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 #if defined(CONFIG_LIB_DATE) || defined(CONFIG_TIMESTAMP)
14
15 #define FEBRUARY 2
16 #define STARTOFTIME 1970
17 #define SECDAY 86400L
18 #define SECYR (SECDAY * 365)
19 #define leapyear(year) ((year) % 4 == 0)
20 #define days_in_year(a) (leapyear(a) ? 366 : 365)
21 #define days_in_month(a) (month_days[(a) - 1])
22
23 static int month_offset[] = {
24 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
25 };
26
27 /*
28 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
29 */
rtc_calc_weekday(struct rtc_time * tm)30 int rtc_calc_weekday(struct rtc_time *tm)
31 {
32 int leaps_to_date;
33 int last_year;
34 int day;
35
36 if (tm->tm_year < 1753)
37 return -1;
38 last_year = tm->tm_year - 1;
39
40 /* Number of leap corrections to apply up to end of last year */
41 leaps_to_date = last_year / 4 - last_year / 100 + last_year / 400;
42
43 /*
44 * This year is a leap year if it is divisible by 4 except when it is
45 * divisible by 100 unless it is divisible by 400
46 *
47 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 is.
48 */
49 if (tm->tm_year % 4 == 0 &&
50 ((tm->tm_year % 100 != 0) || (tm->tm_year % 400 == 0)) &&
51 tm->tm_mon > 2) {
52 /* We are past Feb. 29 in a leap year */
53 day = 1;
54 } else {
55 day = 0;
56 }
57
58 day += last_year * 365 + leaps_to_date + month_offset[tm->tm_mon - 1] +
59 tm->tm_mday;
60 tm->tm_wday = day % 7;
61
62 return 0;
63 }
64
65 /*
66 * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
67 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
68 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
69 *
70 * [For the Julian calendar (which was used in Russia before 1917,
71 * Britain & colonies before 1752, anywhere else before 1582,
72 * and is still in use by some communities) leave out the
73 * -year / 100 + year / 400 terms, and add 10.]
74 *
75 * This algorithm was first published by Gauss (I think).
76 *
77 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
78 * machines where long is 32-bit! (However, as time_t is signed, we
79 * will already get problems at other places on 2038-01-19 03:14:08)
80 */
rtc_mktime(const struct rtc_time * tm)81 unsigned long rtc_mktime(const struct rtc_time *tm)
82 {
83 int mon = tm->tm_mon;
84 int year = tm->tm_year;
85 int days, hours;
86
87 mon -= 2;
88 if (0 >= (int)mon) { /* 1..12 -> 11, 12, 1..10 */
89 mon += 12; /* Puts Feb last since it has leap day */
90 year -= 1;
91 }
92
93 days = (unsigned long)(year / 4 - year / 100 + year / 400 +
94 367 * mon / 12 + tm->tm_mday) +
95 year * 365 - 719499;
96 hours = days * 24 + tm->tm_hour;
97 return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec;
98 }
99
100 #endif /* CONFIG_LIB_DATE || CONFIG_TIMESTAMP */
101
102 #ifdef CONFIG_LIB_DATE
103 /* 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)104 time64_t mktime64(const unsigned int year, const unsigned int mon,
105 const unsigned int day, const unsigned int hour,
106 const unsigned int min, const unsigned int sec)
107 {
108 struct rtc_time time;
109
110 time.tm_year = year;
111 time.tm_mon = mon;
112 time.tm_mday = day;
113 time.tm_hour = hour;
114 time.tm_min = min;
115 time.tm_sec = sec;
116
117 return (time64_t)rtc_mktime((const struct rtc_time *)&time);
118 }
119 #endif
120