hw/arm: Add i.MX 8M Plus EVK board

As a first step, implement the bare minimum: CPUs, RAM, interrupt controller,
serial. All other devices of the A53 memory map are represented as
TYPE_UNIMPLEMENTED_DEVICE, i.e. the whole memory map is provided. This allows
for running Linux without it crashing due to invalid memory accesses.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-id: 20250223114708.1780-5-shentey@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: drop 'static const' from serial_table[] definition to avoid
 compile failure on GCC 7.5]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/system/arm/imx8mp-evk.rst

@@ -0,0 +1,54 @@
+NXP i.MX 8M Plus Evaluation Kit (``imx8mp-evk``)
+================================================
+
+The ``imx8mp-evk`` machine models the i.MX 8M Plus Evaluation Kit, based on an
+i.MX 8M Plus SoC.
+
+Supported devices
+-----------------
+
+The ``imx8mp-evk`` machine implements the following devices:
+
+ * Up to 4 Cortex-A53 cores
+ * Generic Interrupt Controller (GICv3)
+ * 4 UARTs
+
+Boot options
+------------
+
+The ``imx8mp-evk`` machine can start a Linux kernel directly using the standard
+``-kernel`` functionality.
+
+Direct Linux Kernel Boot
+''''''''''''''''''''''''
+
+Probably the easiest way to get started with a whole Linux system on the machine
+is to generate an image with Buildroot. Version 2024.11.1 is tested at the time
+of writing and involves two steps. First run the following commands in the
+toplevel directory of the Buildroot source tree:
+
+.. code-block:: bash
+
+  $ echo "BR2_TARGET_ROOTFS_CPIO=y" >> configs/freescale_imx8mpevk_defconfig
+  $ make freescale_imx8mpevk_defconfig
+  $ make
+
+Once finished successfully there is an ``output/image`` subfolder. Navigate into
+it and patch the device tree with the following commands which will remove the
+``cpu-idle-states`` properties from CPU nodes:
+
+.. code-block:: bash
+
+  $ dtc imx8mp-evk.dtb | sed '/cpu-idle-states/d' > imx8mp-evk-patched.dts
+  $ dtc imx8mp-evk-patched.dts -o imx8mp-evk-patched.dtb
+
+Now that everything is prepared the machine can be started as follows:
+
+.. code-block:: bash
+
+  $ qemu-system-aarch64 -M imx8mp-evk -smp 4 -m 3G \
+      -display none -serial null -serial stdio \
+      -kernel Image \
+      -dtb imx8mp-evk-patched.dtb \
+      -initrd rootfs.cpio \
+      -append "root=/dev/ram"

docs/system/target-arm.rst

@@ -95,6 +95,7 @@ Board-specific documentation
    arm/imx25-pdk
    arm/mcimx6ul-evk
    arm/mcimx7d-sabre
+   arm/imx8mp-evk
    arm/orangepi
    arm/raspi
    arm/collie