFWBuildFlags

   # For 2017.4 and below PetaLinux/Yocto release only
   $ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu/pmu-firmware_%.bbappend
    
   #For v2018.1 to v2020.2 PetaLinux/Yocto releases only
   $ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/pmu-firmware/pmu-firmware_%.bbappend
   
   # For v2021.1 PetaLinux/Yocto releases only
   $ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/emebdeddedsw/pmu-firmware_%.bbappend
   
   # For v2021.2 and later PetaLinux/Yocto releases only
   $ vim <plnx-proj-root>/project-spec/meta-user/recipes-bsp/embeddedsw/pmu-firmware_%.bbappend

   pmu-firmware_%.bbappend

   # pmu-firmware_%.bbappend content
   YAML_COMPILER_FLAGS_append = " -DENABLE_EM -DENABLE_SCHEDULER"

Test Procedure

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

   # echo s > /dev/watchdog0

2. If reset-on-timeout and timeout-sec device-tree node property is enabled in watchdog node, then PMUFW will reset the system and expected output as shown below.
   
   

   ZCU102 board

   PetaLinux 2018.2 xilinx-zcu102-2018_2 /dev/ttyPS0
   
   xilinx-zcu102-2018_2 login: root
   Password:
   root@xilinx-zcu102-2018_2:~#
   root@xilinx-zcu102-2018_2:~# dmesg | grep wdt
   [    1.669543] cdns-wdt fd4d0000.watchdog: Xilinx Watchdog Timer at ffffff800913d000 with timeout 10s
   root@xilinx-zcu102-2018_2:~#
   root@xilinx-zcu102-2018_2:~# echo s > /dev/watchdog0
   [   66.480417] watchdog: watchdog0: watchdog did not stop!
   root@xilinx-zcu102-2018_2:~# Xilinx Zynq MP First Stage Boot Loader
   Release 2018.2   Oct 31 2018  -  15:24:39
   NOTICE:  ATF running on XCZU9EG/silicon v4/RTL5.1 at 0xfffea000
   NOTICE:  BL31: Secure code at 0x0
   NOTICE:  BL31: Non secure code at 0x10080000
   NOTICE:  BL31: v1.4(release):xilinx-v2018.1-4-g93a69a5a
   NOTICE:  BL31: Built : 21:21:00, Oct 31 2018
   PMUFW:  v1.0

3. If reset-on-timeout device-tree node property is not enabled in watchdog node, then PMUFW will not reset the system and expected output as shown below.

   cdns-wdt fd4d0000.watchdog: Watchdog timed out.

Mainline Status

• This driver is currently in sync with the mainline kernel

Change Log

• 2024.2

  • None

•  2024.1

  • None

•  2023.2

  • None

•  2023.1

  • None

Related Links

• Linux Drivers