[PATCH] RTC Subsystem: library functions

RTC and date/time related functions.

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

6 files changed, 120 insertions, 0 deletions

diff --git a/drivers/Kconfig b/drivers/Kconfig
index bddf431bbb72b5..9f5c0da57c9048 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -70,4 +70,6 @@ source "drivers/sn/Kconfig"
 
 source "drivers/edac/Kconfig"
 
+source "drivers/rtc/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index 5c69b86db6247a..424955274e60c2 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_USB_GADGET)	+= usb/gadget/
 obj-$(CONFIG_GAMEPORT)		+= input/gameport/
 obj-$(CONFIG_INPUT)		+= input/
 obj-$(CONFIG_I2O)		+= message/
+obj-$(CONFIG_RTC_LIB)		+= rtc/
 obj-$(CONFIG_I2C)		+= i2c/
 obj-$(CONFIG_W1)		+= w1/
 obj-$(CONFIG_HWMON)		+= hwmon/
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
new file mode 100644
index 00000000000000..15df7c130fa6e0
--- /dev/null
+++ b/drivers/rtc/Kconfig
@@ -0,0 +1,6 @@
+#
+# RTC class/drivers configuration
+#
+
+config RTC_LIB
+	tristate
\ No newline at end of file
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
new file mode 100644
index 00000000000000..eb9ad77c3e9576
--- /dev/null
+++ b/drivers/rtc/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for RTC class/drivers.
+#
+
+obj-$(CONFIG_RTC_LIB)	+= rtc-lib.o
diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
new file mode 100644
index 00000000000000..cfedc1d28ee1ab
--- /dev/null
+++ b/drivers/rtc/rtc-lib.c
@@ -0,0 +1,101 @@
+/*
+ * 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/module.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
+};
+
+#define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
+#define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) || !(year % 400))
+
+int rtc_month_days(unsigned int month, unsigned int year)
+{
+	return rtc_days_in_month[month] + (LEAP_YEAR(year) && month == 1);
+}
+EXPORT_SYMBOL(rtc_month_days);
+
+/*
+ * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
+ */
+void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
+{
+	register int days, month, year;
+
+	days = time / 86400;
+	time -= days * 86400;
+
+	/* 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);
+	if (days < 0) {
+		year -= 1;
+		days += 365 + 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 = time / 3600;
+	time -= tm->tm_hour * 3600;
+	tm->tm_min = time / 60;
+	tm->tm_sec = time - tm->tm_min * 60;
+}
+EXPORT_SYMBOL(rtc_time_to_tm);
+
+/*
+ * Does the rtc_time represent a valid date/time?
+ */
+int rtc_valid_tm(struct rtc_time *tm)
+{
+	if (tm->tm_year < 70
+		|| tm->tm_mon >= 12
+		|| tm->tm_mday < 1
+		|| tm->tm_mday > rtc_month_days(tm->tm_mon, tm->tm_year + 1900)
+		|| tm->tm_hour >= 24
+		|| tm->tm_min >= 60
+		|| tm->tm_sec >= 60)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL(rtc_valid_tm);
+
+/*
+ * Convert Gregorian date to seconds since 01-01-1970 00:00:00.
+ */
+int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time)
+{
+	*time = mktime(tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
+			tm->tm_hour, tm->tm_min, tm->tm_sec);
+	return 0;
+}
+EXPORT_SYMBOL(rtc_tm_to_time);
+
+MODULE_LICENSE("GPL");
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index b739ac1f7ca03f..8454337c70580f 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -95,6 +95,11 @@ struct rtc_pll_info {
 
 #include <linux/interrupt.h>
 
+extern int rtc_month_days(unsigned int month, unsigned int year);
+extern int rtc_valid_tm(struct rtc_time *tm);
+extern int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time);
+extern void rtc_time_to_tm(unsigned long time, struct rtc_time *tm);
+
 typedef struct rtc_task {
 	void (*func)(void *private_data);
 	void *private_data;