v4.19.13 snapshot.
diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
new file mode 100644
index 0000000..4a3c0f3
--- /dev/null
+++ b/drivers/rtc/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_time_to_tm64 - 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);