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/export.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 static const unsigned short rtc_ydays[2][13] = { 22 /* Normal years */ 23 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, 24 /* Leap years */ 25 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } 26 }; 27 28 #define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400) 29 30 /* 31 * The number of days in the month. 32 */ 33 int rtc_month_days(unsigned int month, unsigned int year) 34 { 35 return rtc_days_in_month[month] + (is_leap_year(year) && month == 1); 36 } 37 EXPORT_SYMBOL(rtc_month_days); 38 39 /* 40 * The number of days since January 1. (0 to 365) 41 */ 42 int rtc_year_days(unsigned int day, unsigned int month, unsigned int year) 43 { 44 return rtc_ydays[is_leap_year(year)][month] + day-1; 45 } 46 EXPORT_SYMBOL(rtc_year_days); 47 48 49 /* 50 * rtc_time64_to_tm - Converts time64_t to rtc_time. 51 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date. 52 */ 53 void rtc_time64_to_tm(time64_t time, struct rtc_time *tm) 54 { 55 unsigned int month, year, secs; 56 int days; 57 58 /* time must be positive */ 59 days = div_s64_rem(time, 86400, &secs); 60 61 /* day of the week, 1970-01-01 was a Thursday */ 62 tm->tm_wday = (days + 4) % 7; 63 64 year = 1970 + days / 365; 65 days -= (year - 1970) * 365 66 + LEAPS_THRU_END_OF(year - 1) 67 - LEAPS_THRU_END_OF(1970 - 1); 68 while (days < 0) { 69 year -= 1; 70 days += 365 + is_leap_year(year); 71 } 72 tm->tm_year = year - 1900; 73 tm->tm_yday = days + 1; 74 75 for (month = 0; month < 11; month++) { 76 int newdays; 77 78 newdays = days - rtc_month_days(month, year); 79 if (newdays < 0) 80 break; 81 days = newdays; 82 } 83 tm->tm_mon = month; 84 tm->tm_mday = days + 1; 85 86 tm->tm_hour = secs / 3600; 87 secs -= tm->tm_hour * 3600; 88 tm->tm_min = secs / 60; 89 tm->tm_sec = secs - tm->tm_min * 60; 90 91 tm->tm_isdst = 0; 92 } 93 EXPORT_SYMBOL(rtc_time64_to_tm); 94 95 /* 96 * Does the rtc_time represent a valid date/time? 97 */ 98 int rtc_valid_tm(struct rtc_time *tm) 99 { 100 if (tm->tm_year < 70 101 || ((unsigned)tm->tm_mon) >= 12 102 || tm->tm_mday < 1 103 || tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900) 104 || ((unsigned)tm->tm_hour) >= 24 105 || ((unsigned)tm->tm_min) >= 60 106 || ((unsigned)tm->tm_sec) >= 60) 107 return -EINVAL; 108 109 return 0; 110 } 111 EXPORT_SYMBOL(rtc_valid_tm); 112 113 /* 114 * rtc_tm_to_time64 - Converts rtc_time to time64_t. 115 * Convert Gregorian date to seconds since 01-01-1970 00:00:00. 116 */ 117 time64_t rtc_tm_to_time64(struct rtc_time *tm) 118 { 119 return mktime64(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, 120 tm->tm_hour, tm->tm_min, tm->tm_sec); 121 } 122 EXPORT_SYMBOL(rtc_tm_to_time64); 123 124 /* 125 * Convert rtc_time to ktime 126 */ 127 ktime_t rtc_tm_to_ktime(struct rtc_time tm) 128 { 129 return ktime_set(rtc_tm_to_time64(&tm), 0); 130 } 131 EXPORT_SYMBOL_GPL(rtc_tm_to_ktime); 132 133 /* 134 * Convert ktime to rtc_time 135 */ 136 struct rtc_time rtc_ktime_to_tm(ktime_t kt) 137 { 138 struct timespec64 ts; 139 struct rtc_time ret; 140 141 ts = ktime_to_timespec64(kt); 142 /* Round up any ns */ 143 if (ts.tv_nsec) 144 ts.tv_sec++; 145 rtc_time64_to_tm(ts.tv_sec, &ret); 146 return ret; 147 } 148 EXPORT_SYMBOL_GPL(rtc_ktime_to_tm); 149