nano_matter: add SPI support

Author: silabs-bozont

variants/arduino_nano_matter_mgm240sd22vna/arduino_nano_matter_mgm240sd22vna.conf

@@ -8,4 +8,5 @@ CONFIG_BT_HCI_TX_STACK_SIZE=4096
 
 CONFIG_FPU=y
 CONFIG_I2C=y
+CONFIG_SPI=y
 CONFIG_PWM=y

variants/arduino_nano_matter_mgm240sd22vna/arduino_nano_matter_mgm240sd22vna.overlay

@@ -55,9 +55,9 @@
 				<&timer0_pwm 1 255 PWM_POLARITY_INVERTED>,
 				<&timer0_pwm 2 255 PWM_POLARITY_INVERTED>;
 
-		builtin-led-gpios = <&gpioc 1 0>;
 		serials = <&usart0>;
 		i2cs = <&i2c0>;
+		spis = <&eusart1>;
 	};
 };
 
@@ -68,6 +68,34 @@
 	status = "okay";
 };
 
+&pinctrl {
+	eusart1_default: eusart1_default {
+		group0 {
+			pins = <EUSART1_TX_PA9>, <EUSART1_SCLK_PB4>;
+			drive-push-pull;
+			output-high;
+		};
+
+		group1 {
+			pins = <EUSART1_RX_PA8>;
+			input-enable;
+			silabs,input-filter;
+		};
+	};
+};
+
+&eusart1 {
+	compatible = "silabs,eusart-spi";
+	#address-cells = <1>;
+	#size-cells = <0>;
+	clock-frequency = <4000000>;
+	pinctrl-0 = <&eusart1_default>;
+	pinctrl-names = "default";
+	status = "okay";
+
+	cs-gpios = <&gpiod 5 GPIO_ACTIVE_LOW>;
+};
+
 &timer0 {
 	status = "okay";