projects/linux·blob v3.13 · refs

150 lines · 3.3 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/module.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 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
50 */
51void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
52{
53 unsigned int month, year;
54 int days;
55
56 days = time / 86400;
57 time -= (unsigned int) days * 86400;
58
59 /* day of the week, 1970-01-01 was a Thursday */
60 tm->tm_wday = (days + 4) % 7;
61
62 year = 1970 + days / 365;
63 days -= (year - 1970) * 365
64 + LEAPS_THRU_END_OF(year - 1)
65 - LEAPS_THRU_END_OF(1970 - 1);
66 if (days < 0) {
67 year -= 1;
68 days += 365 + is_leap_year(year);
69 }
70 tm->tm_year = year - 1900;
71 tm->tm_yday = days + 1;
72
73 for (month = 0; month < 11; month++) {
74 int newdays;
75
76 newdays = days - rtc_month_days(month, year);
77 if (newdays < 0)
78 break;
79 days = newdays;
80 }
81 tm->tm_mon = month;
82 tm->tm_mday = days + 1;
83
84 tm->tm_hour = time / 3600;
85 time -= tm->tm_hour * 3600;
86 tm->tm_min = time / 60;
87 tm->tm_sec = time - tm->tm_min * 60;
88
89 tm->tm_isdst = 0;
90}
91EXPORT_SYMBOL(rtc_time_to_tm);
92
93/*
94 * Does the rtc_time represent a valid date/time?
95 */
96int rtc_valid_tm(struct rtc_time *tm)
97{
98 if (tm->tm_year < 70
99 || ((unsigned)tm->tm_mon) >= 12
100 || tm->tm_mday < 1
101 || tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
102 || ((unsigned)tm->tm_hour) >= 24
103 || ((unsigned)tm->tm_min) >= 60
104 || ((unsigned)tm->tm_sec) >= 60)
105 return -EINVAL;
106
107 return 0;
108}
109EXPORT_SYMBOL(rtc_valid_tm);
110
111/*
112 * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
113 */
114int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time)
115{
116 *time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
117 tm->tm_hour, tm->tm_min, tm->tm_sec);
118 return 0;
119}
120EXPORT_SYMBOL(rtc_tm_to_time);
121
122/*
123 * Convert rtc_time to ktime
124 */
125ktime_t rtc_tm_to_ktime(struct rtc_time tm)
126{
127 time_t time;
128 rtc_tm_to_time(&tm, &time);
129 return ktime_set(time, 0);
130}
131EXPORT_SYMBOL_GPL(rtc_tm_to_ktime);
132
133/*
134 * Convert ktime to rtc_time
135 */
136struct rtc_time rtc_ktime_to_tm(ktime_t kt)
137{
138 struct timespec ts;
139 struct rtc_time ret;
140
141 ts = ktime_to_timespec(kt);
142 /* Round up any ns */
143 if (ts.tv_nsec)
144 ts.tv_sec++;
145 rtc_time_to_tm(ts.tv_sec, &ret);
146 return ret;
147}
148EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);
149
150MODULE_LICENSE("GPL");