drivers: pinctrl: nrf: Add support for setting initial pin state

[awojasinski]

The nRF pinctrl driver did not allow for setting the initial state of the pins. This issue specifically affected the SPI SPIM driver, which caused an invalid SCK state when configured with CPOL (Clock Polarity).

With the introduction of the power-optimized SPIM driver, it disables the peripheral instance once the transfer is completed. As a result, the GPIO takes control over the SCK pin and drive it based on its own configuration. However, the pinctrl configures pins for SPIM incorrectly when CPOL is set. This causes that GPIO sets the SCK pin to 0 instead of the expected 1 when idle after SPI transaction is finished.

To address this issue, a patch was introduced.
Now, when an SPIM instance is configured with CPOL, the pinctrl node must have the 'output-high' property set to ensure the correct initial pin state.

Example devicetree fragment:

    spi1_default: spi1_default {
        group1 {
            psels = <NRF_PSEL(SPIM_SCK, 0, 5)>;
            output-high;
        };
        group2 {
            psels = <NRF_PSEL(SPIM_MISO, 0, 6)>,
                    <NRF_PSEL(SPIM_MOSI, 0, 7)>;
        };
    };

[awojasinski]

The described issue has been observed in the nrf_desktop app on a nrf52840gmouse_nrf52840 board while integrating new hal_nordic revision nrfconnect/sdk-nrf#11800

[anangl]

Now, when an SPIM instance is configured with CPOL, the pinctrl node must have the 'output-high' property set to ensure the correct initial pin state.

CPOL is configured at runtime per transfer, so the value set in devicetree may still be incorrect.
Why not just set the proper value for the SCK pin when the SPIM peripheral is configured for a particular transfer, somewhere around:

zephyr/drivers/spi/spi_nrfx_spim.c

Line 181 in d821655

config.mode = get_nrf_spim_mode(spi_cfg->operation);

[awojasinski]

Choose a different solution (#61294). This one can be closed