将TypeC的adb切换到USB3.0口

前言

目前大多数Android的嵌入式系统都会使用TypeC做为adb的调试口，这样很方便。但是在有的时候，迫不得已必须将adb功能切换到USB3.0口，但由于当前的内核USB框架只能支持一个USB口作为Peripheral
功能，所以RK3399 SDK默认配置Type-C0作为OTG mode 支持USB Peripheral功能，而Type-C1只支持Hostmode。

注意: 下面介绍的方法只在rk3399的Industry的7.1版本上实现成功并测试过，其他版本仅做参考，但也大同小异。

Kernel: v4.4.126
Device: rk3399
Platform Version: Android 7.1

硬件

首先，参考原理图如下：

Device Tree

RK提供的dts中默认的rk3399.dtsi，默认

 usbdrd3_0: usb@fe800000 {
  	...
    usbdrd_dwc3_0: dwc3@fe800000 {
        compatible = "snps,dwc3";
        dr_mode = "otg";
    };
...
};
usbdrd3_1: usb@fe900000 {
    ...
    usbdrd_dwc3_1: dwc3@fe900000 {
        compatible = "snps,dwc3";
        dr_mode = "host";
    };
...
};

我们需要在自己的dts中修改usbdrd_dwc3_1的dr_mode模式为otg，将usbdrd_dwc3_0的模式修改为host

&usbdrd_dwc3_0 {
	status = "okay";
	dr_mode = "host";
};

&usbdrd_dwc3_1 {
	status = "okay";
	dr_mode = "otg";
};

Drivers

1. kernel/include/linux/phy/phy.h

    diff --git a/kernel/include/linux/phy/phy.h b/kernel/include/linux/phy/phy.h
    index a3965c3..c0daa66 100644
    --- a/kernel/include/linux/phy/phy.h
    +++ b/kernel/include/linux/phy/phy.h
    @@ -36,6 +36,7 @@ enum phy_mode {
      * @power_on: powering on the phy
      * @power_off: powering off the phy
      * @set_mode: set the mode of the phy
    + * @set_vbusdet: usb disconnect of the phy
      * @reset: resetting the phy
      * @cp_test: prepare for the phy compliance test
      * @owner: the module owner containing the ops
    @@ -46,6 +47,7 @@ struct phy_ops {
    	    int     (*power_on)(struct phy *phy);
    		int     (*power_off)(struct phy *phy);
    		int     (*set_mode)(struct phy *phy, enum phy_mode mode);
    +    int (*set_vbusdet)(struct phy *phy, bool level);
    		int     (*reset)(struct phy *phy);
    		int     (*cp_test)(struct phy *phy);
    		struct module *owner;
    @@ -133,6 +135,7 @@ int phy_exit(struct phy *phy);
     int phy_power_on(struct phy *phy);
     int phy_power_off(struct phy *phy);
     int phy_set_mode(struct phy *phy, enum phy_mode mode);
    +int phy_set_vbusdet(struct phy *phy, bool level);
     int phy_reset(struct phy *phy);
     int phy_cp_test(struct phy *phy);
     static inline int phy_get_bus_width(struct phy *p