1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * (C) Copyright 2001
4 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 */
6
7 #include <common.h>
8 #include <command.h>
9 #include <errno.h>
10 #include <rtc.h>
11 #include <linux/time.h>
12
13 #define FEBRUARY 2
14 #define STARTOFTIME 1970
15 #define SECDAY 86400L
16 #define SECYR (SECDAY * 365)
17 #define leapyear(year) ((year) % 4 == 0)
18 #define days_in_year(a) (leapyear(a) ? 366 : 365)
19 #define days_in_month(a) (month_days[(a) - 1])
20
21 static int month_offset[] = {
22 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
23 };
24
25 /*
26 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
27 */
rtc_calc_weekday(struct rtc_time * tm)28 int rtc_calc_weekday(struct rtc_time *tm)
29 {
30 int leaps_to_date;
31 int last_year;
32 int day;
33
34 if (tm->tm_year < 1753)
35 return -1;
36 last_year = tm->tm_year - 1;
37
38 /* Number of leap corrections to apply up to end of last year */
39 leaps_to_date = last_year / 4 - last_year / 100 + last_year / 400;
40
41 /*
42 * This year is a leap year if it is divisible by 4 except when it is
43 * divisible by 100 unless it is divisible by 400
44 *
45 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 is.
46 */
47 if (tm->tm_year % 4 == 0 &&
48 ((tm->tm_year % 100 != 0) || (tm->tm_year % 400 == 0)) &&
49 tm->tm_mon > 2) {
50 /* We are past Feb. 29 in a leap year */
51 day = 1;
52 } else {
53 day = 0;
54 }
55
56 day += last_year * 365 + leaps_to_date + month_offset[tm->tm_mon - 1] +
57 tm->tm_mday;
58 tm->tm_wday = day % 7;
59
60 return 0;
61 }
62
63 /*
64 * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
65 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
66 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
67 *
68 * [For the Julian calendar (which was used in Russia before 1917,
69 * Britain & colonies before 1752, anywhere else before 1582,
70 * and is still in use by some communities) leave out the
71 * -year / 100 + year / 400 terms, and add 10.]
72 *
73 * This algorithm was first published by Gauss (I think).
74 *
75 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
76 * machines where long is 32-bit! (However, as time_t is signed, we
77 * will already get problems at other places on 2038-01-19 03:14:08)
78 */
rtc_mktime(const struct rtc_time * tm)79 unsigned long rtc_mktime(const struct rtc_time *tm)
80 {
81 int mon = tm->tm_mon;
82 int year = tm->tm_year;
83 int days, hours;
84
85 mon -= 2;
86 if (0 >= (int)mon) { /* 1..12 -> 11, 12, 1..10 */
87 mon += 12; /* Puts Feb last since it has leap day */
88 year -= 1;
89 }
90
91 days = (unsigned long)(year / 4 - year / 100 + year / 400 +
92 367 * mon / 12 + tm->tm_mday) +
93 year * 365 - 719499;
94 hours = days * 24 + tm->tm_hour;
95 return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec;
96 }
97
98 /* for compatibility with linux code */
mktime64(const unsigned int year,const unsigned int mon,const unsigned int day,const unsigned int hour,const unsigned int min,const unsigned int sec)99 time64_t mktime64(const unsigned int year, const unsigned int mon,
100 const unsigned int day, const unsigned int hour,
101 const unsigned int min, const unsigned int sec)
102 {
103 struct rtc_time time;
104
105 time.tm_year = year;
106 time.tm_mon = mon;
107 time.tm_mday = day;
108 time.tm_hour = hour;
109 time.tm_min = min;
110 time.tm_sec = sec;
111
112 return (time64_t)rtc_mktime((const struct rtc_time *)&time);
113 }
114