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Old 08-13-2019, 04:08 AM   #1
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Registered: Aug 2019
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Pin modes - device tree / module

I am trying to write a linux device driver for a SPI device, using Atmels SAMA5d35 MPU. Linux version is 4.19.30.

I have configured the pins in my device tree and set the status to "okay". After that the pins changed mode as expected. My question is then, how do I manipulate pinmodes during runtime? My SPI device is not always on, neither is my driver always loaded. When that is the case I want the configured SPI pins to change mode to normal GPIOs (for power-consumption).

Is it the drivers task to do that, or is it something one can define in the device tree, when the driver for example is not loaded?

I have tried to implement a pinctrl-0 for setting the pins to SPI mode, and then a pinctrl-1 for setting the same pins to normal GPIOs. My idea was to switch between these pin configuration in the device driver, but unfortunately the device tree complaints about using the same pins for both pinctrl-0 and pinctrl-1 (compiles fine, but system wont boot). Although this was just my logical thoughts. I am sure there is a more correct way to do the things I stated above.

        spi0: spi@f0004000 {
            status = "okay";

            ext_adc: ads1258@1 {
                compatible = "ti,ads1258";
                pinctrl-names = "default", "sleep";
                pinctrl-0 = <&pinctrl_spi0_default>;
                pinctrl-1 = <&pinctrl_spi0_sleep>;
                reg = <1>;                                  /* Hardware chipselect SPI0_NPCS1 */
                spi-max-frequency = <16000000>;             /* According to datasheet */
                start-gpios = <&pioD 5 GPIO_ACTIVE_HIGH>;
                drdy-gpios = <&pioD 22 GPIO_ACTIVE_LOW>;
                enaadc-gpios = <&pioA 26 GPIO_ACTIVE_HIGH>; 


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