TFM SecureFault Accessing RTC device on V2.5.0-rc1

RE: TFM SecureFault Accessing RTC device on V2.5.0-rc1

4DoorToyota — Wed, 25 Oct 2023 14:09:15 GMT

Hi,

Did some digging through the code and turns out I was trying to access the RTC device through:

RTCdevice = DEVICE_DT_GET(DT_NODELABEL(pcf8523));

Which in my hubris I assumed would work instead of splitting the DT_NODELABEL off into a define like the examples show.

Spliting this up into two different lines with a define completly fixed the problem.

Thank you very much for taking the time to help me!

RE: TFM SecureFault Accessing RTC device on V2.5.0-rc1

Sigurd Hellesvik — Mon, 23 Oct 2023 13:24:37 GMT

TF-M assigned different parts of hardware as secure and others as non-secure.

The error you face could be caused because the driver tries to access a secure part from non-secure code.
The I2C driver should be non-secure, but to check this, could you try some different I2C instances?

Maybe more likely is that it is using some pins designated as secure. Could you try to change the pins and see if you get the same issue?

RE: TFM SecureFault Accessing RTC device on V2.5.0-rc1

4DoorToyota — Mon, 23 Oct 2023 12:22:51 GMT

The driver is here in the main zephyr repository and is part of the versiion included with NRF V2.5.0-rc1.

https://github.com/zephyrproject-rtos/zephyr/blob/main/drivers/rtc/rtc_pcf8523.c

The device however does not implement all of the features present on the device so I have a couple of functions that get the I2C node and then commmunicate with the chip over the bus. Wasn't sure if it was a relevant thing to mention but wanted to give the full picture and it shows that the device is alive and functioning.

RE: TFM SecureFault Accessing RTC device on V2.5.0-rc1

Sigurd Hellesvik — Mon, 23 Oct 2023 11:45:55 GMT

Hi,

[quote user=""]Communicating with it over I2C works perfectly however when trying to communicate with it using the RTC driver present in zephyr for it[/quote]

Can you link to the RTC driver you refer to?

Are we talking about an external RTC device that you communicate with over I2C?

Regards,
Sigurd Hellesvik