36d46cdb43
If we convert one large time values to rtc_time, in the original formula 'days * 86400' can be overflowed in 'unsigned int' type to make the formula get one incorrect remain seconds value. Thus we can use div_s64_rem() function to avoid this situation. Signed-off-by: Baolin Wang <baolin.wang@linaro.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
148 lines
3.4 KiB
C
148 lines
3.4 KiB
C
/*
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* rtc and date/time utility functions
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*
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* Copyright (C) 2005-06 Tower Technologies
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* Author: Alessandro Zummo <a.zummo@towertech.it>
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*
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* based on arch/arm/common/rtctime.c and other bits
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/export.h>
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#include <linux/rtc.h>
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static const unsigned char rtc_days_in_month[] = {
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31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
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};
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static const unsigned short rtc_ydays[2][13] = {
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/* Normal years */
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{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
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/* Leap years */
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{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
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};
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#define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
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/*
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* The number of days in the month.
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*/
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int rtc_month_days(unsigned int month, unsigned int year)
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{
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return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
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}
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EXPORT_SYMBOL(rtc_month_days);
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/*
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* The number of days since January 1. (0 to 365)
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*/
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int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
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{
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return rtc_ydays[is_leap_year(year)][month] + day-1;
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}
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EXPORT_SYMBOL(rtc_year_days);
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/*
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* rtc_time_to_tm64 - Converts time64_t to rtc_time.
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* Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
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*/
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void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
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{
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unsigned int month, year, secs;
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int days;
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/* time must be positive */
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days = div_s64_rem(time, 86400, &secs);
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/* day of the week, 1970-01-01 was a Thursday */
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tm->tm_wday = (days + 4) % 7;
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year = 1970 + days / 365;
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days -= (year - 1970) * 365
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+ LEAPS_THRU_END_OF(year - 1)
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- LEAPS_THRU_END_OF(1970 - 1);
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if (days < 0) {
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year -= 1;
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days += 365 + is_leap_year(year);
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}
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tm->tm_year = year - 1900;
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tm->tm_yday = days + 1;
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for (month = 0; month < 11; month++) {
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int newdays;
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newdays = days - rtc_month_days(month, year);
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if (newdays < 0)
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break;
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days = newdays;
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}
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tm->tm_mon = month;
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tm->tm_mday = days + 1;
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tm->tm_hour = secs / 3600;
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secs -= tm->tm_hour * 3600;
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tm->tm_min = secs / 60;
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tm->tm_sec = secs - tm->tm_min * 60;
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tm->tm_isdst = 0;
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}
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EXPORT_SYMBOL(rtc_time64_to_tm);
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/*
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* Does the rtc_time represent a valid date/time?
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*/
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int rtc_valid_tm(struct rtc_time *tm)
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{
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if (tm->tm_year < 70
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|| ((unsigned)tm->tm_mon) >= 12
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|| tm->tm_mday < 1
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|| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
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|| ((unsigned)tm->tm_hour) >= 24
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|| ((unsigned)tm->tm_min) >= 60
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|| ((unsigned)tm->tm_sec) >= 60)
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return -EINVAL;
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return 0;
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}
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EXPORT_SYMBOL(rtc_valid_tm);
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/*
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* rtc_tm_to_time64 - Converts rtc_time to time64_t.
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* Convert Gregorian date to seconds since 01-01-1970 00:00:00.
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*/
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time64_t rtc_tm_to_time64(struct rtc_time *tm)
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{
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return mktime64(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
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tm->tm_hour, tm->tm_min, tm->tm_sec);
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}
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EXPORT_SYMBOL(rtc_tm_to_time64);
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/*
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* Convert rtc_time to ktime
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*/
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ktime_t rtc_tm_to_ktime(struct rtc_time tm)
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{
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return ktime_set(rtc_tm_to_time64(&tm), 0);
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}
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EXPORT_SYMBOL_GPL(rtc_tm_to_ktime);
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/*
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* Convert ktime to rtc_time
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*/
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struct rtc_time rtc_ktime_to_tm(ktime_t kt)
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{
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struct timespec64 ts;
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struct rtc_time ret;
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ts = ktime_to_timespec64(kt);
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/* Round up any ns */
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if (ts.tv_nsec)
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ts.tv_sec++;
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rtc_time64_to_tm(ts.tv_sec, &ret);
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return ret;
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}
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EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);
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