/* * 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");