1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2
3 /*
4 * From U-Boot 2016.05
5 */
6
7 #include <console/console.h>
8 #include <rtc.h>
9
10 #define FEBRUARY 2
11 #define STARTOFTIME 1970
12 #define SECDAY 86400L
13 #define SECYR (SECDAY * 365)
14 #define LEAP_YEAR(year) (((year) % 4 == 0 && (year) % 100 != 0) || (year) % 400 == 0)
15 #define DAYS_IN_YEAR(a) (LEAP_YEAR(a) ? 366 : 365)
16 #define DAYS_IN_MONTH(a) (month_days[(a) - 1])
17
18 static const char *const weekdays[] = {
19 "Sun", "Mon", "Tues", "Wednes", "Thurs", "Fri", "Satur"
20 };
21
22 /* Zeller's rule */
rtc_calc_weekday(struct rtc_time * tm)23 static int rtc_calc_weekday(struct rtc_time *tm)
24 {
25 /* In Zeller's rule, January and February are treated as if they
26 are months 13 and 14 of the previous year (March is still month 3) */
27 const int zyear = ((tm->mon < 3) ? tm->year - 1 : tm->year);
28 const int q = tm->mday;
29 const int m = (tm->mon < 3) ? tm->mon + 12 : tm->mon;
30 const int K = zyear % 100;
31 const int J = zyear / 100;
32
33 /*
34 * Because of the way the modulo operator works with negative numbers,
35 * the traditional formulation of Zeller's rule must be modified
36 * slightly to make the numerator positive (i.e., add 5J instead of
37 * subtracting 2J). Also subtract 1 so that Sunday is day 0.
38 */
39 const int h = (q + (13 * (m + 1)) / 5
40 + K + (K / 4) + (J / 4) + (5 * J) - 1) % 7;
41
42 tm->wday = h;
43 return 0;
44 }
45
rtc_to_tm(int tim,struct rtc_time * tm)46 int rtc_to_tm(int tim, struct rtc_time *tm)
47 {
48 int month_days[12] = {
49 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
50 };
51 register int i;
52 register long hms, day;
53
54 day = tim / SECDAY;
55 hms = tim % SECDAY;
56
57 /* Hours, minutes, seconds are easy */
58 tm->hour = hms / 3600;
59 tm->min = (hms % 3600) / 60;
60 tm->sec = (hms % 3600) % 60;
61
62 /* Number of years in days */
63 for (i = STARTOFTIME; day >= DAYS_IN_YEAR(i); i++)
64 day -= DAYS_IN_YEAR(i);
65 tm->year = i;
66
67 /* Number of months in days left */
68 if (LEAP_YEAR(tm->year))
69 DAYS_IN_MONTH(FEBRUARY) = 29;
70 for (i = 1; day >= DAYS_IN_MONTH(i); i++)
71 day -= DAYS_IN_MONTH(i);
72 DAYS_IN_MONTH(FEBRUARY) = 28;
73 tm->mon = i;
74
75 /* Days are what is left over (+1) from all that */
76 tm->mday = day + 1;
77
78 /* Determine the day of week */
79 return rtc_calc_weekday(tm);
80 }
81
82 /*
83 * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
84 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
85 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
86 *
87 * [For the Julian calendar (which was used in Russia before 1917,
88 * Britain & colonies before 1752, anywhere else before 1582,
89 * and is still in use by some communities) leave out the
90 * -year / 100 + year / 400 terms, and add 10.]
91 *
92 * This algorithm was first published by Gauss (I think).
93 *
94 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
95 * machines where long is 32-bit! (However, as time_t is signed, we
96 * will already get problems at other places on 2038-01-19 03:14:08)
97 */
rtc_mktime(const struct rtc_time * tm)98 unsigned long rtc_mktime(const struct rtc_time *tm)
99 {
100 int mon = tm->mon;
101 int year = tm->year;
102 int days, hours;
103
104 mon -= 2;
105 if (0 >= (int)mon) { /* 1..12 -> 11, 12, 1..10 */
106 mon += 12; /* Puts Feb last since it has leap day */
107 year -= 1;
108 }
109
110 days = (unsigned long)(year / 4 - year / 100 + year / 400 +
111 367 * mon / 12 + tm->mday) +
112 year * 365 - 719499;
113 hours = days * 24 + tm->hour;
114 return (hours * 60 + tm->min) * 60 + tm->sec;
115 }
116
rtc_display(const struct rtc_time * tm)117 void rtc_display(const struct rtc_time *tm)
118 {
119 printk(BIOS_INFO, "Date: %5d-%02d-%02d (%sday) Time: %2d:%02d:%02d\n",
120 tm->year, tm->mon, tm->mday,
121 (tm->wday < 0 || tm->wday > 6) ? "unknown " : weekdays[tm->wday],
122 tm->hour, tm->min, tm->sec);
123 }
124
rtc_month_days(unsigned int month,unsigned int year)125 static int rtc_month_days(unsigned int month, unsigned int year)
126 {
127 int month_days[12] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
128
129 return month_days[month] + (LEAP_YEAR(year) && month == 1);
130 }
131
rtc_invalid(const struct rtc_time * tm)132 int rtc_invalid(const struct rtc_time *tm)
133 {
134 if (tm->sec > 59 || tm->min > 59 || tm->hour > 23 || tm->mon == 0 || tm->mon > 12 ||
135 tm->year < 1970 || tm->mday > rtc_month_days(tm->mon - 1, tm->year))
136 return 1;
137 else
138 return 0;
139 }
140