@TOC

gpio 配置注释，不同的厂商会有细微的区别

gpio0: gpio@fd8a0000 {
compatible = "rockchip,gpio-bank"; # 兼容性信息 ----------------- 相当这一个节点存在于设备树中的key，其它的子项是value，代码中就是通过这个key找到其它子项的
reg = <0x0 0xfd8a0000 0x0 0x100>; # 寄存器地址和大小
第一个元素（0x0）表示该寄存器在系统中的偏移地址。
第二个元素（0xfd8a0000）表示该寄存器的物理地址，即该寄存器在CPU外围设备中的实际地址。
第三个元素（0x0）通常不使用，可以忽略。
第四个元素（0x100）表示该寄存器所占用的字节数。
interrupts = ; # 中断类型和编号
clocks = <&cru PCLK_GPIO0>, <&cru DBCLK_GPIO0>; # 时钟配置
gpio-controller; # GPIO控制器声明

gpio-cells = <2>; # GPIO单元格定义

interrupt-controller; # 中断控制器声明

interrupt-cells = <2>; # 中断单元格定义

};

有一组gpio需要处理，一部分需要输入上拉，一部分需要输出16ma

首先需要确保硬件上是支持的，然后可以做如下处理：（高通）

pinctrl部分的定义

    yk_w1_input_active{
        qcom,pins = <&gp 12>, <&gp 13>, <&gp 14>, <&gp 15>, <&gp 18>, <&gp 19>, <&gp 20>, <&gp 21>;
        qcom,num-grp-pins = <8>;
        label = "yk_w1_input_active";
        w1_input_active: w1_input_active {
            drive-strength = <2>;
            bias-pull-up;                     // 输入上拉
        };
    };
    yk_w1_output_active{
        qcom,pins = <&gp 0>, <&gp 1>, <&gp 2>, <&gp 3>, <&gp 8>, <&gp 9>, <&gp 10>, <&gp 11>;
        qcom,num-grp-pins = <8>;
        label = "yk_w1_output_active";
        w1_output_active: w1_output_active {                    
            drive-strength = <16>;                              // 输出16ma
            bias-disable;           /* No PULL */
            output-high;                         
        };
    };

dtsi中配置

test_gpio{
compatible = "test_gpio";
gpios = <&msm_gpio 0 0>,
<&msm_gpio 1 0>,
<&msm_gpio 2 0>,
<&msm_gpio 3 0>,
<&msm_gpio 8 0>,
<&msm_gpio 9 0>,
<&msm_gpio 10 0>,
<&msm_gpio 11 0>,
<&msm_gpio 12 0>,
<&msm_gpio 13 0>,
<&msm_gpio 14 0>,
<&msm_gpio 15 0>,
<&msm_gpio 18 0>,
<&msm_gpio 19 0>,
<&msm_gpio 20 0>,
<&msm_gpio 21 0>;
qcom,num-grp-pins = <16>;
qcom,pin-func = <0>;
pintctrl-names = "yk_w1_inout_active";
pinctrl-0 = <&w1_input_active &w1_output_active>; // 同时设置两种不同的状态
};

内核中的处理

static int w1_gpio_pinctrl_configure(struct pinctrl * p, struct device *dev, const char *name)
{
   
    struct pinctrl_state *set_state;
    int retval;


    set_state =
        pinctrl_lookup_state(p,    name);
    if (IS_ERR(set_state)) {
   
        dev_err(dev,
            "cannot get w1 pinctrl active state\n");
        return PTR_ERR(set_state);
    }

    retval = pinctrl_select_state(p, set_state);    
    if (retval) {
   
        dev_err(dev,
                "cannot set w1 pinctrl active state\n");
        return retval;
    }

    return 0;
}
static int test_gpio_probe(struct platform_device *pdev)
{
   
    int ret = 0;
    int i=0;
    struct device_node *of_node = pdev->dev.of_node;
    struct device *dev = &pdev->dev;

    pr_err("enter test_gpio_probe, begin \n");

    w1_gpio_pinctrl = devm_pinctrl_get(dev);
    if (IS_ERR(w1_gpio_pinctrl)) {
   
        if (PTR_ERR(w1_gpio_pinctrl) == -EPROBE_DEFER)
            return -EPROBE_DEFER;

        pr_debug("W1 Target does not use pinctrl\n");
        w1_gpio_pinctrl = NULL;
    }

    w1_gpio_pinctrl_configure(w1_gpio_pinctrl, dev, "yk_w1_inout_active");

    ...