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

[lupyuen]

Summary

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

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/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 duos:nsh

Updated Documentation

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

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

Impact

This PR is needed to support NuttX on Milk-V Duo S SBC.

No impact on existing code, since the Milk-V Duo S source files are not used by existing code.

Testing

We tested the NuttX Build on Milk-V Duo S SBC via U-Boot Network Boot (TFTP):

tools/configure.sh duos:nsh
make
## Omitted: Build Initial RAM Disk, append to NuttX Kernel with padding, copy to TFTP Server
## https://github.com/lupyuen2/wip-nuttx/releases/tag/sg2000c-1

NuttX boots correctly to NSH Shell. ostest completes successfully:

NuttX Log on Milk-V Duo S

Starting kernel ...
ABC
NuttShell (NSH) NuttX-12.5.1
nsh> uname -a
NuttX 12.5.1 adc0fbe65c Jun 17 2024 11:18:41 risc-v duos
nsh> free
                 total       used       free    maxused    maxfree  nused  nfree
      Kmem:    2061304      11624    2049680      38208    2042848     34      5
      Page:   20971520     647168   20324352   20324352
nsh> ls /dev
/dev:
 console
 null
 ram0
 ttyS0
 zero
nsh> hello
Hello, World!!
nsh> getprime
Set thread priority to 10
Set thread policy to SCHED_RR
Start thread #0
thread #0 started, looking for primes < 10000, doing 10 run(s)
thread #0 finished, found 1230 primes, last one was 9973
Done
getprime took 18484 msec
nsh> ostest
stdio_test: write fd=1
stdio_test: Standard I/O Check: printf
...
user_main: Exiting
ostest_main: Exiting with status 0
nsh>

Watch the Demo Video

See the Build Outputs

See the Build Log