drivers/rtc/rtc-sirfsoc.c: add rtc drivers for CSR SiRFprimaII and SiRFatlasVI

On CSR SiRFprimaII/atlasVI, there is a programmable 16-bit divider
(RTC_DIV) that divides the input 32.768KHz clock to the frequency that
users need (E.g.  1 Hz).  The divided real-time clock will be used to
drive a 32-bit counter (RTC_COUNTER) that provides users with the actual
time.

In each cycle of the divided real-time clock, there is a Hertz interrupt
generated to the RISC.  Users can also configure an alarm (RTC_ALARM).
When RTC_COUNTER matches the alarm, there will be an alarm interrupt
generated to the RISC.

The system RTC can generate an alarm wake-up signal to notify the power
controller to wake up from power saving mode.
Signed-off-by: Xianglong Du <Xianglong.Du@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm/boot/dts/atlas6.dtsi

@@ -613,7 +613,7 @@ rom-interface@57a00000 {
 		};
 
 		rtc-iobg {
-			compatible = "sirf,prima2-rtciobg", "sirf-prima2-rtciobg-bus";
+			compatible = "sirf,prima2-rtciobg", "sirf-prima2-rtciobg-bus", "simple-bus";
 			#address-cells = <1>;
 			#size-cells = <1>;
 			reg = <0x80030000 0x10000>;

arch/arm/boot/dts/prima2.dtsi

@@ -610,7 +610,7 @@ rom-interface@57a00000 {
 		};
 
 		rtc-iobg {
-			compatible = "sirf,prima2-rtciobg", "sirf-prima2-rtciobg-bus";
+			compatible = "sirf,prima2-rtciobg", "sirf-prima2-rtciobg-bus", "simple-bus";
 			#address-cells = <1>;
 			#size-cells = <1>;
 			reg = <0x80030000 0x10000>;

drivers/rtc/Kconfig

@@ -1242,6 +1242,13 @@ config RTC_DRV_SNVS
 	   This driver can also be built as a module, if so, the module
 	   will be called "rtc-snvs".
 
+config RTC_DRV_SIRFSOC
+	tristate "SiRFSOC RTC"
+	depends on ARCH_SIRF
+	help
+	  Say "yes" here to support the real time clock on SiRF SOC chips.
+	  This driver can also be built as a module called rtc-sirfsoc.
+
 comment "HID Sensor RTC drivers"
 
 config RTC_DRV_HID_SENSOR_TIME

drivers/rtc/Makefile

@@ -129,3 +129,4 @@ obj-$(CONFIG_RTC_DRV_VT8500)	+= rtc-vt8500.o
 obj-$(CONFIG_RTC_DRV_WM831X)	+= rtc-wm831x.o
 obj-$(CONFIG_RTC_DRV_WM8350)	+= rtc-wm8350.o
 obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
+obj-$(CONFIG_RTC_DRV_SIRFSOC)	+= rtc-sirfsoc.o