open a pwm beeper on linux and send a frequency to it, pwm_beeper_test 1000 will beep a 1k sound for 1s.

pwm_beeper_test.c

#include<stdint.h>
#include<string.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdio.h>
#include<stdlib.h>
#include<linux/input.h>
#include<unistd.h>

int main(int argc, char *argv[])
{

	int fd, version, ret;
	struct input_event event;

	if ((fd = open("/dev/input/event2", O_RDWR)) < 0) {

		perror("beep test");
		return 1;
	}

	event.type = EV_SND;
	event.code = SND_TONE;
	event.value = atoi(argv[1]);
	printf("will open event2 with SND_TONE %d\n",event.value);

	ret = write(fd, &event, sizeof(struct input_event));
	printf("ret = %d\n", ret);
	sleep(1);
	event.value = 0;
	ret = write(fd, &event, sizeof(struct input_event));
	printf("ret = %d\n", ret);


	close(fd);

	return ret;
}