作者：付汉杰 hankf@amd.com
AMD-Xilinx MPSoC的器件里，提供了内置的Watchdog。在Vivado里选择Watchdog，并在设备树里使能Watchdog，还不能在Linux中正常使用。
pmu-firmware修改
如果要在Linux中使用Watchdog，需要在project-spec/meta-user/recipes-bsp/embeddedsw/pmu-firmware_%.bbappend中添加如下内容：
2021.1以前的版本：
# pmu-firmware_%.bbappend content YAML_COMPILER_FLAGS_append = " -DENABLE_EM -DENABLE_SCHEDULER"
2022.1及以后的版本：
# pmu-firmware_%.bbappend content YAML_COMPILER_FLAGS:append = " -DENABLE_EM -DENABLE_SCHEDULER"
Devicetree
检查Devicetree，确保其中的status为"okay"， 也有属性reset-on-timeout。
watchdog@fd4d0000 {
clocks = <0x03 0x4b>;
compatible = "cdns,wdt-r1p2";
interrupt-parent = <0x04>;
interrupts = <0x00 0x71 0x01>;
phandle = <0x76>;
reg = <0x00 0xfd4d0000 0x00 0x1000>;
reset-on-timeout;
status = "okay";
timeout-sec = <0x3c>;
};
watchdog@ff150000 {
clocks = <0x03 0x70>;
compatible = "cdns,wdt-r1p2";
interrupt-parent = <0x04>;
interrupts = <0x00 0x34 0x01>;
phandle = <0x77>;
reg = <0x00 0xff150000 0x00 0x1000>;
status = "okay";
timeout-sec = <0x0a>;
};启动信息
使用命令“dmesg”检查启动信息，有如下信息。
# dmesg -c | grep watchdog [ 539.845269] watchdog: watchdog0: watchdog did not stop! [ 691.897271] watchdog: watchdog1: watchdog did not stop! [ 702.136679] cdns-wdt ff150000.watchdog: Watchdog timed out. Internal reset not enabled
通过设备节点控制Watchdog
通过设备节点“/dev/watchdog0”可以控制Watchdog。
执行命令“echo s > /dev/watchdog0”，能启动Watchdog，但是没有清狗操作。时间久了，单板会自动重启动。
# echo s > /dev/watchdog0 [ 154.773229] watchdog: watchdog0: watchdog did not stop! # dmesg -c | tail -n 20 [ 154.773229] watchdog: watchdog0: watchdog did not stop! # dmesg -c | tail -n 20 # cat /proc/uptime 193.70 738.72 # Xilinx Zynq MP First Stage Boot Loader Release 2022.1 Apr 11 2022 - 09:29:50 NOTICE: BL31: v2.6(release):v1.1-9207-g67ca59c67
执行命令“echo 'V' > /dev/watchdog0”，能停止Watchdog，单板再也不会自动重启动。
# echo s > /dev/watchdog0 && cat /proc/uptime [ 1850.817370] watchdog: watchdog0: watchdog did not stop! 1850.69 7364.03 # sleep 1 # echo 'V' > /dev/watchdog0 && cat /proc/uptime 1852.40 7370.84 # cat /proc/uptime 1887.11 7509.61 # cat /proc/uptime 1971.67 7847.72 # cat /proc/uptime 2159.96 8600.54
通过应用程序控制Watchdog
Linux也提供了应用程序watchdog控制Watchdog，启动Watchdog并清狗。下面是启动Watchdog的示例。如果由于特殊原因，应用程序watchdog异常退出，就会导致单板复位。下面的例子中，使用kill命令杀死了应用程序watchdog的进程，导致单板复位。
# watchdog -T 10 -t 3 /dev/watchdog0 # ps -A | grep watchdog 95 ? 00:00:00 watchdogd 1159 ? 00:00:00 watchdog # cat /proc/uptime 1880.18 7481.78 # cat /proc/uptime 1895.65 7543.65 # kill -9 1159 # [ 1904.549498] watchdog: watchdog0: watchdog did not stop! # Xilinx Zynq MP First Stage Boot Loader Release 2022.1 Apr 11 2022 - 09:29:50 NOTICE: BL31: v2.6(release):v1.1-9207-g67ca59c67
通过系统脚本启动Watchdog并清狗
Linux也提供系统脚本/etc/init.d/watchdog-init控制Watchdog。
系统脚本/etc/init.d/watchdog-init也使用了应用程序控制Watchdog。如果使用kill命令杀死应用程序watchdog的进程，也会导致单板复位。
# /etc/init.d/watchdog-init start && cat /proc/uptime Set healthy bit /etc/init.d/watchdog-init: line 92: /sys/firmware/zynqmp/health_status: Permission denied Starting WDT 2199.54 8758.78 # ps -A | grep watchdog 95 ? 00:00:00 watchdogd 1110 ? 00:00:00 watchdog # sleep 5 # /etc/init.d/watchdog-init stop && cat /proc/uptime Stoping WDT 2204.62 8779.08 # cat /proc/uptime 2299.32 9157.71 # cat /proc/uptime 2628.22 10472.73
参考文档
测试单板
KV260 2022.1 BSP
