tools/testing/selftests/timers/rtcpie.c

   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 }