drivers: firmware: scmi: add optional crc

[AndreHeinemans-NXP]

An option is added to validate incomming and outgoing SCMI messages on shared memory.

This is needed especially for the imx95_evk/mimx9596/m7 which is used in combination with imx-sm on the M33 core. The imx-sm software uses CRC on SCMI by default. It will be easier to start with this target because it works with the sdcard image that comes with the evk.

[github-actions]

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[LaurentiuM1234]

Enabling CRC by default in Zephyr effectively breaks all upstream applications counting on the fact that it's disabled (e.g: SOF, CC: @yangbolu1991 this might affect you as well). Apart from that, you're enabling a feature which you arguably don't need for your application.

IMO this can be solved by updating the documentation (i.e: https://docs.zephyrproject.org/latest/boards/nxp/imx95_evk/doc/index.html) to tell people which configuration requires CRC and which doesn't. I can just as fine run "Hello, world" using ALT config without changing anything on Zephyr-side.

[yangbolu1991]

For i.mx95, crc was disabled in mx95alt.cfg, which used for m7 tests.
nxp-imx/imx-sm@4d53d16
We had also uploaded imx95 boot firmwares to nxp.com. We are supporting spsdk runner to support west build for bootable firmware. See,
#80507

But I'm not sure if there are any cases requiring CRC. If so, I think it should be documented.
Thanks.

[dbaluta]

For i.mx95, crc was disabled in mx95alt.cfg, which used for m7 tests. nxp-imx/imx-sm@4d53d16 We had also uploaded imx95 boot firmwares to nxp.com. We are supporting spsdk runner to support west build for bootable firmware. See, #80507

But I'm not sure if there are any cases requiring CRC. If so, I think it should be documented. Thanks.

@AndreHeinemans-NXP @PetervdPerk-NXP Would this work for you? Looks like CRC is disabled with newer configurations.

[AndreHeinemans-NXP]

@dbaluta, @LaurentiuM1234 ,
I changed the default to no CRC by disabling CONFIG_ARM_SCMI_SHMEM_VENDOR_NXP. And also added a note in the rst so users know about it and can enable it if needed.

[dbaluta]

In principle, I agree with this PR. It is clean enough to not touch the SCMI core and by default the check is disabled and only activated in specific scenarios.

Will need to get an Ack from @LaurentiuM1234 and we can merge it.

[bperseghetti]

Thanks this patch allows me to use Zephyr on the IMX95-EVK, I tried before but couldn't even get hello world to show up till this patch.

[JiafeiPan]

Actually NXP uses two of the SCMI SMT “implementation defined” words, it is res1[2] in the code, the first one holds the status that indicate if CRC is being used and which algorithm is used, and the second one is the CRC. so we need to check first word firstly and then decide use CRC or not, and also decide which CRC algorithm is used. so that the driver will be compatible for all SM firmware with CRC enabled or not.

[LaurentiuM1234]

as @JiafeiPan pointed out, res1[0] holds the CRC type (algorithm) used and if CRC is enabled. We can use this to dynamically check if CRC is enabled/disabled and which algorithm to use. This way, we can have the CRC NXP vendor extension enabled by default, thus allowing people to use whatever SM configuration they want.

[AndreHeinemans-NXP]

@JiafeiPan, @LaurentiuM1234,

Thanks for pointing this out. It's a perfect solution. I reworked all the comments.

[github-actions]

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