Merge branch 'bvf-gateware-tcl-scripts-structure' into 'main'

BVF: Add gateware TCL scripts structure description.

See merge request docs/docs.beagleboard.io!76

boards/beaglev/fire/demos-and-tutorials/gateware/gateware-tcl-scripts-structure.rst

+Gateware TCL Scripts Structure
+##############################
+
+This document describes the structure of the gateware TCL scripts. It is of interest to understand
+how to extend or customize the gateware.
+
+The `Libero SoC TCL Command Reference Guide <https://coredocs.s3.amazonaws.com/Libero/2023_2/Tool/libero_soc_tcl_cmd_ref_ug.pdf>`_ describes the TCL command used in the gateware scripts.
+
+Gateware Project
+================
+
+The gateware project is made up of:
+
+- TCL scripts
+- HDL/Verilog source code
+- IO pin constraints
+- Placement constraints
+- Device tree overlays
+
+All these files are found in the FPGA-design directory.
+
+.. figure:: media/gateware-source-dir.png
+    :align: center
+
+
+Gateware Components
+===================
+
+The gateware is organized into 6 components:
+
+- Clocks and reset control
+- A base RISC-V microprocessor subsystem
+- Cape interface
+- M.2 interface
+- MIPI camera interface
+- SYZYGY high speed interface
+
+.. figure:: media/gateware-components.png
+    :align: center
+
+Gateware Build Options
+======================
+
+Each interface component may have a number of build options. For example, which cape will be
+supported by the generated gateware.
+
+
+.. figure:: media/gateware-cape-options.png
+    :align: center
+
+The name of the directories within the component's directory are the option names passed to the
+top Libero BUILD_BVF_GATEWATE.tcl script. These directory names are the option name specified in
+the bitstream builder's build option YAML files.
+
+The gateware is extended or customized by creating additional directories within the component
+directory of interest. For example, add a MY_CUSTOM_CAPE directory under the CAPE directory to
+add a gateware build option to support a custom cape.
+
+Gateware Component Directories
+==============================
+
+The component directory contains subdirectories for:
+
+- Constraint files
+- Device tree overlay
+- Optional HDL/Verilog source code
+
+.. figure:: media/gateware-cape-robotics-dirs.png
+    :align: center
+
+Gareware TCL Scripts
+--------------------
+
+The component directory contains the TCL scripts executed by Libero to generate the gateware.
+The TCL script framework executes a hand-crafted ADD_<COMPONENT_NAME>.tcl script which instantiates
+the component and stiches it to the base RISC-V subsystem and top level IOs. The other TCL scripts
+are typically IP configuration scripts and SmartDesign stiching scripts.
+
+.. figure:: media/gateware-cape-robotics-files.png
+    :align: center
+
+