siemens/mc_bdx1: Add usage of external RTC PCF8523

This mainboard contains an external RTC chip PCF8523. Enable usage of
this chip and add some initialization values to device tree.

Change-Id: I25c0a017899ee904f3aa02bdc7dcaf61dee67e3a
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/15642
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/mainboard/siemens/mc_bdx1/Kconfig

@@ -12,6 +12,7 @@ config BOARD_SPECIFIC_OPTIONS
 	select USE_SIEMENS_HWILIB
 	select DRIVER_INTEL_I210
 	select DRIVER_SIEMENS_NC_FPGA
+	select DRIVERS_I2C_PCF8523
 
 config MAINBOARD_DIR
 	string

src/mainboard/siemens/mc_bdx1/devicetree.cb

@@ -9,7 +9,20 @@ chip soc/intel/fsp_broadwell_de
 		device pci 1d.0 on end # EHCI Controller
 		device pci 1f.0 on end # LPC Bridge
 		device pci 1f.2 on end # SATA Controller
-		device pci 1f.3 on end # SMBus Controller
+		device pci 1f.3 on
+			# Enable external RTC chip
+			chip drivers/i2c/pcf8523
+				register "cap_sel" = "CAP_SEL_7_PF"
+				register "power_mode" = "PM_BAT_SW_OFF_LOW_DETECT_OFF"
+				register "cof_selection" = "COF_OFF"
+				register "set_user_date" = "1"
+				register "user_year" = "04"
+				register "user_month" = "07"
+				register "user_day" = "01"
+				register "user_weekday" = "0"
+				device i2c 0x68 on end # RTC PCF8523
+			end
+		end # SMBus Controller
 		device pci 1f.5 on end # SATA Controller
 	end
 end