1992c1db4SHeinrich Schuchardt // SPDX-License-Identifier: GPL-2.0
2992c1db4SHeinrich Schuchardt /*
3992c1db4SHeinrich Schuchardt * rtc and date/time utility functions
4992c1db4SHeinrich Schuchardt *
5992c1db4SHeinrich Schuchardt * Copyright (C) 2005-06 Tower Technologies
6992c1db4SHeinrich Schuchardt * Author: Alessandro Zummo <a.zummo@towertech.it>
7992c1db4SHeinrich Schuchardt *
8992c1db4SHeinrich Schuchardt * U-Boot rtc_time differs from Linux rtc_time:
9992c1db4SHeinrich Schuchardt * - The year field takes the actual value, not year - 1900.
10992c1db4SHeinrich Schuchardt * - January is month 1.
11992c1db4SHeinrich Schuchardt */
12992c1db4SHeinrich Schuchardt
13992c1db4SHeinrich Schuchardt #include <common.h>
14992c1db4SHeinrich Schuchardt #include <rtc.h>
15992c1db4SHeinrich Schuchardt #include <linux/math64.h>
16992c1db4SHeinrich Schuchardt
17992c1db4SHeinrich Schuchardt static const unsigned char rtc_days_in_month[] = {
18992c1db4SHeinrich Schuchardt 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
19992c1db4SHeinrich Schuchardt };
20992c1db4SHeinrich Schuchardt
21992c1db4SHeinrich Schuchardt #define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
22992c1db4SHeinrich Schuchardt
23992c1db4SHeinrich Schuchardt /*
24992c1db4SHeinrich Schuchardt * The number of days in the month.
25992c1db4SHeinrich Schuchardt */
rtc_month_days(unsigned int month,unsigned int year)26992c1db4SHeinrich Schuchardt static int rtc_month_days(unsigned int month, unsigned int year)
27992c1db4SHeinrich Schuchardt {
28992c1db4SHeinrich Schuchardt return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
29992c1db4SHeinrich Schuchardt }
30992c1db4SHeinrich Schuchardt
31992c1db4SHeinrich Schuchardt /*
32992c1db4SHeinrich Schuchardt * rtc_to_tm - Converts u64 to rtc_time.
33992c1db4SHeinrich Schuchardt * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
34*95206135SHeinrich Schuchardt *
35*95206135SHeinrich Schuchardt * This function is copied from rtc_time64_to_tm() in the Linux kernel.
36*95206135SHeinrich Schuchardt * But in U-Boot January is month 1 and we do not subtract 1900 from the year.
37992c1db4SHeinrich Schuchardt */
rtc_to_tm(u64 time,struct rtc_time * tm)38992c1db4SHeinrich Schuchardt void rtc_to_tm(u64 time, struct rtc_time *tm)
39992c1db4SHeinrich Schuchardt {
40*95206135SHeinrich Schuchardt unsigned int month, year, secs;
41*95206135SHeinrich Schuchardt int days;
42992c1db4SHeinrich Schuchardt
43992c1db4SHeinrich Schuchardt days = div_u64_rem(time, 86400, &secs);
44992c1db4SHeinrich Schuchardt
45992c1db4SHeinrich Schuchardt /* day of the week, 1970-01-01 was a Thursday */
46992c1db4SHeinrich Schuchardt tm->tm_wday = (days + 4) % 7;
47992c1db4SHeinrich Schuchardt
48992c1db4SHeinrich Schuchardt year = 1970 + days / 365;
49992c1db4SHeinrich Schuchardt days -= (year - 1970) * 365
50992c1db4SHeinrich Schuchardt + LEAPS_THRU_END_OF(year - 1)
51992c1db4SHeinrich Schuchardt - LEAPS_THRU_END_OF(1970 - 1);
52992c1db4SHeinrich Schuchardt while (days < 0) {
53992c1db4SHeinrich Schuchardt year -= 1;
54992c1db4SHeinrich Schuchardt days += 365 + is_leap_year(year);
55992c1db4SHeinrich Schuchardt }
56992c1db4SHeinrich Schuchardt tm->tm_year = year; /* Not year - 1900 */
57992c1db4SHeinrich Schuchardt tm->tm_yday = days + 1;
58992c1db4SHeinrich Schuchardt
59992c1db4SHeinrich Schuchardt for (month = 0; month < 11; month++) {
60992c1db4SHeinrich Schuchardt int newdays;
61992c1db4SHeinrich Schuchardt
62992c1db4SHeinrich Schuchardt newdays = days - rtc_month_days(month, year);
63992c1db4SHeinrich Schuchardt if (newdays < 0)
64992c1db4SHeinrich Schuchardt break;
65992c1db4SHeinrich Schuchardt days = newdays;
66992c1db4SHeinrich Schuchardt }
67992c1db4SHeinrich Schuchardt tm->tm_mon = month + 1; /* January = 1 */
68992c1db4SHeinrich Schuchardt tm->tm_mday = days + 1;
69992c1db4SHeinrich Schuchardt
70992c1db4SHeinrich Schuchardt tm->tm_hour = secs / 3600;
71992c1db4SHeinrich Schuchardt secs -= tm->tm_hour * 3600;
72992c1db4SHeinrich Schuchardt tm->tm_min = secs / 60;
73992c1db4SHeinrich Schuchardt tm->tm_sec = secs - tm->tm_min * 60;
74992c1db4SHeinrich Schuchardt
75992c1db4SHeinrich Schuchardt /* Zero unused fields */
76992c1db4SHeinrich Schuchardt tm->tm_isdst = 0;
77992c1db4SHeinrich Schuchardt }
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