ARM: dts: r8a7742-iwg21m: Add RTC support

Enable BQ32000 RTC which is connected to I2C0 on the iWave RainboW-G21M-q7
SOM.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Chris Paterson <Chris.Paterson2@renesas.com>
Link: https://lore.kernel.org/r/20200816193316.7641-3-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm/boot/dts/r8a7742-iwg21m.dtsi

@@ -35,6 +35,21 @@ &extal_clk {
 	clock-frequency = <20000000>;
 };
 
+&i2c0 {
+	pinctrl-0 = <&i2c0_pins>;
+	pinctrl-names = "default";
+
+	status = "okay";
+	clock-frequency = <400000>;
+
+	rtc@68 {
+		compatible = "ti,bq32000";
+		reg = <0x68>;
+		interrupt-parent = <&gpio1>;
+		interrupts = <1 IRQ_TYPE_EDGE_FALLING>;
+	};
+};
+
 &mmcif1 {
 	pinctrl-0 = <&mmc1_pins>;
 	pinctrl-names = "default";
@@ -46,6 +61,11 @@ &mmcif1 {
 };
 
 &pfc {
+	i2c0_pins: i2c0 {
+		groups = "i2c0";
+		function = "i2c0";
+	};
+
 	mmc1_pins: mmc1 {
 		groups = "mmc1_data4", "mmc1_ctrl";
 		function = "mmc1";