SPIM/UARTE register conflict with hal_nordic

We are using the Nordic fork of Zephyr on nRF5340.

Looking at the serial interface peripherals (SPI/I2C/UART), we understand that these have shared resources and only one peripheral with a given ID can be active.

However there is a conflict with the register definitions and the reset/default values.

The register at offset 0x56C is used by two peripherals:
* by SPIM as PSELDCX with a reset value of 0xFFFFFFFF
* by UARTE as CONFIG with a reset value of 0x00000000

While investigating with a debugger, we see that the actual reset value is 0x00000000.

It seems that the driver in nrfx/drivers/src/nrfx_spim.c is not aware of this.

The function nrfx_spim_init will not modify the PSELDCX register if p_config->dcx_pin == NRFX_SPIM_PIN_NOT_USED.

Also, nrfx_spim_uninit will wrongly set pin 0 to default GPIO values, because it thinks that DCX is configured to pin 0.

Is this a bug in the hal_nordic code or are we doing something wrong?

As a workaround, we will try setting the register at offset 0x56C to 0xFFFFFFFF, before initializing the hal_nordic driver.

Related