How does the scu interact with m4 or Acore?

[189659318]

hello,

RT, in the imx8qm,  how does the scu interact with m4 or Acore?

In the m4 SDK, it can be seen that m4 communicates with the scu by the following APIs:

1.sc_misc_set_control ();

2.sc_misc_get_control ();

The api1: sc_misc_set_control ();After testing, the communication between m4 and scu can be realized.

Now, I want the scu would reply to m4 when it receives the message from m4. Similar logic has not been found in the SDK....so, I want to ask how does scu send messages to m4 ?  Can you provide the demo?

[igorpadykov]

Hi livan

scu interacion is described in sect.2.2 System Controller Linux Manual

included in Linux 4.19.35_1.1.0 Documentation

and in SCFW Porting Kit

Best regards
igor
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[189659318]

hi,igorpadykov

First of all, thank you for your quick reply!

According to the documentation, the scu interacts with m4 primarily through ipc. In the scfw_api,the communication function is found:

1.ipc_read();

2.ipc_write();

Through these functions, the communication link from m4 to scu can be realized. However, the communication from scu to m4 failed. Can you provide a more detailed example of communication from scu to m4?

BR,

liwan special.

[bulat_a]

Hope it will be useful to you @189659318 

"Now, I want the scu would reply to m4 when it receives the message from m4. Similar logic has not been found in the SDK." - Let's consider a FreeRTOS example for M4 cores:

IPC uses MU that is bi-directional connections, thus, the protocol that is used always works as a following:

M4/AP cores : ipc_write(some command)

SCU ipc_handler:

-----SCU ipc_read(cmd) - > perform command

-----SCU ipc_write(result)

M4/Ap core result =ipc_read()

Take a look at

SCU platform/svc/misc/rpc_clnt.c :  sc_misc_set_control it calls sc_call_rpc

in SDK nxp

NXP SDK devices/MIMX8QM6/scfw_api/main/ipc_imx8qm.c: sc_call_rpc -  

you will see sequential execution of commands:

sc_call_rpc()

....

   sc_ipc_write(ipc, msg);

   sc_ipc_read(ipc, msg);

Regards,

Bulat