rtc: Add ASPEED RTC driver

Read and writes the time to the non-battery backed RTC in the ASPEED BMC
system on chip families.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/Kconfig

@@ -1841,6 +1841,17 @@ config RTC_DRV_RTD119X
 	  If you say yes here, you get support for the RTD1295 SoC
 	  Real Time Clock.
 
+config RTC_DRV_ASPEED
+	tristate "ASPEED RTC"
+	depends on OF
+	depends on ARCH_ASPEED || COMPILE_TEST
+	help
+	  If you say yes here you get support for the ASPEED BMC SoC real time
+	  clocks.
+
+	  This driver can also be built as a module, if so, the module
+	  will be called "rtc-aspeed".
+
 comment "HID Sensor RTC drivers"
 
 config RTC_DRV_HID_SENSOR_TIME