1 /* 2 * (C) Copyright 2001 3 * Wolfgang Denk, DENX Software Engineering, wd@denx.de. 4 * 5 * SPDX-License-Identifier: GPL-2.0+ 6 */ 7 8 /* 9 * Date & Time support for Philips PCF8563 RTC 10 */ 11 12 #include <common.h> 13 #include <command.h> 14 #include <rtc.h> 15 16 #if defined(CONFIG_CMD_DATE) || defined(CONFIG_TIMESTAMP) 17 18 #define FEBRUARY 2 19 #define STARTOFTIME 1970 20 #define SECDAY 86400L 21 #define SECYR (SECDAY * 365) 22 #define leapyear(year) ((year) % 4 == 0) 23 #define days_in_year(a) (leapyear(a) ? 366 : 365) 24 #define days_in_month(a) (month_days[(a) - 1]) 25 26 static int month_days[12] = { 27 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 28 }; 29 30 /* 31 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK) 32 */ 33 void GregorianDay(struct rtc_time * tm) 34 { 35 int leapsToDate; 36 int lastYear; 37 int day; 38 int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 }; 39 40 lastYear=tm->tm_year-1; 41 42 /* 43 * Number of leap corrections to apply up to end of last year 44 */ 45 leapsToDate = lastYear/4 - lastYear/100 + lastYear/400; 46 47 /* 48 * This year is a leap year if it is divisible by 4 except when it is 49 * divisible by 100 unless it is divisible by 400 50 * 51 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be 52 */ 53 if((tm->tm_year%4==0) && 54 ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) && 55 (tm->tm_mon>2)) { 56 /* 57 * We are past Feb. 29 in a leap year 58 */ 59 day=1; 60 } else { 61 day=0; 62 } 63 64 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday; 65 66 tm->tm_wday=day%7; 67 } 68 69 void to_tm(int tim, struct rtc_time * tm) 70 { 71 register int i; 72 register long hms, day; 73 74 day = tim / SECDAY; 75 hms = tim % SECDAY; 76 77 /* Hours, minutes, seconds are easy */ 78 tm->tm_hour = hms / 3600; 79 tm->tm_min = (hms % 3600) / 60; 80 tm->tm_sec = (hms % 3600) % 60; 81 82 /* Number of years in days */ 83 for (i = STARTOFTIME; day >= days_in_year(i); i++) { 84 day -= days_in_year(i); 85 } 86 tm->tm_year = i; 87 88 /* Number of months in days left */ 89 if (leapyear(tm->tm_year)) { 90 days_in_month(FEBRUARY) = 29; 91 } 92 for (i = 1; day >= days_in_month(i); i++) { 93 day -= days_in_month(i); 94 } 95 days_in_month(FEBRUARY) = 28; 96 tm->tm_mon = i; 97 98 /* Days are what is left over (+1) from all that. */ 99 tm->tm_mday = day + 1; 100 101 /* 102 * Determine the day of week 103 */ 104 GregorianDay(tm); 105 } 106 107 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. 108 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 109 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. 110 * 111 * [For the Julian calendar (which was used in Russia before 1917, 112 * Britain & colonies before 1752, anywhere else before 1582, 113 * and is still in use by some communities) leave out the 114 * -year/100+year/400 terms, and add 10.] 115 * 116 * This algorithm was first published by Gauss (I think). 117 * 118 * WARNING: this function will overflow on 2106-02-07 06:28:16 on 119 * machines were long is 32-bit! (However, as time_t is signed, we 120 * will already get problems at other places on 2038-01-19 03:14:08) 121 */ 122 unsigned long 123 mktime (unsigned int year, unsigned int mon, 124 unsigned int day, unsigned int hour, 125 unsigned int min, unsigned int sec) 126 { 127 if (0 >= (int) (mon -= 2)) { /* 1..12 -> 11,12,1..10 */ 128 mon += 12; /* Puts Feb last since it has leap day */ 129 year -= 1; 130 } 131 132 return ((( 133 (unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) + 134 year*365 - 719499 135 )*24 + hour /* now have hours */ 136 )*60 + min /* now have minutes */ 137 )*60 + sec; /* finally seconds */ 138 } 139 140 #endif 141