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 <errno.h> 15 #include <rtc.h> 16 17 #if defined(CONFIG_CMD_DATE) || defined(CONFIG_TIMESTAMP) 18 19 #define FEBRUARY 2 20 #define STARTOFTIME 1970 21 #define SECDAY 86400L 22 #define SECYR (SECDAY * 365) 23 #define leapyear(year) ((year) % 4 == 0) 24 #define days_in_year(a) (leapyear(a) ? 366 : 365) 25 #define days_in_month(a) (month_days[(a) - 1]) 26 27 static int month_days[12] = { 28 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 29 }; 30 31 /* 32 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK) 33 */ 34 int rtc_calc_weekday(struct rtc_time *tm) 35 { 36 int leapsToDate; 37 int lastYear; 38 int day; 39 int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 }; 40 41 if (tm->tm_year < 1753) 42 return -EINVAL; 43 lastYear=tm->tm_year-1; 44 45 /* 46 * Number of leap corrections to apply up to end of last year 47 */ 48 leapsToDate = lastYear/4 - lastYear/100 + lastYear/400; 49 50 /* 51 * This year is a leap year if it is divisible by 4 except when it is 52 * divisible by 100 unless it is divisible by 400 53 * 54 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be 55 */ 56 if((tm->tm_year%4==0) && 57 ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) && 58 (tm->tm_mon>2)) { 59 /* 60 * We are past Feb. 29 in a leap year 61 */ 62 day=1; 63 } else { 64 day=0; 65 } 66 67 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday; 68 69 tm->tm_wday=day%7; 70 71 return 0; 72 } 73 74 int rtc_to_tm(int tim, struct rtc_time *tm) 75 { 76 register int i; 77 register long hms, day; 78 79 day = tim / SECDAY; 80 hms = tim % SECDAY; 81 82 /* Hours, minutes, seconds are easy */ 83 tm->tm_hour = hms / 3600; 84 tm->tm_min = (hms % 3600) / 60; 85 tm->tm_sec = (hms % 3600) % 60; 86 87 /* Number of years in days */ 88 for (i = STARTOFTIME; day >= days_in_year(i); i++) { 89 day -= days_in_year(i); 90 } 91 tm->tm_year = i; 92 93 /* Number of months in days left */ 94 if (leapyear(tm->tm_year)) { 95 days_in_month(FEBRUARY) = 29; 96 } 97 for (i = 1; day >= days_in_month(i); i++) { 98 day -= days_in_month(i); 99 } 100 days_in_month(FEBRUARY) = 28; 101 tm->tm_mon = i; 102 103 /* Days are what is left over (+1) from all that. */ 104 tm->tm_mday = day + 1; 105 106 /* Zero unused fields */ 107 tm->tm_yday = 0; 108 tm->tm_isdst = 0; 109 110 /* 111 * Determine the day of week 112 */ 113 return rtc_calc_weekday(tm); 114 } 115 116 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. 117 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 118 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. 119 * 120 * [For the Julian calendar (which was used in Russia before 1917, 121 * Britain & colonies before 1752, anywhere else before 1582, 122 * and is still in use by some communities) leave out the 123 * -year/100+year/400 terms, and add 10.] 124 * 125 * This algorithm was first published by Gauss (I think). 126 * 127 * WARNING: this function will overflow on 2106-02-07 06:28:16 on 128 * machines were long is 32-bit! (However, as time_t is signed, we 129 * will already get problems at other places on 2038-01-19 03:14:08) 130 */ 131 unsigned long rtc_mktime(const struct rtc_time *tm) 132 { 133 int mon = tm->tm_mon; 134 int year = tm->tm_year; 135 int days, hours; 136 137 mon -= 2; 138 if (0 >= (int)mon) { /* 1..12 -> 11,12,1..10 */ 139 mon += 12; /* Puts Feb last since it has leap day */ 140 year -= 1; 141 } 142 143 days = (unsigned long)(year / 4 - year / 100 + year / 400 + 144 367 * mon / 12 + tm->tm_mday) + 145 year * 365 - 719499; 146 hours = days * 24 + tm->tm_hour; 147 return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec; 148 } 149 150 #endif 151