/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * From U-Boot 2016.05 */ #include <console/console.h> #include <rtc.h> #define FEBRUARY 2 #define STARTOFTIME 1970 #define SECDAY 86400L #define SECYR (SECDAY * 365) #define LEAP_YEAR(year) ((year) % 4 == 0) #define DAYS_IN_YEAR(a) (LEAP_YEAR(a) ? 366 : 365) #define DAYS_IN_MONTH(a) (month_days[(a) - 1]) static const char *const weekdays[] = { "Sun", "Mon", "Tues", "Wednes", "Thurs", "Fri", "Satur" }; /* Zeller's rule */ static int rtc_calc_weekday(struct rtc_time *tm) { if (tm->year < 1971) return -1; /* In Zeller's rule, January and February are treated as if they are months 13 and 14 of the previous year (March is still month 3) */ const int zyear = ((tm->mon < 3) ? tm->year - 1 : tm->year); const int q = tm->mday; const int m = (tm->mon < 3) ? tm->mon + 12 : tm->mon; const int K = zyear % 100; const int J = zyear / 100; /* * Because of the way the modulo operator works with negative numbers, * the traditional formulation of Zeller's rule must be modified * slightly to make the numerator positive (i.e., add 5J instead of * subtracting 2J). Also subtract 1 so that Sunday is day 0. */ const int h = (q + (13 * (m + 1)) / 5 + K + (K / 4) + (J / 4) + (5 * J) - 1) % 7; tm->wday = h; return 0; } int rtc_to_tm(int tim, struct rtc_time *tm) { int month_days[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; register int i; register long hms, day; day = tim / SECDAY; hms = tim % SECDAY; /* Hours, minutes, seconds are easy */ tm->hour = hms / 3600; tm->min = (hms % 3600) / 60; tm->sec = (hms % 3600) % 60; /* Number of years in days */ for (i = STARTOFTIME; day >= DAYS_IN_YEAR(i); i++) day -= DAYS_IN_YEAR(i); tm->year = i; /* Number of months in days left */ if (LEAP_YEAR(tm->year)) DAYS_IN_MONTH(FEBRUARY) = 29; for (i = 1; day >= DAYS_IN_MONTH(i); i++) day -= DAYS_IN_MONTH(i); DAYS_IN_MONTH(FEBRUARY) = 28; tm->mon = i; /* Days are what is left over (+1) from all that */ tm->mday = day + 1; /* Determine the day of week */ return rtc_calc_weekday(tm); } /* * Converts Gregorian date to seconds since 1970-01-01 00:00:00. * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. * * [For the Julian calendar (which was used in Russia before 1917, * Britain & colonies before 1752, anywhere else before 1582, * and is still in use by some communities) leave out the * -year / 100 + year / 400 terms, and add 10.] * * This algorithm was first published by Gauss (I think). * * WARNING: this function will overflow on 2106-02-07 06:28:16 on * machines where long is 32-bit! (However, as time_t is signed, we * will already get problems at other places on 2038-01-19 03:14:08) */ unsigned long rtc_mktime(const struct rtc_time *tm) { int mon = tm->mon; int year = tm->year; int days, hours; mon -= 2; if (0 >= (int)mon) { /* 1..12 -> 11, 12, 1..10 */ mon += 12; /* Puts Feb last since it has leap day */ year -= 1; } days = (unsigned long)(year / 4 - year / 100 + year / 400 + 367 * mon / 12 + tm->mday) + year * 365 - 719499; hours = days * 24 + tm->hour; return (hours * 60 + tm->min) * 60 + tm->sec; } void rtc_display(const struct rtc_time *tm) { printk(BIOS_INFO, "Date: %5d-%02d-%02d (%sday) Time: %2d:%02d:%02d\n", tm->year, tm->mon, tm->mday, (tm->wday < 0 || tm->wday > 6) ? "unknown " : weekdays[tm->wday], tm->hour, tm->min, tm->sec); }