| Alessandro Zummo | c58411e | 2006-03-27 01:16:34 -0800 | [diff] [blame] | 1 | /* |
| 2 | * rtc and date/time utility functions |
| 3 | * |
| 4 | * Copyright (C) 2005-06 Tower Technologies |
| 5 | * Author: Alessandro Zummo <a.zummo@towertech.it> |
| 6 | * |
| 7 | * based on arch/arm/common/rtctime.c and other bits |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License version 2 as |
| 11 | * published by the Free Software Foundation. |
| 12 | */ |
| 13 | |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/rtc.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 | #define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) || !(year % 400)) |
| 23 | |
| 24 | int rtc_month_days(unsigned int month, unsigned int year) |
| 25 | { |
| 26 | return rtc_days_in_month[month] + (LEAP_YEAR(year) && month == 1); |
| 27 | } |
| 28 | EXPORT_SYMBOL(rtc_month_days); |
| 29 | |
| 30 | /* |
| 31 | * Convert seconds since 01-01-1970 00:00:00 to Gregorian date. |
| 32 | */ |
| 33 | void rtc_time_to_tm(unsigned long time, struct rtc_time *tm) |
| 34 | { |
| 35 | register int days, month, year; |
| 36 | |
| 37 | days = time / 86400; |
| 38 | time -= days * 86400; |
| 39 | |
| 40 | /* day of the week, 1970-01-01 was a Thursday */ |
| 41 | tm->tm_wday = (days + 4) % 7; |
| 42 | |
| 43 | year = 1970 + days / 365; |
| 44 | days -= (year - 1970) * 365 |
| 45 | + LEAPS_THRU_END_OF(year - 1) |
| 46 | - LEAPS_THRU_END_OF(1970 - 1); |
| 47 | if (days < 0) { |
| 48 | year -= 1; |
| 49 | days += 365 + LEAP_YEAR(year); |
| 50 | } |
| 51 | tm->tm_year = year - 1900; |
| 52 | tm->tm_yday = days + 1; |
| 53 | |
| 54 | for (month = 0; month < 11; month++) { |
| 55 | int newdays; |
| 56 | |
| 57 | newdays = days - rtc_month_days(month, year); |
| 58 | if (newdays < 0) |
| 59 | break; |
| 60 | days = newdays; |
| 61 | } |
| 62 | tm->tm_mon = month; |
| 63 | tm->tm_mday = days + 1; |
| 64 | |
| 65 | tm->tm_hour = time / 3600; |
| 66 | time -= tm->tm_hour * 3600; |
| 67 | tm->tm_min = time / 60; |
| 68 | tm->tm_sec = time - tm->tm_min * 60; |
| 69 | } |
| 70 | EXPORT_SYMBOL(rtc_time_to_tm); |
| 71 | |
| 72 | /* |
| 73 | * Does the rtc_time represent a valid date/time? |
| 74 | */ |
| 75 | int rtc_valid_tm(struct rtc_time *tm) |
| 76 | { |
| 77 | if (tm->tm_year < 70 |
| 78 | || tm->tm_mon >= 12 |
| 79 | || tm->tm_mday < 1 |
| 80 | || tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900) |
| 81 | || tm->tm_hour >= 24 |
| 82 | || tm->tm_min >= 60 |
| 83 | || tm->tm_sec >= 60) |
| 84 | return -EINVAL; |
| 85 | |
| 86 | return 0; |
| 87 | } |
| 88 | EXPORT_SYMBOL(rtc_valid_tm); |
| 89 | |
| 90 | /* |
| 91 | * Convert Gregorian date to seconds since 01-01-1970 00:00:00. |
| 92 | */ |
| 93 | int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time) |
| 94 | { |
| 95 | *time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, |
| 96 | tm->tm_hour, tm->tm_min, tm->tm_sec); |
| 97 | return 0; |
| 98 | } |
| 99 | EXPORT_SYMBOL(rtc_tm_to_time); |
| 100 | |
| 101 | MODULE_LICENSE("GPL"); |