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TF-A: Documentation Updates and Fixes #483

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5e94192
fix(ATF): improve wording and grammar
DhruvaG2000 Oct 15, 2025
104e16f
fix(ATF): use TF-A instead of ATF throughout
DhruvaG2000 Oct 15, 2025
0d80c6a
fix(ATF): use the correct ATF links to clone
DhruvaG2000 Oct 15, 2025
0fb0130
feat(ATF): document SCMI for AM62L
DhruvaG2000 Oct 15, 2025
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71 changes: 59 additions & 12 deletions source/linux/Foundational_Components_ATF.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
software for Armv7-A and Armv8-A, including a Secure Monitor executing at
Exception Level 3 (EL3).

Arm Trusted Firmware (ATF) is the initial code on ARMv8-A cores for all K3 platforms.
TF-A is the initial code on ARMv8-A cores for all K3 platforms.
After setting up the initial core state and applying any needed errata fixes
it sets up itself as the EL3 monitor handler. Following that, it installs the secure
world open source Trusted Execution Environment (OP-TEE) software and passes execution
Expand All @@ -24,20 +24,67 @@
The SCMI IDs used in the AM62L TF-A implementation are documented in the
`TF-A documentation <https://github.com/TexasInstruments/arm-trusted-firmware/blob/ti-master/docs/plat/ti-am62l.rst>`__.

.. rubric:: SCMI and TI SCI

The AM62Lx represents a transition in Texas Instruments' approach to system control
interfaces. In the previous K3 devices, the Texas Instruments System Controller Interface (TI SCI)
was the primary protocol used for power, clock, and resource management. SCMI now serves
as a replacement for newer devices like the AM62L, offering similar functionality through
an industry-standard ARM protocol. This transition is in part due to the absence of any Device
Management (R5 core) in the AM62Lx.

.. rubric:: Implementation Overview

The AM62L TF-A implementation runs a SCMI server that manages:

* **Power Domains**: Over 100 power domains are defined for various peripherals and subsystems
* **Clock Management**: Extensive clock control for all major peripherals including:

- Multiple clock sources (PLLs, oscillators, external clocks)
- Clock multiplexers for flexible clock routing
- Clock dividers for frequency scaling
- Support for dynamic clock rate configuration

.. rubric:: Clock Infrastructure

The clock management system supports:

* **Parent Clock Selection** - Multiple clock sources can be selected as parents for each peripheral
* **Clock Multiplexing** - Dynamic switching between different clock sources
* **Rate Configuration** - Flexible frequency configuration within supported ranges

.. rubric:: Usage in Linux

Linux kernel drivers can use standard SCMI client APIs to:

* Request power state changes for devices
* Configure clock rates and parents
* Query current power and clock states
* Implement dynamic power management policies

|

.. rubric:: Getting the ATF Source Code
.. rubric:: Getting the TF-A Source Code

The pre-built TF-A binary is in TI Processor SDK:
The pre-built TF-A binary is in the TI Processor SDK:

Check warning on line 69 in source/linux/Foundational_Components_ATF.rst

View workflow job for this annotation

GitHub Actions / vale 

[vale] reported by reviewdog 🐶
[RedHat.SentenceLength] Try to keep sentences to an average of 32 words or fewer.

Raw Output:
{"message": "[RedHat.SentenceLength] Try to keep sentences to an average of 32 words or fewer.", "location": {"path": "source/linux/Foundational_Components_ATF.rst", "range": {"start": {"line": 69, "column": 1}}}, "severity": "INFO"}
<path-to-processor-sdk>/board-support/prebuilt-images/<optional-build-machine-name>/bl31.bin.
Use this binary since it is tested with TI Processor SDK.

If it is not possible to use pre-build binary, use the following:
If it is not possible to use a pre-built binary, use the following:

.. ifconfig:: CONFIG_part_variant in ('AM62LX')

.. code-block:: console

$ git clone https://github.com/TexasInstruments/arm-trusted-firmware.git
$ git checkout <hash>

.. ifconfig:: CONFIG_part_variant not in ('AM62LX')

.. code-block:: console
.. code-block:: console

$ git clone https://github.com/TexasInstruments/arm-trusted-firmware.git
$ git checkout <hash>
$ git clone https://review.trustedfirmware.org/TF-A/trusted-firmware-a.git
$ git checkout <hash>

Where <hash> is the commit shown here: :ref:`tf-a-release-notes` :ref:`release-specific-build-information`.

Expand All @@ -49,7 +96,7 @@
:start-after: .. start_include_yocto_toolchain_host_setup
:end-before: .. end_include_yocto_toolchain_host_setup

.. rubric:: Building ATF
.. rubric:: Building TF-A

.. ifconfig:: CONFIG_part_variant in ('AM62LX', 'AM62X', 'AM62AX', 'AM62PX', 'AM64X', 'J722S')

Expand Down Expand Up @@ -98,7 +145,7 @@
.. code-block:: text

+---------------------------+------------+
| ATF image | 0x701c0000 |
| TF-A image | 0x701c0000 |
+---------------------------+------------+
| OP-TEE image | 0x9e800000 |
+---------------------------+------------+
Expand All @@ -112,7 +159,7 @@
.. code-block:: text

+---------------------------+------------+
| ATF image | 0x80000000 |
| TF-A image | 0x80000000 |
+---------------------------+------------+
| OP-TEE image | 0x80200000 |
+---------------------------+------------+
Expand All @@ -126,7 +173,7 @@
.. code-block:: text

+---------------------------+------------+
| ATF image | 0x70000000 |
| TF-A image | 0x70000000 |
+---------------------------+------------+
| OP-TEE image | 0x9e800000 |
+---------------------------+------------+
Expand All @@ -144,7 +191,7 @@
.. code-block:: text

+-----------------------------------------------------+------------------+-----------------------+---------------------+---------------+-------------------+----------+----------------------------------------+
| Source | ATF | OPTEE | A53 SPL | A53 U-Boot | DTB | kernel | Comments |
| Source | TF-A | OPTEE | A53 SPL | A53 U-Boot | DTB | kernel | Comments |
+=====================================================+==================+=======================+=====================+===============+===================+==========+========================================+
| <atf>/plat/ti/k3/board/lite/board.mk | | BL32_BASE | PRELOADED_BL33_BASE | | K3_HW_CONFIG_BASE | | Change K3_HW_CONFIG_BASE for |
| | | | | | | | u-boot a53 skip case |
Expand Down