docs(u-boot) Add documentation of Ethernet boot for J722s SoC

Ethernet boot support has been added to J722s SoC, add documentation for
the same.

Signed-off-by: Chintan Vankar <c-vankar@ti.com>

Author: chintanv133

configs/J722S/J722S_linux_config.txt

@@ -32,6 +32,10 @@ Replacement Variables
 '__FEATURINGMATRIX__'            : \
 '__SYSFW_CORE_NAME__'            : 'TIFS'
 '__IMAGE_TYPE__'                 : 'adas'
+'__SPL_VCI_STRING_LEN__'         : '19'
+'__SPL_VCI_STRING__'             : 'J722S U-Boot R5 SPL'
+'__UBOOT_VCI_STRING_LEN__'       : '20'
+'__UBOOT_VCI_STRING__'           : 'J722S U-Boot A53 SPL'
 
 Configuration Values
 --------------------

configs/J722S/J722S_linux_toc.txt

@@ -31,6 +31,7 @@ linux/Foundational_Components/U-Boot/UG-NOR
 linux/Foundational_Components/U-Boot/UG-UART
 linux/Foundational_Components/U-Boot/UG-SATA
 linux/Foundational_Components/U-Boot/UG-DDRSS-J7
+linux/Foundational_Components/U-Boot/UG-Network-K3
 linux/Foundational_Components/U-Boot/UG-HyperBus
 linux/Foundational_Components/U-Boot/UG-RemoteProc
 linux/Foundational_Components/U-Boot/Applications

source/linux/Foundational_Components/U-Boot/UG-General-Info.rst

@@ -393,12 +393,12 @@ Build U-Boot
 
    .. ifconfig:: CONFIG_part_variant in ('J722S')
 
-      +----------------------------+---------------------------------+--------------------------------+--------------------------------+------------------------------------------------------+-------------------------------------------------------+
-      |  Board                     |            SD/eMMC Boot         |           UART boot            |           OSPI boot            |                     USB DFU                          |           USB MSC                                     |
-      +============================+=================================+================================+================================+======================================================+=======================================================+
-      |    J722S EVM               |  | ``j722s_evm_r5_defconfig``   |  | ``j722s_evm_r5_defconfig``  |  | ``j722s_evm_r5_defconfig``  |  | ``j722s_evm_r5_defconfig am62x_r5_usbdfu.config`` |  | ``j722s_evm_r5_defconfig am62x_r5_usbmsc.config``  |
-      |                            |  | ``j722s_evm_a53_defconfig``  |  | ``j722s_evm_a53_defconfig`` |  | ``j722s_evm_a53_defconfig`` |  | ``j722s_evm_a53_defconfig``                       |  | ``j722s_evm_a53_defconfig``                        |
-      +----------------------------+---------------------------------+--------------------------------+--------------------------------+------------------------------------------------------+-------------------------------------------------------+
+      +----------------------------+---------------------------------+--------------------------------+--------------------------------+------------------------------------------------------+-------------------------------------------------------+------------------------------------------+
+      |  Board                     |            SD/eMMC Boot         |           UART boot            |           OSPI boot            |                     USB DFU                          |           USB MSC                                     |            Ethernet boot                 |
+      +============================+=================================+================================+================================+======================================================+=======================================================+==========================================+
+      |    J722S EVM               |  | ``j722s_evm_r5_defconfig``   |  | ``j722s_evm_r5_defconfig``  |  | ``j722s_evm_r5_defconfig``  |  | ``j722s_evm_r5_defconfig am62x_r5_usbdfu.config`` |  | ``j722s_evm_r5_defconfig am62x_r5_usbmsc.config``  |   j722s\_evm\_r5\_ethboot\_defconfig     |
+      |                            |  | ``j722s_evm_a53_defconfig``  |  | ``j722s_evm_a53_defconfig`` |  | ``j722s_evm_a53_defconfig`` |  | ``j722s_evm_a53_defconfig``                       |  | ``j722s_evm_a53_defconfig``                        |   j722s\_evm\_a53\_ethboot\_defconfig    |
+      +----------------------------+---------------------------------+--------------------------------+--------------------------------+------------------------------------------------------+-------------------------------------------------------+------------------------------------------+
 
    .. ifconfig:: CONFIG_part_variant in ('J721E','J7200','J721S2','J784S4','J742S2')
 

source/linux/Foundational_Components/U-Boot/UG-Network-K3.rst

@@ -50,7 +50,18 @@ binaries files to be sent over TFTP are listed in the table below.
         - Disable link info Bootmode pin so that ROM can identify the PHY and establishes link with the supported speed and duplex mode.
         - Please note that due to MDIO corruption (Errata i2329), booting over Ethernet is not recommended for production purposes.
 
-.. ifconfig:: CONFIG_part_variant in ('AM64X','AM62X')
+.. ifconfig:: CONFIG_part_variant in ('J722S')
+
+   Build tiboot3.bin using ``j722s_evm_r5_ethboot_defconfig``. Build tispl.bin and u-boot.img using ``j722s_evm_a53_ethboot_defconfig``. For instructions to build the bootloader images please refer to :ref:`Build-U-Boot-label`.
+
+   .. important::
+
+      - Ethernet RGMII boot is supported over RGMII on J722s SoC.
+      - CPSW PHYs should be strapped as per ROM's expectation described in part's TRM.
+      - When the link info Bootmode pin is enabled, this means no auto-negotiation or reading of the Ethernet PHY is needed since the ROM will assume the link is up at 1Gbps, full duplex mode.
+      - Disable link info Bootmode pin so that ROM can identify the PHY and establishes link with the supported speed and duplex mode.
+
+.. ifconfig:: CONFIG_part_variant in ('AM64X','AM62X','J722S')
 
   If using ISC dhcpd an example host entry would look like this: