doc: board: ti: introduce am62px documentation

Introduce basic documentation for the am62p family of SoCs.

Signed-off-by: Bryan Brattlof <bb@ti.com>
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+.. SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+.. sectionauthor:: Bryan Brattlof <bb@ti.com>
+
+AM62Px Platforms
+================
+
+The AM62Px is an extension of the existing Sitara AM62x low-cost family
+of application processors built for Automotive and Linux Application
+development. Scalable Arm Cortex-A53 performance and embedded features,
+such as: multi high-definition display support, 3D-graphics
+acceleration, 4K video acceleration, and extensive peripherals make the
+AM62Px well-suited for a broad range of automation and industrial
+application, including automotive digital instrumentation, automotive
+displays, industrial HMI, and more.
+
+Some highlights of AM62P SoC are:
+
+* Quad-Cortex-A53s (running up to 1.4GHz) in a single cluster.
+  Dual/Single core variants are provided in the same package to allow HW
+  compatible designs.
+
+* One Device manager Cortex-R5F for system power and resource
+  management, and one Cortex-R5F for Functional Safety or
+  general-purpose usage.
+
+* One 3D GPU up to 50 GLFOPS
+
+* H.264/H.265 Video Encode/Decode.
+
+* Display support: 3x display support over OLDI/LVDS (1x OLDI-DL, 1x or
+  2x OLDI-SL), DSI, or DPI. Up to 3840x1080 @ 60fps resolution
+
+* Integrated Giga-bit Ethernet switch supporting up to a total of two
+  external ports (TSN capable).
+
+* 9xUARTs, 5xSPI, 6xI2C, 2xUSB2, 3xCAN-FD, 3xMMC and SD, GPMC for
+  NAND/FPGA connection, OSPI memory controller, 3xMcASP for audio,
+  1xCSI-RX-4L for Camera, eCAP/eQEP, ePWM, among other peripherals.
+
+* Dedicated Centralized Hardware Security Module with support for secure
+  boot, debug security and crypto acceleration and trusted execution
+  environment.
+
+* One 32-bit DDR Subsystem that supports LPDDR4, DDR4 memory types.
+
+* Multiple low power modes support, ex: Deep sleep, Standby, MCU-only,
+  enabling battery powered system design.
+
+For those interested, more details about this SoC can be found in the
+Technical Reference Manual here: https://www.ti.com/lit/pdf/spruj83
+
+Boot Flow:
+----------
+
+The bootflow is exactly the same as all SoCs in the am62xxx extended SoC
+family. Below is the pictorial representation:
+
+.. image:: img/boot_diagram_k3_current.svg
+  :alt: Boot flow diagram
+
+- Here TIFS acts as master and provides all the critical services. R5/A53
+  requests TIFS to get these services done as shown in the above diagram.
+
+Sources:
+--------
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_boot_sources
+    :end-before: .. k3_rst_include_end_boot_sources
+
+Build procedure:
+----------------
+
+0. Setup the environment variables:
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_common_env_vars_desc
+    :end-before: .. k3_rst_include_end_common_env_vars_desc
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_board_env_vars_desc
+    :end-before: .. k3_rst_include_end_board_env_vars_desc
+
+Set the variables corresponding to this platform:
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_common_env_vars_defn
+    :end-before: .. k3_rst_include_end_common_env_vars_defn
+
+.. code-block:: bash
+
+ $ export UBOOT_CFG_CORTEXR=am62px_evm_r5_defconfig
+ $ export UBOOT_CFG_CORTEXA=am62px_evm_a53_defconfig
+ $ export TFA_BOARD=lite
+ $ # we dont use any extra TFA parameters
+ $ unset TFA_EXTRA_ARGS
+ $ export OPTEE_PLATFORM=k3-am62x
+ $ export OPTEE_EXTRA_ARGS="CFG_WITH_SOFTWARE_PRNG=y"
+
+.. am62px_evm_rst_include_start_build_steps
+
+1. Trusted Firmware-A:
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_build_steps_tfa
+    :end-before: .. k3_rst_include_end_build_steps_tfa
+
+
+2. OP-TEE:
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_build_steps_optee
+    :end-before: .. k3_rst_include_end_build_steps_optee
+
+3. U-Boot:
+
+* 3.1 R5:
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_build_steps_spl_r5
+    :end-before: .. k3_rst_include_end_build_steps_spl_r5
+
+* 3.2 A53:
+
+.. include::  ../ti/k3.rst
+    :start-after: .. k3_rst_include_start_build_steps_uboot
+    :end-before: .. k3_rst_include_end_build_steps_uboot
+.. am62px_evm_rst_include_end_build_steps
+
+Target Images
+--------------
+
+In order to boot we need tiboot3.bin, tispl.bin and u-boot.img.  Each SoC
+variant (HS-FS, HS-SE) requires a different source for these files.
+
+ - HS-FS
+
+        * tiboot3-am62px-hs-fs-evm.bin from step 3.1
+        * tispl.bin, u-boot.img from step 3.2
+
+ - HS-SE
+
+        * tiboot3-am62px-hs-evm.bin from step 3.1
+        * tispl.bin, u-boot.img from step 3.2
+
+Image formats:
+--------------
+
+- tiboot3.bin
+
+.. image:: img/multi_cert_tiboot3.bin.svg
+  :alt: tiboot3.bin image format
+
+- tispl.bin
+
+.. image:: img/dm_tispl.bin.svg
+  :alt: tispl.bin image format
+
+A53 SPL DDR Memory Layout
+-------------------------
+
+.. am62px_evm_rst_include_start_ddr_mem_layout
+
+This provides an overview memory usage in A53 SPL stage.
+
+.. list-table::
+   :widths: 16 16 16
+   :header-rows: 1
+
+   * - Region
+     - Start Address
+     - End Address
+
+   * - EMPTY
+     - 0x80000000
+     - 0x80080000
+
+   * - TEXT BASE
+     - 0x80080000
+     - 0x800d8000
+
+   * - EMPTY
+     - 0x800d8000
+     - 0x80200000
+
+   * - BMP IMAGE
+     - 0x80200000
+     - 0x80b77660
+
+   * - STACK
+     - 0x80b77660
+     - 0x80b77e60
+
+   * - GD
+     - 0x80b77e60
+     - 0x80b78000
+
+   * - MALLOC
+     - 0x80b78000
+     - 0x80b80000
+
+   * - EMPTY
+     - 0x80b80000
+     - 0x80c80000
+
+   * - BSS
+     - 0x80c80000
+     - 0x80d00000
+
+   * - BLOBS
+     - 0x80d00000
+     - 0x80d00400
+
+   * - EMPTY
+     - 0x80d00400
+     - 0x81000000
+.. am62px_evm_rst_include_end_ddr_mem_layout
+
+Switch Setting for Boot Mode
+----------------------------
+
+Boot Mode pins provide means to select the boot mode and options before the
+device is powered up. After every POR, they are the main source to populate
+the Boot Parameter Tables.
+
+The following table shows some common boot modes used on AM62Px
+platforms. More details can be found in the Technical Reference Manual:
+https://www.ti.com/lit/pdf/spruj83 under the `Boot Mode Pins` section.
+
+.. note::
+
+   This device is very new. Currently only UART boot is available while
+   we continue to add support for the other bootmodes.
+
+.. list-table:: Boot Modes
+   :widths: 16 16 16
+   :header-rows: 1
+
+   * - Switch Label
+     - SW2: 12345678
+     - SW3: 12345678
+
+   * - SD
+     - 01000000
+     - 11000010
+
+   * - OSPI
+     - 00000000
+     - 11001110
+
+   * - EMMC
+     - 00000000
+     - 11010010
+
+   * - UART
+     - 00000000
+     - 11011100
+
+   * - USB DFU
+     - 00000000
+     - 11001010
+
+For SW2 and SW1, the switch state in the "ON" position = 1.
+
+Debugging U-Boot
+----------------
+
+See :ref:`Common Debugging environment - OpenOCD<k3_rst_refer_openocd>`: for
+detailed setup information.
+
+.. warning::
+
+  **OpenOCD support after**: v0.12.0
+
+  While support for the entire K3 generation including the am62xxx
+  extended family was added before v0.12.0, the tcl scripts for the
+  am62px have been accepted and will be available in the next release of
+  OpenOCD. It may be necessary to build OpenOCD from source depending on
+  the version your distribution has packaged.
+
+.. include::  k3.rst
+    :start-after: .. k3_rst_include_start_openocd_connect_XDS110
+    :end-before: .. k3_rst_include_end_openocd_connect_XDS110
+
+To start OpenOCD and connect to the board
+
+.. code-block:: bash
+
+  openocd -f board/ti_am62pevm.cfg