PROCESSOR-SDK-AM62A: Using IO Expander's GPIO as wakeup source.

Hi Sathiya,

From the device tree bindings, the IO expander doesn't seem to have wakeup support: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/Documentation/devicetree/bindings/gpio/gpio-pca95xx.yaml?h=ti-linux-6.6.y

From the IO expander data sheet (https://www.ti.com/lit/ds/symlink/tca6424a.pdf), Section 8.5.3 you can see how the interrupt logic works.

You can set the GPIO used by the SoC for the IO expander and track that interrupt to wakeup or directly from the I2C bus.

Best Regards,

Anshu

Hi anshu,

Anshu Madwesh said:

From the device tree bindings, the IO expander doesn't seem to have wakeup support: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/Documentation/devicetree/bindings/gpio/gpio-pca95xx.yaml?h=ti-linux-6.6.y

From the device tree bindings, the IO expander seem to have wakeup support. Ref Line 103 of the gpio-pca95xx.yaml file

Anshu Madwesh said:

You can set the GPIO used by the SoC for the IO expander and track that interrupt to wakeup or directly from the I2C bus.

You are saying that I can use interuppt similar to main_uart0, and instead of setting SDA or SCL pin, I should be setting Interrupt pin of IO expander?

Hi Anshu,

Anshu Madwesh said:

You can set the GPIO used by the SoC for the IO expander and track that interrupt to wakeup or directly from the I2C bus.

&main_i2c1 {
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&main_i2c1_pins_default>;
	clock-frequency = <400000>;

	interrupts-extended = <&gic500 GIC_SPI 161 IRQ_TYPE_LEVEL_HIGH>,
			<&main_pmx0 0x1d4>;
	interrupt-names = "wakeup";

	exp1: gpio@22 {
		compatible = "ti,tca6424";
		reg = <0x22>;
		gpio-controller;
		#gpio-cells = <2>;

		interrupt-parent = <&main_gpio1>;
		interrupts = <23 IRQ_TYPE_EDGE_FALLING>;
		interrupt-controller;
		#interrupt-cells = <2>;

		pinctrl-names = "default";
		pinctrl-0 = <&main_gpio1_ioexp_intr_pins_default>;
	};
};

I have given interrupt to I2C as Above. But I am getting following error.
Basically these are my keyboard keys from main_gpio0 and main_gpio1

[   10.988432] irq: type mismatch, failed to map hwirq-39 for gpio@600000!
[   10.988503] irq: type mismatch, failed to map hwirq-41 for gpio@600000!
[   10.988527] irq: type mismatch, failed to map hwirq-33 for gpio@600000!
[   10.988552] irq: type mismatch, failed to map hwirq-10 for gpio@601000!
[   10.988573] irq: type mismatch, failed to map hwirq-42 for gpio@600000!
[   10.988594] irq: type mismatch, failed to map hwirq-36 for gpio@600000!
[   10.988615] irq: type mismatch, failed to map hwirq-38 for gpio@600000!

Hi anshu,
If i use like this, then  I am getting the following error.

    keys {
		compatible = "gpio-keys";
		autorepeat;
		
		switch-power {
			label = "Key-Power";
			linux,code = <KEY_P>;
			gpios = <&exp1 6 GPIO_ACTIVE_LOW>;
			
			interrupts-extended = <&main_gpio1 24 IRQ_TYPE_EDGE_RISING>,
				<&main_pmx0 0x1d4>;
			interrupt-names = "irq", "wakeup";
		};
	};
	
	exp1: gpio@22 {
		compatible = "ti,tca6424";
		reg = <0x22>;
		gpio-controller;
		#gpio-cells = <2>;

		interrupt-parent = <&main_gpio1>;
		interrupts = <23 IRQ_TYPE_EDGE_FALLING>;
		interrupt-controller;
		#interrupt-cells = <2>;

		pinctrl-names = "default";
		pinctrl-0 = <&main_gpio1_ioexp_intr_pins_default>;

	};

the error:

[    0.455854] irq: type mismatch, failed to map hwirq-23 for gpio@601000!
[    0.455890] irq: type mismatch, failed to map hwirq-23 for gpio@601000!

Hi Sathiya,

Can you explain why you want to use an IO expander as a wakeup source?

Sathiya Narayanan said:

Ref Line 103 of the gpio-pca95xx.yaml file

Thank you, I over looked this.

Sathiya Narayanan said:

I should be setting Interrupt pin of IO expander?

If setting the IO Expander node with wakeup doesn't work, then you can try on the GPIO itself that connected to the SoC.

I don't have a way to test this at the moment so I can't replicate it on my end.

Thanks,

Anshu

Hi Anshu,

Anshu Madwesh said:

Can you explain why you want to use an IO expander as a wakeup source?

Because the design was made. And I can't change at this point.

Hi Sathiya,

As a simple test, you can just enable a normal GPIO as a wakeup source just to make sure its work. Then you can add the IO expander components to see where things might change.

Thanks,

Anshu

Hi Anshu,

Normal GPIO is working fine as the wakeup source.

Hi Sathiya,

Good to know that the GPIO itself works fine. Maybe try to enable the interrupt on the IO expander node rather than I2C bus.

Thanks,

Anshu