arm64: dts: qcom: msm8916-samsung-a5u: Add touch key regulator

On the Samsung Galaxy A5 the touch key is supplied by a single fixed
regulator (enabled via GPIO 97) that supplies both MCU and LED.
Add it to the device tree.
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20210604172742.10593-3-stephan@gerhold.netSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

arch/arm64/boot/dts/qcom/msm8916-samsung-a5u-eur.dts

@@ -7,6 +7,19 @@
 / {
 	model = "Samsung Galaxy A5U (EUR)";
 	compatible = "samsung,a5u-eur", "qcom,msm8916";
+
+	reg_touch_key: regulator-touch-key {
+		compatible = "regulator-fixed";
+		regulator-name = "touch_key";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+
+		gpio = <&msmgpio 97 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+
+		pinctrl-names = "default";
+		pinctrl-0 = <&tkey_en_default>;
+	};
 };
 
 &accelerometer {
@@ -42,7 +55,20 @@ iris {
 	};
 };
 
+&touchkey {
+	vcc-supply = <&reg_touch_key>;
+	vdd-supply = <&reg_touch_key>;
+};
+
 &msmgpio {
+	tkey_en_default: tkey-en-default {
+		pins = "gpio97";
+		function = "gpio";
+
+		drive-strength = <2>;
+		bias-disable;
+	};
+
 	ts_int_default: ts-int-default {
 		pins = "gpio13";
 		function = "gpio";