[J-u-boot.git] / lib / rtc-lib.c

// SPDX-License-Identifier: GPL-2.0
/*
 * rtc and date/time utility functions
 *
 * Copyright (C) 2005-06 Tower Technologies
 * Author: Alessandro Zummo <[email protected]>
 *
 * U-Boot rtc_time differs from Linux rtc_time:
 * - The year field takes the actual value, not year - 1900.
 * - January is month 1.
 */

#include <common.h>
#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;
}
Commit	Line	Data
992c1db4 HS	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* rtc and date/time utility functions
	4	*
	5	* Copyright (C) 2005-06 Tower Technologies
	6	* Author: Alessandro Zummo <[email protected]>
	7	*
	8	* U-Boot rtc_time differs from Linux rtc_time:
	9	* - The year field takes the actual value, not year - 1900.
	10	* - January is month 1.
	11	*/
	12
	13	#include <common.h>
	14	#include <rtc.h>
	15	#include <linux/math64.h>
	16
	17	static const unsigned char rtc_days_in_month[] = {
	18	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
	19	};
	20
	21	#define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
	22
	23	/*
	24	* The number of days in the month.
	25	*/
3c1889e6	26	int rtc_month_days(unsigned int month, unsigned int year)
992c1db4 HS	27	{
	28	return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
	29	}
	30
	31	/*
	32	* rtc_to_tm - Converts u64 to rtc_time.
	33	* Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
95206135 HS	34	*
	35	* This function is copied from rtc_time64_to_tm() in the Linux kernel.
	36	* But in U-Boot January is month 1 and we do not subtract 1900 from the year.
992c1db4 HS	37	*/
	38	void rtc_to_tm(u64 time, struct rtc_time *tm)
	39	{
95206135 HS	40	unsigned int month, year, secs;
95206135 HS	41	int days;
992c1db4 HS	42
	43	days = div_u64_rem(time, 86400, &secs);
	44
	45	/* day of the week, 1970-01-01 was a Thursday */
	46	tm->tm_wday = (days + 4) % 7;
	47
	48	year = 1970 + days / 365;
	49	days -= (year - 1970) * 365
	50	+ LEAPS_THRU_END_OF(year - 1)
	51	- LEAPS_THRU_END_OF(1970 - 1);
	52	while (days < 0) {
	53	year -= 1;
	54	days += 365 + is_leap_year(year);
	55	}
	56	tm->tm_year = year; /* Not year - 1900 */
	57	tm->tm_yday = days + 1;
	58
	59	for (month = 0; month < 11; month++) {
	60	int newdays;
	61
	62	newdays = days - rtc_month_days(month, year);
	63	if (newdays < 0)
	64	break;
	65	days = newdays;
	66	}
	67	tm->tm_mon = month + 1; /* January = 1 */
	68	tm->tm_mday = days + 1;
	69
	70	tm->tm_hour = secs / 3600;
	71	secs -= tm->tm_hour * 3600;
	72	tm->tm_min = secs / 60;
	73	tm->tm_sec = secs - tm->tm_min * 60;
	74
	75	/* Zero unused fields */
	76	tm->tm_isdst = 0;
	77	}