Linux RTC Test Example rtctest.c hacking

/**********************************************************************
 *            Linux RTC Test Example rtctest.c hacking
 * 说明：
 *     之前的Linux版本都没有这种针对硬件的测试代码示例，比较新的内核里
 * 好像对了这些内核测试用例。
 *
 *                                   2017-8-15 深圳 龙华樟坑村 曾剑锋
 *********************************************************************/

// 参考文档：
//      1. https://github.com/torvalds/linux/tree/master/tools/testing/selftests
//      2. Real Time Clock (RTC) Drivers for Linux
//          https://android.googlesource.com/kernel/common/+/android-4.4/Documentation/rtc.txt

/*
 *      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.
 *
 */

#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.
 */
// 默认rtc设备节点
static const char default_rtc[] = "/dev/rtc0";

// 后面用于设置rtc时间，获取rtc时间，然后对比设置、获取的时间来判断是否正确
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,
    },
};

// 时间对比函数
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;
}

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;
    struct timeval start, end, diff;

    // 这里的倒序的case可以借鉴
    switch (argc) {
    case 3:
        if (*argv[2] == 'd')
            dangerous = 1;          // 没搞懂这里为什么叫dangerous
    case 2:
        rtc = argv[1];              // rtc设备节点
        /* FALLTHROUGH */
    case 1:
        break;
    default:
        fprintf(stderr, "usage:  rtctest [rtcdev] [d]
");
        return 1;
    }

    fd = open(rtc, O_RDONLY);

    if (fd ==  -1) {
        perror(rtc);
        exit(errno);
    }

    fprintf(stderr, "
			RTC Driver Test Example.

");

    /* Turn on update interrupts (one per second) */
    // 这里算是自动时间更新中断，有些芯片可能不支持的，我现在使用的就不支持
    retval = ioctl(fd, RTC_UIE_ON, 0);
    if (retval == -1) {
        if (errno == EINVAL) {
            fprintf(stderr,
                "
...Update IRQs not supported.
");
            goto test_READ;
        }
        perror("RTC_UIE_ON ioctl");
        exit(errno);
    }

    // 直接读取
    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++;
    }

    // select读取
    fprintf(stderr, "
Again, 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 */
    // 读取RTC时间
    retval = ioctl(fd, RTC_RD_TIME, &rtc_tm);
    if (retval == -1) {
        perror("RTC_RD_TIME ioctl");
        exit(errno);
    }

    fprintf(stderr, "

Current RTC date/time is %d-%d-%d, %02d:%02d:%02d.
",
        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;

    // 设置闹钟
    retval = ioctl(fd, RTC_ALM_SET, &rtc_tm);
    if (retval == -1) {
        if (errno == EINVAL) {
            fprintf(stderr,
                "
...Alarm IRQs not supported.
");
            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) {
        perror("RTC_ALM_READ ioctl");
        exit(errno);
    }

    fprintf(stderr, "Alarm time now set to %02d:%02d:%02d.
",
        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) {
            fprintf(stderr,
                "
...Alarm IRQs not supported.
");
            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.
");

    /* 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, "
No periodic IRQ support
");
            goto test_DATE;
        }
        perror("RTC_IRQP_READ ioctl");
        exit(errno);
    }
    fprintf(stderr, "
Periodic IRQ rate is %ldHz.
", 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,
                    "
...Periodic IRQ rate is fixed
");
                goto test_DATE;
            }
            perror("RTC_IRQP_SET ioctl");
            exit(errno);
        }

        fprintf(stderr, "
%ldHz:	", 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, "
PIE delta error: %ld.%06ld should be close to 0.%06ld
",
                       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, "
Testing problematic dates
");

    for (i = 0; i < ARRAY_SIZE(cutoff_dates); i++) {
        struct rtc_time current;

        /* Write the new date in RTC */
        // 设置RTC时间
        retval = ioctl(fd, RTC_SET_TIME, &cutoff_dates[i]);
        if (retval == -1) {
            perror("RTC_SET_TIME ioctl");
            close(fd);
            exit(errno);
        }

        /* Read back */
        // 读取RTC时间
        retval = ioctl(fd, RTC_RD_TIME, &current);
        if (retval == -1) {
            perror("RTC_RD_TIME ioctl");
            exit(errno);
        }

        // 对比RTC时间
        if(compare_dates(&cutoff_dates[i], &current)) {
            fprintf(stderr,"Setting date %d failed
",
                    cutoff_dates[i].tm_year + 1900);
            goto done;
        }

        cutoff_dates[i].tm_sec += 5;

        /* Write the new alarm in RTC */
        // 设置闹钟时间
        retval = ioctl(fd, RTC_ALM_SET, &cutoff_dates[i]);
        if (retval == -1) {
            perror("RTC_ALM_SET ioctl");
            close(fd);
            exit(errno);
        }

        /* Read back */
        // 读取闹钟时间
        retval = ioctl(fd, RTC_ALM_READ, &current);
        if (retval == -1) {
            perror("RTC_ALM_READ ioctl");
            exit(errno);
        }

        // 对比闹钟时间
        if(compare_dates(&cutoff_dates[i], &current)) {
            fprintf(stderr,"Setting alarm %d failed
",
                    cutoff_dates[i].tm_year + 1900);
            goto done;
        }

        fprintf(stderr, "Setting year %d is OK 
",
            cutoff_dates[i].tm_year + 1900);
    }
done:
    fprintf(stderr, "

			 *** Test complete ***
");

    close(fd);

    return 0;
}