Referencing Predefined Device Tree Node with No Label in another File

Question

Hello I have a device tree that looks like this. I need to reference the dma@40400000 node in another file where this device tree is included. In this device tree the dma@40400000 node does not have a label.

device-tree1.dtsi

/dts-v1/;
/ {
    amba_pl {
    #address-cells = <0x1>;
    #size-cells = <0x1>;
    compatible = "simple-bus";
    ranges;

    dma@40400000 {
        #dma-cells = <0x1>;
        clock-names = "s_axi_lite_aclk", "m_axi_sg_aclk", "m_axi_mm2s_aclk", "m_axi_s2mm_aclk";
        clocks = <0x1 0xf 0x1 0xf 0x1 0xf 0x1 0xf>;
        compatible = "xlnx,axi-dma-1.00.a";
        interrupt-parent = <0x4>;
        interrupts = <0x0 0x1d 0x4 0x0 0x1e 0x4>;
        reg = <0x40400000 0x10000>;
        xlnx,addrwidth = <0x20>;

        dma-channel@40400000 {
            compatible = "xlnx,axi-dma-mm2s-channel";
            dma-channels = <0x1>;
            interrupts = <0x0 0x1d 0x4>;
            xlnx,datawidth = <0x20>;
            xlnx,device-id = <0x0>;
        };

        dma-channel@40400030 {
            compatible = "xlnx,axi-dma-s2mm-channel";
            dma-channels = <0x1>;
            interrupts = <0x0 0x1e 0x4>;
            xlnx,datawidth = <0x20>;
            xlnx,device-id = <0x0>;
        };
    };
};
};

I would like to redefine it or optionally the amba_pl node such that the node dma@40400000 is not changed but has a label axi_dma

device-tree2.dtsi

/include/ "device-tree1.dtsi"
/ {
&amba_pl {  
        axi_dma: dma@40400000 {
            #dma-cells = <0x1>;
            clock-names = "s_axi_lite_aclk", "m_axi_sg_aclk", "m_axi_mm2s_aclk", "m_axi_s2mm_aclk";
            clocks = <0x1 0xf 0x1 0xf 0x1 0xf 0x1 0xf>;
            compatible = "xlnx,axi-dma-1.00.a";
            interrupt-parent = <0x4>;
            interrupts = <0x0 0x1d 0x4 0x0 0x1e 0x4>;
            reg = <0x40400000 0x10000>;
            xlnx,addrwidth = <0x20>;

            dma-channel@40400000 {
                compatible = "xlnx,axi-dma-mm2s-channel";
                dma-channels = <0x1>;
                interrupts = <0x0 0x1d 0x4>;
                xlnx,datawidth = <0x20>;
                xlnx,device-id = <0x0>;
            };

            dma-channel@40400030 {
                compatible = "xlnx,axi-dma-s2mm-channel";
                dma-channels = <0x1>;
                interrupts = <0x0 0x1e 0x4>;
                xlnx,datawidth = <0x20>;
                xlnx,device-id = <0x0>;
            };
        };
    };
};

However when I try to redefine amba_pl from device-tree1.dtsi in device-tree2.dtsi, the compiler fails to parse the device tree. How can I add a label to the node dma@40400000 from device-tree1.dtsi?

UPDATE

Having looked through the spec, I want to reword my question. How can I add a phandle to a node that is included from a different dtsi file or reference the node without a phandle?

FYI per the Devicetree specification: "The name of include files should end with “.dtsi”.", and not .dts as you have. See devicetree.org/specifications — sawdust
– sawdust, Commented Feb 1, 2018 at 1:29

Ezequiel Garcia · Accepted Answer · 2018-02-04 23:47:28Z

2

What you are trying to do is perfectly possible (I just tested it, just in case). If you are having a compiler error, my guess is that there is a syntax error.

Two notes before continuing: 1) perhaps you should consider update your question showing the full dtc compiler error. 2) keep in mind @sawdust comment about both files being .dtsi suffixed.

Now, about your error. I'm only guessing but it seems your are mixing phandles are "full path" references.

Your pasted dtsi, which is wrong

/include/ "device-tree1.dtsi"
/ {
    &amba_pl { /* wrong, amba_pl is not a phandle, can't use & */
        axi_dma: dma@40400000 {
        /* properties here */

        dma-channel@40400000 {
          /* blah */
        };
      };
    };
};

Correct

/include/ "device-tree1.dtsi"
/ {
    amba_pl {
        axi_dma: dma@40400000 {

            /* properties here */

            dma-channel@40400000 {
                /* blah */
            };
        };
    };
};

answered Feb 4, 2018 at 23:47

Ezequiel Garcia

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1 Comment

Tomas Novotny Over a year ago

I'm also referencing nodes without labels in included dtsi files (just simple redefinitions). I'm using that syntax to access the node: &{/backlight} { /* foo */ };

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