ARM: dts: koelsch: use demuxer for I2C1

Make it possible to fallback to GPIO for I2C1 on the EXIO-C connector.

This is based on reference work for the I2C0 core of the lager/r8a7790
by Wolfram Sang.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
[wsa: rebased and fixed aliases]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

arch/arm/boot/dts/r8a7791-koelsch.dts

@@ -50,6 +50,8 @@ / {
 	aliases {
 		serial0 = &scif0;
 		serial1 = &scif1;
+		i2c9 = &gpioi2c1;
+		i2c12 = &i2cexio1;
 	};
 
 	chosen {
@@ -298,6 +300,29 @@ x13_clk: x13-clock {
 		#clock-cells = <0>;
 		clock-frequency = <148500000>;
 	};
+
+	gpioi2c1: i2c-9 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "i2c-gpio";
+		status = "disabled";
+		gpios = <&gpio7 16 GPIO_ACTIVE_HIGH /* sda */
+			 &gpio7 15 GPIO_ACTIVE_HIGH /* scl */
+			>;
+		i2c-gpio,delay-us = <5>;
+	};
+
+	/*
+	 * I2C1 is routed to EXIO connector B, pins 64 (SCL) + 66 (SDA).
+	 * A fallback to GPIO is provided.
+	 */
+	i2cexio1: i2c-12 {
+		compatible = "i2c-demux-pinctrl";
+		i2c-parent = <&i2c1>, <&gpioi2c1>;
+		i2c-bus-name = "i2c-exio1";
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
 };
 
 &du {
@@ -333,6 +358,11 @@ &pfc {
 	pinctrl-0 = <&scif_clk_pins>;
 	pinctrl-names = "default";
 
+	i2c1_pins: i2c1 {
+		groups = "i2c1";
+		function = "i2c1";
+	};
+
 	i2c2_pins: i2c2 {
 		groups = "i2c2";
 		function = "i2c2";
@@ -581,6 +611,11 @@ pmic: pmic@0 {
 	};
 };
 
+&i2c1 {
+	pinctrl-0 = <&i2c1_pins>;
+	pinctrl-names = "i2c-exio1";
+};
+
 &i2c2 {
 	pinctrl-0 = <&i2c2_pins>;
 	pinctrl-names = "default";