| /* 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 && (year) % 100 != 0) || (year) % 400 == 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) |
| { |
| /* 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); |
| } |