boards: ti: Add SK-AM64 M4 support

Add initial support for the SK-AM64 MCU domain Cortex-M4F core.

SK-AM64: https://www.ti.com/tool/SK-AM64B

Signed-off-by: Andrew Davis <afd@ti.com>

boards/ti/sk_am64/Kconfig.sk_am64

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+# Texas Instruments SK-AM64
+#
+# Copyright (c) 2025 Texas Instruments Incorporated
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_SK_AM64
+	select SOC_AM6442_M4 if BOARD_SK_AM64_AM6442_M4

boards/ti/sk_am64/board.yml

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+board:
+  name: sk_am64
+  full_name: SK-AM64
+  vendor: ti
+  socs:
+  - name: am6442

boards/ti/sk_am64/doc/index.rst

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+.. zephyr:board:: sk_am64
+
+Overview
+********
+
+The SK-AM64 board configuration is used by Zephyr applications that run on
+the TI AM64x platform. The board configuration provides support for the ARM
+Cortex-M4F MCU core and the following features:
+
+- Nested Vector Interrupt Controller (NVIC)
+- System Tick System Clock (SYSTICK)
+
+The board configuration also enables support for the semihosting debugging console.
+
+See the `TI AM64 Product Page`_ for details.
+
+Hardware
+********
+The SK-AM64 EVM features the AM64 SoC, which is composed of a dual Cortex-A53
+cluster and a single Cortex-M4 core in the MCU domain. Zephyr is ported to run on
+the M4F core and the following listed hardware specifications are used:
+
+- Low-power ARM Cortex-M4F
+- Memory
+
+   - 256KB of SRAM
+   - 2GB of DDR4
+
+- Debug
+
+   - XDS110 based JTAG
+
+Supported Features
+==================
+
+.. zephyr:board-supported-hw::
+
+Devices
+========
+System Clock
+------------
+
+This board configuration uses a system clock frequency of 400 MHz.
+
+DDR RAM
+-------
+
+The board has 2GB of DDR RAM available. This board configuration
+allocates Zephyr 4kB of RAM (only for resource table: 0xa4100000 to 0xa4100400).
+
+Serial Port
+-----------
+
+This board configuration uses a single serial communication channel with the
+MCU domain UART (MCU_UART0).
+
+GPIO
+----
+
+The SK-AM64 has a heartbeat LED connected to MCU_GPIO0_6. It's configured
+to build and run the :zephyr:code-sample:`blinky` sample.
+
+SD Card
+*******
+
+Download TI's official `WIC`_ and flash the WIC file with an etching software
+onto an SD card. This will boot Linux on the A53 application cores of the EVM.
+These cores will then load the zephyr binary on the M4 core using remoteproc.
+
+The default configuration can be found in
+:zephyr_file:`boards/ti/sk_am64/sk_am64_am6442_m4_defconfig`
+
+Flashing
+********
+
+The board can using remoteproc, and uses the OpenAMP resource table to accomplish this.
+
+The testing requires the binary to be copied to the SD card to allow the A53 cores to load it while booting using remoteproc.
+
+To test the M4F core, we build the :zephyr:code-sample:`hello_world` sample with the following command.
+
+.. code-block:: console
+
+   # From the root of the Zephyr repository
+   west build -p -b sk_am64/am6442/m4 samples/hello_world
+
+This builds the program and the binary is present in the :file:`build/zephyr` directory as
+:file:`zephyr.elf`.
+
+We now copy this binary onto the SD card in the :file:`/lib/firmware` directory and name it as
+:file:`am64-mcu-m4f0_0-fw`.
+
+.. code-block:: console
+
+   # Mount the SD card at sdcard for example
+   sudo mount /dev/sdX sdcard
+   # copy the elf to the /lib/firmware directory
+   sudo cp --remove-destination zephyr.elf sdcard/lib/firmware/am64-mcu-m4f0_0-fw
+
+The SD card can now be used for booting. The binary will now be loaded onto the M4F core on boot.
+
+To allow the board to boot using the SD card, set the boot pins to the SD Card boot mode. Refer to `SK-AM64B EVM User's Guide`_.
+
+After changing the boot mode, the board should go through the boot sequence on powering up.
+The binary will run and print Hello world to the MCU_UART0 port.
+
+References
+**********
+
+.. _TI AM64 Product Page:
+   https://www.ti.com/product/AM6442
+
+.. _WIC:
+   https://dr-download.ti.com/software-development/software-development-kit-sdk/MD-yXgchBCk98/10.01.10.04/tisdk-default-image-am64xx-evm-10.01.10.04.rootfs.wic.xz
+
+.. _SK-AM64B EVM User's Guide:
+   https://www.ti.com/lit/ug/spruj64/spruj64.pdf
+
+.. _build OpenOCD from source:
+   https://docs.u-boot.org/en/latest/board/ti/k3.html#building-openocd-from-source

boards/ti/sk_am64/sk_am64_am6442_m4-pinctrl.dtsi

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+/*
+ * Copyright (c) 2025 Texas Instruments Incorporated
+ *	Andrew Davis <afd@ti.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/dt-bindings/pinctrl/ti-k3-pinctrl.h>
+
+&pinctrl {
+	mcu_uart0_rx_default: mcu_uart0_rx_default {
+		pinmux = <K3_PINMUX(0x028, PIN_INPUT, MUX_MODE_0)>; /* (A9) MCU_UART0_RXD */
+	};
+
+	mcu_uart0_tx_default: mcu_uart0_tx_default {
+		pinmux = <K3_PINMUX(0x002C, PIN_OUTPUT, MUX_MODE_0)>; /* (A8) MCU_UART0_TXD */
+	};
+
+	mcu_gpio0_led_default: mcu_gpio0_led_default {
+		pinmux = <K3_PINMUX(0x0014, PIN_INPUT, MUX_MODE_7)>; /* (A7) MCU_GPIO0_5 */
+	};
+};

boards/ti/sk_am64/sk_am64_am6442_m4.dts

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+/*
+ * Copyright (c) 2024 Texas Instruments Incorporated
+ *	Andrew Davis <afd@ti.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+
+#include <ti/am64x_m4.dtsi>
+#include "sk_am64_am6442_m4-pinctrl.dtsi"
+
+/ {
+	model = "TI AM64x STARTER KIT (SK) M4";
+	compatible = "ti,am64x_m4_sk", "ti,am6442";
+
+	chosen {
+		zephyr,sram = &sram0;
+		zephyr,console = &uart0;
+		zephyr,shell-uart = &uart0;
+		zephyr,ipc = &ipc0;
+		zephyr,ipc_shm = &ddr0;
+	};
+
+	aliases {
+		led0 = &heartbeat_led;
+	};
+
+	cpus {
+		cpu@0 {
+			status = "okay";
+			clock-frequency = <DT_FREQ_M(400)>;
+		};
+	};
+
+	ddr0: memory@a4000000 {
+		compatible = "mmio-sram";
+		reg = <0xa4000000 DT_SIZE_M(1)>;
+	};
+
+	rsc_table: memory@a4100000 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0xa4100000 DT_SIZE_K(4)>;
+		zephyr,memory-region = "RSC_TABLE";
+	};
+
+	ddr1: memory@a4200000 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0xa4200000 (DT_SIZE_M(15) - DT_SIZE_K(4))>;
+		zephyr,memory-region = "DDR";
+	};
+
+	leds: leds {
+		compatible = "gpio-leds";
+
+		heartbeat_led: led_0 {
+			gpios = <&gpio0 5 GPIO_ACTIVE_HIGH>;
+			label = "Heartbeat LED";
+		};
+	};
+
+	ipc0: ipc {
+		compatible = "zephyr,mbox-ipm";
+		mboxes = <&mbox6 0>, <&mbox6 1>;
+		mbox-names = "tx", "rx";
+	};
+};
+
+&uart0 {
+	current-speed = <115200>;
+	pinctrl-0 = <&mcu_uart0_rx_default &mcu_uart0_tx_default>;
+	pinctrl-names = "default";
+	status = "okay";
+};
+
+&gpio0 {
+	pinctrl-0 = <&mcu_gpio0_led_default>;
+	pinctrl-names = "default";
+	status = "okay";
+};

boards/ti/sk_am64/sk_am64_am6442_m4.yaml

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+identifier: sk_am64/am6442/m4
+name: TI AM64X M4 Starter Kit (SK)
+type: mcu
+arch: arm
+toolchain:
+  - zephyr
+ram: 192
+vendor: ti

boards/ti/sk_am64/sk_am64_am6442_m4_defconfig

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+# Copyright (c) 2024 Texas Instruments Incorporated
+#	Andrew Davis <afd@ti.com>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# Platform Configuration
+CONFIG_CORTEX_M_SYSTICK=y
+
+# Zephyr Kernel Configuration
+CONFIG_XIP=n
+
+# Serial Driver
+CONFIG_SERIAL=y
+
+# GPIO Driver
+CONFIG_GPIO=y
+
+# Enable Console
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y