rtc: Philips PCF2123 RTC SPI driver

Add support for the Philips/NXP PCF2123 RTC.

Signed-off: Chris Verges <chrisv@cyberswitching.com>
Tested-by: Chris Verges <chrisv@cyberswitching.com>
Signed-off: Christian Pellegrin <chripell@fsfe.org>
Tested-by: Christian Pellegrin <chripell@fsfe.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
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 73771b0..2ccd351 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -378,6 +378,15 @@
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-ds3234.
 
+config RTC_DRV_PCF2123
+	tristate "NXP PCF2123"
+	help
+	  If you say yes here you get support for the NXP PCF2123
+	  RTC chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-pcf2123.
+
 endif # SPI_MASTER
 
 comment "Platform RTC drivers"