LXR linux/drivers/rtc/rtc-lib.c

   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
  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, 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}
  93EXPORT_SYMBOL(rtc_time64_to_tm);
  94
  95/*
  96 * Does the rtc_time represent a valid date/time?
  97 */
  98int 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}
 111EXPORT_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 */
 117time64_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}
 122EXPORT_SYMBOL(rtc_tm_to_time64);
 123
 124/*
 125 * Convert rtc_time to ktime
 126 */
 127ktime_t rtc_tm_to_ktime(struct rtc_time tm)
 128{
 129        return ktime_set(rtc_tm_to_time64(&tm), 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 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}
 148EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);
 149