Can't find expected node in the .dts nor any .dtsi file

General Discussion
1

Hi,

I recently started taking the udemy course “Linux Device Driver Programming Using Beaglebone Black” and while comparing the device tree shown in the lectures with the ones I have, I found some differences which I don’t understand.

1.) The am335x-bonegreen-wireless.dts I’m looking at starts out like this:

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Texas Instruments Incorporated - https://www.ti.com/
 */
/dts-v1/;

#include "am33xx.dtsi"
#include "am335x-bone-common.dtsi"
#include "am335x-bonegreen-common.dtsi"
#include <dt-bindings/interrupt-controller/irq.h>

So I opened all the .dtsi files mentioned here side by side and in am335x-bone-common.dtsi I find this snippet:

&i2c0 {
	pinctrl-names = "default";
	pinctrl-0 = <&i2c0_pins>;

	status = "okay";
	clock-frequency = <400000>;
	symlink = "bone/i2c/0";

	tps: tps@24 {
		reg = <0x24>;
	};

	baseboard_eeprom: baseboard_eeprom@50 {
		compatible = "atmel,24c256";
		reg = <0x50>;

		#address-cells = <1>;
		#size-cells = <1>;
		baseboard_data: baseboard_data@0 {
			reg = <0 0x100>;
		};
	};
};

So, as mentioned in the lecture I assumed I would find a node called i2c0, in the more general am33xx.dtsi file. However, i2c0 is only mentioned once in the aliases node:

/ {
	compatible = "ti,am33xx";
	interrupt-parent = <&intc>;
	#address-cells = <1>;
	#size-cells = <1>;
	chosen { };

	aliases {
		i2c0 = &i2c0;
		i2c1 = &i2c1;
		i2c2 = &i2c2;
		serial0 = &uart0;
...

Also, when looking up the aliases node in the device tree specification I found that “the property value [here &i2c0] specifies the full path to a node in the devicetree.” How can I find this node? I also tried looking for a node with compatible = ti,omap4-i2c but couldn’t fin any…

Regards

1 Like
2

Did you also check any includes in the files you opened. You will find there are several levels of files.

Best option when looking is to use grep if in linux or whatever file text search you prefer.

1 Like
3

Yes the includes of the am335x-bonegreen-wireless.dts do themselves not include any other .dtsi …

4

Are you just checking the top of the files, because the “#include” can come anywhere.

However from doing a quick search myself, the file you are looking for is probably am33xx-l4.dtsi which is included in am33xx.dtsi

5

:grimacing: I didn’t expect there to be "#include"s in the middle of the file…
yes the node I was looking for is in “am33xx-l4.dtsi”

1 Like