How to enable and use watchdog of SP7021

~ # 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
~ #

#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

int wd_fd;
int wd_feed_time = 8;           // Feed watchdog every 8 second by default.
int wd_timeout = 10;            // Timeout time of watchdog. Reset event occurs if watchdog is not fed within this time.


// A thread for feeding watchdog.
void* feedwdt_thd()
{
	int ret;

	while (1) {
		// Feed (reset) watchdog.
		ret = ioctl(wd_fd, WDIOC_KEEPALIVE, 0);
		if (ret != 0) {
	    		printf("Failed to feed watchdog!\n");
	    		close(wd_fd);
		} else {
	    		printf("Feed watchdog every %d seconds.\n", wd_feed_time);
		}

		sleep(wd_feed_time);
	}
}

int main(void)
{
	pthread_t wd_thread;
	int wd_option;
	char str[10];
	int num = 0;
	int ret;

	// 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_thread, NULL, feedwdt_thd, NULL);
	if (ret< 0)
	printf("Failed to create feeddog thread!\n");

	while (1) {
		printf("Press 'e' to disable watchdog and exit.\n");
		printf("Enter a number for new feed time (default feed time is 8 seconds, timeout time is 10 seconds):\n");
		scanf("%s", str);

		if (!strcmp(str,"e")) {
			// Disable watchdog.
			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;
}

CC=/home/your_home_dir/your_sp7021_project_folder/crossgcc/arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc
LDFLAGS=-lpthread

.PHONY: all clean
all: watchdog

watchdog: watchdog.c
	$(CC) $< -o $@ $(LDFLAGS)

clean:
	rm -f watchdog