rtc: convert LEAP_YEAR into an inline

- the LEAP_YEAR macro is buggy - it references its arg multiple times.
  Fix this by turning it into a C function.

- give it a more approriate name

- Move it to rtc.h so that other .c files can use it, instead of copying it.

Cc: dann frazier <dannf@hp.com>
Acked-by: NAlessandro Zummo <alessandro.zummo@towertech.it>
Cc: stephane eranian <eranian@googlemail.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-lib.c

@@ -26,14 +26,13 @@ static const unsigned short rtc_ydays[2][13] = {
 };
 
 #define LEAPS_THRU_END_OF(y) ((y)/4 - (y)/100 + (y)/400)
-#define LEAP_YEAR(year) ((!(year % 4) && (year % 100)) || !(year % 400))
 
 /*
  * The number of days in the month.
  */
 int rtc_month_days(unsigned int month, unsigned int year)
 {
-	return rtc_days_in_month[month] + (LEAP_YEAR(year) && month == 1);
+	return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
 }
 EXPORT_SYMBOL(rtc_month_days);
 
@@ -42,7 +41,7 @@ EXPORT_SYMBOL(rtc_month_days);
  */
 int rtc_year_days(unsigned int day, unsigned int month, unsigned int year)
 {
-	return rtc_ydays[LEAP_YEAR(year)][month] + day-1;
+	return rtc_ydays[is_leap_year(year)][month] + day-1;
 }
 EXPORT_SYMBOL(rtc_year_days);
 
@@ -66,7 +65,7 @@ void rtc_time_to_tm(unsigned long time, struct rtc_time *tm)
 		- LEAPS_THRU_END_OF(1970 - 1);
 	if (days < 0) {
 		year -= 1;
-		days += 365 + LEAP_YEAR(year);
+		days += 365 + is_leap_year(year);
 	}
 	tm->tm_year = year - 1900;
 	tm->tm_yday = days + 1;

include/linux/rtc.h

@@ -99,6 +99,7 @@ struct rtc_pll_info {
 
 #ifdef __KERNEL__
 
+#include <linux/types.h>
 #include <linux/interrupt.h>
 
 extern int rtc_month_days(unsigned int month, unsigned int year);
@@ -232,6 +233,11 @@ int rtc_register(rtc_task_t *task);
 int rtc_unregister(rtc_task_t *task);
 int rtc_control(rtc_task_t *t, unsigned int cmd, unsigned long arg);
 
+static inline bool is_leap_year(unsigned int year)
+{
+	return (!(year % 4) && (year % 100)) || !(year % 400);
+}
+
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_RTC_H_ */