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// SPDX-License-Identifier: GPL-2.0
/*
* rtc and date/time utility functions
*
* Copyright (C) 2005-06 Tower Technologies
* Author: Alessandro Zummo <a.zummo@towertech.it>
*
* U-Boot rtc_time differs from Linux rtc_time:
* - The year field takes the actual value, not year - 1900.
* - January is month 1.
*/
#include <rtc.h>
#include <linux/math64.h>
static const unsigned char rtc_days_in_month[] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
#define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
/*
* The number of days in the month.
*/
int rtc_month_days(unsigned int month, unsigned int year)
{
return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
}
/*
* rtc_to_tm - Converts u64 to rtc_time.
* Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
*
* This function is copied from rtc_time64_to_tm() in the Linux kernel.
* But in U-Boot January is month 1 and we do not subtract 1900 from the year.
*/
void rtc_to_tm(u64 time, struct rtc_time *tm)
{
unsigned int month, year, secs;
int days;
days = div_u64_rem(time, 86400, &secs);
/* day of the week, 1970-01-01 was a Thursday */
tm->tm_wday = (days + 4) % 7;
year = 1970 + days / 365;
days -= (year - 1970) * 365
+ LEAPS_THRU_END_OF(year - 1)
- LEAPS_THRU_END_OF(1970 - 1);
while (days < 0) {
year -= 1;
days += 365 + is_leap_year(year);
}
tm->tm_year = year; /* Not year - 1900 */
tm->tm_yday = days + 1;
for (month = 0; month < 11; month++) {
int newdays;
newdays = days - rtc_month_days(month, year);
if (newdays < 0)
break;
days = newdays;
}
tm->tm_mon = month + 1; /* January = 1 */
tm->tm_mday = days + 1;
tm->tm_hour = secs / 3600;
secs -= tm->tm_hour * 3600;
tm->tm_min = secs / 60;
tm->tm_sec = secs - tm->tm_min * 60;
/* Zero unused fields */
tm->tm_isdst = 0;
}
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