CODEWITHSUNDEEP
embedded-linuxdevice-tree
Jack Frye
Jack Frye

Reputation: 583

Add Property to Linux Device Tree from other FIle

I have a tool that is automatically generating a device tree for an embedded system with custom peripherals. I need to reference a node in this auto-generated file and add properties to the node without actually changing the auto-generated file since it will be overwritten each time I build the kernel/device-tree/boatloaders, etc. I am not exactly sure how to do this. In the auto-generated file called pl.dtsi the device tree node looks like this 

vid_phy_controller_0: vid_phy_controller@80060000 {
        clock-names = "mgtrefclk0_pad_p_in", "mgtrefclk0_pad_n_in", "mgtrefclk1_pad_p_in", "mgtrefclk1_pad_n_in", "gtnorthrefclk1_in", "gtnorthrefclk1_odiv2_in", "vid_phy_tx_axi4s_aclk", "vid_phy_rx_axi4s_aclk", "vid_phy_sb_aclk", "vid_phy_axi4lite_aclk", "drpclk";
        clocks = <&misc_clk_2>, <&misc_clk_2>, <&misc_clk_2>, <&misc_clk_2>, <&misc_clk_2>, <&misc_clk_2>, <&misc_clk_0>, <&misc_clk_0>, <&clk 71>, <&clk 71>, <&clk 71>;
        compatible = "xlnx,vid-phy-controller-2.2", "xlnx,vid-phy-controller-2.1";
        interrupt-names = "irq";
        interrupt-parent = <&gic>;
        interrupts = <0 89 4>;
        reg = <0x0 0x80060000 0x0 0x10000>;
        xlnx,hdmi-fast-switch = <1>;
        xlnx,input-pixels-per-clock = <2>;
        xlnx,nidru = <1>;
        xlnx,nidru-refclk-sel = <3>;
        xlnx,rx-no-of-channels = <3>;
        xlnx,rx-pll-selection = <0>;
        xlnx,rx-protocol = <1>;
        xlnx,rx-refclk-sel = <1>;
        xlnx,transceiver-type = <5>;
        xlnx,transceiver-width = <2>;
        xlnx,tx-buffer-bypass = <1>;
        xlnx,tx-no-of-channels = <3>;
        xlnx,tx-pll-selection = <6>;
        xlnx,tx-protocol = <1>;
        xlnx,tx-refclk-sel = <0>;
        vphy_lane0: vphy_lane@0 {
            #phy-cells = <4>;
        };
        vphy_lane1: vphy_lane@1 {
            #phy-cells = <4>;
        };
        vphy_lane2: vphy_lane@2 {
            #phy-cells = <4>;
        };
        vphy_lane3: vphy_lane@3 {
            #phy-cells = <4>;
        };
    };

I need to add a "clock-name" and corresponding clock for which I already have the phandle, based on the fact that the clock is the same clock this is referenced under other clock-names listed. I just need to know how to touch this node from another device tree file.

Clearly I will need to include a reference to the pl.dtsi file

/include/ "pl.dtsi"

But after that how do I reference the vid_phy_controller_0 phandle and what is the syntax for adding strings/clock references to its properties

Upvotes: 0

Views: 2329

Answers (1)

user656347
user656347

Reputation:

You can define your own device tree file which includes the pl.dtsi file. In your device tree file, you can then add the required properties as below.

&vid_phy_controller_0 {
        clocks = <..>;
        clock-names = <..>;
};

Note that to compile your own device tree file, you will have to add it to the Makefile accordingly.

Upvotes: 2

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