[MIPS] Switch from to_tm to rtc_time_to_tm

This replaces the MIPS-specific to_tm function with the generic
rtc_time_to_tm function.  The big difference between the two functions is
that rtc_time_to_tm uses epoch 70 while to_tm uses 1970, so the result of
rtc_time_to_tm needs to be fixed up.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -3,6 +3,7 @@ config MIPS
 	default y
 	# Horrible source of confusion.  Die, die, die ...
 	select EMBEDDED
+	select RTC_LIB
 
 mainmenu "Linux/MIPS Kernel Configuration"
 

arch/mips/kernel/time.c

@@ -397,52 +397,3 @@ void __init time_init(void)
 
 	init_mips_clocksource();
 }
-
-#define FEBRUARY		2
-#define STARTOFTIME		1970
-#define SECDAY			86400L
-#define SECYR			(SECDAY * 365)
-#define leapyear(y)		((!((y) % 4) && ((y) % 100)) || !((y) % 400))
-#define days_in_year(y)		(leapyear(y) ? 366 : 365)
-#define days_in_month(m)	(month_days[(m) - 1])
-
-static int month_days[12] = {
-	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
-};
-
-void to_tm(unsigned long tim, struct rtc_time *tm)
-{
-	long hms, day, gday;
-	int i;
-
-	gday = 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 - 1;		/* tm_mon starts from 0 to 11 */
-
-	/* Days are what is left over (+1) from all that. */
-	tm->tm_mday = day + 1;
-
-	/*
-	 * Determine the day of week
-	 */
-	tm->tm_wday = (gday + 4) % 7;	/* 1970/1/1 was Thursday */
-}
-
-EXPORT_SYMBOL(to_tm);

arch/mips/pmc-sierra/yosemite/setup.c

@@ -100,8 +100,12 @@ int rtc_mips_set_time(unsigned long tim)
 	struct rtc_time tm;
 	unsigned long flags;
 
-	/* convert to a more useful format -- note months count from 0 */
-	to_tm(sec, &tm);
+	/*
+	 * Convert to a more useful format -- note months count from 0
+	 * and years from 1900
+	 */
+	rtc_time_to_tm(tim, &tm);
+	tm.tm_year += 1900;
 	tm.tm_mon += 1;
 
 	spin_lock_irqsave(&rtc_lock, flags);

arch/mips/sgi-ip22/ip22-time.c

@@ -29,7 +29,7 @@
 #include <asm/sgi/ip22.h>
 
 /*
- * note that mktime uses month from 1 to 12 while to_tm
+ * Note that mktime uses month from 1 to 12 while rtc_time_to_tm
  * uses 0 to 11.
  */
 unsigned long read_persistent_clock(void)
@@ -66,10 +66,10 @@ int rtc_mips_set_time(unsigned long tim)
 	unsigned int save_control;
 	unsigned long flags;
 
-	to_tm(tim, &tm);
+	rtc_time_to_tm(tim, &tm);
 
 	tm.tm_mon += 1;		/* tm_mon starts at zero */
-	tm.tm_year -= 1940;
+	tm.tm_year -= 40;
 	if (tm.tm_year >= 100)
 		tm.tm_year -= 100;
 

arch/mips/sibyte/swarm/rtc_m41t81.c

@@ -146,7 +146,8 @@ int m41t81_set_time(unsigned long t)
 	struct rtc_time tm;
 	unsigned long flags;
 
-	to_tm(t, &tm);
+	/* Note we don't care about the century */
+	rtc_time_to_tm(t, &tm);
 
 	/*
 	 * Note the write order matters as it ensures the correctness.

arch/mips/sibyte/swarm/rtc_xicor1241.c

@@ -115,7 +115,8 @@ int xicor_set_time(unsigned long t)
 	int tmp;
 	unsigned long flags;
 
-	to_tm(t, &tm);
+	rtc_time_to_tm(t, &tm);
+	tm.tm_year += 1900;
 
 	spin_lock_irqsave(&rtc_lock, flags);
 	/* unlock writes to the CCR */

include/asm-mips/time.h

@@ -48,13 +48,6 @@ extern void (*mips_timer_ack)(void);
  */
 extern struct clocksource clocksource_mips;
 
-/*
- * to_tm() converts system time back to (year, mon, day, hour, min, sec).
- * It is intended to help implement rtc_set_time() functions.
- * Copied from PPC implementation.
- */
-extern void to_tm(unsigned long tim, struct rtc_time *tm);
-
 /*
  * high-level timer interrupt routines.
  */