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 <a.zummo@towertech.it> 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 * rtc_time64_to_tm - Converts time64_t to rtc_time. 47 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date. 48 */ 49 void rtc_time64_to_tm(time64_t time, struct rtc_time *tm) 50 { 51 unsigned int month, year, secs; 52 int days; 53 54 /* time must be positive */ 55 days = div_s64_rem(time, 86400, &secs); 56 57 /* day of the week, 1970-01-01 was a Thursday */ 58 tm->tm_wday = (days + 4) % 7; 59 60 year = 1970 + days / 365; 61 days -= (year - 1970) * 365 62 + LEAPS_THRU_END_OF(year - 1) 63 - LEAPS_THRU_END_OF(1970 - 1); 64 while (days < 0) { 65 year -= 1; 66 days += 365 + is_leap_year(year); 67 } 68 tm->tm_year = year - 1900; 69 tm->tm_yday = days + 1; 70 71 for (month = 0; month < 11; month++) { 72 int newdays; 73 74 newdays = days - rtc_month_days(month, year); 75 if (newdays < 0) 76 break; 77 days = newdays; 78 } 79 tm->tm_mon = month; 80 tm->tm_mday = days + 1; 81 82 tm->tm_hour = secs / 3600; 83 secs -= tm->tm_hour * 3600; 84 tm->tm_min = secs / 60; 85 tm->tm_sec = secs - tm->tm_min * 60; 86 87 tm->tm_isdst = 0; 88 } 89 EXPORT_SYMBOL(rtc_time64_to_tm); 90 91 /* 92 * Does the rtc_time represent a valid date/time? 93 */ 94 int rtc_valid_tm(struct rtc_time *tm) 95 { 96 if (tm->tm_year < 70 || 97 tm->tm_year > (INT_MAX - 1900) || 98 ((unsigned int)tm->tm_mon) >= 12 || 99 tm->tm_mday < 1 || 100 tm->tm_mday > rtc_month_days(tm->tm_mon, 101 ((unsigned int)tm->tm_year + 1900)) || 102 ((unsigned int)tm->tm_hour) >= 24 || 103 ((unsigned int)tm->tm_min) >= 60 || 104 ((unsigned int)tm->tm_sec) >= 60) 105 return -EINVAL; 106 107 return 0; 108 } 109 EXPORT_SYMBOL(rtc_valid_tm); 110 111 /* 112 * rtc_tm_to_time64 - Converts rtc_time to time64_t. 113 * Convert Gregorian date to seconds since 01-01-1970 00:00:00. 114 */ 115 time64_t rtc_tm_to_time64(struct rtc_time *tm) 116 { 117 return mktime64(((unsigned int)tm->tm_year + 1900), tm->tm_mon + 1, 118 tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec); 119 } 120 EXPORT_SYMBOL(rtc_tm_to_time64); 121 122 /* 123 * Convert rtc_time to ktime 124 */ 125 ktime_t rtc_tm_to_ktime(struct rtc_time tm) 126 { 127 return ktime_set(rtc_tm_to_time64(&tm), 0); 128 } 129 EXPORT_SYMBOL_GPL(rtc_tm_to_ktime); 130 131 /* 132 * Convert ktime to rtc_time 133 */ 134 struct rtc_time rtc_ktime_to_tm(ktime_t kt) 135 { 136 struct timespec64 ts; 137 struct rtc_time ret; 138 139 ts = ktime_to_timespec64(kt); 140 /* Round up any ns */ 141 if (ts.tv_nsec) 142 ts.tv_sec++; 143 rtc_time64_to_tm(ts.tv_sec, &ret); 144 return ret; 145 } 146 EXPORT_SYMBOL_GPL(rtc_ktime_to_tm); 147