feat(security): Generalize boot flow page for non-AM64x SoCs

Currently, the secure boot section is tailored for AM64x. But the same
information is applicable to non-AM64x SoCs, that is AM62x, AM62P. Therefore
generalize the page and add it these other devices' TOCs.

In addition, fix the language in the file to simplify it by changing a few
passive voice statements into active voice, using easier words etc. Also fix
headings and remove TRM links.

Signed-off-by: Suhaas Joshi <s-joshi@ti.com>

Author: jsuhaas22

configs/AM62AX/AM62AX_linux_toc.txt

@@ -98,6 +98,7 @@ linux/Foundational_Components/System_Security/Security_overview
 linux/Foundational_Components/System_Security/SELinux
 linux/Foundational_Components/System_Security/Auth_boot
 linux/Foundational_Components/System_Security/Memory_Firewalls
+linux/Foundational_Components_Secure_Boot
 
 linux/Foundational_Components_Kernel_Users_Guide
 linux/Foundational_Components_Kernel_LTP-DDT_Validation

configs/AM62PX/AM62PX_linux_toc.txt

@@ -103,6 +103,7 @@ linux/Foundational_Components/System_Security/Security_overview
 linux/Foundational_Components/System_Security/SELinux
 linux/Foundational_Components/System_Security/Auth_boot
 linux/Foundational_Components/System_Security/Memory_Firewalls
+linux/Foundational_Components_Secure_Boot
 
 linux/Foundational_Components_Kernel_Users_Guide
 linux/Foundational_Components_Kernel_LTP-DDT_Validation

configs/AM62X/AM62X_linux_toc.txt

@@ -100,6 +100,7 @@ linux/Foundational_Components/System_Security/Security_overview
 linux/Foundational_Components/System_Security/SELinux
 linux/Foundational_Components/System_Security/Auth_boot
 linux/Foundational_Components/System_Security/Memory_Firewalls
+linux/Foundational_Components_Secure_Boot
 
 linux/Foundational_Components_PRU_Subsystem
 linux/Foundational_Components/PRU-ICSS-Linux-Drivers

source/linux/Foundational_Components/System_Security/Security_overview.rst

@@ -71,8 +71,12 @@ The following table lists some of the key Security Features:
   +-------------------------+-----------------------------------------------------------+--------------------------------------+
   | Security Feature        | Description                                               | Links                                |
   +=========================+===========================================================+======================================+
-  | **Authenticated Boot**  | Verifies each boot component to ensure only authorized    | :ref:`auth_boot_guide`               |
-  |                         | code executes on the device                               |                                      |
+  | **Secure Boot**         | Verifies and decrypts each boot stage, establishing a     | :ref:`foundational-secure-boot`      |
+  |                         | hardware-backed chain of trust from ROM to Linux using    |                                      |
+  |                         | customer-programmable keys                                |                                      |
+  +-------------------------+-----------------------------------------------------------+--------------------------------------+
+  | **Authenticated Boot**  | Transparent disk encryption using the Linux kernel        | :ref:`auth_boot_guide`               |
+  |                         | device mapper (dm-crypt) for data confidentiality         |                                      |
   +-------------------------+-----------------------------------------------------------+--------------------------------------+
   | **Crypto Acceleration** | Hardware driver support for cryptographic algorithms      | :ref:`crypto-accelerator`            |
   +-------------------------+-----------------------------------------------------------+--------------------------------------+

source/linux/Foundational_Components_Secure_Boot.rst

@@ -1,9 +1,11 @@
+.. _foundational-secure-boot:
+
 **********************************
 Secure Boot
 **********************************
 
-Authenticated Boot
---------------------
+Introduction
+------------
 
 Each device contains customer programmable keys used to authenticate, and optionally decrypt, code/data to be used on the device. A job for
 the Public Boot ROM of both General Purpose (GP) and High Security (HS) devices is to load the next stage of the boot process into memory. On
@@ -30,16 +32,19 @@ The following is an example list where Chain-of-Trust should be maintained.
 - Disable kernel debug options
 - Disable/remove userspace debug tools, devmem disable, etc..
 
-We provide methods for U-Boot's SPL loader to securely verify/encrypt the U-Boot proper. This is accomplished by calling into TIFS via TI-SCI
-(Texas Instruments System Controller Interface). For more infomation using TI_SCI methods refer to the
-`TISCI User Guide <https://software-dl.ti.com/tisci/esd/22_01_02/index.html>`__. U-Boot proper then securely verifies/decrypts the Kernel/DTB/initramfs.
+We offer methods for U-Boot's Secondary Program Loader (SPL) to securely verify the U-Boot
+proper. U-Boot calls Texas Instrument Foundational Security (TIFS) through Texas Instruments System Controller Interface (TISCI)
+to do this. For more information about using TISCI methods see the
+`TISCI User Guide <https://software-dl.ti.com/tisci/esd/22_01_02/index.html>`__. U-Boot proper then securely verifies and decrypts the kernel, Device Tree Blobs (DTB), and initramfs.
 
 .. Image:: /images/K3_KF.png
         :scale: 70%
 
-Secure boot has layers. Some layers are trusted more than others. Secure ROM has the highest trust and REE (Run-time Execution
-Environment) non-trustzone user-space applications have the least. If any higher trust code is to be loaded by a lower trust entity, it must be verified
-by an even higher trust entity and not allowed to be accessed by the lower trust entity after that point. Some such trust inversions are listed below:
+Secure boot has layers. Some layers are trusted more than others. Secure ROM has the highest trust and Runtime Execution
+Environment (REE) non-trustzone user-space applications have the least. If a
+lower trust entity must load a higher trust code, an even higher trust entity
+must verify it and not allow access by the lower trust entity after that
+point. Some such trust inversions are as follows:
 
 - R5 U-Boot loading ATF/OP-TEE
 - R5 Public Boot ROM loading TIFS
@@ -62,21 +67,17 @@ The exact location is device dependent. More details can be found in the device
 
 .. ifconfig:: CONFIG_part_variant in ('AM64x')
 
-    - `AM64x TRM <https://www.ti.com/lit/pdf/spruim2>`_
-
     The contents of this first stage image are authenticated and decrypted by the Secure ROM. Contents include:
 
     * DMSC firmware: `Texas Instruments Foundational Security (TIFS)` + Device/Power Manager: After authentication/decryption, DMSC firmware replaces the Secure ROM as the authenticator entity executing on the DMSC core.
     * R5 SPL: The R5 SPL bootloader is executed on the R5 core.
 
-.. ifconfig:: CONFIG_part_variant in ('AM62x')
-
-    - `AM62x TRM <https://www.ti.com/lit/pdf/spruiv7>`_
+.. ifconfig:: CONFIG_part_variant not in ('AM64X')
 
-    The contents of this first stage image are authenticated and decrypted by the Secure ROM. Contents include:
+   The contents of this first stage image are authenticated and decrypted by the Secure ROM. Contents include:
 
-    * `Texas Instruments Foundational Security (TIFS)` firmware: After authentication/decryption, TIFS firmware replaces the Secure ROM as the authenticator entity executing on the TIFS core.
-    * R5 SPL`: The R5 SPL bootloader is executed on the R5 core.
+   * `Texas Instruments Foundational Security (TIFS)` firmware: After authentication/decryption, TIFS firmware replaces the Secure ROM as the authenticator entity executing on the TIFS core.
+   * R5 SPL`: The R5 SPL bootloader is executed on the R5 core.
 
 .. rubric:: R5 SPL
 
@@ -195,9 +196,9 @@ HS Boot Flow Tools
 
 U-boot:
 
-    The ti-u-boot source is a project used to create tiboot3.bin, tispl.bin, and u-boot.img. To create  tiboot3.bin for AM64x family devices, u-boot builds R5 SPL and
+    The ti-u-boot source is a project used to create tiboot3.bin, tispl.bin, and u-boot.img. To create  tiboot3.bin for K3 family devices, u-boot builds R5 SPL and
     binman packages it in a `tiboot3.bin` image. To build A53 SPL, binman takes ATF (bl31.bin), OPTEE (bl32.bin), A53 SPL, and A53 DTBs and packages
-    them in a `tispl.bin` image. The openssl library can then then be used to sign each component as specified in k3-am64x-binman.dtsi.
+    them in a `tispl.bin` image. U-Boot can then use the openssl library to sign each component as specified in k3-<soc>-binman.dtsi.
 
     .. code-block:: console
 
@@ -246,7 +247,7 @@ OPTEE:
 Ti-linux-firmware:
 
     The ti-linux-firmware is a TI repository where all firmware releases are stored. Firmwares for a device family can also be found in the pre-built SDK
-    under <path-to-tisdk>/board-support/prebuilt-images/am64xx-evm. Binman expects to find the device firmware with the following appended to u-boot build command:
+    under :file:`<path-to-tisdk>/board-support/prebuilt-images/<evm>`. Binman expects to find the device firmware with the following appended to u-boot build command:
     BINMAN_INDIRS=<path-to-tisdk>/board-support/prebuilt-images, and expects to find a ti-sysfw directory in this path.
 
     .. code-block:: console