projects/linux·blob v4.13 · refs

150 lines · 3.4 KiB

1/*
2 * rtc and date/time utility functions
3 *
4 * Copyright (C) 2005-06 Tower Technologies
5 * Author: Alessandro Zummo <[email protected]>
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
17static const unsigned char rtc_days_in_month[] = {
18 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
19};
20
21static 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 */
33int rtc_month_days(unsigned int month, unsigned int year)
34{
35 return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
36}
37EXPORT_SYMBOL(rtc_month_days);
38
39/*
40 * The number of days since January 1. (0 to 365)
41 */
42int 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}
46EXPORT_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 */
53void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
54{
55 unsigned int month, year;
56 unsigned long secs;
57 int days;
58
59 /* time must be positive */
60 days = div_s64(time, 86400);
61 secs = time - (unsigned int) days * 86400;
62
63 /* day of the week, 1970-01-01 was a Thursday */
64 tm->tm_wday = (days + 4) % 7;
65
66 year = 1970 + days / 365;
67 days -= (year - 1970) * 365
68 + LEAPS_THRU_END_OF(year - 1)
69 - LEAPS_THRU_END_OF(1970 - 1);
70 if (days < 0) {
71 year -= 1;
72 days += 365 + is_leap_year(year);
73 }
74 tm->tm_year = year - 1900;
75 tm->tm_yday = days + 1;
76
77 for (month = 0; month < 11; month++) {
78 int newdays;
79
80 newdays = days - rtc_month_days(month, year);
81 if (newdays < 0)
82 break;
83 days = newdays;
84 }
85 tm->tm_mon = month;
86 tm->tm_mday = days + 1;
87
88 tm->tm_hour = secs / 3600;
89 secs -= tm->tm_hour * 3600;
90 tm->tm_min = secs / 60;
91 tm->tm_sec = secs - tm->tm_min * 60;
92
93 tm->tm_isdst = 0;
94}
95EXPORT_SYMBOL(rtc_time64_to_tm);
96
97/*
98 * Does the rtc_time represent a valid date/time?
99 */
100int rtc_valid_tm(struct rtc_time *tm)
101{
102 if (tm->tm_year < 70
103 || ((unsigned)tm->tm_mon) >= 12
104 || tm->tm_mday < 1
105 || tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
106 || ((unsigned)tm->tm_hour) >= 24
107 || ((unsigned)tm->tm_min) >= 60
108 || ((unsigned)tm->tm_sec) >= 60)
109 return -EINVAL;
110
111 return 0;
112}
113EXPORT_SYMBOL(rtc_valid_tm);
114
115/*
116 * rtc_tm_to_time64 - Converts rtc_time to time64_t.
117 * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
118 */
119time64_t rtc_tm_to_time64(struct rtc_time *tm)
120{
121 return mktime64(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
122 tm->tm_hour, tm->tm_min, tm->tm_sec);
123}
124EXPORT_SYMBOL(rtc_tm_to_time64);
125
126/*
127 * Convert rtc_time to ktime
128 */
129ktime_t rtc_tm_to_ktime(struct rtc_time tm)
130{
131 return ktime_set(rtc_tm_to_time64(&tm), 0);
132}
133EXPORT_SYMBOL_GPL(rtc_tm_to_ktime);
134
135/*
136 * Convert ktime to rtc_time
137 */
138struct rtc_time rtc_ktime_to_tm(ktime_t kt)
139{
140 struct timespec64 ts;
141 struct rtc_time ret;
142
143 ts = ktime_to_timespec64(kt);
144 /* Round up any ns */
145 if (ts.tv_nsec)
146 ts.tv_sec++;
147 rtc_time64_to_tm(ts.tv_sec, &ret);
148 return ret;
149}
150EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);