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 <[email protected]> 7 * 8 * based on arch/arm/common/rtctime.c and other bits 9 */ 10 11 #include <linux/export.h> 12 #include <linux/rtc.h> 13 14 static const unsigned char rtc_days_in_month[] = { 15 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 16 }; 17 18 static const unsigned short rtc_ydays[2][13] = { 19 /* Normal years */ 20 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, 21 /* Leap years */ 22 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } 23 }; 24 25 #define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400) 26 27 /* 28 * The number of days in the month. 29 */ 30 int rtc_month_days(unsigned int month, unsigned int year) 31 { 32 return rtc_days_in_month[month] + (is_leap_year(year) && month == 1); 33 } 34 EXPORT_SYMBOL(rtc_month_days); 35 36 /* 37 * The number of days since January 1. (0 to 365) 38 */ 39 int rtc_year_days(unsigned int day, unsigned int month, unsigned int year) 40 { 41 return rtc_ydays[is_leap_year(year)][month] + day-1; 42 } 43 EXPORT_SYMBOL(rtc_year_days); 44 45 46 /* 47 * rtc_time64_to_tm - Converts time64_t to rtc_time. 48 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date. 49 */ 50 void rtc_time64_to_tm(time64_t time, struct rtc_time *tm) 51 { 52 unsigned int month, year, secs; 53 int days; 54 55 /* time must be positive */ 56 days = div_s64_rem(time, 86400, &secs); 57 58 /* day of the week, 1970-01-01 was a Thursday */ 59 tm->tm_wday = (days + 4) % 7; 60 61 year = 1970 + days / 365; 62 days -= (year - 1970) * 365 63 + LEAPS_THRU_END_OF(year - 1) 64 - LEAPS_THRU_END_OF(1970 - 1); 65 while (days < 0) { 66 year -= 1; 67 days += 365 + is_leap_year(year); 68 } 69 tm->tm_year = year - 1900; 70 tm->tm_yday = days + 1; 71 72 for (month = 0; month < 11; month++) { 73 int newdays; 74 75 newdays = days - rtc_month_days(month, year); 76 if (newdays < 0) 77 break; 78 days = newdays; 79 } 80 tm->tm_mon = month; 81 tm->tm_mday = days + 1; 82 83 tm->tm_hour = secs / 3600; 84 secs -= tm->tm_hour * 3600; 85 tm->tm_min = secs / 60; 86 tm->tm_sec = secs - tm->tm_min * 60; 87 88 tm->tm_isdst = 0; 89 } 90 EXPORT_SYMBOL(rtc_time64_to_tm); 91 92 /* 93 * Does the rtc_time represent a valid date/time? 94 */ 95 int rtc_valid_tm(struct rtc_time *tm) 96 { 97 if (tm->tm_year < 70 98 || ((unsigned)tm->tm_mon) >= 12 99 || tm->tm_mday < 1 100 || tm->tm_mday > rtc_month_days(tm->tm_mon, ((unsigned)tm->tm_year + 1900)) 101 || ((unsigned)tm->tm_hour) >= 24 102 || ((unsigned)tm->tm_min) >= 60 103 || ((unsigned)tm->tm_sec) >= 60) 104 return -EINVAL; 105 106 return 0; 107 } 108 EXPORT_SYMBOL(rtc_valid_tm); 109 110 /* 111 * rtc_tm_to_time64 - Converts rtc_time to time64_t. 112 * Convert Gregorian date to seconds since 01-01-1970 00:00:00. 113 */ 114 time64_t rtc_tm_to_time64(struct rtc_time *tm) 115 { 116 return mktime64(((unsigned)tm->tm_year + 1900), tm->tm_mon + 1, 117 tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); 118 } 119 EXPORT_SYMBOL(rtc_tm_to_time64); 120 121 /* 122 * Convert rtc_time to ktime 123 */ 124 ktime_t rtc_tm_to_ktime(struct rtc_time tm) 125 { 126 return ktime_set(rtc_tm_to_time64(&tm), 0); 127 } 128 EXPORT_SYMBOL_GPL(rtc_tm_to_ktime); 129 130 /* 131 * Convert ktime to rtc_time 132 */ 133 struct rtc_time rtc_ktime_to_tm(ktime_t kt) 134 { 135 struct timespec64 ts; 136 struct rtc_time ret; 137 138 ts = ktime_to_timespec64(kt); 139 /* Round up any ns */ 140 if (ts.tv_nsec) 141 ts.tv_sec++; 142 rtc_time64_to_tm(ts.tv_sec, &ret); 143 return ret; 144 } 145 EXPORT_SYMBOL_GPL(rtc_ktime_to_tm); 146