Initial revision

diff --git a/rtc/date.c b/rtc/date.c
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+/*
+ * (C) Copyright 2001
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * Date & Time support for Philips PCF8563 RTC
+ */
+
+#include <common.h>
+#include <command.h>
+#include <rtc.h>
+
+#if (CONFIG_COMMANDS & CFG_CMD_DATE) || defined(CONFIG_TIMESTAMP)
+
+#define FEBRUARY               2
+#define        STARTOFTIME             1970
+#define SECDAY                 86400L
+#define SECYR                  (SECDAY * 365)
+#define        leapyear(year)          ((year) % 4 == 0)
+#define        days_in_year(a)         (leapyear(a) ? 366 : 365)
+#define        days_in_month(a)        (month_days[(a) - 1])
+
+static int month_days[12] = {
+       31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+};
+
+/*
+ * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
+ */
+void GregorianDay(struct rtc_time * tm)
+{
+       int leapsToDate;
+       int lastYear;
+       int day;
+       int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 };
+
+       lastYear=tm->tm_year-1;
+
+       /*
+        * Number of leap corrections to apply up to end of last year
+        */
+       leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;
+
+       /*
+        * This year is a leap year if it is divisible by 4 except when it is
+        * divisible by 100 unless it is divisible by 400
+        *
+        * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be
+        */
+       if((tm->tm_year%4==0) &&
+          ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
+          (tm->tm_mon>2)) {
+               /*
+                * We are past Feb. 29 in a leap year
+                */
+               day=1;
+       } else {
+               day=0;
+       }
+
+       day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday;
+
+       tm->tm_wday=day%7;
+}
+
+void to_tm(int tim, struct rtc_time * tm)
+{
+       register int    i;
+       register long   hms, day;
+
+       day = tim / SECDAY;
+       hms = tim % SECDAY;
+
+       /* Hours, minutes, seconds are easy */
+       tm->tm_hour = hms / 3600;
+       tm->tm_min = (hms % 3600) / 60;
+       tm->tm_sec = (hms % 3600) % 60;
+
+       /* Number of years in days */
+       for (i = STARTOFTIME; day >= days_in_year(i); i++) {
+               day -= days_in_year(i);
+       }
+       tm->tm_year = i;
+
+       /* Number of months in days left */
+       if (leapyear(tm->tm_year)) {
+               days_in_month(FEBRUARY) = 29;
+       }
+       for (i = 1; day >= days_in_month(i); i++) {
+               day -= days_in_month(i);
+       }
+       days_in_month(FEBRUARY) = 28;
+       tm->tm_mon = i;
+
+       /* Days are what is left over (+1) from all that. */
+       tm->tm_mday = day + 1;
+
+       /*
+        * Determine the day of week
+        */
+       GregorianDay(tm);
+}
+
+/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
+ * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
+ * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
+ *
+ * [For the Julian calendar (which was used in Russia before 1917,
+ * Britain & colonies before 1752, anywhere else before 1582,
+ * and is still in use by some communities) leave out the
+ * -year/100+year/400 terms, and add 10.]
+ *
+ * This algorithm was first published by Gauss (I think).
+ *
+ * WARNING: this function will overflow on 2106-02-07 06:28:16 on
+ * machines were long is 32-bit! (However, as time_t is signed, we
+ * will already get problems at other places on 2038-01-19 03:14:08)
+ */
+unsigned long
+mktime (unsigned int year, unsigned int mon,
+       unsigned int day, unsigned int hour,
+       unsigned int min, unsigned int sec)
+{
+       if (0 >= (int) (mon -= 2)) {    /* 1..12 -> 11,12,1..10 */
+               mon += 12;              /* Puts Feb last since it has leap day */
+               year -= 1;
+       }
+
+       return (((
+               (unsigned long) (year/4 - year/100 + year/400 + 367*mon/12 + day) +
+                       year*365 - 719499
+           )*24 + hour /* now have hours */
+         )*60 + min /* now have minutes */
+       )*60 + sec; /* finally seconds */
+}
+
+#endif /* CFG_CMD_DATE */