Creating own device tree node doesn't work

[ErwinCes]

Hello,

I try to create and use my own device tree node.

For that I created a very basic yaml file:

compatible: "bat-measurement"

properties:
   channel1:
      type: int
      required: true

which I use in by dts file as:

/ {
    batmeasure {
        compatible = "bat-measurement";
        channel1 = <4>;
    };
};

Compiling this leads to no error. In devicetree-unfixed.h I found the node batmeasure. But I would expect to find there also something for channel1, which is not the case.

Even changing my dts file to a combination that should not work, doesn't lead to a compiler error (required parameter is not there).

/ {
    batmeasure {
        compatible = "bat-measurement";
        newValue = <5>;
    };
};

Where is my mistake?

Erwin

[Marte Myrvold]

Hi Erwin,

The bindings file must be located under dts/bindings. So if your binding is in your application folder you need to have it located like this:

myapp
 |___ src
 |___ CMakeLists.txt
 |___ prj.conf
 |___ dts
       |___ bindings
               |___ bat-measurement.yaml
 |___ ...

Make sure to also give your node and its properties descriptions, or you will get an error.

Best regards,

Marte

[ErwinCes]

I guess you are mostly Right. Only the proposed path cannot be used in our case. We have one application Folder with one prj.conf but different boards.

myRoot
|__ boards
|    |__ arm
|         |__ ourBoardA
|         |     |__ A_app.dts
|         |     |__ A_app.yaml
|         |     |__ A_app_defconfig
|         |__ ourBoardB
|               |__ B_app.dts
|               |__ B_app.yaml
|               |__ B_app_defconfig                
|__ PrjData
     |__ CMakeLists.txt
     |__ prj.conf
     |__ build_A
     |     |__ all the build stuff with board A
     |__ build_B
           |__ all the build stuff with board B
     

When I Build with west I give the Parameter -DBOARD_ROOT:STRING="myRoot"

I thought I can put my new yaml file into the same Directory where my board is. But that is wrong as even in docs.zephyrproject.org/.../bindings.html is stated (I overlooked the dts/bindings):

The build system looks for bindings in dts/bindings subdirectories of the following places:
    the zephyr repository
    your application source directory
    your board directory
    any directories in the DTS_ROOT CMake variable
    any module that defines a dts_root in its Build settings

So I guess I could use the Folder structur:

myRoot
|__ boards
|    |__ arm
|         |__ ourBoardA
|         |     |__ A_app.dts
|         |     |__ A_app.yaml
|         |     |__ A_app_defconfig
|         |__ ourBoardB
|               |__ B_app.dts
|               |__ B_app.yaml
|               |__ B_app_defconfig                
|__ PrjData
|    |__ CMakeLists.txt
|    |__ prj.conf
|    |__ build_A
|    |     |__ all the build stuff with board A
|    |__ build_B
|          |__ all the build stuff with board B
|
|__ dts
     |__ bindings
          |__ bat-measurement.yaml

I will try it.

Thanks

[ErwinCes]

My Explanation was wrong. Of Course the dts can be loaded below my PrjData. 

When trying the Folder structure described in my first answer, I got again no error, Nothing.

But moving below PrjData I get an error, that the description is missing. That Looks promising.

[ErwinCes]

I now get even an error when the required channel1 property is not given in my dts file. So yaml and dts seems to be parsed.

Unfortunately I don't see and channel 1 line in devicetree_unfixed.h. There are 33 occasions of batmeasure. All from the node. But shouldn't there be something for my channel1 Parameter? Later I will use some macros to get the value 4 in my Code. 

Or do I lack some understanding?

[ErwinCes]

I have to say sorry!

There are the lines

#define DT_N_S_batmeasure_P_channel1 5

#define DT_N_S_batmeasure_P_channel1_EXISTS 1

in devicetree_unfixed.h I should have looked more carefully

So everything works!!