arm64: dts: st: add stm32mp257f-dk board support

Add STM32MP257F Discovery board support. It embeds a STM32MP257FAL SoC,
with 4GB of LPDDR4, 2*USB typeA, 1*USB3 typeC, 1*ETH, wifi/BT combo,
DSI HDMI, LVDS connector ...

Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20250225-b4-stm32mp2_new_dts-v2-2-1a628c1580c7@foss.st.com
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

arch/arm64/boot/dts/st/Makefile

@@ -1,2 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-dtb-$(CONFIG_ARCH_STM32) += stm32mp257f-ev1.dtb
+dtb-$(CONFIG_ARCH_STM32) += \
+	stm32mp257f-dk.dtb \
+	stm32mp257f-ev1.dtb

arch/arm64/boot/dts/st/stm32mp257f-dk.dts

@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+/*
+ * Copyright (C) STMicroelectronics 2025 - All Rights Reserved
+ * Author: Alexandre Torgue <alexandre.torgue@foss.st.com> for STMicroelectronics.
+ */
+
+/dts-v1/;
+
+#include <dt-bindings/gpio/gpio.h>
+#include <dt-bindings/input/input.h>
+#include <dt-bindings/leds/common.h>
+#include "stm32mp257.dtsi"
+#include "stm32mp25xf.dtsi"
+#include "stm32mp25-pinctrl.dtsi"
+#include "stm32mp25xxak-pinctrl.dtsi"
+
+/ {
+	model = "STMicroelectronics STM32MP257F-DK Discovery Board";
+	compatible = "st,stm32mp257f-dk", "st,stm32mp257";
+
+	aliases {
+		serial0 = &usart2;
+	};
+
+	chosen {
+		stdout-path = "serial0:115200n8";
+	};
+
+	gpio-keys {
+		compatible = "gpio-keys";
+
+		button-user-1 {
+			label = "User-1";
+			linux,code = <BTN_1>;
+			gpios = <&gpioc 5 GPIO_ACTIVE_HIGH>;
+		};
+
+		button-user-2 {
+			label = "User-2";
+			linux,code = <BTN_2>;
+			gpios = <&gpioc 11 GPIO_ACTIVE_HIGH>;
+		};
+	};
+
+	gpio-leds {
+		compatible = "gpio-leds";
+
+		led-blue {
+			function = LED_FUNCTION_HEARTBEAT;
+			color = <LED_COLOR_ID_BLUE>;
+			gpios = <&gpioh 7 GPIO_ACTIVE_HIGH>;
+			linux,default-trigger = "heartbeat";
+			default-state = "off";
+		};
+	};
+
+	memory@80000000 {
+		device_type = "memory";
+		reg = <0x0 0x80000000 0x1 0x0>;
+	};
+
+	reserved-memory {
+		#address-cells = <2>;
+		#size-cells = <2>;
+		ranges;
+
+		fw@80000000 {
+			compatible = "shared-dma-pool";
+			reg = <0x0 0x80000000 0x0 0x4000000>;
+			no-map;
+		};
+	};
+};
+
+&arm_wdt {
+	timeout-sec = <32>;
+	status = "okay";
+};
+
+&scmi_regu {
+	scmi_vddio1: regulator@0 {
+		regulator-min-microvolt = <1800000>;
+		regulator-max-microvolt = <3300000>;
+	};
+	scmi_vdd_sdcard: regulator@23 {
+		reg = <VOLTD_SCMI_STPMIC2_LDO7>;
+		regulator-name = "vdd_sdcard";
+	};
+};
+
+&sdmmc1 {
+	pinctrl-names = "default", "opendrain", "sleep";
+	pinctrl-0 = <&sdmmc1_b4_pins_a>;
+	pinctrl-1 = <&sdmmc1_b4_od_pins_a>;
+	pinctrl-2 = <&sdmmc1_b4_sleep_pins_a>;
+	cd-gpios = <&gpiod 3 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
+	disable-wp;
+	st,neg-edge;
+	bus-width = <4>;
+	vmmc-supply = <&scmi_vdd_sdcard>;
+	vqmmc-supply = <&scmi_vddio1>;
+	status = "okay";
+};
+
+&usart2 {
+	pinctrl-names = "default", "idle", "sleep";
+	pinctrl-0 = <&usart2_pins_a>;
+	pinctrl-1 = <&usart2_idle_pins_a>;
+	pinctrl-2 = <&usart2_sleep_pins_a>;
+	/delete-property/dmas;
+	/delete-property/dma-names;
+	status = "okay";
+};