dm: rtc: Rename gregorian day function

Change this function name to something more descriptive. Also return a
failure code if it cannot calculate a correct value.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

common/cmd_date.c

@@ -201,7 +201,7 @@ int mk_date (const char *datestr, struct rtc_time *tmp)
 		tmp->tm_min  = val;
 
 		/* calculate day of week */
-		GregorianDay (tmp);
+		rtc_calc_weekday(tmp);
 
 		return (0);
 	default:

drivers/rtc/date.c

@@ -11,6 +11,7 @@
 
 #include <common.h>
 #include <command.h>
+#include <errno.h>
 #include <rtc.h>
 
 #if defined(CONFIG_CMD_DATE) || defined(CONFIG_TIMESTAMP)
@@ -30,13 +31,15 @@ static int month_days[12] = {
 /*
  * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
  */
-void GregorianDay(struct rtc_time * tm)
+int rtc_calc_weekday(struct rtc_time *tm)
 {
 	int leapsToDate;
 	int lastYear;
 	int day;
 	int MonthOffset[] = { 0,31,59,90,120,151,181,212,243,273,304,334 };
 
+	if (tm->tm_year < 1753)
+		return -EINVAL;
 	lastYear=tm->tm_year-1;
 
 	/*
@@ -64,6 +67,8 @@ void GregorianDay(struct rtc_time * tm)
 	day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] + tm->tm_mday;
 
 	tm->tm_wday=day%7;
+
+	return 0;
 }
 
 void to_tm(int tim, struct rtc_time * tm)
@@ -101,7 +106,7 @@ void to_tm(int tim, struct rtc_time * tm)
 	/*
 	 * Determine the day of week
 	 */
-	GregorianDay(tm);
+	rtc_calc_weekday(tm);
 }
 
 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.

drivers/rtc/ds1306.c

@@ -110,7 +110,7 @@ int rtc_get (struct rtc_time *tmp)
 	immap->im_cpm.cp_pbdat &= ~PB_SPI_CE;	/* Disable DS1306 Chip */
 	udelay (10);
 
-	GregorianDay (tmp);	/* Determine the day of week */
+	rtc_calc_weekday(tmp);	/* Determine the day of week */
 
 	debug ("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 	       tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,

include/rtc.h

@@ -45,7 +45,6 @@ int rtc_get (struct rtc_time *);
 int rtc_set (struct rtc_time *);
 void rtc_reset (void);
 
-void GregorianDay (struct rtc_time *);
 void to_tm (int, struct rtc_time *);
 unsigned long mktime (unsigned int, unsigned int, unsigned int,
 		      unsigned int, unsigned int, unsigned int);
@@ -87,4 +86,15 @@ void rtc_write32(int reg, u32 value);
  */
 void rtc_init(void);
 
+/**
+ * rtc_calc_weekday() - Work out the weekday from a time
+ *
+ * This only works for the Gregorian calendar - i.e. after 1752 (in the UK).
+ * It sets time->tm_wdaay to the correct day of the week.
+ *
+ * @time:	Time to inspect. tm_wday is updated
+ * @return 0 if OK, -EINVAL if the weekday could not be determined
+ */
+int rtc_calc_weekday(struct rtc_time *time);
+
 #endif	/* _RTC_H_ */