libnvdimm/altmap: Track namespace boundaries in altmap
[linux-2.6-block.git] / drivers / rtc / lib.c
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cdf7545a 1// SPDX-License-Identifier: GPL-2.0
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2/*
3 * rtc and date/time utility functions
4 *
5 * Copyright (C) 2005-06 Tower Technologies
6 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 *
8 * based on arch/arm/common/rtctime.c and other bits
cdf7545a 9 */
c58411e9 10
87ebfd64 11#include <linux/export.h>
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12#include <linux/rtc.h>
13
14static const unsigned char rtc_days_in_month[] = {
15 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
16};
17
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18static const unsigned short rtc_ydays[2][13] = {
19 /* Normal years */
20 { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
21 /* Leap years */
22 { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
23};
24
606cc43c 25#define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
c58411e9 26
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27/*
28 * The number of days in the month.
29 */
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30int rtc_month_days(unsigned int month, unsigned int year)
31{
78d89ef4 32 return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
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33}
34EXPORT_SYMBOL(rtc_month_days);
35
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36/*
37 * The number of days since January 1. (0 to 365)
38 */
39int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
40{
606cc43c 41 return rtc_ydays[is_leap_year(year)][month] + day - 1;
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42}
43EXPORT_SYMBOL(rtc_year_days);
44
c58411e9 45/*
0ae3f24d 46 * rtc_time64_to_tm - Converts time64_t to rtc_time.
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47 * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
48 */
c2c11ae4 49void rtc_time64_to_tm(time64_t time, struct rtc_time *tm)
c58411e9 50{
36d46cdb 51 unsigned int month, year, secs;
73442daf 52 int days;
c58411e9 53
c2c11ae4 54 /* time must be positive */
36d46cdb 55 days = div_s64_rem(time, 86400, &secs);
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56
57 /* day of the week, 1970-01-01 was a Thursday */
58 tm->tm_wday = (days + 4) % 7;
59
60 year = 1970 + days / 365;
61 days -= (year - 1970) * 365
62 + LEAPS_THRU_END_OF(year - 1)
63 - LEAPS_THRU_END_OF(1970 - 1);
f18046c5 64 while (days < 0) {
c58411e9 65 year -= 1;
78d89ef4 66 days += 365 + is_leap_year(year);
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67 }
68 tm->tm_year = year - 1900;
69 tm->tm_yday = days + 1;
70
71 for (month = 0; month < 11; month++) {
72 int newdays;
73
74 newdays = days - rtc_month_days(month, year);
75 if (newdays < 0)
76 break;
77 days = newdays;
78 }
79 tm->tm_mon = month;
80 tm->tm_mday = days + 1;
81
c2c11ae4 82 tm->tm_hour = secs / 3600;
83 secs -= tm->tm_hour * 3600;
84 tm->tm_min = secs / 60;
85 tm->tm_sec = secs - tm->tm_min * 60;
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86
87 tm->tm_isdst = 0;
c58411e9 88}
c2c11ae4 89EXPORT_SYMBOL(rtc_time64_to_tm);
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90
91/*
92 * Does the rtc_time represent a valid date/time?
93 */
94int rtc_valid_tm(struct rtc_time *tm)
95{
606cc43c 96 if (tm->tm_year < 70 ||
73f28f71 97 tm->tm_year > (INT_MAX - 1900) ||
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98 ((unsigned int)tm->tm_mon) >= 12 ||
99 tm->tm_mday < 1 ||
100 tm->tm_mday > rtc_month_days(tm->tm_mon,
101 ((unsigned int)tm->tm_year + 1900)) ||
102 ((unsigned int)tm->tm_hour) >= 24 ||
103 ((unsigned int)tm->tm_min) >= 60 ||
104 ((unsigned int)tm->tm_sec) >= 60)
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105 return -EINVAL;
106
107 return 0;
108}
109EXPORT_SYMBOL(rtc_valid_tm);
110
111/*
c2c11ae4 112 * rtc_tm_to_time64 - Converts rtc_time to time64_t.
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113 * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
114 */
c2c11ae4 115time64_t rtc_tm_to_time64(struct rtc_time *tm)
c58411e9 116{
606cc43c 117 return mktime64(((unsigned int)tm->tm_year + 1900), tm->tm_mon + 1,
074b01a5 118 tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
c58411e9 119}
c2c11ae4 120EXPORT_SYMBOL(rtc_tm_to_time64);
c58411e9 121
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122/*
123 * Convert rtc_time to ktime
124 */
125ktime_t rtc_tm_to_ktime(struct rtc_time tm)
126{
c2c11ae4 127 return ktime_set(rtc_tm_to_time64(&tm), 0);
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128}
129EXPORT_SYMBOL_GPL(rtc_tm_to_ktime);
130
131/*
132 * Convert ktime to rtc_time
133 */
134struct rtc_time rtc_ktime_to_tm(ktime_t kt)
135{
c2c11ae4 136 struct timespec64 ts;
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137 struct rtc_time ret;
138
c2c11ae4 139 ts = ktime_to_timespec64(kt);
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140 /* Round up any ns */
141 if (ts.tv_nsec)
142 ts.tv_sec++;
c2c11ae4 143 rtc_time64_to_tm(ts.tv_sec, &ret);
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144 return ret;
145}
146EXPORT_SYMBOL_GPL(rtc_ktime_to_tm);