rtc: add NXP PCF8523 support

Add an RTC driver for PCF8523 chips by NXP Semiconductors.  No support is
currently provided for the alarm and interrupt functions.  Only the time
and date functionality is implemented.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 608a7b1..5bb0314 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -269,6 +269,15 @@
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-x1205.
 
+config RTC_DRV_PCF8523
+	tristate "NXP PCF8523"
+	help
+	  If you say yes here you get support for the NXP PCF8523 RTC
+	  chips.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-pcf8523.
+
 config RTC_DRV_PCF8563
 	tristate "Philips PCF8563/Epson RTC8564"
 	help