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 #define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
22 #define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) || !(year % 400))
24 int rtc_month_days(unsigned int month
, unsigned int year
)
26 return rtc_days_in_month
[month
] + (LEAP_YEAR(year
) && month
== 1);
28 EXPORT_SYMBOL(rtc_month_days
);
31 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
33 void rtc_time_to_tm(unsigned long time
, struct rtc_time
*tm
)
35 register int days
, month
, year
;
40 /* day of the week, 1970-01-01 was a Thursday */
41 tm
->tm_wday
= (days
+ 4) % 7;
43 year
= 1970 + days
/ 365;
44 days
-= (year
- 1970) * 365
45 + LEAPS_THRU_END_OF(year
- 1)
46 - LEAPS_THRU_END_OF(1970 - 1);
49 days
+= 365 + LEAP_YEAR(year
);
51 tm
->tm_year
= year
- 1900;
52 tm
->tm_yday
= days
+ 1;
54 for (month
= 0; month
< 11; month
++) {
57 newdays
= days
- rtc_month_days(month
, year
);
63 tm
->tm_mday
= days
+ 1;
65 tm
->tm_hour
= time
/ 3600;
66 time
-= tm
->tm_hour
* 3600;
67 tm
->tm_min
= time
/ 60;
68 tm
->tm_sec
= time
- tm
->tm_min
* 60;
70 EXPORT_SYMBOL(rtc_time_to_tm
);
73 * Does the rtc_time represent a valid date/time?
75 int rtc_valid_tm(struct rtc_time
*tm
)
80 || tm
->tm_mday
> rtc_month_days(tm
->tm_mon
, tm
->tm_year
+ 1900)
88 EXPORT_SYMBOL(rtc_valid_tm
);
91 * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
93 int rtc_tm_to_time(struct rtc_time
*tm
, unsigned long *time
)
95 *time
= mktime(tm
->tm_year
+ 1900, tm
->tm_mon
+ 1, tm
->tm_mday
,
96 tm
->tm_hour
, tm
->tm_min
, tm
->tm_sec
);
99 EXPORT_SYMBOL(rtc_tm_to_time
);
101 MODULE_LICENSE("GPL");