doc: board: apalis-imx8x: add documentation

This documents the u-boot build and deployment procedure.
Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>

doc/board/toradex/apalix-imx8x.rst

+.. SPDX-License-Identifier: GPL-2.0+
+
+Apalis iMX8X V1.1A Module
+==========================
+
+Quick Start
+-----------
+
+- Build the ARM trusted firmware binary
+- Get scfw_tcm.bin and ahab-container.img
+- Build U-Boot
+- Load U-Boot binary using uuu
+- Flash U-Boot binary into the eMMC
+- Boot
+
+Get and Build the ARM Trusted Firmware
+--------------------------------------
+
+.. code-block:: bash
+
+    $ git clone -b toradex_imx_5.4.24_2.1.0 http://git.toradex.com/cgit/imx-atf.git
+    $ cd imx-atf/
+    $ make PLAT=imx8qx bl31
+
+Get scfw_tcm.bin and ahab-container.img
+---------------------------------------
+
+.. code-block:: bash
+
+    $ wget https://github.com/toradex/i.MX-System-Controller-Firmware/blob/master/src/scfw_export_mx8qx_b0/build_mx8qx_b0/mx8qx-apalis-scfw-tcm.bin
+    $ wget https://www.nxp.com/lgfiles/NMG/MAD/YOCTO/imx-seco-3.6.3.bin
+    $ chmod +x imx-seco-3.6.3.bin
+    $ ./imx-seco-3.6.3.bin
+
+Copy the following binaries to the U-Boot folder:
+
+.. code-block:: bash
+
+    $ cp imx-atf/build/imx8qx/release/bl31.bin .
+    $ cp imx-seco-3.6.3/firmware/seco/mx8qxb0-ahab-container.img mx8qx-ahab-container.imx8_defconfig
+
+Build U-Boot
+------------
+.. code-block:: bash
+
+    $ make apalis-imx8x_defconfig
+    $ make u-boot-dtb.imx
+
+Load the U-Boot Binary Using UUU
+--------------------------------
+
+Get the latest version of the universal update utility (uuu) aka ``mfgtools 3.0``:
+
+https://community.nxp.com/external-link.jspa?url=https%3A%2F%2Fgithub.com%2FNXPmicro%2Fmfgtools%2Freleases
+
+Put the module into USB recovery aka serial downloader mode, connect USB device
+to your host and execute uuu:
+
+.. code-block:: bash
+
+    sudo ./uuu u-boot/u-boot-dtb.imx
+
+Flash the U-Boot Binary into the eMMC
+-------------------------------------
+
+Burn the ``u-boot-dtb.imx`` binary to the primary eMMC hardware boot area
+partition and boot:
+
+.. code-block:: bash
+
+    load mmc 1:1 $loadaddr u-boot-dtb.imx
+    setexpr blkcnt ${filesize} + 0x1ff && setexpr blkcnt ${blkcnt} / 0x200
+    mmc dev 0 1
+    mmc write ${loadaddr} 0x0 ${blkcnt}

doc/board/toradex/index.rst

@@ -7,6 +7,7 @@ Toradex
    :maxdepth: 2
 
    apalix-imx8
+   apalix-imx8x
    colibri_imx7
    colibri-imx8x
    verdin-imx8mm