2 * This file is part of the coreboot project.
4 * (C) Copyright 2001 Wolfgang Denk, DENX Software Engineering, wd@denx.de.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; version 2 of the License or (at your
9 * option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
19 #include <console/console.h>
23 #define STARTOFTIME 1970
25 #define SECYR (SECDAY * 365)
26 #define LEAP_YEAR(year) ((year) % 4 == 0)
27 #define DAYS_IN_YEAR(a) (LEAP_YEAR(a) ? 366 : 365)
28 #define DAYS_IN_MONTH(a) (month_days[(a) - 1])
30 static const int month_offset
[] = {
31 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
34 static const char * const weekdays
[] = {
35 "Sun", "Mon", "Tues", "Wednes", "Thurs", "Fri", "Satur",
38 static int leaps_to_year(int year
)
40 return year
/ 4 - year
/ 100 + year
/ 400;
43 /* This only works for the Gregorian calendar after Jan 1 1971. */
44 static int rtc_calc_weekday(struct rtc_time
*tm
)
52 day
= 4; /* Jan 1 1970 was a Thursday. */
54 /* Number of leap corrections to apply up to end of last year */
55 leaps_to_date
= leaps_to_year(tm
->year
- 1) - leaps_to_year(1970);
58 * This year is a leap year if it is divisible by 4 except when it is
59 * divisible by 100 unless it is divisible by 400
61 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 is.
64 ((tm
->year
% 100 != 0) || (tm
->year
% 400 == 0)) &&
66 /* We are past Feb. 29 in a leap year */
70 day
+= (tm
->year
- 1970) * 365 + leaps_to_date
+
71 month_offset
[tm
->mon
-1] + tm
->mday
;
77 int rtc_to_tm(int tim
, struct rtc_time
*tm
)
79 int month_days
[12] = {
80 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
83 register long hms
, day
;
88 /* Hours, minutes, seconds are easy */
89 tm
->hour
= hms
/ 3600;
90 tm
->min
= (hms
% 3600) / 60;
91 tm
->sec
= (hms
% 3600) % 60;
93 /* Number of years in days */
94 for (i
= STARTOFTIME
; day
>= DAYS_IN_YEAR(i
); i
++)
95 day
-= DAYS_IN_YEAR(i
);
98 /* Number of months in days left */
99 if (LEAP_YEAR(tm
->year
))
100 DAYS_IN_MONTH(FEBRUARY
) = 29;
101 for (i
= 1; day
>= DAYS_IN_MONTH(i
); i
++)
102 day
-= DAYS_IN_MONTH(i
);
103 DAYS_IN_MONTH(FEBRUARY
) = 28;
106 /* Days are what is left over (+1) from all that */
109 /* Determine the day of week */
110 return rtc_calc_weekday(tm
);
114 * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
115 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
116 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
118 * [For the Julian calendar (which was used in Russia before 1917,
119 * Britain & colonies before 1752, anywhere else before 1582,
120 * and is still in use by some communities) leave out the
121 * -year / 100 + year / 400 terms, and add 10.]
123 * This algorithm was first published by Gauss (I think).
125 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
126 * machines where long is 32-bit! (However, as time_t is signed, we
127 * will already get problems at other places on 2038-01-19 03:14:08)
129 unsigned long rtc_mktime(const struct rtc_time
*tm
)
136 if (0 >= (int)mon
) { /* 1..12 -> 11, 12, 1..10 */
137 mon
+= 12; /* Puts Feb last since it has leap day */
141 days
= (unsigned long)(year
/ 4 - year
/ 100 + year
/ 400 +
142 367 * mon
/ 12 + tm
->mday
) +
144 hours
= days
* 24 + tm
->hour
;
145 return (hours
* 60 + tm
->min
) * 60 + tm
->sec
;
148 void rtc_display(const struct rtc_time
*tm
)
150 printk(BIOS_INFO
, "Date: %4d-%02d-%02d (%sday) Time: %2d:%02d:%02d\n",
151 tm
->year
, tm
->mon
, tm
->mday
,
152 (tm
->wday
< 0 || tm
->wday
> 6) ? "unknown " : weekdays
[tm
->wday
],
153 tm
->hour
, tm
->min
, tm
->sec
);