rtc-m48t59: shift zero year to 1968 on sparc (rev 2)

Shift the first year to 1968 for Sun SPARC machines.

Move this logic from platform specific files to rtc driver
as this fixes problems with calculating a century bit.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Tested-by: Alexander Beregalov
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/rtc/rtc-m48t59.c b/drivers/rtc/rtc-m48t59.c
index 04b63da..43afb7a 100644
--- a/drivers/rtc/rtc-m48t59.c
+++ b/drivers/rtc/rtc-m48t59.c
@@ -87,6 +87,10 @@
 		dev_dbg(dev, "Century bit is enabled\n");
 		tm->tm_year += 100;	/* one century */
 	}
+#ifdef CONFIG_SPARC
+	/* Sun SPARC machines count years since 1968 */
+	tm->tm_year += 68;
+#endif
 
 	tm->tm_wday	= bcd2bin(val & 0x07);
 	tm->tm_hour	= bcd2bin(M48T59_READ(M48T59_HOUR) & 0x3F);
@@ -110,11 +114,20 @@
 	struct m48t59_private *m48t59 = platform_get_drvdata(pdev);
 	unsigned long flags;
 	u8 val = 0;
+	int year = tm->tm_year;
+
+#ifdef CONFIG_SPARC
+	/* Sun SPARC machines count years since 1968 */
+	year -= 68;
+#endif
 
 	dev_dbg(dev, "RTC set time %04d-%02d-%02d %02d/%02d/%02d\n",
-		tm->tm_year + 1900, tm->tm_mon, tm->tm_mday,
+		year + 1900, tm->tm_mon, tm->tm_mday,
 		tm->tm_hour, tm->tm_min, tm->tm_sec);
 
+	if (year < 0)
+		return -EINVAL;
+
 	spin_lock_irqsave(&m48t59->lock, flags);
 	/* Issue the WRITE command */
 	M48T59_SET_BITS(M48T59_CNTL_WRITE, M48T59_CNTL);
@@ -125,9 +138,9 @@
 	M48T59_WRITE((bin2bcd(tm->tm_mday) & 0x3F), M48T59_MDAY);
 	/* tm_mon is 0-11 */
 	M48T59_WRITE((bin2bcd(tm->tm_mon + 1) & 0x1F), M48T59_MONTH);
-	M48T59_WRITE(bin2bcd(tm->tm_year % 100), M48T59_YEAR);
+	M48T59_WRITE(bin2bcd(year % 100), M48T59_YEAR);
 
-	if (pdata->type == M48T59RTC_TYPE_M48T59 && (tm->tm_year / 100))
+	if (pdata->type == M48T59RTC_TYPE_M48T59 && (year / 100))
 		val = (M48T59_WDAY_CEB | M48T59_WDAY_CB);
 	val |= (bin2bcd(tm->tm_wday) & 0x07);
 	M48T59_WRITE(val, M48T59_WDAY);
@@ -159,6 +172,10 @@
 	M48T59_SET_BITS(M48T59_CNTL_READ, M48T59_CNTL);
 
 	tm->tm_year = bcd2bin(M48T59_READ(M48T59_YEAR));
+#ifdef CONFIG_SPARC
+	/* Sun SPARC machines count years since 1968 */
+	tm->tm_year += 68;
+#endif
 	/* tm_mon is 0-11 */
 	tm->tm_mon = bcd2bin(M48T59_READ(M48T59_MONTH)) - 1;
 
@@ -192,11 +209,20 @@
 	struct rtc_time *tm = &alrm->time;
 	u8 mday, hour, min, sec;
 	unsigned long flags;
+	int year = tm->tm_year;
+
+#ifdef CONFIG_SPARC
+	/* Sun SPARC machines count years since 1968 */
+	year -= 68;
+#endif
 
 	/* If no irq, we don't support ALARM */
 	if (m48t59->irq == NO_IRQ)
 		return -EIO;
 
+	if (year < 0)
+		return -EINVAL;
+
 	/*
 	 * 0xff means "always match"
 	 */
@@ -228,7 +254,7 @@
 	spin_unlock_irqrestore(&m48t59->lock, flags);
 
 	dev_dbg(dev, "RTC set alarm time %04d-%02d-%02d %02d/%02d/%02d\n",
-		tm->tm_year + 1900, tm->tm_mon, tm->tm_mday,
+		year + 1900, tm->tm_mon, tm->tm_mday,
 		tm->tm_hour, tm->tm_min, tm->tm_sec);
 	return 0;
 }