TODO: translate rtc.txt kernel documentation
From the kernel: linux4.14.39 / tools / testing / selftests / timers / rtctest.c
/* * Real Time Clock Driver Test/Example Program * * Compile with: * gcc -s -Wall -Wstrict-prototypes rtctest.c -o rtctest * * Copyright (C) 1996, Paul Gortmaker. * * Released under the GNU General Public License, version 2, * included herein by reference. * */ /* 直接: # gcc rtctest.c -o pp # ./pp 编译就可以运行 */ #include <stdio.h> #include <linux/rtc.h> #include <sys/ioctl.h> #include <sys/time.h> #include <sys/types.h> #include <fcntl.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> #ifndef ARRAY_SIZE # define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) #endif /* * This expects the new RTC class driver framework, working with * clocks that will often not be clones of what the PC-AT had. * Use the command line to specify another RTC if you need one. */ static const char default_rtc[] = "/dev/rtc0"; static struct rtc_time cutoff_dates[] = { { .tm_year = 70, /* 1970 -1900 */ .tm_mday = 1, }, /* signed time_t 19/01/2038 3:14:08 */ { .tm_year = 138, .tm_mday = 19, }, { .tm_year = 138, .tm_mday = 20, }, { .tm_year = 199, /* 2099 -1900 */ .tm_mday = 1, }, { .tm_year = 200, /* 2100 -1900 */ .tm_mday = 1, }, /* unsigned time_t 07/02/2106 7:28:15*/ { .tm_year = 205, .tm_mon = 1, .tm_mday = 7, }, { .tm_year = 206, .tm_mon = 1, .tm_mday = 8, }, /* signed time on 64bit in nanoseconds 12/04/2262 01:47:16*/ { .tm_year = 362, .tm_mon = 3, .tm_mday = 12, }, { .tm_year = 362, /* 2262 -1900 */ .tm_mon = 3, .tm_mday = 13, }, }; static int compare_dates(struct rtc_time *a, struct rtc_time *b) { if (a->tm_year != b->tm_year || a->tm_mon != b->tm_mon || a->tm_mday != b->tm_mday || a->tm_hour != b->tm_hour || a->tm_min != b->tm_min || ((b->tm_sec - a->tm_sec) > 1)) return 1; return 0; } /* struct rtc_time { int tm_sec; int tm_min; int tm_hour; int tm_mday; int tm_mon; int tm_year; int tm_wday; int tm_yday; int tm_isdst; }; */ int main(int argc, char **argv) { int i, fd, retval, irqcount = 0, dangerous = 0; unsigned long tmp, data; struct rtc_time rtc_tm; const char *rtc = default_rtc; /*"/dev/rtc0"*/ struct timeval start, end, diff; switch (argc) { case 3: if (*argv[2] == 'd') dangerous = 1; case 2: rtc = argv[1]; /* FALLTHROUGH */ case 1: break; default: fprintf(stderr, "usage: rtctest [rtcdev] [d]\n"); return 1; } fd = open(rtc, O_RDONLY); if (fd == -1) { perror(rtc); exit(errno); } fprintf(stderr, "\n\t\t\tRTC Driver Test Example.\n\n"); /* Turn on update interrupts (one per second) */ retval = ioctl(fd, RTC_UIE_ON, 0); if (retval == -1) { if (errno == EINVAL) { fprintf(stderr, "\n...Update IRQs not supported.\n"); goto test_READ; } perror("RTC_UIE_ON ioctl"); exit(errno); } fprintf(stderr, "Counting 5 update (1/sec) interrupts from reading %s:", rtc); fflush(stderr); for (i=1; i<6; i++) { /* This read will block */ retval = read(fd, &data, sizeof(unsigned long)); if (retval == -1) { perror("read"); exit(errno); } fprintf(stderr, " %d",i); fflush(stderr); irqcount++; } fprintf(stderr, "\nAgain, from using select(2) on /dev/rtc:"); fflush(stderr); for (i=1; i<6; i++) { struct timeval tv = {5, 0}; /* 5 second timeout on select */ fd_set readfds; FD_ZERO(&readfds); FD_SET(fd, &readfds); /* The select will wait until an RTC interrupt happens. */ retval = select(fd+1, &readfds, NULL, NULL, &tv); if (retval == -1) { perror("select"); exit(errno); } /* This read won't block unlike the select-less case above. */ retval = read(fd, &data, sizeof(unsigned long)); if (retval == -1) { perror("read"); exit(errno); } fprintf(stderr, " %d",i); fflush(stderr); irqcount++; } /* Turn off update interrupts */ retval = ioctl(fd, RTC_UIE_OFF, 0); if (retval == -1) { perror("RTC_UIE_OFF ioctl"); exit(errno); } test_READ: /* Read the RTC time/date */ retval = ioctl(fd, RTC_RD_TIME, &rtc_tm); if (retval == -1) { perror("RTC_RD_TIME ioctl"); exit(errno); } fprintf(stderr, "\n\nCurrent RTC date/time is %d-%d-%d, %02d:%02d:%02d.\n", rtc_tm.tm_mday, rtc_tm.tm_mon + 1, rtc_tm.tm_year + 1900, rtc_tm.tm_hour, rtc_tm.tm_min, rtc_tm.tm_sec); /* Set the alarm to 5 sec in the future, and check for rollover */ rtc_tm.tm_sec += 5; if (rtc_tm.tm_sec >= 60) { rtc_tm.tm_sec %= 60; rtc_tm.tm_min++; } if (rtc_tm.tm_min == 60) { rtc_tm.tm_min = 0; rtc_tm.tm_hour++; } if (rtc_tm.tm_hour == 24) rtc_tm.tm_hour = 0; retval = ioctl(fd, RTC_ALM_SET, &rtc_tm); if (retval == -1) { if (errno == EINVAL) { fprintf(stderr, "\n...Alarm IRQs not supported.\n"); goto test_PIE; } perror("RTC_ALM_SET ioctl"); exit(errno); } /* Read the current alarm settings */ retval = ioctl(fd, RTC_ALM_READ, &rtc_tm); if (retval == -1) { if (errno == EINVAL) { fprintf(stderr, "\n...EINVAL reading current alarm setting.\n"); goto test_PIE; } perror("RTC_ALM_READ ioctl"); exit(errno); } fprintf(stderr, "Alarm time now set to %02d:%02d:%02d.\n", rtc_tm.tm_hour, rtc_tm.tm_min, rtc_tm.tm_sec); /* Enable alarm interrupts */ retval = ioctl(fd, RTC_AIE_ON, 0); if (retval == -1) { if (errno == EINVAL || errno == EIO) { fprintf(stderr, "\n...Alarm IRQs not supported.\n"); goto test_PIE; } perror("RTC_AIE_ON ioctl"); exit(errno); } fprintf(stderr, "Waiting 5 seconds for alarm..."); fflush(stderr); /* This blocks until the alarm ring causes an interrupt */ retval = read(fd, &data, sizeof(unsigned long)); if (retval == -1) { perror("read"); exit(errno); } irqcount++; fprintf(stderr, " okay. Alarm rang.\n"); /* Disable alarm interrupts */ retval = ioctl(fd, RTC_AIE_OFF, 0); if (retval == -1) { perror("RTC_AIE_OFF ioctl"); exit(errno); } test_PIE: /* Read periodic IRQ rate */ retval = ioctl(fd, RTC_IRQP_READ, &tmp); if (retval == -1) { /* not all RTCs support periodic IRQs */ if (errno == EINVAL) { fprintf(stderr, "\nNo periodic IRQ support\n"); goto test_DATE; } perror("RTC_IRQP_READ ioctl"); exit(errno); } fprintf(stderr, "\nPeriodic IRQ rate is %ldHz.\n", tmp); fprintf(stderr, "Counting 20 interrupts at:"); fflush(stderr); /* The frequencies 128Hz, 256Hz, ... 8192Hz are only allowed for root. */ for (tmp=2; tmp<=64; tmp*=2) { retval = ioctl(fd, RTC_IRQP_SET, tmp); if (retval == -1) { /* not all RTCs can change their periodic IRQ rate */ if (errno == EINVAL) { fprintf(stderr, "\n...Periodic IRQ rate is fixed\n"); goto test_DATE; } perror("RTC_IRQP_SET ioctl"); exit(errno); } fprintf(stderr, "\n%ldHz:\t", tmp); fflush(stderr); /* Enable periodic interrupts */ retval = ioctl(fd, RTC_PIE_ON, 0); if (retval == -1) { perror("RTC_PIE_ON ioctl"); exit(errno); } for (i=1; i<21; i++) { gettimeofday(&start, NULL); /* This blocks */ retval = read(fd, &data, sizeof(unsigned long)); if (retval == -1) { perror("read"); exit(errno); } gettimeofday(&end, NULL); timersub(&end, &start, &diff); if (diff.tv_sec > 0 || diff.tv_usec > ((1000000L / tmp) * 1.10)) { fprintf(stderr, "\nPIE delta error: %ld.%06ld should be close to 0.%06ld\n", diff.tv_sec, diff.tv_usec, (1000000L / tmp)); fflush(stdout); exit(-1); } fprintf(stderr, " %d",i); fflush(stderr); irqcount++; } /* Disable periodic interrupts */ retval = ioctl(fd, RTC_PIE_OFF, 0); if (retval == -1) { perror("RTC_PIE_OFF ioctl"); exit(errno); } } test_DATE: if (!dangerous) goto done; fprintf(stderr, "\nTesting problematic dates\n"); for (i = 0; i < ARRAY_SIZE(cutoff_dates); i++) { struct rtc_time current; /* Write the new date in RTC */ retval = ioctl(fd, RTC_SET_TIME, &cutoff_dates[i]); if (retval == -1) { perror("RTC_SET_TIME ioctl"); close(fd); exit(errno); } /* Read back */ retval = ioctl(fd, RTC_RD_TIME, ¤t); if (retval == -1) { perror("RTC_RD_TIME ioctl"); exit(errno); } if(compare_dates(&cutoff_dates[i], ¤t)) { fprintf(stderr,"Setting date %d failed\n", cutoff_dates[i].tm_year + 1900); goto done; } cutoff_dates[i].tm_sec += 5; /* Write the new alarm in RTC */ retval = ioctl(fd, RTC_ALM_SET, &cutoff_dates[i]); if (retval == -1) { perror("RTC_ALM_SET ioctl"); close(fd); exit(errno); } /* Read back */ retval = ioctl(fd, RTC_ALM_READ, ¤t); if (retval == -1) { perror("RTC_ALM_READ ioctl"); exit(errno); } if(compare_dates(&cutoff_dates[i], ¤t)) { fprintf(stderr,"Setting alarm %d failed\n", cutoff_dates[i].tm_year + 1900); goto done; } fprintf(stderr, "Setting year %d is OK \n", cutoff_dates[i].tm_year + 1900); } done: fprintf(stderr, "\n\n\t\t\t *** Test complete ***\n"); close(fd); return 0; }