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}
143