DESK-MP1-L/Development/Asymmetric Multiprocessing (AMP) with OpenAMP

History
Issue Date	Notes
03/08/2023	DESK-MP1-L-1.0.0 release

Introduction

As known, the STM32MP115x SoC is powered by a heterogeneous architecture comprising a single/dual ARM Cortex-A7 (CA7) and an ARM Cortex-M4 (CM4). When the application requires implementing an Asymmetric Multiprocessing configuration (AMP), the most common scenario is to use Linux on the CA7, and bare metal or RTOS-based firmware on the CM4. In either case, the [OpenAMP framework] is typically used to establish a communication channel between the cores. DESK-MP1-L provides some examples based on this framework to demonstrate how to set up AMP configurations. The following section illustrates one of them, namely OpenAMP_TTY_echo.

For more details please see the STM32CubeMP1 firmware and the source code.

Running the OpenAMP_TTY_echo example

The example is automatically built by Yocto. To run it, please issue the following commands on the target's console:

root@desk-mp1:~# cp /usr/local/Cube-M4-examples/STM32MP157C-DK2/Applications/OpenAMP/OpenAMP_TTY_echo/lib/firmware/OpenAMP_TTY_echo.elf /lib/firmware/
root@desk-mp1:~# echo -n OpenAMP_TTY_echo.elf  > /sys/class/remoteproc/remoteproc0/firmware
root@desk-mp1:~# echo start >/sys/class/remoteproc/remoteproc0/state
root@desk-mp1:~# dmesg | tail -n 8
[   69.935241] remoteproc remoteproc0: powering up m4
[   69.940260] remoteproc remoteproc0: Booting fw image OpenAMP_TTY_echo.elf, size 219192
[   69.947843]  remoteproc0#vdev0buffer: assigned reserved memory node vdev0buffer@10042000
[   69.957458] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty addr 0x400
[   69.964031] virtio_rpmsg_bus virtio0: rpmsg host is online
[   69.968816]  remoteproc0#vdev0buffer: registered virtio0 (type 7)
[   69.976364] remoteproc remoteproc0: remote processor m4 is now up
[   69.981515] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty addr 0x401
root@desk-mp1:~# stty -onlcr -echo -F /dev/ttyRPMSG0
root@desk-mp1:~# cat /dev/ttyRPMSG0 &
root@desk-mp1:~# echo "Hello Virtual UART0" > /dev/ttyRPMSG0
Hello Virtual UART0
root@desk-mp1:~# cat /sys/class/remoteproc/remoteproc0/state
running

To stop the demo:

root@desk-mp1:~# echo stop > /sys/class/remoteproc/remoteproc0/state
[  104.989459] remoteproc remoteproc0: warning: remote FW shutdown without ack
[1]+  Done                       cat /dev/ttyRPMSG0
root@desk-mp1:~# cat /sys/class/remoteproc/remoteproc0/state
offline
root@desk-mp1:~#