android usb解析（一）(and5.1)

先来理下整个usb的架构，用户从UsbManager调用接口，会binder通信到UsbService。而UsbService又有两个实例，一个



UsbHostManager，一个UsbDeviceManager。UsbDeviceManager和



UsbHostManager是一个相对的概念，



UsbHostManager是手机作为一个host，比如键盘、鼠标通过usb连接手机。而UsbDeviceManager是手机与电脑连接。

先看下UsbDevice的代码：就看构造函数和systemReady

    public UsbService(Context context) {
        mContext = context;

        final PackageManager pm = mContext.getPackageManager();
        if (pm.hasSystemFeature(PackageManager.FEATURE_USB_HOST)) {
            mHostManager = new UsbHostManager(context);//new UsbHostManager
        }
        if (new File("/sys/class/android_usb").exists()) {
            mDeviceManager = new UsbDeviceManager(context);//new UsbDeviceManager
        }

        setCurrentUser(UserHandle.USER_OWNER);

        final IntentFilter userFilter = new IntentFilter();
        userFilter.addAction(Intent.ACTION_USER_SWITCHED);
        userFilter.addAction(Intent.ACTION_USER_STOPPED);
        mContext.registerReceiver(mUserReceiver, userFilter, null, null);
    }

    public void systemReady() {
        if (mDeviceManager != null) {
            mDeviceManager.systemReady();
        }
        if (mHostManager != null) {
            mHostManager.systemReady();
        }
    }

今天主要介绍下UsbDeviceManager，先来看下构造函数：

    public UsbDeviceManager(Context context) {
        Log.d(TAG,"UsbDeviceManager start , persist.sys.usb.config =" + SystemProperties.get("persist.sys.usb.config", ""));
        mContext = context;
        mContentResolver = context.getContentResolver();
        mMassStorageEnable = SystemProperties.get("persist.mass_storage.enable", "true");//大容量属性
        PackageManager pm = mContext.getPackageManager();
        mHasUsbAccessory = pm.hasSystemFeature(PackageManager.FEATURE_USB_ACCESSORY);
        initRndisAddress();//初始化usb共享的地址，用手机序列码作为地址，序列码是存在系统属性中的

        readOemUsbOverrideConfig();//读取厂家设置

        mHandler = new UsbHandler(FgThread.get().getLooper());//构造UsbHandler，后面详细看

        if (nativeIsStartRequested()) {
            if (DEBUG) Slog.d(TAG, "accessory attached at boot");
            startAccessoryMode();
        }

        boolean secureAdbEnabled = SystemProperties.getBoolean("ro.adb.secure", false);
        boolean dataEncrypted = "1".equals(SystemProperties.get("vold.decrypt"));
        if (secureAdbEnabled && !dataEncrypted) {
            mDebuggingManager = new UsbDebuggingManager(context);
        }
    }

接下来看UsbHandler这个内部类：

先看usbHandler构造函数的前半部分：

        public UsbHandler(Looper looper) {
            super(looper);
            try {
                // persist.sys.usb.config should never be unset.  But if it is, set it to "adb"
                // so we have a chance of debugging what happened.
                Log.d(TAG,"UsbHandler , persist.sys.usb.config :" + SystemProperties.get("persist.sys.usb.config"));
                if(SystemProperties.get("persist.sys.usb.config", "") == null || SystemProperties.get("persist.sys.usb.config", "") == "none"){//永久性属性里面没有就设置
                   if("false".equals(mMassStorageEnable)){
                        SystemProperties.set("persist.sys.usb.config", "mtp,adb");
                   }else{
                        SystemProperties.set("persist.sys.usb.config", "mtp,mass_storage,adb");
                    }
                }
                if("false".equals(mMassStorageEnable)){//有的话就直接将获取的属性放在mDefaultFunctions
                    mDefaultFunctions = SystemProperties.get("persist.sys.usb.config", "mtp,adb");
                }else{
                    mDefaultFunctions = SystemProperties.get("persist.sys.usb.config", "mtp,mass_storage,adb");
                }
                Log.d(TAG,"mMassStorageEnable ="+ mMassStorageEnable +", mDefaultFunctions :" + mDefaultFunctions);
                // Check if USB mode needs to be overridden depending on OEM specific bootmode.
                mDefaultFunctions = processOemUsbOverride(mDefaultFunctions);//厂家定制的

                // sanity check the sys.usb.config system property
                // this may be necessary if we crashed while switching USB configurations
                String config = SystemProperties.get("sys.usb.config", "none");
                if (!config.equals(mDefaultFunctions)) {//如果mDefaultFunctions与"sys.usb.config“属性不一样，就重新设置属性
                    Slog.w(TAG, "resetting config to persistent property: " + mDefaultFunctions);
                    SystemProperties.set("sys.usb.config", mDefaultFunctions);
                }

上面理论上persist.sys.usb.config 与sys.usb.config属性一样的

因为在init.usb.rc中设置persist.sys.usb.config 属性，也会将sys.usb.config一同设置了。

# Used to set USB configuration at boot and to switch the configuration
# when changing the default configuration
on property:persist.sys.usb.config=*
    setprop sys.usb.config $persist.sys.usb.config

继续分析usbHandler的构造函数

                mCurrentFunctions = getDefaultFunctions();
                String state = FileUtils.readTextFile(new File(STATE_PATH), 0, null).trim();
                Log.d(TAG,"UsbHandler updateState  state:" + state);
                mAdbEnabled = containsFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_ADB);//属性中如果有adb，就置位true
                updateState(state);
                Log.d(TAG," UsbHandler charging_value:" + SystemProperties.get("sys.usb.charging", "")
                        + "  ro.debuggable:" + SystemProperties.get("ro.debuggable", ""));
                if(SystemProperties.get("sys.usb.charging", "").equals("yes") && SystemProperties.get("ro.debuggable","").equals("1")){
                    

下面再看看updateState函数，state从下面这个节点读取状态

private static final String STATE_PATH =
            "/sys/class/android_usb/android0/state"

updateState函数如下：

        public void updateState(String state) {
            Log.d(TAG, "updateState : state = " + state );
            int connected, configured;

            if ("DISCONNECTED".equals(state)) {
                connected = 0;
                configured = 0;
                SystemProperties.set("sys.lc.usb.state", "0");
            } else if ("CONNECTED".equals(state)) {
                connected = 1;
                configured = 0;
            } else if ("CONFIGURED".equals(state)) {
                connected = 1;
                configured = 1;
                SystemProperties.set("sys.lc.usb.state", "1");
            } else {
                Slog.e(TAG, "unknown state " + state);
                return;
            }
            removeMessages(MSG_UPDATE_STATE);
            Message msg = Message.obtain(this, MSG_UPDATE_STATE);
            msg.arg1 = connected;
            msg.arg2 = configured;
            // debounce disconnects to avoid problems bringing up USB tethering
            sendMessage(msg);//参数配置后发送消息

收到消息后处理

        public void handleMessage(Message msg) {
            Log.d(TAG," handleMessage msg:" + msg + " msg.arg1:" + msg.arg1 + "  msg.arg2  "+ msg.arg2);
            switch (msg.what) {
                case MSG_UPDATE_STATE:
                    mConnected = (msg.arg1 == 1);
                    mConfigured = (msg.arg2 == 1);
                    updateUsbNotification();
                    updateAdbNotification();
                    if (containsFunction(mCurrentFunctions,
                            UsbManager.USB_FUNCTION_ACCESSORY)) {
                        updateCurrentAccessory();
                    } else if (!mConnected) {//usb断开连接后，属性设置成默认的
                        // restore defaults when USB is disconnected
                        setEnabledFunctions(getDefaultFunctions(), false);
                    }
                    if (mBootCompleted) {
                        updateUsbState();//发送广播
                        updateAudioSourceFunction();
                    }
                    break;

继续分析

                String value = SystemProperties.get("persist.service.adb.enable", "");
                if (value.length() > 0) {
                    char enable = value.charAt(0);
                    if (enable == '1') {
                        setAdbEnabled(true);
                    } else if (enable == '0') {
                        setAdbEnabled(false);
                    }
                    SystemProperties.set("persist.service.adb.enable", "");
                }

分析setAdbEnabled函数

        private void setAdbEnabled(boolean enable) {
            if (DEBUG) Slog.d(TAG, "setAdbEnabled: " + enable + " mCurrentFunctions:" + mCurrentFunctions);
            if (enable != mAdbEnabled) {//当mAdbEnabled改变时
                mAdbEnabled = enable;
                // Due to the persist.sys.usb.config property trigger, changing adb state requires
                // persisting default function
                if(!mCurrentFunctions.equals(UsbManager.USB_FUNCTION_CHARGING)){
                    setEnabledFunctions(mDefaultFunctions, true);//先设置永久属性
                    // After persisting them use the lock-down aware function set
                    setEnabledFunctions(getDefaultFunctions(), false);//再设置usb.config属性
                    updateAdbNotification();
                }
            }
            if (mDebuggingManager != null) {
                mDebuggingManager.setAdbEnabled(mAdbEnabled);
            }
        }

再来看看setEnabledFunctions函数

        private void setEnabledFunctions(String functions, boolean makeDefault) {
            if (DEBUG) Slog.d(TAG, "setEnabledFunctions " + functions
                    + " makeDefault: " + makeDefault);
            // Do not update persystent.sys.usb.config if the device is booted up
            // with OEM specific mode.
            if (functions != null && makeDefault && !needsOemUsbOverride()) {//设置永久属性
                if (mAdbEnabled && !functions.equals(UsbManager.USB_FUNCTION_CHARGING)) {
                    functions = addFunction(functions, UsbManager.USB_FUNCTION_ADB);//根据mAdbEnabled设置系统属性
                } else {
                    functions = removeFunction(functions, UsbManager.USB_FUNCTION_ADB);
                }
                if (!mDefaultFunctions.equals(functions)) {//当functions改变时
                    if (!setUsbConfig("none")) {//设置none，直接断开usb，也就是差不多每次设置不一样属性。都要先断开usb。稍后详细看看setUsbConfig这个函数
                        Slog.e(TAG, "Failed to disable USB");
                        // revert to previous configuration if we fail
                        setUsbConfig(mCurrentFunctions);//
                        return;
                    }
                    // setting this property will also change the current USB state
                    // via a property trigger
                    SystemProperties.set("persist.sys.usb.config", functions);// 设置永久属性
                    if (waitForState(functions)) {//就是设置的属性，去读取属性是否和设置的一样
                        if(mCurrentFunctions.equals(UsbManager.USB_FUNCTION_CHARGING) && !mCurrentFunctions.equals(functions)){
                            if (DEBUG) Slog.d(TAG, " change charging functions to new functions: " + functions);
                                SystemProperties.set("sys.usb.charging", "no");
                        }
                        mCurrentFunctions = functions;
                        mDefaultFunctions = functions;
                    } else {//不成功，设置层默认的
                        Slog.e(TAG, "Failed to switch persistent USB config to " + functions);
                        // revert to previous configuration if we fail
                        SystemProperties.set("persist.sys.usb.config", mDefaultFunctions);
                    }
                }
            }

非永久属性的，和永久属性的差不多。只是一个是设置永久属性。一个是设置usb.config这个属性

else {
                if (functions == null) {
                    functions = mDefaultFunctions;
                }

                // Override with bootmode specific usb mode if needed
                functions = processOemUsbOverride(functions);

                if (mAdbEnabled && !functions.equals(UsbManager.USB_FUNCTION_CHARGING)) {
                    functions = addFunction(functions, UsbManager.USB_FUNCTION_ADB);
                } else {
                    functions = removeFunction(functions, UsbManager.USB_FUNCTION_ADB);
                }
                if (!mCurrentFunctions.equals(functions)) {
                    if (!setUsbConfig("none")) {//断开usb
                        Slog.e(TAG, "Failed to disable USB");
                        // revert to previous configuration if we fail
                        setUsbConfig(mCurrentFunctions);
                        return;
                    }
                    if (setUsbConfig(functions)) {
                        if(mCurrentFunctions.equals(UsbManager.USB_FUNCTION_CHARGING) && !mCurrentFunctions.equals(functions)){
                            if (DEBUG) Slog.d(TAG, " change charging functions to new functions: " + functions);
                                SystemProperties.set("sys.usb.charging", "no");
                        }
                        mCurrentFunctions = functions;
                    } else {
                        Slog.e(TAG, "Failed to switch USB config to " + functions);
                        // revert to previous configuration if we fail
                        setUsbConfig(mCurrentFunctions);
                    }
                }
            }

下面我们再来看看setUsbConfig这个函数

        private boolean setUsbConfig(String config) {
            if (DEBUG) Slog.d(TAG, "setUsbConfig(" + config + ")");
            // set the new configuration
            SystemProperties.set("sys.usb.config", config);
            return waitForState(config);
        }

waitForState函数

        private boolean waitForState(String state) {
            // wait for the transition to complete.
            // give up after 1 second.
            for (int i = 0; i < 40; i++) {
                // State transition is done when sys.usb.state is set to the new configuration
                if (state.equals(SystemProperties.get("sys.usb.state"))){//设置的属性和读取的属性相同
                    Log.i(TAG,"Setting SystemProperties ,i =  "+i);
                    if(state.equals("none")){
                        if(SystemProperties.get("sys.lc.usb.state").equals("0")){
                            return true;
                        }else{
                            Log.i(TAG,"sys.lc.usb.state ="+SystemProperties.get("sys.lc.usb.state"));
                        }
                    }else{
                        return true;
                    }
                }
                SystemClock.sleep(50);//不相同，睡50ms 也就是最多会睡2s
            }
            Slog.e(TAG, "waitForState(" + state + ") FAILED");
            return false;
        }

继续分析usbhandler

                mContentResolver.registerContentObserver(
                        Settings.Global.getUriFor(Settings.Global.ADB_ENABLED),
                                false, new AdbSettingsObserver());//注册一个adb的观察者，会发送消息。

                // Watch for USB configuration changes
                mUEventObserver.startObserving(USB_STATE_MATCH);//开启两个节点的监控。
                mUEventObserver.startObserving(ACCESSORY_START_MATCH);

                IntentFilter filter = new IntentFilter(Intent.ACTION_BOOT_COMPLETED);
                filter.setPriority(IntentFilter.SYSTEM_HIGH_PRIORITY);
                mContext.registerReceiver(mBootCompletedReceiver, filter);
                mContext.registerReceiver(
                        mUserSwitchedReceiver, new IntentFilter(Intent.ACTION_USER_SWITCHED));
                mContext.registerReceiver(
                        mBatteryChangedReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

AdbSettingsObserver 发送消息

    private class AdbSettingsObserver extends ContentObserver {
        public AdbSettingsObserver() {
            super(null);
        }
        @Override
        public void onChange(boolean selfChange) {
            boolean enable = (Settings.Global.getInt(mContentResolver,
                    Settings.Global.ADB_ENABLED, 0) > 0);
            mHandler.sendMessage(MSG_ENABLE_ADB, enable);
        }
    }

消息处理，调用setAdbEnabled

                case MSG_ENABLE_ADB:
                    setAdbEnabled(msg.arg1 == 1);
                    break;

UEventObserver 分析

    private final UEventObserver mUEventObserver = new UEventObserver() {
        @Override
        public void onUEvent(UEventObserver.UEvent event) {
            if (DEBUG) Slog.v(TAG, "USB UEVENT: " + event.toString());

            String state = event.get("USB_STATE");
            String accessory = event.get("ACCESSORY");
            if (state != null) {//state对应一个节点
                mHandler.updateState(state);//updateState函数前面分析过了
            } else if ("START".equals(accessory)) {//accessory对应一个节点
                if (DEBUG) Slog.d(TAG, "got accessory start");
                startAccessoryMode();
            }
        }
    }

startAccessoryMode函数

    private void startAccessoryMode() {
        if (!mHasUsbAccessory) return;

        mAccessoryStrings = nativeGetAccessoryStrings();
        boolean enableAudio = (nativeGetAudioMode() == AUDIO_MODE_SOURCE);
        // don't start accessory mode if our mandatory strings have not been set
        boolean enableAccessory = (mAccessoryStrings != null &&
                        mAccessoryStrings[UsbAccessory.MANUFACTURER_STRING] != null &&
                        mAccessoryStrings[UsbAccessory.MODEL_STRING] != null);
        String functions = null;

        if (enableAccessory && enableAudio) {
            functions = UsbManager.USB_FUNCTION_ACCESSORY + ","
                    + UsbManager.USB_FUNCTION_AUDIO_SOURCE;
        } else if (enableAccessory) {
            functions = UsbManager.USB_FUNCTION_ACCESSORY;
        } else if (enableAudio) {
            functions = UsbManager.USB_FUNCTION_AUDIO_SOURCE;
        }

        if (functions != null) {
            mAccessoryModeRequestTime = SystemClock.elapsedRealtime();
            setCurrentFunctions(functions, false);//设置属性
        }
    }

还有就是用户调用usbmanger中的setCurrentFunction

    public void setCurrentFunction(String function, boolean makeDefault) {
        try {
            mService.setCurrentFunction(function, makeDefault);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in setCurrentFunction", e);
        }
    }

接着调用usbservice中的setCurrentFunction函数

    public void setCurrentFunction(String function, boolean makeDefault) {
        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.MANAGE_USB, null);

        // If attempt to change USB function while file transfer is restricted, ensure that
        // the current function is set to "none", and return.
        UserManager userManager = (UserManager) mContext.getSystemService(Context.USER_SERVICE);
        if (userManager.hasUserRestriction(UserManager.DISALLOW_USB_FILE_TRANSFER)) {
            if (mDeviceManager != null) mDeviceManager.setCurrentFunctions("none", false);
            return;
        }

        if (mDeviceManager != null) {
            mDeviceManager.setCurrentFunctions(function, makeDefault);
        } else {
            throw new IllegalStateException("USB device mode not supported");
        }
    }

最后调用usbdevicemanager中的setCurrentFunctions函数

    public void setCurrentFunctions(String functions, boolean makeDefault) {
        String currentUsbConfig = SystemProperties.get("sys.usb.config", "none");// 先从属性里面读出来，主要看有没有adb
        Log.i(TAG, "begin to setCurrentFunction : sys.usb.config = " + currentUsbConfig + " , mMassStorageEnable:"
                            + mMassStorageEnable + " , functions =" + functions +" , makeDefault =" + makeDefault);
        if(functions != null){
            if(containsFunction(functions,UsbManager.USB_FUNCTION_ENABLE_SERIAL)){
                functions = "serial";
            }else if(containsFunction(functions,UsbManager.USB_FUNCTION_DISABLE_SERIAL)){
                if("false".equals(mMassStorageEnable)){
                    functions = "mtp";
                }else{
                    functions = "mtp,mass_storage";
                }
            }else if(containsFunction(functions,UsbManager.USB_FUNCTION_RNDIS)){// usb共享要看，串口有没有开，
                if(containsFunction(currentUsbConfig,UsbManager.USB_FUNCTION_SERIAL)){
                    functions = "rndis,serial";//开了串口才能把这两项都设置到属性中去
                }
            }
        }
        if(containsFunction(currentUsbConfig,UsbManager.USB_FUNCTION_ADB)){
            if(functions != null)addFunction(functions,UsbManager.USB_FUNCTION_ADB);
        }
        Log.i(TAG, "setCurrentFunction  finally  function:"  + fixFunction(functions) + " makeDefault:" + makeDefault);
        mHandler.sendMessage(MSG_SET_CURRENT_FUNCTIONS, fixFunction(functions), makeDefault);
    }

fixFunction的话是将一些其他的属性加入，因为设置属性每次都要设置所有的

    private String fixFunction(String function) {
        Log.d(TAG," fixFunction: function:" + function);
        String ret = function;
        if (null == function) {
            return null;
        }

        if (containsFunction(function, UsbManager.USB_FUNCTION_MTP)){
            if("false".equals(mMassStorageEnable)){
                ret = "mtp";
            } else {
                ret = "mtp,mass_storage";
            }
        } else if (containsFunction(function, UsbManager.USB_FUNCTION_PTP)) {
            if("false".equals(mMassStorageEnable)){
                ret = "ptp";
            } else {
                ret = "ptp,mass_storage";
            }
        } else {
            return ret;
        }

        if (containsFunction(function, UsbManager.USB_FUNCTION_ADB)) {
            addFunction(ret, UsbManager.USB_FUNCTION_ADB);
        }

        return ret;
    }

发送消息之后，消息处理。主要还是调用setEnabledFunctions设置属性。当属性中含有rndis和accessory经常导致不能及时获取的属性值一样。而waitforstate时会等待，所有这边就起了一个线程。

                case MSG_SET_CURRENT_FUNCTIONS:
                    final String functions = (String)msg.obj;
                    final boolean makeDefault = (msg.arg1 == 1);
                    Log.d(TAG, "set current funtion to " + functions);
                    if (null != functions){
                        if(!functions.contains(UsbManager.USB_FUNCTION_CHARGING)){
                            mConnected_InChargeOnlyMode = false;
                        }else{
                            mConnected_InChargeOnlyMode = true;
                        }
                    }
                    if (null != functions && (functions.contains("rndis")||functions.contains("accessory"))) {
                        new Thread() {
                            public void run() {
                                 Log.d(TAG, "new Thread setEnabledFunctions to " + functions);
                               setEnabledFunctions(functions, makeDefault);
                             }
                            }.start();
                       } else {
                           setEnabledFunctions(functions, makeDefault);
                    }
                    break;

下面大致说下各个属性。

    public static final String USB_FUNCTION_ADB = "adb";

    /**
     * Name of the RNDIS ethernet USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     *
     * {@hide}
     */
    public static final String USB_FUNCTION_RNDIS = "rndis";//usb共享

    /**
     * Name of the MTP USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     *
     * {@hide}
     */
    public static final String USB_FUNCTION_MTP = "mtp";

    /**
     * Name of the PTP USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     *
     * {@hide}
     */
    public static final String USB_FUNCTION_PTP = "ptp";

    /**
     * Name of the audio source USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     *
     * {@hide}
     */
    public static final String USB_FUNCTION_AUDIO_SOURCE = "audio_source";

    /**
     * Name of the Accessory USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     *
     * {@hide}
     */
    public static final String USB_FUNCTION_ACCESSORY = "accessory";

     /**
     * Name of the charging USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     *
     * {@hide}
     */
    public static final String USB_FUNCTION_CHARGING = "charging";

        /**
     * Name of the serial USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     *
     * {@hide}
     */
    public static final String USB_FUNCTION_SERIAL = "serial";//开启串口的

还有整个usb.config属性设置后。会触发init.usb.rc中的一些触发器。这在init的博客中分析过了。

下面我们看下整个init.usb.rc，是各个排列组合都列出来了。最后一个是设置persist.sys.usb.config永久系统属性的时候也会设置 sys.usb.config属性。

# Used to disable USB when switching states
on property:sys.usb.config=none//设置属性none
    stop adbd
    write /sys/class/android_usb/android0/enable 0//写enable为0
    write /sys/class/android_usb/android0/bDeviceClass 0
    setprop sys.usb.state $sys.usb.config

#mtp,mass_storage,adb
on property:sys.usb.config=mtp,mass_storage,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181C
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#mtp,mass_storage
on property:sys.usb.config=mtp,mass_storage
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181C
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config

#ptp,mass_storage,adb
on property:sys.usb.config=ptp,mass_storage,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181D
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#ptp,mass_storage
on property:sys.usb.config=ptp,mass_storage
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181D
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config

#rndis,adb,serial
on property:sys.usb.config=rndis,adb,serial
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181F
    write /sys/class/android_usb/android0/functions rndis,serial,adb
    write /sys/class/android_usb/android0/f_rndis/wceis 1
    write /sys/class/android_usb/android0/f_serial/serial_port_num 4
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state rndis,serial,adb

#rndis,serial,adb
on property:sys.usb.config=rndis,serial,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181F
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/f_rndis/wceis 1
    write /sys/class/android_usb/android0/f_serial/serial_port_num 4
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#rndis,serial
on property:sys.usb.config=rndis,serial
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181F
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/f_rndis/wceis 1
    write /sys/class/android_usb/android0/f_serial/serial_port_num 4
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config

#rndis,adb
on property:sys.usb.config=rndis,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181E
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/f_rndis/wceis 1
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#rndis
on property:sys.usb.config=rndis
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181E
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/f_rndis/wceis 1
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config

#mass_storage,serial,adb
on property:sys.usb.config=mass_storage,serial,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181B
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/f_serial/serial_port_num 5
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config


#accessory,adb
on property:sys.usb.config=accessory,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 2D00
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#accessory
on property:sys.usb.config=accessory
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 2D01
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config

#adb
on property:sys.usb.config=adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 1819
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#mtp,adb
on property:sys.usb.config=mtp,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 1818
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#mtp
on property:sys.usb.config=mtp
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 1818
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#ptp,adb
on property:sys.usb.config=ptp,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 1817
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config

#ptp
on property:sys.usb.config=ptp
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 1817
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config

#serial,adb
on property:sys.usb.config=serial,adb
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 1816
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/f_serial/serial_port_num 4
    write /sys/class/android_usb/android0/enable 1
    start adbd
    setprop sys.usb.state $sys.usb.config


#serial
on property:sys.usb.config=serial
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 1816
    write /sys/class/android_usb/android0/functions $sys.usb.config
    write /sys/class/android_usb/android0/f_serial/serial_port_num 4
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config


#USB Charging Only configuration
#for android_usb device should not been none,so set a default function in this mode
on property:sys.usb.config=charging
    write /sys/class/android_usb/android0/enable 0
    write /sys/class/android_usb/android0/idVendor 18D1
    write /sys/class/android_usb/android0/idProduct 181C
    write /sys/class/android_usb/android0/functions mtp,mass_storage,adb
    write /sys/class/android_usb/android0/enable 1
    setprop sys.usb.state $sys.usb.config
    setprop sys.usb.charging yes

on property:sys.usb.charging=yes
    write /sys/devices/platform/comip-u2d/charge_mode 1

on property:sys.usb.charging=no
    write /sys/devices/platform/comip-u2d/charge_mode 0

# Used to set USB configuration at boot and to switch the configuration
# when changing the default configuration
on property:persist.sys.usb.config=*
    setprop sys.usb.config $persist.sys.usb.config

usbdevicemanager差不多分析完了。usb这块暂时先这样后续还会继续深入分析，比如UsbHostManager和UsbSettingsManager那块。