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 <common.h> 8 #include <command.h> 9 #include <errno.h> 10 #include <rtc.h> 11 12 #if defined(CONFIG_CMD_DATE) || defined(CONFIG_DM_RTC) || \ 13 defined(CONFIG_TIMESTAMP) 14 15 #define FEBRUARY 2 16 #define STARTOFTIME 1970 17 #define SECDAY 86400L 18 #define SECYR (SECDAY * 365) 19 #define leapyear(year) ((year) % 4 == 0) 20 #define days_in_year(a) (leapyear(a) ? 366 : 365) 21 #define days_in_month(a) (month_days[(a) - 1]) 22 23 static int month_offset[] = { 24 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 25 }; 26 27 /* 28 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK) 29 */ 30 int rtc_calc_weekday(struct rtc_time *tm) 31 { 32 int leaps_to_date; 33 int last_year; 34 int day; 35 36 if (tm->tm_year < 1753) 37 return -1; 38 last_year = tm->tm_year - 1; 39 40 /* Number of leap corrections to apply up to end of last year */ 41 leaps_to_date = last_year / 4 - last_year / 100 + last_year / 400; 42 43 /* 44 * This year is a leap year if it is divisible by 4 except when it is 45 * divisible by 100 unless it is divisible by 400 46 * 47 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 is. 48 */ 49 if (tm->tm_year % 4 == 0 && 50 ((tm->tm_year % 100 != 0) || (tm->tm_year % 400 == 0)) && 51 tm->tm_mon > 2) { 52 /* We are past Feb. 29 in a leap year */ 53 day = 1; 54 } else { 55 day = 0; 56 } 57 58 day += last_year * 365 + leaps_to_date + month_offset[tm->tm_mon - 1] + 59 tm->tm_mday; 60 tm->tm_wday = day % 7; 61 62 return 0; 63 } 64 65 /* 66 * Converts Gregorian date to seconds since 1970-01-01 00:00:00. 67 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 68 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. 69 * 70 * [For the Julian calendar (which was used in Russia before 1917, 71 * Britain & colonies before 1752, anywhere else before 1582, 72 * and is still in use by some communities) leave out the 73 * -year / 100 + year / 400 terms, and add 10.] 74 * 75 * This algorithm was first published by Gauss (I think). 76 * 77 * WARNING: this function will overflow on 2106-02-07 06:28:16 on 78 * machines where long is 32-bit! (However, as time_t is signed, we 79 * will already get problems at other places on 2038-01-19 03:14:08) 80 */ 81 unsigned long rtc_mktime(const struct rtc_time *tm) 82 { 83 int mon = tm->tm_mon; 84 int year = tm->tm_year; 85 int days, hours; 86 87 mon -= 2; 88 if (0 >= (int)mon) { /* 1..12 -> 11, 12, 1..10 */ 89 mon += 12; /* Puts Feb last since it has leap day */ 90 year -= 1; 91 } 92 93 days = (unsigned long)(year / 4 - year / 100 + year / 400 + 94 367 * mon / 12 + tm->tm_mday) + 95 year * 365 - 719499; 96 hours = days * 24 + tm->tm_hour; 97 return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec; 98 } 99 100 #endif 101