boards/risc-v: Add support for Milk-V Duo S SBC (SOPHGO SG2000 SoC)

This PR adds support for Milk-V Duo S 64-bit RISC-V SBC, based on SOPHGO SG2000 SoC (T-Head C906 Core). Most of the code is derived from NuttX for Ox64 BL808. The source files are explained in the articles here: https://github.com/lupyuen/nuttx-sg2000

Modified Files:

`boards/Kconfig`: Added Milk-V Duo S board

`arch/risc-v/src/sg2000/sg2000_timerisr.c`: Fixed MTIMER_FREQ for sleep() to work correctly

New Files in boards/risc-v/sg2000/milkv_duos:

`src/sg2000_appinit.c`: Startup Code

`include/board.h`: Milk-V Duo S Definitions

`include/board_memorymap.h`: Memory Map

`src/etc/init.d/rc.sysinit`, `rcS`: Startup Script

`src/.gitignore`: Ignore the tmp filesystem

`scripts/ld.script`: Linker Script

`scripts/Make.defs`: Milk-V Duo S Makefile

`src/Makefile`: Milk-V Duo S Makefile

`Kconfig`: Milk-V Duo S Config

`configs/nsh/defconfig`: Build Config for `milkv_duos:nsh`

Updated Documentation:

`platforms/risc-v/sg2000/index.rst`: New page for SOPHGO SG2000 SoC

`platforms/risc-v/sg2000/boards/milkv_duos/index.rst`: Building and booting NuttX for Milk-V Duo S

Documentation/platforms/risc-v/sg2000/boards/milkv_duos/index.rst

@@ -0,0 +1,183 @@
+============
+Milk-V Duo S
+============
+
+`Milk-V Duo S <https://milkv.io/duo-s>`_ is a RISC-V Single-Board Computer
+based on the SOPHGO SG2000 RISC-V SoC with T-Head C906 64-bit Main Processor,
+512 MB of SIP DRAM memory and 100 Mbps Ethernet.
+
+Features
+========
+
+- **System on Chip:** SOPHGO SG2000
+    - **CPU:** 
+        - 64-bit T-Head C906 1.0 GHz (Main Processor)
+        - 64-bit T-Head C906 700 MHz (Co-Processor)
+        - 64-bit Arm Cortex-A53 1.0 GHz (Alternate Main Processor)
+
+- **MCU:** 8051 with 6 KB SRAM
+- **Memory:** SIP DRAM 512 MB
+- **TPU:** 0.5 TOPS INT8
+- **Storage:** 1 x microSD Connector, 1 x eMMC Pad
+- **USB:** 1 x Type-C for Power and Data or 1 x USB 2.0 A Port Host
+- **MIPI CSI:** 1 x 16P FPC Connector (MIPI CSI 2-Lane), 1 x 15P FPC Connector (MIPI CSI 2-Lane)	
+- **Sensor Support:** 5M @ 30 FPS
+- **MIPI DSI:** Via GPIO Header (MIPI DSI 4-Lane)	
+- **Ethernet:** 100 Mbps Ethernet Port (RJ45)
+- **Wireless:** Optional Wi-Fi 6 / Bluetooth 5
+- **Audio:** Via GPIO Pin	
+- **GPIO:** Up to 39 x GPIO Pin (via 2 x 26-Pin GPIO Header)
+- **Others:** 1 x Boot Switch, 1 x Recovery Key, 1 x Reset Key
+
+Serial Console
+==============
+
+A **USB Serial Adapter** is required to run NuttX on Milk-V Duo S,
+**CP2102** is recommended. CH340 might not work correctly with Duo S.
+
+Connect the USB Serial Adapter to Duo S Serial Console at:
+
+========== ================
+USB Serial Milk-V Duo S Pin
+========== ================
+GND        Pin 6 (GND)
+RX         Pin 8 (XGPIOA 16 / UART0 TX)
+TX         Pin 10 (XGPIOA 17 / UART0 RX)
+========== ================
+
+On the USB Serial Adapter, set the **Voltage Level** to 3V3.
+
+Connect Duo S 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 Duo S.
+
+RISC-V Toolchain
+================
+
+Before building NuttX for Milk-V Duo S, 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 Milk-V Duo S, :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 milkv_duos: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-sg2000
+
+The NuttX Image ``Image-sg2000`` will be copied to the TFTP Server in the next step.
+
+Booting
+=======
+
+NuttX requires a microSD Card with U-Boot Bootloader. Prepare a
+`Linux microSD Card <https://lupyuen.github.io/articles/sg2000#download-the-linux-microsd>`_
+for Duo S.
+
+To boot NuttX on Milk-V Duo S, flip the `Main Processor Switch <https://lupyuen.github.io/articles/sg2000#boot-without-microsd>`_
+to **RV** (RISC-V).
+On our computer, `install the TFTP Server <https://lupyuen.github.io/articles/sg2000#boot-nuttx-over-tftp>`_.
+
+Copy the file ``Image-sg2000`` from the previous section to the TFTP Server,
+together with the Device Tree:
+
+.. code:: console
+
+   $ wget https://github.com/lupyuen2/wip-nuttx/releases/download/sg2000-1/cv181x_milkv_duos_sd.dtb
+   $ scp Image-sg2000 \
+      tftpserver:/tftpfolder/Image-sg2000
+   $ scp cv181x_milkv_duos_sd.dtb \
+      tftpserver:/tftpfolder/cv181x_milkv_duos_sd.dtb
+
+Check that Duo S is connected to our computer via a USB Serial Adapter at 115.2 kbps:
+
+.. code:: console
+
+   $ screen /dev/ttyUSB0 115200
+
+Insert the microSD Card into Duo S, connect the Ethernet Port and power up via the USB-C Port.
+
+When Duo S boots, press Enter to see the U-Boot Prompt.
+Run these commands to `boot NuttX over TFTP <https://lupyuen.github.io/articles/sg2000#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-sg2000
+   $ tftpboot ${fdt_addr_r} ${tftp_server}:cv181x_milkv_duos_sd.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/sg2000#boot-nuttx-over-tftp>`_.
+
+NuttX boots on Duo S 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 Milk-V Duo S supports these peripherals:
+
+======================== ======= =====
+Peripheral               Support NOTES
+======================== ======= =====
+UART                     Yes
+======================== ======= =====

Documentation/platforms/risc-v/sg2000/index.rst

@@ -0,0 +1,36 @@
+=============
+SOPHGO SG2000
+=============
+
+`SOPHGO SG2000 <https://milkv.io/chips/sg2000>`_ is a 64-bit RISC-V SoC with 2 RISC-V Cores and 1 Arm Core:
+
+- **Main Processor:** T-Head C906 1.0 GHz 64-bit RISC-V Core
+    - 32 KB I-Cache, 64KB D-Cache
+    - Integrated Vector and Floating-Point Operation Unit (FPU)
+
+- **Co-Processor:** T-Head C906 700 MHz 64-bit RISC-V Core
+    - Integrated Floating-Point Unit (FPU)
+
+- **Alternate Main Processor:** Cortex-A53 1.0 GHz 64-bit Arm Core
+    - 32 KB I-Cache, 32 KB D-Cache
+    - 128 KB L2 Cache
+    - Support Neon and Floating-Point Operation Unit (FPU)
+
+- **MCU:** 8051 with 6 KB SRAM
+- **TPU:** 0.5 TOPS INT8
+- **Memory:** SIP DRAM 512 MB
+- **Video Module:** ISP 5M @ 30 FPS, 2L MIPI DSI 5M @ 30 FPS, 4L or 2L+2L MIPI CSI 5M @ 30 FPS, H.265 / H.264 Decoding and Encoding 5M @ 30 FPS
+- **Audio Module:** 16-bit Audio Codec, 2 x I2S / PCM, 1 x DMIC
+- **Storage:** SPI-NOR, SPI-NAND, eMMC 5.0, 2 x SDIO 3.0
+- **Network:** 10M / 100M MAC PHY
+- **Security Module:** Crypto, Secure Boot, TRNG, Efuse
+- **Peripherals:** 1 x USB 2.0 DRD, 5 x UART, 4 x SPI, 16 x PWM, 1 x IR, 6 x I2C, 6 x ADC, GPIOs
+
+Supported Boards
+================
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   boards/*/*

arch/risc-v/src/sg2000/sg2000_timerisr.c

@@ -38,7 +38,7 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define MTIMER_FREQ 1000000
+#define MTIMER_FREQ 25000000ul
 
 /****************************************************************************
  * Public Functions

boards/Kconfig

@@ -2007,6 +2007,13 @@ config ARCH_BOARD_BL808_OX64
 		This options selects support for NuttX on PINE64 Ox64 based
 		on Bouffalo Lab BL808 SoC.
 
+config ARCH_BOARD_SG2000_MILKV_DUOS
+	bool "Milk-V Duo S"
+	depends on ARCH_CHIP_SG2000
+	---help---
+		This options selects support for NuttX on Milk-V Duo S based
+		on SOPHGO SG2000 SoC.
+
 config ARCH_BOARD_S32K118EVB
 	bool "NXP S32K118EVB"
 	depends on ARCH_CHIP_S32K118
@@ -3368,6 +3375,7 @@ config ARCH_BOARD
 	default "star64"                    if ARCH_BOARD_JH7110_STAR64
 	default "canmv230"                  if ARCH_BOARD_K230_CANMV
 	default "ox64"                      if ARCH_BOARD_BL808_OX64
+	default "milkv_duos"                if ARCH_BOARD_SG2000_MILKV_DUOS
 	default "sabre-6quad"               if ARCH_BOARD_SABRE_6QUAD
 	default "tc397"                     if ARCH_BOARD_TC397
 	default "qemu-armv7a"               if ARCH_BOARD_QEMU_ARMV7A
@@ -4302,6 +4310,9 @@ endif
 if ARCH_BOARD_BL808_OX64
 source "boards/risc-v/bl808/ox64/Kconfig"
 endif
+if ARCH_BOARD_SG2000_MILKV_DUOS
+source "boards/risc-v/sg2000/milkv_duos/Kconfig"
+endif
 if ARCH_BOARD_ESP32C3_DEVKIT
 source "boards/risc-v/esp32c3-legacy/esp32c3-devkit/Kconfig"
 endif

boards/risc-v/sg2000/milkv_duos/configs/nsh/defconfig

@@ -0,0 +1,93 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_DISABLE_OS_API is not set
+# CONFIG_NSH_DISABLE_LOSMART is not set
+CONFIG_16550_ADDRWIDTH=0
+CONFIG_16550_REGINCR=4
+CONFIG_16550_UART0=y
+CONFIG_16550_UART0_BASE=0x04140000
+CONFIG_16550_UART0_CLOCK=24883200
+CONFIG_16550_UART0_IRQ=69
+CONFIG_16550_UART0_SERIAL_CONSOLE=y
+CONFIG_16550_UART=y
+CONFIG_16550_WAIT_LCR=y
+CONFIG_ARCH="risc-v"
+CONFIG_ARCH_ADDRENV=y
+CONFIG_ARCH_BOARD="milkv_duos"
+CONFIG_ARCH_BOARD_SG2000_MILKV_DUOS=y
+CONFIG_ARCH_CHIP="sg2000"
+CONFIG_ARCH_CHIP_SG2000=y
+CONFIG_ARCH_DATA_NPAGES=128
+CONFIG_ARCH_DATA_VBASE=0xC0100000
+CONFIG_ARCH_HEAP_NPAGES=128
+CONFIG_ARCH_HEAP_VBASE=0xC0200000
+CONFIG_ARCH_INTERRUPTSTACK=2048
+CONFIG_ARCH_KERNEL_STACKSIZE=3072
+CONFIG_ARCH_PGPOOL_MAPPING=y
+CONFIG_ARCH_PGPOOL_PBASE=0x80600000
+CONFIG_ARCH_PGPOOL_SIZE=4194304
+CONFIG_ARCH_PGPOOL_VBASE=0x80600000
+CONFIG_ARCH_RISCV=y
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_ARCH_TEXT_NPAGES=128
+CONFIG_ARCH_TEXT_VBASE=0xC0000000
+CONFIG_ARCH_USE_MMU=y
+CONFIG_ARCH_USE_MPU=y
+CONFIG_ARCH_USE_S_MODE=y
+CONFIG_BOARDCTL_ROMDISK=y
+CONFIG_BOARD_LATE_INITIALIZE=y
+CONFIG_BOARD_LOOPSPERMSEC=1120
+CONFIG_BUILD_KERNEL=y
+CONFIG_DEBUG_ASSERTIONS=y
+CONFIG_DEBUG_ASSERTIONS_EXPRESSION=y
+CONFIG_DEBUG_FEATURES=y
+CONFIG_DEBUG_FULLOPT=y
+CONFIG_DEBUG_SYMBOLS=y
+CONFIG_DEV_ZERO=y
+CONFIG_ELF=y
+CONFIG_EXAMPLES_HELLO=m
+CONFIG_FS_PROCFS=y
+CONFIG_FS_ROMFS=y
+CONFIG_IDLETHREAD_STACKSIZE=3072
+CONFIG_INIT_FILEPATH="/system/bin/init"
+CONFIG_INIT_MOUNT=y
+CONFIG_INIT_MOUNT_FLAGS=0x1
+CONFIG_INIT_MOUNT_TARGET="/system/bin"
+CONFIG_INIT_STACKSIZE=3072
+CONFIG_INTELHEX_BINARY=y
+CONFIG_LIBC_ENVPATH=y
+CONFIG_LIBC_EXECFUNCS=y
+CONFIG_LIBC_PERROR_STDOUT=y
+CONFIG_LIBC_STRERROR=y
+CONFIG_MEMSET_64BIT=y
+CONFIG_MEMSET_OPTSPEED=y
+CONFIG_MM_PGALLOC=y
+CONFIG_NFILE_DESCRIPTORS_PER_BLOCK=6
+CONFIG_NSH_ARCHINIT=y
+CONFIG_NSH_FILEIOSIZE=512
+CONFIG_NSH_FILE_APPS=y
+CONFIG_NSH_READLINE=y
+CONFIG_PATH_INITIAL="/system/bin"
+CONFIG_RAM_SIZE=1048576
+CONFIG_RAM_START=0x80200000
+CONFIG_RAW_BINARY=y
+CONFIG_READLINE_CMD_HISTORY=y
+CONFIG_RR_INTERVAL=200
+CONFIG_SCHED_HAVE_PARENT=y
+CONFIG_SCHED_LPWORK=y
+CONFIG_SCHED_WAITPID=y
+CONFIG_SERIAL_UART_ARCH_MMIO=y
+CONFIG_STACK_COLORATION=y
+CONFIG_START_MONTH=12
+CONFIG_START_YEAR=2021
+CONFIG_SYMTAB_ORDEREDBYNAME=y
+CONFIG_SYSTEM_NSH=y
+CONFIG_SYSTEM_NSH_PROGNAME="init"
+CONFIG_TESTING_GETPRIME=y
+CONFIG_TESTING_OSTEST=y
+CONFIG_USEC_PER_TICK=1000