1// SPDX-License-Identifier: GPL-2.0+ 2/* 3 * (C) Copyright 2001 4 * Wolfgang Denk, DENX Software Engineering, wd@denx.de. 5 */ 6 7#include <command.h> 8#include <errno.h> 9#include <rtc.h> 10#include <linux/time.h> 11 12#define FEBRUARY 2 13#define STARTOFTIME 1970 14#define SECDAY 86400L 15#define SECYR (SECDAY * 365) 16#define leapyear(year) ((year) % 4 == 0) 17#define days_in_year(a) (leapyear(a) ? 366 : 365) 18#define days_in_month(a) (month_days[(a) - 1]) 19 20static int month_offset[] = { 21 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 22}; 23 24/* 25 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK) 26 */ 27int rtc_calc_weekday(struct rtc_time *tm) 28{ 29 int leaps_to_date; 30 int last_year; 31 int day; 32 33 if (tm->tm_year < 1753) 34 return -1; 35 last_year = tm->tm_year - 1; 36 37 /* Number of leap corrections to apply up to end of last year */ 38 leaps_to_date = last_year / 4 - last_year / 100 + last_year / 400; 39 40 /* 41 * This year is a leap year if it is divisible by 4 except when it is 42 * divisible by 100 unless it is divisible by 400 43 * 44 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 is. 45 */ 46 if (tm->tm_year % 4 == 0 && 47 ((tm->tm_year % 100 != 0) || (tm->tm_year % 400 == 0)) && 48 tm->tm_mon > 2) { 49 /* We are past Feb. 29 in a leap year */ 50 day = 1; 51 } else { 52 day = 0; 53 } 54 55 day += last_year * 365 + leaps_to_date + month_offset[tm->tm_mon - 1] + 56 tm->tm_mday; 57 tm->tm_wday = day % 7; 58 59 return 0; 60} 61 62/* 63 * Converts Gregorian date to seconds since 1970-01-01 00:00:00. 64 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 65 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. 66 * 67 * [For the Julian calendar (which was used in Russia before 1917, 68 * Britain & colonies before 1752, anywhere else before 1582, 69 * and is still in use by some communities) leave out the 70 * -year / 100 + year / 400 terms, and add 10.] 71 * 72 * This algorithm was first published by Gauss (I think). 73 */ 74time64_t rtc_mktime(const struct rtc_time *tm) 75{ 76 int mon = tm->tm_mon; 77 int year = tm->tm_year; 78 unsigned long days; 79 time64_t hours; 80 81 mon -= 2; 82 if (0 >= mon) { /* 1..12 -> 11, 12, 1..10 */ 83 mon += 12; /* Puts Feb last since it has leap day */ 84 year -= 1; 85 } 86 87 days = (unsigned long)(year / 4 - year / 100 + year / 400 + 88 367 * mon / 12 + tm->tm_mday) + 89 year * 365 - 719499; 90 hours = days * 24 + tm->tm_hour; 91 return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec; 92} 93 94/* for compatibility with linux code */ 95time64_t mktime64(const unsigned int year, const unsigned int mon, 96 const unsigned int day, const unsigned int hour, 97 const unsigned int min, const unsigned int sec) 98{ 99 struct rtc_time time; 100 101 time.tm_year = year; 102 time.tm_mon = mon; 103 time.tm_mday = day; 104 time.tm_hour = hour; 105 time.tm_min = min; 106 time.tm_sec = sec; 107 108 return rtc_mktime((const struct rtc_time *)&time); 109} 110