Microchip Polarfile (MPFS)
RV64 64-bit RISC-V multiprocessor-based Microcontroller Subsystem (MPFS025T, MPFS095T, MPFS160T, MPFS250T, MPFS460T)
MPFS Toolchain
A generic RISC-V toolchain can be used to build MPFS projects. Like: https://xpack.github.io/riscv-none-embed-gcc or https://github.com/sifive/freedom-tools/releases
Booting
The NuttX works as a standalone operating system that may initialize all the required clocks and peripherals including DDR memory. Alternatively, the vendor’s HSS bootloader may be used instead to perform all the initialization steps.
Building and flashing
Configure the NuttX project: ./tools/configure.sh icicle:nsh
Run make
to build the project.
If NuttX is built as a standalone OS with the config option CONFIG_MPFS_BOOTLOADER set, it’s important to note that the image size is very limited: only (128K - 256) bytes. 256 bytes are reserved for the header that must be prepended into the NuttX binary. This binary is called hss-envm-wrapper-bm1-dummySbic.bin and may be found from the vendor’s HSS implementation. Moreover, after prepending the 256-byte header, the LMA section needs to be adjusted, for example:
riscv64-unknown-elf-objcopy -I binary -O ihex --change-section-lma *+0x20220000 nuttx.bin nuttx.hex
The output binary nuttx.hex may be flashed with the LiberoSoc tool. The tool is available from: https://www.microchip.com/en-us/products/fpgas-and-plds/fpga-and-soc-design-tools/fpga/libero-software-later-versions#Documents%20and%20Downloads
There’s an alternative way to use NuttX, without the CONFIG_MPFS_BOOTLOADER option set. This expects the
HSS bootloader sets up the system (memories, caches, initializes clocks etc.).
First make sure that hss-payload-generator
is installed.
Available from: https://github.com/polarfire-soc/hart-software-services
This tool is used to convert the ELF/bin to a compatible HSS payload image
Create HSS payload bin:
hss-payload-generator -v -c hss-nuttx.yml payload.bin
Debugging with OpenOCD
Compatible OpenOCD and configs can be downloaded from: https://www.microsemi.com/product-directory/design-tools/4879-softconsole#downloads
OpenOCD can then be used:
openocd -c "set DEVICE MPFS" --file board/microsemi-riscv.cfg
Peripheral Support
The following list indicates the state of peripherals’ support in NuttX:
Peripheral |
Support |
NOTES |
---|---|---|
GPIO |
Yes |
|
MMUART |
Yes |
Uart mode only |
SPI |
Yes |
|
I2C |
Yes |
|
eMMC SD/SDIO |
Yes |
No PHY training |
Timers |
No |
|
Watchdog |
No |
|
RTC |
No |
|
CAN |
No |
|
eNVM |
No |
|
USB |
No |