STM32MP1 DTS file pin pull up

[scotty]

I've tried following the examples given here and here, but it will not work. I just want to enable a pull up resistor in the DTS file. Here is my DTS file. If anyone can please tell me why it's not working I would appreciate it.

/dts-v1/;
 
#include "stm32mp157.dtsi"
#include "stm32mp15xa.dtsi"
#include "stm32mp15-pinctrl.dtsi"
#include "stm32mp15xxac-pinctrl.dtsi"
#include "stm32mp15xx-dkx.dtsi"
 
&pinctrl {
	button_pins_a: button-0 {
		pins {
			pinmux = <STM32_PINMUX('B', 12, GPIO)>;
			bias-pull-up;
		};
	};
};
 
/ {
	model = "STMicroelectronics STM32MP157A-DK1 Discovery Board";
	compatible = "st,stm32mp157a-dk1", "st,stm32mp157";
 
	chosen {
		stdout-path = "serial0:115200n8";
	};
 
	button {
		compatible = "test,button";
		pinctrl-names="default";
		pinctrl-0 = <&button_pins_a>;
		status = "okay";
	};
	
	led {
		extern-led {
			compatible = "test,led";
			gpios = <&gpiob 10 GPIO_ACTIVE_HIGH>;
			linux,default-trigger = "cpu";
		};
	};
};

[OlivierK]

Hi scotty (Community Member)

GPIOs mappings are defined in the consumer device's node, in a property named

<function>-gpios, where <function> is the function the driver will request

through gpiod_get()

Also if the compatible field of DT doesn't match, nothing will happen.

So in your DT, you should add a prefix before "gpios", that is present in your driver.

ie: gpiod_get(&pdev->dev, "led", GPIOD_OUT);

led-gpios = <&gpiob 10 GPIO_ACTIVE_HIGH | GPIO_PULL_UP>;

Unless PB10 is already used by another instance.

Regards,

Olivier

[scotty]

@OlivierK​ 

While this works for the LED, and indeed the pullup can be activated this way, I was asking how to make the button on the pinctrl work with a bias-pull-up. Please let me know how to configure it this was. Thank you.

[OlivierK]

Hi scotty (Community Member)

bias-pull-up or down should work the same for the button.

&pinctrl {

    goodix_pins_a: goodix-0 {

        pins {

            pinmux = <STM32_PINMUX('F', 5, GPIO)>;

            bias-pull-down;

        };

}

root@stm32mp1:~# cat /sys/kernel/debug/pinctrl/soc:pinctrl@50002000/pinconf-pins | grep PF5                                 

pin 85 (PF5): input - high - pull down 

For button key, you can use also the gpio-keys driver.

    joystick {

        compatible = "gpio-keys";

        pinctrl-0 = <&joystick_pins>;

        pinctrl-names = "default";

        button-0 {

            label = "JoySel";

            linux,code = <KEY_ENTER>;

            interrupt-parent = <&stmfx_pinctrl>;

            interrupts = <0 IRQ_TYPE_EDGE_RISING>;

        };

Rgds,

Olivier

[scotty]

I understand now. I thought this device tree configuration would be immediately used on boot, but I must first load the LKM for the driver to instantiate these pins. Sorry for the confusion.

[OlivierK]

Hi scotty (Community Member)

Happy to read that this is clearer now.

Best Regards,

Olivier

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