Add linux-next specific files for 20110831
[linux-2.6/next.git] / drivers / rtc / rtc-lib.c
blob075f1708deae844499b8de25e2b0c523846b9299
1 /*
2 * rtc and date/time utility functions
4 * Copyright (C) 2005-06 Tower Technologies
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 * based on arch/arm/common/rtctime.c and other bits
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.
14 #include <linux/module.h>
15 #include <linux/rtc.h>
17 static const unsigned char rtc_days_in_month[] = {
18 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
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 }
28 #define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
31 * The number of days in the month.
33 int rtc_month_days(unsigned int month, unsigned int year)
35 return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
37 EXPORT_SYMBOL(rtc_month_days);
40 * The number of days since January 1. (0 to 365)
42 int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
44 return rtc_ydays[is_leap_year(year)][month] + day-1;
46 EXPORT_SYMBOL(rtc_year_days);
49 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
51 void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
53 unsigned int month, year;
54 int days;
56 days = time / 86400;
57 time -= (unsigned int) days * 86400;
59 /* day of the week, 1970-01-01 was a Thursday */
60 tm->tm_wday = (days + 4) % 7;
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);
70 tm->tm_year = year - 1900;
71 tm->tm_yday = days + 1;
73 for (month = 0; month < 11; month++) {
74 int newdays;
76 newdays = days - rtc_month_days(month, year);
77 if (newdays < 0)
78 break;
79 days = newdays;
81 tm->tm_mon = month;
82 tm->tm_mday = days + 1;
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;
89 EXPORT_SYMBOL(rtc_time_to_tm);
92 * Does the rtc_time represent a valid date/time?
94 int rtc_valid_tm(struct rtc_time *tm)
96 if (tm->tm_year < 70
97 || ((unsigned)tm->tm_mon) >= 12
98 || tm->tm_mday < 1
99 || tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
100 || ((unsigned)tm->tm_hour) >= 24
101 || ((unsigned)tm->tm_min) >= 60
102 || ((unsigned)tm->tm_sec) >= 60)
103 return -EINVAL;
105 return 0;
107 EXPORT_SYMBOL(rtc_valid_tm);
110 * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
112 int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time)
114 *time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
115 tm->tm_hour, tm->tm_min, tm->tm_sec);
116 return 0;
118 EXPORT_SYMBOL(rtc_tm_to_time);
121 * Convert rtc_time to ktime
123 ktime_t rtc_tm_to_ktime(struct rtc_time tm)
125 time_t time;
126 rtc_tm_to_time(&tm, &time);
127 return ktime_set(time, 0);
129 EXPORT_SYMBOL_GPL(rtc_tm_to_ktime);
132 * Convert ktime to rtc_time
134 struct rtc_time rtc_ktime_to_tm(ktime_t kt)
136 struct timespec ts;
137 struct rtc_time ret;
139 ts = ktime_to_timespec(kt);
140 /* Round up any ns */
141 if (ts.tv_nsec)
142 ts.tv_sec++;
143 rtc_time_to_tm(ts.tv_sec, &ret);
144 return ret;
146 EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);
148 MODULE_LICENSE("GPL");