Multiple drivers on one UART on runtime

[Romain_KM]

On nRF5340, we are using Thread communication, Wifi and LTE-M module.

User can change the interface board, between Wifi or LTE-M module on the same UART bus.

&uart0 {

    compatible = "nordic,nrf-uarte";

    status = "okay";

    current-speed = <115200>;

    tx-pin = <19>;

    rx-pin = <15>;

    rts-pin = <21>;

    cts-pin = <16>;

   

quectel {

        compatible = "quectel,bg9x";

        label = "BG95";

        mdm-wdisable-gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;

        mdm-power-gpios = <&gpio0 3 GPIO_ACTIVE_HIGH>;

        mdm-reset-gpios = <&gpio0 10 GPIO_ACTIVE_HIGH>;

        status = "okay";

    };

nina_w132 {

        compatible = "ublox,nina-w132";

        label = "WLAN_0";

        power-gpios = <&gpio0 9 GPIO_ACTIVE_LOW>;

        reset-gpios = <&gpio0 7 (GPIO_ACTIVE_HIGH | GPIO_PULL_UP)>;

        status = "disabled";

    };

};

My question: is it possible to load the correct driver on boot? Or is it mandatory to use two specific UART bus for Wifi and another for LTE-M?

Thank you for your help

[Kenneth]

Hello,

This is not straight forward, and honestly not sure.

I assume you are talking about deciding at runtime during boot which chip is there via some out of band means or something like that, I am not sure how to represent that in terms of what we can do in devicetree and the driver model today. There are some ongoing discussions upstream zephyr project about how one could be turning devices on and off. I want to point your to the following discussions in the zephyr community (likely there are other discussions also):

The power management APIs might be sufficient if device init / de-init are not needed (see for instance last comment in this thread): https://github.com/zephyrproject-rtos/zephyr/issues/20012 . If that thread did not get you further, then there seems to be ongoing discussions at the architecture working group around how they can evolve the device model which are tracked under the umbrella issue https://github.com/zephyrproject-rtos/zephyr/issues/22941 .

I suggest that you try to check out the above links, and possible share your use case in the last link if the power management API or other suggestions are not sufficient for your use case.

Best regards,
Kenneth