[PATCH v3] doc: board: ti: Add J742S2 support

[Udit Kumar <u-kumar1@ti.com>]

J742S2 SOC is derivative of J784S4, most of build infra of j784s4 is used
to build u-boot for J742S2 EVM board.

Add guide users on how to build for that board.

Signed-off-by: Udit Kumar <u-kumar1@ti.com>
---
Test logs
https://gist.github.com/uditkumarti/28d9d698f7f74cbb9da76047ce1ce60f

Changelog:
Chnages in v3:
- Moved defconfig into AM69 block
- Moved GP information note just after GP Images

Changes in v2:
- Removed extra =

Patch link
v2: https://lore.kernel.org/all/20251205043602.845730-1-u-kumar1@ti.com/
v1: https://lore.kernel.org/all/20251204142451.834404-1-u-kumar1@ti.com/

 doc/board/ti/j784s4_evm.rst | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/doc/board/ti/j784s4_evm.rst b/doc/board/ti/j784s4_evm.rst
index 22442874110..d858dc7cdbb 100644
--- a/doc/board/ti/j784s4_evm.rst
+++ b/doc/board/ti/j784s4_evm.rst
@@ -1,8 +1,8 @@
 .. SPDX-License-Identifier: GPL-2.0-or-later OR BSD-3-Clause
 .. sectionauthor:: Apurva Nandan <a-nandan@ti.com>
 
-J784S4 and AM69 Platforms
-=========================
+J742S2, J784S4 and AM69 Platforms
+=================================
 
 Introduction
 ------------
@@ -37,6 +37,11 @@ Platform information:
 * https://www.ti.com/tool/J784S4XEVM
 * https://www.ti.com/tool/SK-AM69
 
+J742S2 is derivative of J784S24 SOC, More info can be found in
+
+* TRM : https://www.ti.com/lit/ug/spruje3/spruje3.pdf
+* Platform Information : https://www.ti.com/tool/J742S2XH01EVM
+
 Boot Flow
 ---------
 Below is the pictorial representation of boot flow:
@@ -99,6 +104,13 @@ Set the variables corresponding to this platform:
       export UBOOT_CFG_CORTEXR=am69_sk_r5_defconfig
       export UBOOT_CFG_CORTEXA=am69_sk_a72_defconfig
 
+   For J742S2-EVM, use the following U_BOOT_CFG instead:
+
+   .. prompt:: bash
+
+      export UBOOT_CFG_CORTEXR=j742s2_evm_r5_defconfig
+      export UBOOT_CFG_CORTEXA=j742s2_evm_a72_defconfig
+
 .. j784s4_evm_rst_include_start_build_steps
 
 1. Trusted Firmware-A
@@ -143,14 +155,21 @@ variant (GP, HS-FS, HS-SE) requires a different source for these files.
     * tiboot3-j784s4-gp-evm.bin from :ref:`step 3.1 <j784s4_evm_rst_u_boot_r5>`
     * tispl.bin_unsigned, u-boot.img_unsigned from :ref:`step 3.2 <j784s4_evm_rst_u_boot_a72>`
 
+  .. note::
+
+    For J742S2, GP variant is not available.
+
+
  - HS-FS
 
     * tiboot3-j784s4-hs-fs-evm.bin from :ref:`step 3.1 <j784s4_evm_rst_u_boot_r5>`
+    * tiboot3-j742s2-hs-fs-evm.bin from :ref:`step 3.1 <j784s4_evm_rst_u_boot_r5>`
     * tispl.bin, u-boot.img from :ref:`step 3.2 <j784s4_evm_rst_u_boot_a72>`
 
  - HS-SE
 
     * tiboot3-j784s4-hs-evm.bin from :ref:`step 3.1 <j784s4_evm_rst_u_boot_r5>`
+    * tiboot3-j742s2-hs-evm.bin from :ref:`step 3.1 <j784s4_evm_rst_u_boot_r5>`
     * tispl.bin, u-boot.img from :ref:`step 3.2 <j784s4_evm_rst_u_boot_a72>`
 
 Image formats
-- 
2.34.1