.. SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
.. sectionauthor:: Nishanth Menon <nm@ti.com>

AM62x Beagleboard.org Beagleplay
================================

Introduction:
-------------

BeagleBoard.org BeaglePlay is an easy to use, affordable open source
hardware single board computer based on the Texas Instruments AM625
SoC that allows you to create connected devices that work even at long
distances using IEEE 802.15.4g LR-WPAN and IEEE 802.3cg 10Base-T1L.
Expansion is provided over open standards based mikroBUS, Grove and
QWIIC headers among other interfaces.

Further information can be found at:

* Product Page: https://beagleplay.org/
* Hardware documentation: https://git.beagleboard.org/beagleplay/beagleplay

Boot Flow:
----------
Below is the pictorial representation of boot flow:

.. image:: img/boot_diagram_k3_current.svg
  :alt: Boot flow diagram

- On this platform, 'TI Foundational Security' (TIFS) functions as the
  security enclave master while 'Device Manager' (DM), also known as the
  'TISCI server' in "TI terminology", offers all the essential services.
  The A53 or M4F (Aux core) sends requests to TIFS/DM to accomplish these
  services, as illustrated in the diagram above.

Sources:
--------
.. include::  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::  k3.rst
    :start-after: .. k3_rst_include_start_common_env_vars_desc
    :end-before: .. k3_rst_include_end_common_env_vars_desc

.. include::  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::  k3.rst
    :start-after: .. k3_rst_include_start_common_env_vars_defn
    :end-before: .. k3_rst_include_end_common_env_vars_defn
.. prompt:: bash $

  export UBOOT_CFG_CORTEXR="am62x_evm_r5_defconfig beagleplay_r5.config"
  export UBOOT_CFG_CORTEXA="am62x_evm_a53_defconfig beagleplay_a53.config"
  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"

.. include::  am62x_sk.rst
    :start-after: .. am62x_evm_rst_include_start_build_steps
    :end-before: .. am62x_evm_rst_include_end_build_steps

Target Images
-------------
Copy the below images to an SD card and boot:

* tiboot3-am62x-gp-evm.bin from R5 build as tiboot3.bin
* tispl.bin_unsigned from Cortex-A build as tispl.bin
* u-boot.img_unsigned from Cortex-A build as u-boot.img

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

Additional hardware for U-Boot development
------------------------------------------

* Serial Console is critical for U-Boot development on BeaglePlay. See
  `BeaglePlay serial console documentation
  <https://docs.beagleboard.org/latest/boards/beagleplay/demos-and-tutorials/using-serial-console.html>`_.
* uSD is preferred option over eMMC, and a SD/MMC reader will be needed.
* (optionally) JTAG is useful when working with very early stages of boot.

Default storage options
-----------------------

There are multiple storage media options on BeaglePlay, but primarily:

* Onboard eMMC (default) - reliable, fast and meant for deployment use.
* SD/MMC card interface (hold 'USR' switch and power on) - Entirely
  depends on the SD card quality.

Flash to uSD card or how to deal with "bricked" Board
-----------------------------------------------------

When deploying or working on Linux, it's common to use the onboard
eMMC. However, avoiding the eMMC and using the uSD card is safer when
working with U-Boot.

If you choose to  hand format your own bootable uSD card, be
aware that it can be difficult. The following information
may be helpful, but remember that it is only sometimes
reliable, and partition options can cause issues. These
can potentially help:

* https://git.ti.com/cgit/arago-project/tisdk-setup-scripts/tree/create-sdcard.sh
* https://elinux.org/Beagleboard:Expanding_File_System_Partition_On_A_microSD

The simplest option is to start with a standard distribution
image like those in `BeagleBoard.org Distros Page
<https://www.beagleboard.org/distros>`_ and download a disk image for
BeaglePlay. Pick a 16GB+ uSD card to be on the safer side.

With an SD/MMC Card reader and `Balena Etcher
<https://etcher.balena.io/>`_, having a functional setup in minutes is
a trivial matter, and it works on almost all Host Operating Systems.
Yes Windows users, Windows Subsystem for Linux(WSL) based development
with U-Boot and update uSD card is practical.

Updating U-Boot is a matter of copying the tiboot3.bin, tispl.bin and
u-boot.img to the "BOOT" partition of the uSD card. Remember to sync
and unmount (or Eject - depending on the Operating System) the uSD
card prior to physically removing from SD card reader.

Also see following section on switch setting used for booting using
uSD card.

.. note::
  Great news! If the board has not been damaged physically, there's no
  need to worry about it being "bricked" on this platform. You only have
  to flash an uSD card, plug it in, and reinstall the image on eMMC. This
  means that even if you make a mistake, you can quickly fix it and rest
  easy.

  If you are frequently working with uSD cards, you might find the
  following useful:

  * `USB-SD-Mux <https://www.linux-automation.com/en/products/usb-sd-mux.html>`_
  * `SD-Wire <https://wiki.tizen.org/SDWire>`_

Flash to eMMC
-------------

The eMMC layout selected is user-friendly for developers. The
boot hardware partition of the eMMC only contains the fixed-size
tiboot3.bin image. This is because the contents of the boot partitions
need to run from the SoC's internal SRAM, which remains a fixed size
constant. The other components of the boot sequence, such as tispl.bin
and u-boot.img, are located in the /BOOT partition in the User Defined
Area (UDA) hardware partition of the eMMC. These components can vary
significantly in size. The choice of keeping tiboot3.bin in boot0 or
boot1 partition depends on A/B update requirements.

.. image:: img/beagleplay_emmc.svg
  :alt: eMMC partitions and boot file organization for BeaglePlay

The following are the steps from Linux shell to program eMMC:

.. prompt:: bash #

  # Enable Boot0 boot
  mmc bootpart enable 1 2 /dev/mmcblk0
  mmc bootbus set single_backward x1 x8 /dev/mmcblk0
  mmc hwreset enable /dev/mmcblk0

  # Clear eMMC boot0
  echo '0' >> /sys/class/block/mmcblk0boot0/force_ro
  dd if=/dev/zero of=/dev/mmcblk0boot0 count=32 bs=128k
  # Write tiboot3.bin
  dd if=tiboot3.bin of=/dev/mmcblk0boot0 bs=128k

  # Copy the rest of the boot binaries
  mount /dev/mmcblk0p1 /boot/firmware
  cp tispl.bin /boot/firmware
  cp u-boot.img /boot/firmware
  sync

.. warning ::

  U-Boot is configured to prioritize booting from an SD card if it
  detects a valid boot partition and boot files on it, even if the
  system initially booted from eMMC. The boot order is set as follows:

  * SD/MMC
  * eMMC
  * USB
  * PXE

LED patterns during boot
------------------------

.. list-table:: USR LED status indication
   :widths: 16 16
   :header-rows: 1

   * - USR LEDs (012345)
     - Indicates

   * - 00000
     - Boot failure or R5 image not started up

   * - 11111
     - A53 SPL/U-boot has started up

   * - 10101
     - OS boot process has been initiated

   * - 01010
     - OS boot process failed and drops to U-Boot shell

.. note ::

  In the table above, 0 indicates LED switched off and 1 indicates LED
  switched ON.

.. warning ::

  If the "red" power LED is not glowing, the system power supply is not
  functional. Please refer to `BeaglePlay documentation
  <https://beagleplay.org/>`_ for further information.

A53 SPL DDR Memory Layout
-------------------------

.. include::  am62x_sk.rst
    :start-after: .. am62x_evm_rst_include_start_ddr_mem_layout
    :end-before: .. am62x_evm_rst_include_end_ddr_mem_layout

Switch Setting for Boot Mode
----------------------------

The boot time option is configured via "USR" button on the board.
See `Beagleplay Schematics <https://git.beagleboard.org/beagleplay/beagleplay/-/blob/main/BeaglePlay_sch.pdf>`_
for details.

.. list-table:: Boot Modes
   :widths: 16 16 16
   :header-rows: 1

   * - USR Switch Position
     - Primary Boot
     - Secondary Boot

   * - Not Pressed
     - eMMC
     - UART

   * - Pressed
     - SD/MMC File System (FS) mode
     - USB Device Firmware Upgrade (DFU) mode

To switch to SD card boot mode, hold the USR button while powering on
with Type-C power supply, then release when power LED lights up.

Debugging U-Boot
----------------

See :ref:`Common Debugging environment - OpenOCD<k3_rst_refer_openocd>`: for
detailed setup and debugging information.

.. warning::

  **OpenOCD support since**: v0.12.0

  If the default package version of OpenOCD in your development
  environment's distribution needs to be updated, it might be necessary to
  build OpenOCD from the source.

.. include::  k3.rst
    :start-after: .. k3_rst_include_start_openocd_connect_tag_connect
    :end-before: .. k3_rst_include_end_openocd_connect_tag_connect

.. include::  k3.rst
    :start-after: .. k3_rst_include_start_openocd_cfg_external_intro
    :end-before: .. k3_rst_include_end_openocd_cfg_external_intro

For example, with BeaglePlay (AM62X platform), the openocd_connect.cfg:

.. code-block:: tcl

  # TUMPA example:
  # http://www.tiaowiki.com/w/TIAO_USB_Multi_Protocol_Adapter_User's_Manual
  source [find interface/ftdi/tumpa.cfg]

  transport select jtag

  # default JTAG configuration has only SRST and no TRST
  reset_config srst_only srst_push_pull

  # delay after SRST goes inactive
  adapter srst delay 20

  if { ![info exists SOC] } {
    # Set the SoC of interest
    set SOC am625
  }

  source [find target/ti_k3.cfg]

  ftdi tdo_sample_edge falling

  # Speeds for FT2232H are in multiples of 2, and 32MHz is tops
  # max speed we seem to achieve is ~20MHz.. so we pick 16MHz
  adapter speed 16000
