boards: variscite: Add Variscite DART-MX8M-PLUS board

Add Variscite DART-MX8M-PLUS board support. This SoM is based on NXP's
i.MX8M Plus SoC. It includes Cortex-A53 and Cortex-M7 support.

Signed-off-by: Andre Morishita <andre.m@variscite.com>

Author: morishitaandre

boards/variscite/imx8mp_var_dart/Kconfig.imx8mp_var_dart

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+# Copyright 2025 Variscite Ltd.
+# Copyright 2021-2022, 2024 NXP
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_IMX8MP_VAR_DART
+	select SOC_MIMX8ML8_A53 if BOARD_IMX8MP_VAR_DART_MIMX8ML8_A53
+	select SOC_MIMX8ML8_M7 if BOARD_IMX8MP_VAR_DART_MIMX8ML8_M7 || BOARD_IMX8MP_VAR_DART_MIMX8ML8_M7_DDR
+	select SOC_PART_NUMBER_MIMX8ML8DVNLZ

boards/variscite/imx8mp_var_dart/board.cmake

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+#
+# Copyright 2025 Variscite Ltd.
+# Copyright (c) 2024 NXP
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+if(CONFIG_SOC_MIMX8ML8_M7)
+  board_set_debugger_ifnset(jlink)
+  board_set_flasher_ifnset(jlink)
+
+  board_runner_args(jlink "--device=MIMX8ML8_M7")
+  include(${ZEPHYR_BASE}/boards/common/jlink.board.cmake)
+endif()

boards/variscite/imx8mp_var_dart/board.yml

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+boards:
+  - name: imx8mp_var_dart
+    full_name: DART-MX8M-PLUS
+    vendor: variscite
+    socs:
+      - name: mimx8ml8
+        variants:
+          - name: ddr
+            cpucluster: m7

boards/variscite/imx8mp_var_dart/doc/imx8mp_var_dart.webp

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+.. zephyr:board:: imx8mp_var_dart
+
+Overview
+********
+
+Variscite's DART-MX8M-PLUS System on Module (SoM) is based on the i.MX 8M Plus family,
+which is a set of NXP products built to achieve both high performance and low power
+consumption and relies on a powerful, fully coherent core complex based on a quad Cortex®-A53
+cluster and Cortex®-M7 low-power coprocessor, audio digital signal processor, machine learning
+and graphics accelerators.
+
+Zephyr OS is ported to run on either the Cortex®-A53 or the Cortex®-M7.
+
+Specs Summary
+***************
+
+  - CPU
+
+    - NXP i.MX8M Plus:
+    - Up to 4x Cortex®-A53 @ 1.8GHz
+    - 1x Cortex®-M7 @ 800 MHz
+    - 1x NPU 2.3 TOPS
+  - Memory
+
+    - Up to 8GB LPDDR4 RAM @ 2000MHz
+    - 8-bit up to 128GB eMMC boot and storage
+  - GPU
+
+    - 3D: Vivante™ GC7000UltraLite (2 shaders) OpenGL ES 3.0, OpenCL1.2, Vulkan
+    - 2D: Vivante™ GC520L
+  - NPU (Neural Processing Unit)
+
+    - 2.3 TOPS Neural Network performance
+  - Display
+
+    - 2x LVDS interface 4-lane each up to 1080p60
+    - HDMI 2.0a up to 4Kp30
+    - 1x MIPI DSI with up to 4 data lanes 1080p60
+  - Network
+
+    - 2x 10/100/1000 Mbit/s Ethernet Interface
+    - Certified Wi-Fi 6 dual-band 802.11ax/ac/a/b/g/n with optional 802.15.4
+    - Bluetooth/BLE 5.4
+  - Camera
+
+    - Up to 2x MIPI CSI – CMOS Serial camera Interface 4 lanes
+    - 375 Mpixel/s HDR ISP (Image Sensor Processor)
+  - Audio
+
+    - Headphones
+    - Microphone: Digital, Analog (stereo)
+    - 6x I2S(SAI), S/PDIF RX TX, PDM 8CH, Line In/Out
+  - USB
+
+    - 2x USB 3.0/2.0 Host/Device
+  - Serial interfaces
+
+    - SPI: x3
+    - I2C: x5
+    - UART: x4, up to 5 Mbps
+    - CAN: x2
+  - Temperature range
+
+    - -40°C to 85°C
+
+More information about the SoM can be found at the
+`Variscite Wiki`_ and
+`Variscite website`_.
+
+Supported Features
+==================
+
+.. zephyr:board-supported-hw::
+
+.. note::
+
+   It is recommended to disable peripherals used by the M7 core on the Linux host.
+
+Devices
+========
+System Clock
+------------
+
+This board configuration uses a system clock frequency of 8 MHz.
+
+The M7 core is configured to run at an 800 MHz clock speed.
+
+Serial Port
+-----------
+
+This board configuration uses a single serial communication channel with the
+CPU's UART3.
+
+Programming and Debugging (A53)
+*******************************
+
+Copy the compiled ``zephyr.bin`` to the boot directory of the SD card and
+plug the SD card into the board. Power it up and stop the U-Boot execution at
+prompt.
+
+Use U-Boot to load and run zephyr.bin on the Cortex-A53:
+
+.. code-block:: console
+
+   load mmc $mmcdev:$mmcpart $loadaddr /boot/zephyr.bin
+   dcache flush; icache flush; go $loadaddr
+
+Use this configuration to run basic Zephyr applications and kernel tests,
+for example, with the :zephyr:code-sample:`hello_world` sample:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/hello_world
+   :host-os: unix
+   :board: imx8mp_var_dart/mimx8ml8/a53
+   :goals: build
+
+This will build an image with the hello_world sample app. When loaded and executed
+it will display the following ram console output:
+
+.. code-block:: console
+
+   *** Booting Zephyr OS build v4.0.0-3113-g5aeda6fe7dfa ***
+   Hello World! imx8mp_var_dart/mimx8ml8/a53
+
+
+Programming and Debugging (M7)
+******************************
+
+.. zephyr:board-supported-runners::
+
+The DART-MX8M-PLUS doesn't have QSPI flash for the M7, and it needs to be
+started by the A53 core. The A53 core is responsible to load the M7 binary
+application into the RAM, put the M7 in reset, set the M7 Program Counter and
+Stack Pointer, and get the M7 out of reset. The A53 can perform these steps at
+bootloader level or after the Linux system has booted.
+
+The M7 can use up to 3 different RAMs (currently, only two configurations are
+supported: ITCM and DDR). These are the memory mapping for A53 and M7:
+
++------------+-------------------------+------------------------+-----------------------+----------------------+
+| Region     | Cortex-A53              | Cortex-M7 (System Bus) | Cortex-M7 (Code Bus)  | Size                 |
++============+=========================+========================+=======================+======================+
+| OCRAM      | 0x00900000-0x0098FFFF   | 0x20200000-0x2028FFFF  | 0x00900000-0x0098FFFF | 576KB                |
++------------+-------------------------+------------------------+-----------------------+----------------------+
+| DTCM       | 0x00800000-0x0081FFFF   | 0x20000000-0x2001FFFF  |                       | 128KB                |
++------------+-------------------------+------------------------+-----------------------+----------------------+
+| ITCM       | 0x007E0000-0x007FFFFF   |                        | 0x00000000-0x0001FFFF | 128KB                |
++------------+-------------------------+------------------------+-----------------------+----------------------+
+| OCRAM_S    | 0x00180000-0x00188FFF   | 0x20180000-0x20188FFF  | 0x00180000-0x00188FFF | 36KB                 |
++------------+-------------------------+------------------------+-----------------------+----------------------+
+| DDR        | 0x80000000-0x803FFFFF   | 0x7B200000-0x7B3FFFFF  | 0x7B000000-0x7B1FFFFF | 2MB                  |
++------------+-------------------------+------------------------+-----------------------+----------------------+
+
+For more information about memory mapping see the
+`i.MX 8M Applications Processor Reference Manual`_  (section 2.1 to 2.3)
+
+At compilation time you have to choose which RAM will be used. This
+configuration is done based on board name (e.g. imx8mp_var_dart/mimx8ml8/m7
+for ITCM and imx8mp_var_dart/mimx8ml8/m7/ddr for DDR).
+
+There are two methods to load M7 Core images: U-Boot command and Linux remoteproc.
+
+Load and Run M7 Zephyr Image from U-Boot
+========================================
+
+Load and run Zephyr on M7 from A53 using U-Boot by copying the compiled
+``zephyr.bin`` to the boot directory of the SD card and plug the SD
+card into the board. Power it up and stop the U-Boot execution at prompt.
+
+Load the M7 binary onto the desired memory and start its execution using:
+
+ITCM
+====
+
+.. code-block:: console
+
+   load mmc 1:1 0x48000000 /boot/zephyr.bin
+   cp.b 0x48000000 0x7e0000 20000
+   bootaux 0x7e0000
+
+DDR
+===
+
+.. code-block:: console
+
+   load mmc 1:1 0x7b000000 /boot/zephyr.bin
+   dcache flush
+   bootaux 0x7b000000
+
+Load and Run M7 Zephyr Image by using Linux remoteproc
+======================================================
+
+Transfer built binaries ``zephyr.bin`` and ``zephyr.elf`` to the SoM's ``/boot`` and
+``/lib/firmware`` respectively using ``scp`` or through an USB drive.
+
+It is possible to execute Zephyr binaries using Variscite remoteproc scripts made
+for MCUXpresso binaries:
+
+.. code-block:: console
+
+   root@imx8mp-var-dart:~# /etc/remoteproc/variscite-rproc-linux -f /lib/firmware/zephyr.elf
+   [  212.888118] remoteproc remoteproc0: powering up imx-rproc
+   [  212.899215] remoteproc remoteproc0: Booting fw image zephyr.elf, size 515836
+   [  212.912070] remoteproc remoteproc0: No resource table in elf
+   [  213.444675] remoteproc remoteproc0: remote processor imx-rproc is now up
+
+Which should yield the following result on the UART3 serial console:
+
+.. code-block:: console
+
+   *** Booting Zephyr OS build v4.0.0-3113-g5aeda6fe7dfa ***
+   Hello World! imx8mp_var_dart/mimx8ml8/m7
+
+If the device tree dedicated to be used with Cortex-M7 applications is not being
+currently used, the script will give instructions on how to do so:
+
+.. code-block:: console
+
+   Error: /sys/class/remoteproc/remoteproc0 not found.
+   Please enable remoteproc driver.
+   Most likely you need to use the correct device tree, for example:
+   fw_setenv fdt_file imx8mp-var-dart-dt8mcustomboard-m7.dtb && reboot
+
+You can also configure U-Boot to load firmware on boot:
+
+.. code-block:: console
+
+   root@imx8mp-var-dart:~# /etc/remoteproc/variscite-rproc-u-boot -f /boot/zephyr.bin
+   Configuring for TCM memory
+   + fw_setenv m7_addr 0x7E0000
+   + fw_setenv fdt_file imx8mp-var-dart-dt8mcustomboard-m7.dtb
+   + fw_setenv use_m7 yes
+   + fw_setenv m7_bin zephyr.bin
+
+   Finished: Please reboot, the m7 firmware will run during U-Boot
+
+For more information about Variscite remoteproc scripts and general Cortex-M7
+support, visit `Variscite Wiki`_.
+
+Debugging
+=========
+
+DART-MX8M-PLUS board can be debugged by connecting an external
+JLink JTAG debugger to the J29 of the DT8MCustomBoard and to the PC.
+Then the application can be debugged using the usual way.
+
+Here is an example for the :zephyr:code-sample:`hello_world` application.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/hello_world
+   :board: imx8mp_var_dart/mimx8ml8/m7
+   :goals: debug
+
+Open a serial terminal, step through the application in your debugger, and you
+should see the following message in the terminal:
+
+.. code-block:: console
+
+   *** Booting Zephyr OS build v4.0.0-3113-g5aeda6fe7dfa ***
+   Hello World! imx8mp_var_dart/mimx8ml8/m7
+
+References
+==========
+
+- `Variscite Wiki`_
+- `Variscite website`_
+- `i.MX 8M Applications Processor Reference Manual`_
+
+.. _Variscite Wiki:
+   https://variwiki.com/index.php?title=DART-MX8M-PLUS
+
+.. _Variscite website:
+   https://www.variscite.com/product/system-on-module-som/cortex-a53-krait/dart-mx8m-plus-nxp-i-mx-8m-plus
+
+.. _i.MX 8M Applications Processor Reference Manual:
+   https://www.nxp.com/webapp/Download?colCode=IMX8MPRM

boards/variscite/imx8mp_var_dart/doc/index.rst

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+/*
+ * Copyright 2025 Variscite Ltd.
+ * Copyright 2022-2024 NXP
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ */
+
+#include <nxp/nxp_imx/mimx8ml8dvnlz-pinctrl.dtsi>
+
+&pinctrl {
+	uart1_default: uart1_default {
+		group0 {
+			pinmux = <&iomuxc_uart1_rxd_uart_rx_uart1_rx>,
+				<&iomuxc_uart1_txd_uart_tx_uart1_tx>;
+			bias-pull-up;
+			slew-rate = "slow";
+			drive-strength = "x1";
+		};
+	};
+
+	uart3_default: uart3_default {
+		group0 {
+			pinmux = <&iomuxc_uart3_rxd_uart_rx_uart3_rx>,
+				<&iomuxc_uart3_txd_uart_tx_uart3_tx>;
+			bias-pull-up;
+			slew-rate = "slow";
+			drive-strength = "x1";
+		};
+	};
+
+	uart4_default: uart4_default {
+		group0 {
+			pinmux = <&iomuxc_uart4_rxd_uart_rx_uart4_rx>,
+				<&iomuxc_uart4_txd_uart_tx_uart4_tx>;
+			bias-pull-up;
+			slew-rate = "slow";
+			drive-strength = "x1";
+		};
+	};
+};

boards/variscite/imx8mp_var_dart/imx8mp_var_dart-pinctrl.dtsi

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+/*
+ * Copyright 2025 Variscite Ltd.
+ * Copyright (c) 2021, Laird Connectivity
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <nxp/nxp_imx8ml_m7.dtsi>
+
+/ {
+	soc {
+		uart3: uart@30880000 {
+			compatible = "nxp,imx-iuart";
+			reg = <0x30880000 0x10000>;
+			interrupts = <28 3>;
+			clocks = <&ccm IMX_CCM_UART3_CLK 0x68 12>;
+			status = "disabled";
+		};
+	};
+};