Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0
       2             : /*
       3             :  * rtc and date/time utility functions
       4             :  *
       5             :  * Copyright (C) 2005-06 Tower Technologies
       6             :  * Author: Alessandro Zummo <a.zummo@towertech.it>
       7             :  *
       8             :  * based on arch/arm/common/rtctime.c and other bits
       9             :  */
      10             : 
      11             : #include <linux/export.h>
      12             : #include <linux/rtc.h>
      13             : 
      14             : static const unsigned char rtc_days_in_month[] = {
      15             :         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
      16             : };
      17             : 
      18             : static const unsigned short rtc_ydays[2][13] = {
      19             :         /* Normal years */
      20             :         { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
      21             :         /* Leap years */
      22             :         { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
      23             : };
      24             : 
      25             : #define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
      26             : 
      27             : /*
      28             :  * The number of days in the month.
      29             :  */
      30           0 : int rtc_month_days(unsigned int month, unsigned int year)
      31             : {
      32           0 :         return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
      33             : }
      34             : EXPORT_SYMBOL(rtc_month_days);
      35             : 
      36             : /*
      37             :  * The number of days since January 1. (0 to 365)
      38             :  */
      39           0 : int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
      40             : {
      41           0 :         return rtc_ydays[is_leap_year(year)][month] + day - 1;
      42             : }
      43             : EXPORT_SYMBOL(rtc_year_days);
      44             : 
      45             : /*
      46             :  * rtc_time64_to_tm - Converts time64_t to rtc_time.
      47             :  * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
      48             :  */
      49           0 : void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
      50             : {
      51           0 :         unsigned int month, year, secs;
      52           0 :         int days;
      53             : 
      54             :         /* time must be positive */
      55           0 :         days = div_s64_rem(time, 86400, &secs);
      56             : 
      57             :         /* day of the week, 1970-01-01 was a Thursday */
      58           0 :         tm->tm_wday = (days + 4) % 7;
      59             : 
      60           0 :         year = 1970 + days / 365;
      61           0 :         days -= (year - 1970) * 365
      62           0 :                 + LEAPS_THRU_END_OF(year - 1)
      63             :                 - LEAPS_THRU_END_OF(1970 - 1);
      64           0 :         while (days < 0) {
      65           0 :                 year -= 1;
      66           0 :                 days += 365 + is_leap_year(year);
      67             :         }
      68           0 :         tm->tm_year = year - 1900;
      69           0 :         tm->tm_yday = days + 1;
      70             : 
      71           0 :         for (month = 0; month < 11; month++) {
      72           0 :                 int newdays;
      73             : 
      74           0 :                 newdays = days - rtc_month_days(month, year);
      75           0 :                 if (newdays < 0)
      76             :                         break;
      77           0 :                 days = newdays;
      78             :         }
      79           0 :         tm->tm_mon = month;
      80           0 :         tm->tm_mday = days + 1;
      81             : 
      82           0 :         tm->tm_hour = secs / 3600;
      83           0 :         secs -= tm->tm_hour * 3600;
      84           0 :         tm->tm_min = secs / 60;
      85           0 :         tm->tm_sec = secs - tm->tm_min * 60;
      86             : 
      87           0 :         tm->tm_isdst = 0;
      88           0 : }
      89             : EXPORT_SYMBOL(rtc_time64_to_tm);
      90             : 
      91             : /*
      92             :  * Does the rtc_time represent a valid date/time?
      93             :  */
      94           0 : int rtc_valid_tm(struct rtc_time *tm)
      95             : {
      96           0 :         if (tm->tm_year < 70 ||
      97           0 :             tm->tm_year > (INT_MAX - 1900) ||
      98           0 :             ((unsigned int)tm->tm_mon) >= 12 ||
      99           0 :             tm->tm_mday < 1 ||
     100           0 :             tm->tm_mday > rtc_month_days(tm->tm_mon,
     101           0 :                                          ((unsigned int)tm->tm_year + 1900)) ||
     102           0 :             ((unsigned int)tm->tm_hour) >= 24 ||
     103           0 :             ((unsigned int)tm->tm_min) >= 60 ||
     104           0 :             ((unsigned int)tm->tm_sec) >= 60)
     105           0 :                 return -EINVAL;
     106             : 
     107             :         return 0;
     108             : }
     109             : EXPORT_SYMBOL(rtc_valid_tm);
     110             : 
     111             : /*
     112             :  * rtc_tm_to_time64 - Converts rtc_time to time64_t.
     113             :  * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
     114             :  */
     115           0 : time64_t rtc_tm_to_time64(struct rtc_time *tm)
     116             : {
     117           0 :         return mktime64(((unsigned int)tm->tm_year + 1900), tm->tm_mon + 1,
     118           0 :                         tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
     119             : }
     120             : EXPORT_SYMBOL(rtc_tm_to_time64);
     121             : 
     122             : /*
     123             :  * Convert rtc_time to ktime
     124             :  */
     125           0 : ktime_t rtc_tm_to_ktime(struct rtc_time tm)
     126             : {
     127           0 :         return ktime_set(rtc_tm_to_time64(&tm), 0);
     128             : }
     129             : EXPORT_SYMBOL_GPL(rtc_tm_to_ktime);
     130             : 
     131             : /*
     132             :  * Convert ktime to rtc_time
     133             :  */
     134           0 : struct rtc_time rtc_ktime_to_tm(ktime_t kt)
     135             : {
     136           0 :         struct timespec64 ts;
     137           0 :         struct rtc_time ret;
     138             : 
     139           0 :         ts = ktime_to_timespec64(kt);
     140             :         /* Round up any ns */
     141           0 :         if (ts.tv_nsec)
     142           0 :                 ts.tv_sec++;
     143           0 :         rtc_time64_to_tm(ts.tv_sec, &ret);
     144           0 :         return ret;
     145             : }
     146             : EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);