Zynq UltraScale+ MPSoC/RFSoC

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

# 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>;
};

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.

&watchdog0 {
    status = "okay";
};

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

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

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 content
YAML_COMPILER_FLAGS_append = " -DENABLE_EM -DENABLE_SCHEDULER"