ARM: dts: turris-omnia: Add MCU system-controller node

Turris Omnia's MCU provides various features that can be configured over
I2C at address 0x2a. Add device-tree node.

This does not carry a Fixes tag - we do not want this to get backported
to stable kernels for the following reason: U-Boot since v2022.10
inserts a phy-reset-gpio property into the WAN ethernet node pointing to
the MCU node if it finds the MCU node with a cznic,turris-omnia-mcu
compatible. Thus if this change got backported to a stable kernel, the
WAN interface driver would defer probe indefinitely (since it would wait
for the turris-omnia-mcu driver which would not be present).
Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20240701113010.16447-8-kabel@kernel.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/boot/dts/marvell/armada-385-turris-omnia.dts

@@ -218,7 +218,22 @@ i2c@0 {
 			#size-cells = <0>;
 			reg = <0>;
 
-			/* STM32F0 command interface at address 0x2a */
+			mcu: system-controller@2a {
+				compatible = "cznic,turris-omnia-mcu";
+				reg = <0x2a>;
+
+				pinctrl-names = "default";
+				pinctrl-0 = <&mcu_pins>;
+
+				interrupt-parent = <&gpio1>;
+				interrupts = <11 IRQ_TYPE_NONE>;
+
+				gpio-controller;
+				#gpio-cells = <3>;
+
+				interrupt-controller;
+				#interrupt-cells = <2>;
+			};
 
 			led-controller@2b {
 				compatible = "cznic,turris-omnia-leds";
@@ -501,6 +516,11 @@ fixed-link {
 };
 
 &pinctrl {
+	mcu_pins: mcu-pins {
+		marvell,pins = "mpp43";
+		marvell,function = "gpio";
+	};
+
 	pcawan_pins: pcawan-pins {
 		marvell,pins = "mpp46";
 		marvell,function = "gpio";