Configurate alternate function pins in zephyr device tree

[JoachimO]

Hello,

I have created my own board in zephyr (using STM32U575).

Now I would like to configure the power mode pins (CSLEEP, CDSTOP, SRDSTOP ) in the devicetree of the board.

I have therefore implemented the configuration for the pins in the .dts file:

&pinctrl {
    csleep: csleep {
        pinmux = <STM32_PINMUX('A', 5, AF0)>;
    };
    cdstop: cdstop {
        pinmux = <STM32_PINMUX('A', 6, AF0)>;
    };
    srdstop: srdstop {
        pinmux = <STM32_PINMUX('A', 7, AF0)>;
    };
};

However, the pins are not set correctly with this setting alone.

Normally, the pins should now be assigned to a periphery.

If I now assign these pins to any periphery, it works:

&lpuart1 {
    pinctrl-0 = <&lpuart1_tx_pa2 &lpuart1_rx_pa3 &csleep &cdstop &srdstop>;
    pinctrl-names = "default";
    current-speed = <115200>;
    status = "okay";
};

But these pins have nothing to do with any peripheral.

How else could I solve this if I don't want to make any settings in the application code?

Thank you for the answers.

[Pavel A.]

The declaration of pinctrl by itself does not do anything. Notice the  status = "okay" in the uart node, this is what causes activation of this node and pinctrl as its dependency. It looks like you need some fake device node with status = okay.

[JoachimO]

How can I do this?

Are any changes necessary in the soc driver?