How can I trigger an FCCU misc IRQ in Linux?

[Jeff-CF-Huang]

Hi Sir,

We want to trigger FCCU misc IRQ to show "interrupt handler: misc. No action performed".

The detailed code can be found at the link below.
https://github.com/nxp-auto-linux/linux/blob/be2b4ba5591b690e6036c1585a960295d1972bf0/drivers/misc/f...

We have just enabled the FCCU driver. Is there a straightforward way to test it using s32cc_regacces or T32?

Best regards,
Jeff Huang

[alejandro_e]

Hello @Jeff-CF-Huang,

Thanks for contacting NXP support and sorry for the late reply. I tried analyzing the code ant matching it with the information in the reference manual and BSP user manual. However I was not able to find the required process to trigger the misc IRQ. 

I raised this topic with the internal team for better support, I will come back with their feedback.

Thanks for understanding

[alejandro_e]

Hello @Jeff-CF-Huang.

Sorry for the late reply, the internal team has been overloaded these past weeks. They shared the following:

"

This interrupt is related to the FCCU timeout configuration, not to any FCCU fault. If the customer intends to trigger this interrupt, it would require a specific timeout setup in the FCCU configuration. Therefore, there should be no need for the customer to monitor this interrupt.

Why is the customer interested in triggering/monitoring this IRQ?

" 

Pleas help me by answering my colleague's question.

Thanks!

[Jeff-CF-Huang]

Hi Alejandro,

We need to record any FCCU faults on the A53 Linux side for debugging on the real car.

From my understanding:
S32CC_FCCU_REACTION_NONE maps to the misc IRQ.
S32CC_FCCU_REACTION_ALARM maps to the alarm IRQ.

If using the alarm IRQ is possible, that works for me as well.

Best regards,
Jeff Huang

[alejandro_e]

Hello @Jeff-CF-Huang,

I understand, I have already requested that exact information. I will share your feedback with the internal team and let you know any relevant updated.

Thanks for your patience. 

[alejandro_e]

Hello @Jeff-CF-Huang,

Thanks a lot for your patience. I have received feedback from the internal team:

"

I understand that the customer intends to log all faults recorded by the FCCU, which are listed in the fault map (attached with the reference manual). This is not directly related to the mentioned misc IRQ, which only handles interrupts from the FCCU controller itself (like FCCU configure timeout) and not the fault records.

To log all FCCU faults, either monitor the NCF_S register periodically or read it when the FCCU enters the alarm/NMI interrupt.

To trigger the misc IRQ the customer can, for example, lower the CFG_TO register value, this can potentially trigger an FCCU configuration timeout, but this depends on how long the system remains in the configuration state. In practice, FCCU rarely times out. If the customer requires testing this, please note that the configuration will not take effect during that attempt, as stated in the documentation[page 4146, S32G3 Reference Manual, Rev. 4, 02/2024]:

Refer to the table below for timing details:

"

Please let me know if this information solved all your questions related to this topic.

[Jeff-CF-Huang]

How about the alarm IRQ? It can be triggered when an FCCU fault occurs.

[alejandro_e · Accepted solution]

Hello @Jeff-CF-Huang,

For the FCCU Alarm handler, please check the information in the BSP user manual, for instance, in BSP44:

Basically any NCF configured with S32CC_FCCU_REACTION_ALARM will trigger the irq_alarm_handler, in turn, this will execute the clear_fault_status which will log the fault information in the kernel's log.

Please let me know if you have more questions.