#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/rtc.h>
#include <fcntl.h>

int main(int argc, char *argv[])
{
	int fd = open("/dev/rtc", O_RDONLY);
	long rate, fast = 8192;


	if (fd < 0) {
		perror("error opening /dev/rtc");
		exit(1);
	}

	if (ioctl(fd, RTC_IRQP_READ, &rate) < 0) {
		perror("error fetching rate");
		exit(2);
	}

	printf("Current RTC IRQ rate = %ld\n", rate);
	printf("New RTC IRQ rate = %ld\n", fast);

	if (ioctl(fd, RTC_IRQP_SET, fast) < 0) {
		perror("error setting fast rate");
		exit(3);
	}

	if (ioctl(fd, RTC_PIE_ON, 0) < 0) {
		perror("error enabling interrupts");
		exit(4);
	}


	printf("Press enter to stop\n", fast);
	getchar();

	if (ioctl(fd, RTC_IRQP_SET, rate) < 0) {
		perror("error setting original rate");
		exit(5);
	}
	if (ioctl(fd, RTC_PIE_OFF, 0) < 0) {
		perror("error disabling interrupts");
		exit(6);
	}

	return 0;
}