rtc: move date.c from drivers/rtc/ to lib/

In the next commit, rtc_mktime(), for compatibility with linux, will be
implemented using rtc_mktime(), which is no longer drivers/rtc specific.
So move this file under lib/.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

3 files changed, 104 insertions, 0 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index 55dedcbcdd2..2c018cb096b 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -574,4 +574,7 @@ config TEST_FDTDEC
 	bool "enable fdtdec test"
 	depends on OF_LIBFDT
 
+config LIB_DATE
+	bool
+
 endmenu
diff --git a/lib/Makefile b/lib/Makefile
index e15a189f65b..90d4425bd67 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -117,4 +117,6 @@ else
 obj-y += vsprintf.o strto.o
 endif
 
+obj-y += date.o
+
 subdir-ccflags-$(CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED) += -O2
diff --git a/lib/date.c b/lib/date.c
new file mode 100644
index 00000000000..63af4a14261
--- /dev/null
+++ b/lib/date.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2001
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ */
+
+#include <common.h>
+#include <command.h>
+#include <errno.h>
+#include <rtc.h>
+
+#if defined(CONFIG_LIB_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_offset[] = {
+	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
+};
+
+/*
+ * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
+ */
+int rtc_calc_weekday(struct rtc_time *tm)
+{
+	int leaps_to_date;
+	int last_year;
+	int day;
+
+	if (tm->tm_year < 1753)
+		return -1;
+	last_year = tm->tm_year - 1;
+
+	/* Number of leap corrections to apply up to end of last year */
+	leaps_to_date = last_year / 4 - last_year / 100 + last_year / 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 is.
+	 */
+	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 += last_year * 365 + leaps_to_date + month_offset[tm->tm_mon - 1] +
+			tm->tm_mday;
+	tm->tm_wday = day % 7;
+
+	return 0;
+}
+
+/*
+ * 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 where 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 rtc_mktime(const struct rtc_time *tm)
+{
+	int mon = tm->tm_mon;
+	int year = tm->tm_year;
+	int days, hours;
+
+	mon -= 2;
+	if (0 >= (int)mon) {	/* 1..12 -> 11, 12, 1..10 */
+		mon += 12;	/* Puts Feb last since it has leap day */
+		year -= 1;
+	}
+
+	days = (unsigned long)(year / 4 - year / 100 + year / 400 +
+			367 * mon / 12 + tm->tm_mday) +
+			year * 365 - 719499;
+	hours = days * 24 + tm->tm_hour;
+	return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec;
+}
+
+#endif /* CONFIG_LIB_DATE || CONFIG_TIMESTAMP */