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  */
28 static const char default_rtc[] = "/dev/rtc0";
29 
30 int 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 
134 done:
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