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本文鏈接：https://blog.csdn.net/kc58236582/article/details/47810987
先來理下整個usb的架構，用戶從UsbManager調用接口，會binder通信到UsbService。而UsbService又有兩個實例，一個
UsbHostManager，一個UsbDeviceManager。UsbDeviceManager和
UsbHostManager是一個相對的概念，
UsbHostManager是手機作爲一個host，比如鍵盤、鼠標通過usb連接手機。而UsbDeviceManager是手機與電腦連接。
先看下UsbDevice的代碼：就看構造函數和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();
}
}
今天主要介紹下UsbDeviceManager，先來看下構造函數：
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");//大容量屬性
PackageManager pm = mContext.getPackageManager();
mHasUsbAccessory = pm.hasSystemFeature(PackageManager.FEATURE_USB_ACCESSORY);
initRndisAddress();//初始化usb共享的地址，用手機序列碼作爲地址，序列碼是存在系統屬性中的
readOemUsbOverrideConfig();//讀取廠家設置
mHandler = new UsbHandler(FgThread.get().getLooper());//構造UsbHandler，後面詳細看
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);
}
}
接下來看UsbHandler這個內部類：
先看usbHandler構造函數的前半部分：
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"){//永久性屬性裏面沒有就設置
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)){//有的話就直接將獲取的屬性放在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);//廠家定製的
// 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與"sys.usb.config“屬性不一樣，就重新設置屬性
Slog.w(TAG, "resetting config to persistent property: " + mDefaultFunctions);
SystemProperties.set("sys.usb.config", mDefaultFunctions);
}
上面理論上persist.sys.usb.config 與sys.usb.config屬性一樣的
因爲在init.usb.rc中設置persist.sys.usb.config 屬性，也會將sys.usb.config一同設置了。
# 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
繼續分析usbHandler的構造函數
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);//屬性中如果有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函數，state從下面這個節點讀取狀態
private static final String STATE_PATH =
"/sys/class/android_usb/android0/state"
updateState函數如下：
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);//參數配置後發送消息
收到消息後處理
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斷開連接後，屬性設置成默認的
// restore defaults when USB is disconnected
setEnabledFunctions(getDefaultFunctions(), false);
}
if (mBootCompleted) {
updateUsbState();//發送廣播
updateAudioSourceFunction();
}
break;
繼續分析
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函數
private void setAdbEnabled(boolean enable) {
if (DEBUG) Slog.d(TAG, "setAdbEnabled: " + enable + " mCurrentFunctions:" + mCurrentFunctions);
if (enable != mAdbEnabled) {//當mAdbEnabled改變時
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);//先設置永久屬性
// After persisting them use the lock-down aware function set
setEnabledFunctions(getDefaultFunctions(), false);//再設置usb.config屬性
updateAdbNotification();
}
}
if (mDebuggingManager != null) {
mDebuggingManager.setAdbEnabled(mAdbEnabled);
}
}
再來看看setEnabledFunctions函數
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()) {//設置永久屬性
if (mAdbEnabled && !functions.equals(UsbManager.USB_FUNCTION_CHARGING)) {
functions = addFunction(functions, UsbManager.USB_FUNCTION_ADB);//根據mAdbEnabled設置系統屬性
} else {
functions = removeFunction(functions, UsbManager.USB_FUNCTION_ADB);
}
if (!mDefaultFunctions.equals(functions)) {//當functions改變時
if (!setUsbConfig("none")) {//設置none，直接斷開usb，也就是差不多每次設置不一樣屬性。都要先斷開usb。稍後詳細看看setUsbConfig這個函數
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);// 設置永久屬性
if (waitForState(functions)) {//就是設置的屬性，去讀取屬性是否和設置的一樣
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，設置層默認的
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);
}
}
}
非永久屬性的，和永久屬性的差不多。只是一個是設置永久屬性。一個是設置usb.config這個屬性
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")) {//斷開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);
}
}
}
下面我們再來看看setUsbConfig這個函數
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函數
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"))){//設置的屬性和讀取的屬性相同
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 也就是最多會睡2s
}
Slog.e(TAG, "waitForState(" + state + ") FAILED");
return false;
}
繼續分析usbhandler
mContentResolver.registerContentObserver(
Settings.Global.getUriFor(Settings.Global.ADB_ENABLED),
false, new AdbSettingsObserver());//註冊一個adb的觀察者，會發送消息。
// Watch for USB configuration changes
mUEventObserver.startObserving(USB_STATE_MATCH);//開啓兩個節點的監控。
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 發送消息
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);
}
}
消息處理，調用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對應一個節點
mHandler.updateState(state);//updateState函數前面分析過了
} else if ("START".equals(accessory)) {//accessory對應一個節點
if (DEBUG) Slog.d(TAG, "got accessory start");
startAccessoryMode();
}
}
}
startAccessoryMode函數
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);//設置屬性
}
}
還有就是用戶調用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);
}
}
接着調用usbservice中的setCurrentFunction函數
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");
}
}
最後調用usbdevicemanager中的setCurrentFunctions函數
public void setCurrentFunctions(String functions, boolean makeDefault) {
String currentUsbConfig = SystemProperties.get("sys.usb.config", "none");// 先從屬性裏面讀出來，主要看有沒有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，串口有沒有開，
if(containsFunction(currentUsbConfig,UsbManager.USB_FUNCTION_SERIAL)){
functions = "rndis,serial";//開了串口才能把這兩項都設置到屬性中去
}
}
}
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的話是將一些其他的屬性加入，因爲設置屬性每次都要設置所有的
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;
}
發送消息之後，消息處理。主要還是調用setEnabledFunctions設置屬性。當屬性中含有rndis和accessory經常導致不能及時獲取的屬性值一樣。而waitforstate時會等待，所有這邊就起了一個線程。
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;
下面大致說下各個屬性。
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";//開啓串口的
還有整個usb.config屬性設置後。會觸發init.usb.rc中的一些觸發器。這在init的博客中分析過了。
下面我們看下整個init.usb.rc，是各個排列組合都列出來了。最後一個是設置persist.sys.usb.config永久系統屬性的時候也會設置 sys.usb.config屬性。
# Used to disable USB when switching states
on property:sys.usb.config=none//設置屬性none
stop adbd
write /sys/class/android_usb/android0/enable 0//寫enable爲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這塊暫時先這樣後續還會繼續深入分析，比如UsbHostManager和UsbSettingsManager那塊。
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原文鏈接：https://blog.csdn.net/kc58236582/article/details/47810987