[ARM] Add generic RTC implementation.

This provides a number of helper functions and data structures
for RTC implementations to make use of, including a standard
implemention for /proc/driver/rtc and the rtc miscdevice.  It
supports runtime registration of RTC timekeeping sources.

arch/arm/common/Makefile

@@ -2,6 +2,7 @@
 # Makefile for the linux kernel.
 #
 
+obj-y				+= rtctime.o
 obj-$(CONFIG_ARM_AMBA)		+= amba.o
 obj-$(CONFIG_ICST525)		+= icst525.o
 obj-$(CONFIG_SA1111)		+= sa1111.o

include/asm-arm/rtc.h

+/*
+ *  linux/include/asm-arm/rtc.h
+ *
+ *  Copyright (C) 2003 Deep Blue Solutions Ltd.
+ *
+ * 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.
+ */
+#ifndef ASMARM_RTC_H
+#define ASMARM_RTC_H
+
+struct module;
+
+struct rtc_ops {
+	struct module	*owner;
+	int		(*open)(void);
+	void		(*release)(void);
+	int		(*ioctl)(unsigned int, unsigned long);
+
+	void		(*read_time)(struct rtc_time *);
+	int		(*set_time)(struct rtc_time *);
+	void		(*read_alarm)(struct rtc_wkalrm *);
+	int		(*set_alarm)(struct rtc_wkalrm *);
+	int		(*proc)(char *buf);
+};
+
+void rtc_time_to_tm(unsigned long, struct rtc_time *);
+int rtc_tm_to_time(struct rtc_time *, unsigned long *);
+void rtc_next_alarm_time(struct rtc_time *, struct rtc_time *, struct rtc_time *);
+void rtc_update(unsigned long, unsigned long);
+int register_rtc(struct rtc_ops *);
+void unregister_rtc(struct rtc_ops *);
+
+static inline int rtc_periodic_alarm(struct rtc_time *tm)
+{
+	return  (tm->tm_year == -1) ||
+		((unsigned)tm->tm_mon >= 12) ||
+		((unsigned)(tm->tm_mday - 1) >= 31) ||
+		((unsigned)tm->tm_hour > 23) ||
+		((unsigned)tm->tm_min > 59) ||
+		((unsigned)tm->tm_sec > 59);
+}
+
+#endif