The goal of the document is to illustrate how to enable and use watchdog of SP7021.
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Run make kconfig command in project top folder, or go to linux/kernel folder and run make menuconfig command. When “Linux/arm 5.4.35 Kernel Configuration” menu pops up, please use arrow key to move cursor down to “Device Drivers”. Refer to screenshot below, cursor is moved to “Device Drivers”:
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Press <Enter> to enter “Device Driver” sub-menu. Next, move cursor down to “Watchdog Timer Support” and press <Space> or “y” to enable it. Refer to screenshot below, “Watchdog Timer Support” is enabled:
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Next, press <Enter> to enter “Watchdog Timer Support” sub-menu. Next, move cursor down to “Sunplus to “Device Drivers > Watchdog Timer Support > Sunplus watchdog support” and press <Space> or “y” to enable it. Refer to screenshot below, “Sunplus watchdog support” is enabled:
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Refer to the following C example code of watchdog setup and feeding application. The application setups, starts, and then feeds watchdog every 12 seconds. The maximum time-out time of watchdog of SP7021 have no limit.
watchdog.c
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#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;
}
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