How to use GPIO Expander IO as SPI Interrupts?

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
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1

Hi ,

We want to use multi SPI devices(up to 8 or 6), so we need 8 gpio as cs signal and 8 gpios as interrupt signal. But the spi register failed with “could not get #gpio-cells for /interrupt-controller@3881000”?

kernel dmesg logs:

[    1.661962] OF: /spi@3210000: could not get #gpio-cells for /interrupt-controller@3881000
[    1.662181] spi-tegra114 3210000.spi: can not register to master err -22
[    1.662559] spi-tegra114: probe of 3210000.spi failed with error -22

Can you give some help about interrupts settings through GPIO Expander?

HW: SPI1(3210000), two GPIO Expander TCA6408
SW: DTS configuration


	i2c@31e0000 {
		tca6408_20: tca6408@20 {
			compatible = "ti,tca6408";
			gpio-controller;
			#gpio-cells = <2>;
			reg = <0x20>;
			vcc-supply = <&p2822_vdd_1v8_cvb>;
			cs_outlow {
				/*
				 * GPIO-0 : CS1
				 * GPIO-1 : CS2
				 * GPIO-2 : CS3
				 * GPIO-3 : CS4
				 * GPIO-4 : CS5
				 * GPIO-5 : CS6
				 * GPIO-6 : CS7
				 * GPIO-7 : CS8
				 */
				gpio-hog;
				gpios = <0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0>;
				output-low;
				label = "cs1",
					"cs2",
					"cs3",
					"cs4",
					"cs5",
					"cs6",
					"cs7",
					"cs8";
			};
			cs_outhigh {
				status = "disabled";
			};
			cs_input {
				status = "disabled";
			};
		};
		
		tca6408_21: tca6408@21 {
			compatible = "ti,tca6408";
			reg = <0x21>;
			gpio-controller;
			#gpio-cells = <2>;
			interrupt-controller;
			#interrupt-cells = <2>;
			vcc-supply = <&p2822_vdd_1v8_cvb>;
			int_outlow {
				status = "disabled";
			};
			int_outhigh {
				status = "disabled";
			};
			? How to configure interrupts ?
		};
	};
		
	spi@3210000 {
		status = "okay";
		compatible = "nvidia,tegra186-spi";
		cs-gpios = <&tca6408_20 0 >,
		           <&tca6408_20 1 >,
		           <&tca6408_20 2 >,
		           <&tca6408_20 3 >,
		           <&tca6408_20 4 >,
		           <&tca6408_20 5 >,
		           <&tca6408_20 6 >,
		           <&tca6408_20 7 >;
				   
		spidev0: spidev@0 {
			compatible = "microchip,mcp28xd";
			status = "okay";
			reg = <0x0>;
			interrupt-parent = <&tca6408_21>;
			interrupts = <1 IRQ_TYPE_LEVEL_LOW>;
			spi-max-frequency = <20000000>;
			controller-data {
				nvidia,cs-setup-clk-count = <0xF>;
				nvidia,cs-hold-clk-count = <0xF>;
				nvidia,tx-clk-tap-delay = <0x7>;
				nvidia,rx-clk-tap-delay = <0x0>;
			};
		};
		spidev1: spidev@1 {
			compatible = "microchip,mcp28xd";
			status = "okay";
			reg = <0x1>;
			interrupt-parent = <&tca6408_21>;
			interrupts = <2 IRQ_TYPE_LEVEL_LOW>;
			spi-max-frequency = <20000000>;
			controller-data {
				nvidia,cs-setup-clk-count = <0xF>;
				nvidia,cs-hold-clk-count = <0xF>;
				nvidia,tx-clk-tap-delay = <0x7>;
				nvidia,rx-clk-tap-delay = <0x0>;
			};
		};
	};
4

Hi NV_Team,

Can anyone help me to check about this issue?

Thanks

5

Check the INT pin connect to Tegra which GPIO and add the interrupt-parent = <&tegra_main_gpio>; and interrupts = <> in the tca6408_2x scope.

6

Hi ShaneCCC,

I don’t need add interrupt to tca6408, and now the 8 io of tca6408 expand success.
I want to use the expand 8 IOs as interrupt for other devices, such as we use the expanded io as an interrupt for SPI devices, and how to configure the interrupt for SPI, just like

interrupt-parent = <&tegra_main_gpio>;
/*HDR PIN22, TEGRA spi3_miso_py1 */
interrupts = <TEGRA194_MAIN_GPIO(M, 1) IRQ_TYPE_LEVEL_LOW>;

Thanks .

7

I think the tca6408 have INT pin that connect to Tegra for interrupt then you can configure the GPIO of the expander to issue interrupt to the system.

8

Hi ShaneCCC,

Okay, we will try to test it. Thanks so much.