Utilizing Watchdog Functionality

The goal of the document is to illustrate how to use watchdog of SP7350.

Table of Contents

1 1. Checking Watchdog Device Existence
2 2. Implementing Watchdog Setup and Feeding Application
- 2.1 watchdog.c
- 2.2 Makefile (You need to modify CC path):

1. Checking Watchdog Device Existence

1.1 Checking Watchdog Devices in /dev/

To verify the existence of watchdog devices, execute the command:

ls /dev/watchdog*

Typically, two watchdog devices are present, as illustrated below:

~ # ls -l /dev/watchdog*
crw-rw----    1 root     root       10, 130 Jan  1 00:00 /dev/watchdog
crw-rw----    1 root     root      252,   0 Jan  1 00:00 /dev/watchdog0
~ #

If watchdog devices are not found, ensure to:

Verify if the watchdog node in dts is not set as "disabled".
Confirm the watchdog driver is enabled.

1.2 Verifying Watchdog Node Status in dts

Refer to the watchdog node in DTS:

&watchdog {
  timeout-sec = <10>;
};

1.3 Ensuring Watchdog Driver Enablement

To verify the watchdog driver's status, navigate to the project's top directory and execute:

make kconfig

In the kernel configuration menu, locate "Device Drivers > Watchdog Timer Support > Sunplus watchdog support" and ensure "Sunplus watchdog support" is enabled. Refer to the Linux kernel configuration menu below:

2. Implementing Watchdog Setup and Feeding Application

Refer to the following C example code demonstrating watchdog setup and feeding application. This application configures, initiates, and feeds the watchdog every 12 seconds. The watchdog on SP7350 has no maximum timeout limit.

watchdog.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <pthread.h>
#include <sys/ioctl.h>

#define	WATCHDOG_IOCTL_BASE	'W'

#define	WDIOC_SETOPTIONS	_IOR(WATCHDOG_IOCTL_BASE, 4, int)
#define	WDIOC_KEEPALIVE		_IOR(WATCHDOG_IOCTL_BASE, 5, int)
#define	WDIOC_SETTIMEOUT    _IOWR(WATCHDOG_IOCTL_BASE, 6, int)

#define WDIOS_DISABLECARD   1
#define	WDIOS_ENABLECARD	2

#define	WDIOC_GETTIMELEFT	_IOR(WATCHDOG_IOCTL_BASE, 10, int)

int ret;
int wd_fd;
volatile int wd_feed_time = 12;	// Feed watchdog every 12 second by default.
int wd_timeout = 15;			// Timeout time of watchdog. Reset event occurs if watchdog is not fed within this time.

/* a thread feed dog */
void *feedwdt_thd()
{
    while(1) {
        // Feed (reset) watchdog.
        ret = ioctl(wd_fd, WDIOC_KEEPALIVE, 0);
        if (ret != 0) {
            printf("Feed watchdog failed. \n");
            close(wd_fd);
        } else {
            printf("Feed watchdog every %d seconds.\n", wd_feed_time);
        }

        sleep(wd_feed_time);
    }
}

/* a thread read counter and print the value */
void *readwdt_thd()
{
    int arg;
    int i;

    while(1)
    {
        ret = ioctl(wd_fd, WDIOC_GETTIMELEFT, &arg);
        if (ret != 0) {
            printf("get data failed. \n");
        }
        printf("cnt value is 0x%x\n", arg);
        usleep(200000);
    }
}

int main(void)
{
    pthread_t wd_feed_thread;
    pthread_t wd_read_thread;

    int wd_option;
    char str[10];
    int num = 0;
    char* ptr = str;

    // Get file handle of watchdog device.
    wd_fd = open("/dev/watchdog0", O_WRONLY);
    if (wd_fd == -1) {
        perror("watchdog");
        exit(EXIT_FAILURE);
    }

    // Enable wacthdog.
    wd_option = WDIOS_ENABLECARD;
    ret = ioctl(wd_fd, WDIOC_SETOPTIONS, &wd_option);
    if (ret != 0) {
        printf("Failed to start watchdog!\n");
        close(wd_fd);
        return -1;
    }

    // Setup timeout time.
    ret = ioctl(wd_fd, WDIOC_SETTIMEOUT, &wd_timeout);
    if (ret != 0) {
        printf("Failed to set timeout time!n");
        close(wd_fd);
        return -1;
    } 

    // Create a thread for feeding watchdog.
    ret = pthread_create(&wd_feed_thread, NULL, feedwdt_thd, NULL);
    if (ret < 0)
        printf("Failed to create feeddog thread!\n");
#if 0 
    // Create a thread for reading and printing counter value.
    ret = pthread_create(&wd_read_thread, NULL, readwdt_thd, NULL);
    if (ret < 0)
        printf("Failed to create read counter thread!\n");
#endif
    while(1) {
        printf("Press 'e' to disable watchdog and exit.\n");
        printf("Enter a number for new feed time (current feed time is %d seconds, timeout time is %d seconds):\n", wd_feed_time, wd_timeout);
        scanf("%s", str);
        //printf("debug why feedtime invarible  %s\n",str);

        if (!strcmp(str,"e")) {
            wd_option = WDIOS_DISABLECARD;
            ret = ioctl(wd_fd, WDIOC_SETOPTIONS, &wd_option);
            if (ret != 0) {
                printf("Failed to stop watchdog!\n");
            }
            printf("Disabled watchdog!\n");
            close(wd_fd);
            break;
        }
        if (strspn(str, "0123456789") == strlen(str)) {
            // Get new feed time.
            num = atoi(str);
            if (num > 0) {
                wd_feed_time = num;
            } else {
                printf("Feed time can not be zero!\n");
            }
        } else {
            printf("Invalid feed time!\n");
        }
    }
    return 0;
}