linux内核dts sgpio_out参数含义

Question

这是 dts 文件中的一个示例

    led-s0-green {
        label = "s0:green";
        gpios = <&sgpio_out 2 1 GPIO_ACTIVE_LOW>;
        default-state = "off";
    };

    led-s1-blue {
        label = "s1:blue";
        gpios = <&sgpio_out 3 0 GPIO_ACTIVE_LOW>;
        default-state = "off";
    };

    led-s1-green {
        label = "s1:green";
        gpios = <&sgpio_out 3 1 GPIO_ACTIVE_LOW>;
        default-state = "off";
    };

谁能告诉我

<&sgpio_out 2 0 GPIO_ACTIVE_LOW>

中的2和0是什么意思？我找不到任何信息。谢谢你。

我搜遍了网站，没有相关文件。

Answer 1

谁能告诉我

<&sgpio_out 2 0 GPIO_ACTIVE_LOW>

中的2和0是什么意思？

属性的数据格式应该记录在内核源代码中Documentation/devicetree/bindings/的绑定文档中。正如gpio/gpio.txt中所写：

The exact meaning of each specifier cell is controller specific, and must be documented 
in the device tree binding for the device.

---

在本例中，“设备”是由标签

sgpio_out

标识的 GPIO 控制器，该标签在包含的文件 lan966x.dtsi:

中定义

        sgpio: gpio@e2004190 {
            compatible = "microchip,sparx5-sgpio";
            ...
            sgpio_out: gpio@1 {
                compatible = "microchip,sparx5-sgpio-bank";
                reg = <1>;
                gpio-controller;
                #gpio-cells = <3>;
            };
            ...
        };

此设备的绑定文档（由其

compatible

属性标识）显然是 Documentation/devicetree/bindings/pinctrl/microchip,sparx5-sgpio.yaml，并且似乎包含您问题的答案：

Note that the SGIO pin is defined by *2* numbers, 
a port number between 0 and 31,
and a **bit index**, 0 to 3.