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

source code of linux/tools/testing/selftests/timers/rtcpie.c