linux - 用于与 DSA 交换机的无 PHY 连接的设备树

Question

我们在为 Marvell DSA 交换机和 Xilinx Zynq 处理器的配置创 build 备树时遇到了一个小问题。它们是这样连接的:

|——————————————|               |——————————————————————————————|
|     e000b000—|———— SGMII ————|—port6 (0x16)      port3 —— PHY3
| Zynq         |               |         mv88e6321            |
|     e000c000—|—x           x—|—port5             port4 —— PHY4
|——————————————|               |——————————————————————————————|
        |___________ MDIO _______________|

我们有一个 Linux 内核的设备树，如下所示:

ps7_ethernet_0: ps7-ethernet@e000b000 {
            #address-cells = <1>;
            #size-cells = <0>;
            clock-names = "ref_clk", "aper_clk";
            clocks = <&clkc 13>, <&clkc 30>;
            compatible = "xlnx,ps7-ethernet-1.00.a";
            interrupt-parent = <&ps7_scugic_0>;
            interrupts = <0 22 4>;
            local-mac-address = [00 0a 35 00 00 00];
            phy-handle = <&phy0>;
            phy-mode = "gmii";
            reg = <0xe000b000 0x1000>;
            xlnx,ptp-enet-clock = <0x69f6bcb>;
            xlnx,enet-reset = "";
            xlnx,eth-mode = <0x0>;
            xlnx,has-mdio = <0x1>;
            mdio_0: mdio {
                #address-cells = <1>;
                #size-cells = <0>;
                phy0: phy@16 {
                    compatiable = "marvell,dsa";
                    reg = <0x16>;
                } ;
            } ;

} ;

    dsa@0 {
            compatible = "marvell,dsa";

            #address-cells = <2>;
            #size-cells = <0>;

            interrupts = <10>;

            dsa,ethernet = <&ps7_ethernet_0>;
            dsa,mii-bus = <&mdio_0>;

            switch@0 {
                #address-cells = <1>;
                #size-cells = <0>;
                reg = <0 0>;
             port@3 {
                    reg = <3>;
                    label = "lan0";                
             };
             port@4 {
                    reg = <4>;
                    label = "lan1";
             };
             port@5 {
                    reg = <5>;
                    label = "lan2";
             };
             port@6 {
                    reg = <6>;
                    label = "cpu";       
             };
        };
        };     
} ;

问题是，正如您从图片中看到的那样，没有 PHY 连接到端口 6，即 Zynq 和交换机之间的连接是无 PHY 的，但我必须指定 <phy0>在设备树中使 dsa 驱动程序看到开关。但随后它尝试与不存在的 PHY 通信，但显然失败了。

所以问题是:如何为连接到处理器的 dsa 交换机创建合适的设备树？

感谢您的帮助!

(有一个有点类似的问题 P1010 MAC to Switch port direct connection without PHY 但我无法评论它，不幸的是没有答案)

Answer 1

当没有 &phy0 时，您可以将其写为固定链接，而不是指定 &phy0

固定链接 = <0 1 1000 0 0>;

其中 0 是仿真 PHY ID，1-> 全双工，速度为 1000 Mb/s。您还希望禁用交换机端口 6 所连接的处理器端口的自动协商。

ps7_ethernet_0: ps7-ethernet@e000b000 {
        #address-cells = <1>;
        #size-cells = <0>;
        clock-names = "ref_clk", "aper_clk";
        clocks = <&clkc 13>, <&clkc 30>;
        compatible = "xlnx,ps7-ethernet-1.00.a";
        interrupt-parent = <&ps7_scugic_0>;
        interrupts = <0 22 4>;
        local-mac-address = [00 0a 35 00 00 00];
        fixed-link = <0 1 1000 0 0>;
        phy-mode = "gmii";
        reg = <0xe000b000 0x1000>;
        xlnx,ptp-enet-clock = <0x69f6bcb>;
        xlnx,enet-reset = "";
        xlnx,eth-mode = <0x0>;
        xlnx,has-mdio = <0x1>;
        mdio_0: mdio {
            #address-cells = <1>;
            #size-cells = <0>;
        } ;

};

dsa@0 {
        compatible = "marvell,dsa";

        #address-cells = <2>;
        #size-cells = <0>;

        interrupts = <10>;

        dsa,ethernet = <&ps7_ethernet_0>;
        dsa,mii-bus = <&mdio_0>;

        switch@0 {
            #address-cells = <1>;
            #size-cells = <0>;
            reg = <22 0>;
         port@3 {
                reg = <3>;
                label = "lan0";                
         };
         port@4 {
                reg = <4>;
                label = "lan1";
         };
         port@5 {
                reg = <5>;
                label = "lan2";
         };
         port@6 {
                reg = <6>;
                label = "cpu";       
         };
    };
    };     

};

我假设交换芯片 SMI 地址是 0x16；如果不是，请将 reg = <22,0> 设置为 <0,0>，就像之前在 switch@0 下一样。此外，您可能需要添加 mdio 驱动程序注册地址和兼容属性，这些在您的设备树中未指定。