rockchip平台ov9281驱动设备树

以下是Rockchip平台上OV9281摄像头的设备树示例：

&i2c1 {
    ov9281@30 {
        compatible = "ovti,ov9281";
        reg = <0x30>;
        clocks = <&cru SCLK_I2C1>;
        clock-names = "xclk";
        reset-gpios = <&gpio3 RK_PD0 GPIO_ACTIVE_LOW>;
        powerdown-gpios = <&gpio3 RK_PD1 GPIO_ACTIVE_HIGH>;
        pinctrl-names = "default";
        pinctrl-0 = <&ov9281_mclk &ov9281_pwdn &ov9281_rst>;
        mclk = <24000000>;
        mclk_source = <0>;
        mclk_inv;
        mclk_ext;
        mclk_initial_skip;
        mclk_cont;
        mclk_no_stop;
        mclk_sample_delay = <0>;
        mclk_sample_edge = <0>;
        mclk_sample_phase = <0>;
        mclk_calculate_rate;
        mclk_calculate_div;
        avdd-supply = <&vcc_3v3>;
        dvdd-supply = <&vcc_1v8>;
        iovdd-supply = <&vcc_io>;
        pwnn-supply = <&vcc_1v8>;
        reset-gpio = <&gpio3 RK_PD0 GPIO_ACTIVE_LOW>;
        status = "okay";
    };
};

&vcc_io {
    regulator-name = "vcc-io";
    regulator-min-microvolt = <1800000>;
    regulator-max-microvolt = <1800000>;
    regulator-always-on;
};

&vcc_1v8 {
    regulator-name = "vcc-1v8";
    regulator-min-microvolt = <1800000>;
    regulator-max-microvolt = <1800000>;
    regulator-always-on;
};

&vcc_3v3 {
    regulator-name = "vcc-3v3";
    regulator-min-microvolt = <3300000>;
    regulator-max-microvolt = <3300000>;
    regulator-always-on;
};

&gpio3 {
    ov9281_mclk: ov9281-mclk {
        rockchip,pins = <3 RK_PD3 RK_FUNC_GPIO &pcfg_pull_none>;
        rockchip,pinmux = <3 RK_PD3 RK_FUNC_GPIO &pcfg_pull_none>;
        rockchip,direction = <0>;
        rockchip,output = <0>;
    };

    ov9281_pwdn: ov9281-pwdn {
        rockchip,pins = <0 RK_PD0 RK_FUNC_GPIO &pcfg_pull_none>;
        rockchip,pinmux = <0 RK_PD0 RK_FUNC_GPIO &pcfg_pull_none>;
        rockchip,direction = <0>;
        rockchip,output = <1>;
    };

    ov9281_rst: ov9281-rst {
        rockchip,pins = <1 RK_PD1 RK_FUNC_GPIO &pcfg_pull_none>;
        rockchip,pinmux = <1 RK_PD1 RK_FUNC_GPIO &pcfg_pull_none>;
        rockchip,direction = <0>;
        rockchip,output = <1>;
    };
};

需要注意以下几点：
- `compatible` 属性必须为 "ovti,ov9281"。
- `reg` 属性为 OV9281 I2C 地址。
- `mclk` 属性为 OV9281 的时钟频率。
- `reset-gpios` 和 `powerdown-gpios` 属性为 OV9281 的复位和电源管理引脚。
- `pinctrl-names` 和 `pinctrl-0` 属性为 OV9281 的引脚配置信息。
- `avdd-supply`、`dvdd-supply`、`iovdd-supply` 和 `pwnn-supply` 属性为 OV9281 的电源供应信息。
- `status` 属性为 "okay" 表示设备节点已启用。