Documentation/platforms/risc-v/eic7700x/boards/starpro64: Add support for PINE64 StarPro64 SBC (ESWIN EIC7700X SoC)

This PR adds support for the PINE64 StarPro64 64-bit RISC-V SBC,
based on ESWIN EIC7700X SoC. Most of the code was derived from NuttX
for Milk-V Duo S (SOPHGO SG2000). The modified code is explained here:
https://lupyuen.github.io/articles/starpro64#appendix-port-nuttx-to-starpro64

`platforms/risc-v/eic7700x/index.rst`:
  Added StarPro64 to EIC7700X SoC
`platforms/risc-v/eic7700x/boards/starpro64/index.rst`:
  Building and booting NuttX for StarPro64

Signed-off-by: Lup Yuen Lee <luppy@appkaki.com>

Documentation/platforms/risc-v/eic7700x/boards/starpro64/index.rst

@@ -0,0 +1,168 @@
+================
+PINE64 StarPro64
+================
+
+`PINE64 StarPro64 <https://lupyuen.github.io/articles/starpro64>`_
+is a RISC-V Single-Board Computer based on the ESWIN EIC7700X RISC-V SoC
+with Quad-Core 64-bit RISC-V CPU, 32 GB LPDDR5 RAM and 100 Mbps Ethernet.
+
+Features
+========
+
+- **System on Chip:** ESWIN EIC7700X
+- **Processors:** 4 x RV64GC 1.4 GHz 64-bit RISC-V Cores
+- **NPU:** 19.95 TOPS INT8
+- **Memory:** 32 GB 64-bit LPDDR5
+- **Storage:** 1 x microSD Connector, 1 x eMMC Pad
+- **Network:** 2 x GMAC, RGMII supported
+- **PCI Express:** 4-lane PCIe 3.0 (RC + EP)
+- **Wireless:** WiFi, Bluetooth
+- **USB:** USB 2.0 and 3.0
+- **GPIO:** Full GPIO Header
+
+Serial Console
+==============
+
+A **USB Serial Adapter** (CH340 or CP2102) is required to run NuttX
+on StarPro64.
+
+Connect the USB Serial Adapter to StarPro64 Serial Console at:
+
+========== =================
+USB Serial StarPro64 Pin
+========== =================
+GND        Pin 6 (GND)
+RX         Pin 8 (UART0 TX)
+TX         Pin 10 (UART0 RX)
+========== =================
+
+On the USB Serial Adapter, set the **Voltage Level** to 3V3.
+
+Connect StarPro64 to our computer with the USB Serial Adapter.
+On our computer, start a Serial Terminal and connect to the USB Serial Port
+at **115.2 kbps**:
+
+.. code:: console
+
+   $ screen /dev/ttyUSB0 115200
+
+NuttX will appear in the Serial Console when it boots on StarPro64.
+
+RISC-V Toolchain
+================
+
+Before building NuttX for StarPro64, download the toolchain for
+`xPack GNU RISC-V Embedded GCC (riscv-none-elf) <https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack/releases>`_.
+
+Add the downloaded toolchain ``xpack-riscv-none-elf-gcc-.../bin``
+to the ``PATH`` Environment Variable.
+
+Check the RISC-V Toolchain:
+
+.. code:: console
+
+   $ riscv-none-elf-gcc -v
+
+Building
+========
+
+To build NuttX for StarPro64, :doc:`install the prerequisites </quickstart/install>` and
+:doc:`clone the git repositories </quickstart/install>` for ``nuttx`` and ``apps``.
+
+Configure the NuttX project and build the project:
+
+.. code:: console
+
+   $ cd nuttx
+   $ tools/configure.sh starpro64:nsh
+   $ make
+
+This produces the NuttX Kernel ``nuttx.bin``.  Next, build the NuttX Apps Filesystem:
+
+.. code:: console
+
+   $ make export
+   $ pushd ../apps
+   $ tools/mkimport.sh -z -x ../nuttx/nuttx-export-*.tar.gz
+   $ make import
+   $ popd
+   $ genromfs -f initrd -d ../apps/bin -V "NuttXBootVol"
+
+This generates the Initial RAM Disk ``initrd``.
+
+Package the NuttX Kernel and Initial RAM Disk into a NuttX Image:
+
+.. code:: console
+
+   $ head -c 65536 /dev/zero >/tmp/nuttx.pad
+   $ cat nuttx.bin /tmp/nuttx.pad initrd >Image-starpro64
+
+The NuttX Image ``Image-starpro64`` will be copied to the TFTP Server in the next step.
+
+Booting
+=======
+
+To boot NuttX on StarPro64, `install a TFTP Server <https://lupyuen.github.io/articles/starpro64#boot-nuttx-over-tftp>`_
+on our computer.
+
+Copy the file ``Image-starpro64`` from the previous section to the TFTP Server,
+together with the Device Tree:
+
+.. code:: console
+
+   $ wget https://github.com/lupyuen/nuttx-starpro64/raw/refs/heads/main/eic7700-evb.dtb
+   $ scp Image-starpro64 \
+      tftpserver:/tftpfolder/Image-starpro64
+   $ scp eic7700-evb.dtb \
+      tftpserver:/tftpfolder/eic7700-evb.dtb
+
+Check that StarPro64 is connected to our computer via a USB Serial Adapter at 115.2 kbps:
+
+.. code:: console
+
+   $ screen /dev/ttyUSB0 115200
+
+When StarPro64 boots, press Ctrl-C until U-Boot stops.
+At the U-Boot Prompt, run these commands to
+`boot NuttX over TFTP <https://lupyuen.github.io/articles/starpro64#boot-nuttx-over-tftp>`_:
+
+.. code:: console
+
+   # Change to your TFTP Server
+   $ setenv tftp_server 192.168.x.x
+   $ saveenv
+   $ dhcp ${kernel_addr_r} ${tftp_server}:Image-starpro64
+   $ tftpboot ${fdt_addr_r} ${tftp_server}:eic7700-evb.dtb
+   $ fdt addr ${fdt_addr_r}
+   $ booti ${kernel_addr_r} - ${fdt_addr_r}
+
+Or configure U-Boot to `boot NuttX automatically <https://lupyuen.github.io/articles/starpro64#boot-nuttx-over-tftp>`_.
+
+NuttX boots on StarPro64 and NuttShell (nsh) appears in the Serial Console.
+To see the available commands in NuttShell:
+
+.. code:: console
+
+   $ help
+
+Configurations
+==============
+
+nsh
+---
+
+Basic configuration that runs NuttShell (nsh).
+This configuration is focused on low level, command-line driver testing.
+Built-in applications are supported, but none are enabled.
+Serial Console is enabled on UART0 at 115.2 kbps.
+
+Peripheral Support
+==================
+
+NuttX for StarPro64 supports these peripherals:
+
+======================== ======= =====
+Peripheral               Support NOTES
+======================== ======= =====
+UART                     Yes
+======================== ======= =====

Documentation/platforms/risc-v/eic7700x/index.rst

@@ -14,3 +14,12 @@ ESWIN EIC7700X
 - **Network:** 2 x GMAC, RGMII supported
 - **PCI Express:** 4-lane PCIe 3.0 (RC + EP)
 - **Peripherals:** 2 x USB 3.0 DRD (Host + Device), 12 x I2C, 5 x UART, 2 x SPI, 3 x I2S (Slave + Master)
+
+Supported Boards
+================
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   boards/*/*