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 <a.zummo@towertech.it> 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 */ 26 static int rtc_month_days(unsigned int month, unsigned int year) 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. 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. 37 */ 38 void rtc_to_tm(u64 time, struct rtc_time *tm) 39 { 40 unsigned int month, year, secs; 41 int days; 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 } 78