1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Real Time Clock Periodic Interrupt test program
  4 *
  5 * Since commit 6610e0893b8bc ("RTC: Rework RTC code to use timerqueue for
  6 * events"), PIE are completely handled using hrtimers, without actually using
  7 * any underlying hardware RTC.
  8 *
  9 */
 10
 11#include <stdio.h>
 12#include <linux/rtc.h>
 13#include <sys/ioctl.h>
 14#include <sys/time.h>
 15#include <sys/types.h>
 16#include <fcntl.h>
 17#include <unistd.h>
 18#include <stdlib.h>
 19#include <errno.h>
 20
 21#include "../kselftest.h"
 22
 23/*
 24 * This expects the new RTC class driver framework, working with
 25 * clocks that will often not be clones of what the PC-AT had.
 26 * Use the command line to specify another RTC if you need one.
 27 */
 28static const char default_rtc[] = "/dev/rtc0";
 29
 30int main(int argc, char **argv)
 31{
 32	int i, fd, retval, irqcount = 0;
 33	unsigned long tmp, data, old_pie_rate;
 34	const char *rtc = default_rtc;
 35	struct timeval start, end, diff;
 36
 37	switch (argc) {
 38	case 2:
 39		rtc = argv[1];
 40		break;
 41	case 1:
 42		fd = open(default_rtc, O_RDONLY);
 43		if (fd == -1) {
 44			printf("Default RTC %s does not exist. Test Skipped!\n", default_rtc);
 45			exit(KSFT_SKIP);
 46		}
 47		close(fd);
 48		break;
 49	default:
 50		fprintf(stderr, "usage:  rtctest [rtcdev] [d]\n");
 51		return 1;
 52	}
 53
 54	fd = open(rtc, O_RDONLY);
 55
 56	if (fd ==  -1) {
 57		perror(rtc);
 58		exit(errno);
 59	}
 60
 61	/* Read periodic IRQ rate */
 62	retval = ioctl(fd, RTC_IRQP_READ, &old_pie_rate);
 63	if (retval == -1) {
 64		/* not all RTCs support periodic IRQs */
 65		if (errno == EINVAL) {
 66			fprintf(stderr, "\nNo periodic IRQ support\n");
 67			goto done;
 68		}
 69		perror("RTC_IRQP_READ ioctl");
 70		exit(errno);
 71	}
 72	fprintf(stderr, "\nPeriodic IRQ rate is %ldHz.\n", old_pie_rate);
 73
 74	fprintf(stderr, "Counting 20 interrupts at:");
 75	fflush(stderr);
 76
 77	/* The frequencies 128Hz, 256Hz, ... 8192Hz are only allowed for root. */
 78	for (tmp=2; tmp<=64; tmp*=2) {
 79
 80		retval = ioctl(fd, RTC_IRQP_SET, tmp);
 81		if (retval == -1) {
 82			/* not all RTCs can change their periodic IRQ rate */
 83			if (errno == EINVAL) {
 84				fprintf(stderr,
 85					"\n...Periodic IRQ rate is fixed\n");
 86				goto done;
 87			}
 88			perror("RTC_IRQP_SET ioctl");
 89			exit(errno);
 90		}
 91
 92		fprintf(stderr, "\n%ldHz:\t", tmp);
 93		fflush(stderr);
 94
 95		/* Enable periodic interrupts */
 96		retval = ioctl(fd, RTC_PIE_ON, 0);
 97		if (retval == -1) {
 98			perror("RTC_PIE_ON ioctl");
 99			exit(errno);
100		}
101
102		for (i=1; i<21; i++) {
103			gettimeofday(&start, NULL);
104			/* This blocks */
105			retval = read(fd, &data, sizeof(unsigned long));
106			if (retval == -1) {
107				perror("read");
108				exit(errno);
109			}
110			gettimeofday(&end, NULL);
111			timersub(&end, &start, &diff);
112			if (diff.tv_sec > 0 ||
113			    diff.tv_usec > ((1000000L / tmp) * 1.10)) {
114				fprintf(stderr, "\nPIE delta error: %ld.%06ld should be close to 0.%06ld\n",
115				       diff.tv_sec, diff.tv_usec,
116				       (1000000L / tmp));
117				fflush(stdout);
118				exit(-1);
119			}
120
121			fprintf(stderr, " %d",i);
122			fflush(stderr);
123			irqcount++;
124		}
125
126		/* Disable periodic interrupts */
127		retval = ioctl(fd, RTC_PIE_OFF, 0);
128		if (retval == -1) {
129			perror("RTC_PIE_OFF ioctl");
130			exit(errno);
131		}
132	}
133
134done:
135	ioctl(fd, RTC_IRQP_SET, old_pie_rate);
136
137	fprintf(stderr, "\n\n\t\t\t *** Test complete ***\n");
138
139	close(fd);
140
141	return 0;
142}