diff options
Diffstat (limited to 'drivers/rtc/lib.c')
| -rw-r--r-- | drivers/rtc/lib.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/drivers/rtc/lib.c b/drivers/rtc/lib.c new file mode 100644 index 000000000000..ef160da84220 --- /dev/null +++ b/drivers/rtc/lib.c @@ -0,0 +1,148 @@ +/* + * rtc and date/time utility functions + * + * Copyright (C) 2005-06 Tower Technologies + * Author: Alessandro Zummo <a.zummo@towertech.it> + * + * based on arch/arm/common/rtctime.c and other bits + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. +*/ + +#include <linux/export.h> +#include <linux/rtc.h> + +static const unsigned char rtc_days_in_month[] = { + 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 +}; + +static const unsigned short rtc_ydays[2][13] = { + /* Normal years */ + { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, + /* Leap years */ + { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } +}; + +#define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400) + +/* + * The number of days in the month. + */ +int rtc_month_days(unsigned int month, unsigned int year) +{ + return rtc_days_in_month[month] + (is_leap_year(year) && month == 1); +} +EXPORT_SYMBOL(rtc_month_days); + +/* + * The number of days since January 1. (0 to 365) + */ +int rtc_year_days(unsigned int day, unsigned int month, unsigned int year) +{ + return rtc_ydays[is_leap_year(year)][month] + day-1; +} +EXPORT_SYMBOL(rtc_year_days); + + +/* + * rtc_time64_to_tm - Converts time64_t to rtc_time. + * Convert seconds since 01-01-1970 00:00:00 to Gregorian date. + */ +void rtc_time64_to_tm(time64_t time, struct rtc_time *tm) +{ + unsigned int month, year, secs; + int days; + + /* time must be positive */ + days = div_s64_rem(time, 86400, &secs); + + /* day of the week, 1970-01-01 was a Thursday */ + tm->tm_wday = (days + 4) % 7; + + year = 1970 + days / 365; + days -= (year - 1970) * 365 + + LEAPS_THRU_END_OF(year - 1) + - LEAPS_THRU_END_OF(1970 - 1); + while (days < 0) { + year -= 1; + days += 365 + is_leap_year(year); + } + tm->tm_year = year - 1900; + tm->tm_yday = days + 1; + + for (month = 0; month < 11; month++) { + int newdays; + + newdays = days - rtc_month_days(month, year); + if (newdays < 0) + break; + days = newdays; + } + tm->tm_mon = month; + tm->tm_mday = days + 1; + + tm->tm_hour = secs / 3600; + secs -= tm->tm_hour * 3600; + tm->tm_min = secs / 60; + tm->tm_sec = secs - tm->tm_min * 60; + + tm->tm_isdst = 0; +} +EXPORT_SYMBOL(rtc_time64_to_tm); + +/* + * Does the rtc_time represent a valid date/time? + */ +int rtc_valid_tm(struct rtc_time *tm) +{ + if (tm->tm_year < 70 + || ((unsigned)tm->tm_mon) >= 12 + || tm->tm_mday < 1 + || tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900) + || ((unsigned)tm->tm_hour) >= 24 + || ((unsigned)tm->tm_min) >= 60 + || ((unsigned)tm->tm_sec) >= 60) + return -EINVAL; + + return 0; +} +EXPORT_SYMBOL(rtc_valid_tm); + +/* + * rtc_tm_to_time64 - Converts rtc_time to time64_t. + * Convert Gregorian date to seconds since 01-01-1970 00:00:00. + */ +time64_t rtc_tm_to_time64(struct rtc_time *tm) +{ + return mktime64(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, + tm->tm_hour, tm->tm_min, tm->tm_sec); +} +EXPORT_SYMBOL(rtc_tm_to_time64); + +/* + * Convert rtc_time to ktime + */ +ktime_t rtc_tm_to_ktime(struct rtc_time tm) +{ + return ktime_set(rtc_tm_to_time64(&tm), 0); +} +EXPORT_SYMBOL_GPL(rtc_tm_to_ktime); + +/* + * Convert ktime to rtc_time + */ +struct rtc_time rtc_ktime_to_tm(ktime_t kt) +{ + struct timespec64 ts; + struct rtc_time ret; + + ts = ktime_to_timespec64(kt); + /* Round up any ns */ + if (ts.tv_nsec) + ts.tv_sec++; + rtc_time64_to_tm(ts.tv_sec, &ret); + return ret; +} +EXPORT_SYMBOL_GPL(rtc_ktime_to_tm); |