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 */
rtc_month_days(unsigned int month,unsigned int year)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 */
rtc_year_days(unsigned int day,unsigned int month,unsigned int year)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_time_to_tm64 - Converts time64_t to rtc_time.
51 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
52 */
rtc_time64_to_tm(time64_t time,struct rtc_time * tm)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 */
rtc_valid_tm(struct rtc_time * tm)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 */
rtc_tm_to_time64(struct rtc_time * tm)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 */
rtc_tm_to_ktime(struct rtc_time tm)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 */
rtc_ktime_to_tm(ktime_t kt)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
