/* * rtc and date/time utility functions * * Copyright (C) 2005-06 Tower Technologies * Author: Alessandro Zummo <a.zummo@towertech.it> * * based on arch/arm/common/rtctime.c and other bits * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/module.h> #include <linux/rtc.h> static const unsigned char rtc_days_in_month[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; static const unsigned short rtc_ydays[2][13] = { /* Normal years */ { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, /* Leap years */ { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } }; #define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400) #define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) || !(year % 400)) /* * The number of days in the month. */ int rtc_month_days(unsigned int month, unsigned int year) { return rtc_days_in_month[month] + (LEAP_YEAR(year) && month == 1); } EXPORT_SYMBOL(rtc_month_days); /* * The number of days since January 1. (0 to 365) */ int rtc_year_days(unsigned int day, unsigned int month, unsigned int year) { return rtc_ydays[LEAP_YEAR(year)][month] + day-1; } EXPORT_SYMBOL(rtc_year_days); /* * Convert seconds since 01-01-1970 00:00:00 to Gregorian date. */ void rtc_time_to_tm(unsigned long time, struct rtc_time *tm) { register int days, month, year; days = time / 86400; time -= days * 86400; /* 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); if (days < 0) { year -= 1; days += 365 + LEAP_YEAR(year); } tm->tm_year = 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; tm->tm_mday = days + 1; tm->tm_hour = time / 3600; time -= tm->tm_hour * 3600; tm->tm_min = time / 60; tm->tm_sec = time - tm->tm_min * 60; } EXPORT_SYMBOL(rtc_time_to_tm); /* * Does the rtc_time represent a valid date/time? */ int rtc_valid_tm(struct rtc_time *tm) { if (tm->tm_year < 70 || ((unsigned)tm->tm_mon) >= 12 || tm->tm_mday < 1 || tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900) || ((unsigned)tm->tm_hour) >= 24 || ((unsigned)tm->tm_min) >= 60 || ((unsigned)tm->tm_sec) >= 60) return -EINVAL; return 0; } EXPORT_SYMBOL(rtc_valid_tm); /* * Convert Gregorian date to seconds since 01-01-1970 00:00:00. */ int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time) { *time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); return 0; } EXPORT_SYMBOL(rtc_tm_to_time); /* Merge the valid (i.e. non-negative) fields of alarm into the current * time. If the valid alarm fields are earlier than the equivalent * fields in the time, carry one into the least significant invalid * field, so that the alarm expiry is in the future. It assumes that the * least significant invalid field is more significant than the most * significant valid field, and that the seconds field is valid. * * This is used by alarms that take relative (rather than absolute) * times, and/or have a simple binary second counter instead of * day/hour/minute/sec registers. */ void rtc_merge_alarm(struct rtc_time *now, struct rtc_time *alarm) { int *alarmp = &alarm->tm_sec; int *timep = &now->tm_sec; int carry_into, i; /* Ignore everything past the 6th element (tm_year). */ for (i = 5; i > 0; i--) { if (alarmp[i] < 0) alarmp[i] = timep[i]; else break; } /* No carry needed if all fields are valid. */ if (i == 5) return; for (carry_into = i + 1; i >= 0; i--) { if (alarmp[i] < timep[i]) break; if (alarmp[i] > timep[i]) return; } switch (carry_into) { case 1: alarm->tm_min++; if (alarm->tm_min < 60) return; alarm->tm_min = 0; /* fall-through */ case 2: alarm->tm_hour++; if (alarm->tm_hour < 60) return; alarm->tm_hour = 0; /* fall-through */ case 3: alarm->tm_mday++; if (alarm->tm_mday <= rtc_days_in_month[alarm->tm_mon]) return; alarm->tm_mday = 1; /* fall-through */ case 4: alarm->tm_mon++; if (alarm->tm_mon <= 12) return; alarm->tm_mon = 1; /* fall-through */ case 5: alarm->tm_year++; } } EXPORT_SYMBOL(rtc_merge_alarm); MODULE_LICENSE("GPL");