1.setting中改变USB状态

    在setting中关于改变USB状态的有两个重要的类：UsbSettings和UsbSettingsExts。UsbSettings实际上是一个PreferenceFragment，它负责展示界面；UsbSettingsExts负责保存USB状态的。

UsbSettings.java

 @Overridepublic boolean onPreferenceChange(Preference preference, Object newValue) {// Don't allow any changes to take effect as the USB host will be disconnected, killing// the monkeysif (Utils.isMonkeyRunning()) {return true;}// If this user is disallowed from using USB, don't handle their attempts to change the// setting.UserManager um = (UserManager) getActivity().getSystemService(Context.USER_SERVICE);if (um.hasUserRestriction(UserManager.DISALLOW_USB_FILE_TRANSFER)) {return true;}String function = mUsbExts.getFunction(preference);boolean makeDefault = mUsbExts.isMakeDefault(preference);mUsbManager.setCurrentFunction(function, makeDefault);//改变USB状态updateToggles(function);mUsbExts.setNeedUpdate(false);return true;}

UsbSettingsExts.java

    public String getFunction(Preference preference) {String function = FUNCTION_NONE;if (preference == mMtp && mMtp.isChecked()) {function = UsbManager.USB_FUNCTION_MTP;} else if (preference == mPtp && mPtp.isChecked()) {function = UsbManager.USB_FUNCTION_PTP;} else if (preference == mUms && mUms.isChecked()) {function = UsbManager.USB_FUNCTION_MASS_STORAGE;} else if (preference == mCharge && mCharge.isChecked()) {function = UsbManager.USB_FUNCTION_CHARGING_ONLY;} else if (preference == mBicr && mBicr.isChecked()) {function = UsbManager.USB_FUNCTION_BICR;}return function;}

下面来看下USB的管理类UsbManager.java

    public void setCurrentFunction(String function, boolean makeDefault) {try {mService.setCurrentFunction(function, makeDefault);//调用usbservice，改变USB状态} catch (RemoteException e) {Log.e(TAG, "RemoteException in setCurrentFunction", e);}}

UsbService.java

    @Overridepublic 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");}}

UsbDeviceManager.java

    public void setCurrentFunctions(String functions, boolean makeDefault) {if (DEBUG) Slog.d(TAG, "setCurrentFunctions(" + functions + ") default: " + makeDefault);mHandler.sendMessage(MSG_SET_CURRENT_FUNCTIONS, functions, makeDefault);}

case MSG_SET_CURRENT_FUNCTIONS:String functions = (String)msg.obj;boolean makeDefault = (msg.arg1 == 1);mSettingUsbCharging = false;mSettingUsbBicr = false;/* In BICR evo, it's hard to confirm that the current disconnect is caused by switching usb function or unplugging usb cable*//* So add a flag to know it*/mIsUserSwitch = true;if (functions != null && functions.equals(UsbManager.USB_FUNCTION_CHARGING_ONLY)) {mSettingUsbCharging = true;mCurrentFunctions = removeFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_MTP);mCurrentFunctions = removeFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_PTP);updateUsbState();Slog.d(TAG, "handleMessage - MSG_SET_CURRENT_FUNCTION - CHARGING_ONLY - makeDefault: " + makeDefault);} else if (functions != null && functions.equals(UsbManager.USB_FUNCTION_BICR)) {mSettingUsbBicr = true;Slog.d(TAG, "handleMessage - MSG_SET_CURRENT_FUNCTION - BICR - makeDefault: " + makeDefault);} else if (functions == null && mDefaultFunctions.equals(UsbManager.USB_FUNCTION_CHARGING_ONLY)) {functions = mDefaultFunctions;mSettingUsbCharging = true;makeDefault = true;updateUsbState();Slog.d(TAG, "handleMessage - MSG_SET_CURRENT_FUNCTION - [Tethering Off] USB_FUNCTION_CHARGING_ONLY - makeDefault: " + makeDefault);} setEnabledFunctions(functions, makeDefault);mIsUserSwitch = false;//ALPS00428998if(mMtpAskDisconnect) mMtpAskDisconnect = false;//ALPS00428998Slog.d(TAG, "handleMessage - MSG_SET_CURRENT_FUNCTION - functions: " + functions);break;

 private void setEnabledFunctions(String functions, boolean makeDefault) {if (DEBUG) {Slog.d(TAG, "setEnabledFunctions - functions: " + functions);Slog.d(TAG, "setEnabledFunctions - mDefaultFunctions: " + mDefaultFunctions);Slog.d(TAG, "setEnabledFunctions - mCurrentFunctions: " + mCurrentFunctions);Slog.d(TAG, "setEnabledFunctions - mSettingFunction: " + mSettingFunction);}if (mCurrentFunctions.equals(UsbManager.USB_FUNCTION_CHARGING_ONLY)) {Slog.d(TAG, "setEnabledFunctions - [Disable USB Charging]");SystemProperties.set("sys.usb.charging","no");}if (containsFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_BICR)) {if (mIsUsbBicrEvo) {Slog.w(TAG, "====mIsPcKnowMe:" + mIsPcKnowMe + ", mIsBicrSet:" + mIsBicrSet + ", mHwDisconnected:" + mHwDisconnected);if (mIsBicrSet && mHwDisconnected) {Slog.d(TAG, "Do not set sys.usb.bicr=no again!!!");} else {Slog.d(TAG, "setEnabledFunctions1 - [Disable USB BICR]");SystemProperties.set("sys.usb.bicr","no");//设置为光驱}} else {Slog.d(TAG, "setEnabledFunctions2 - [Disable USB BICR]");SystemProperties.set("sys.usb.bicr","no");}}if (mIsUsbBicrEvo && functions != null) {if( containsFunction(functions, UsbManager.USB_FUNCTION_RNDIS) || containsFunction(functions, UsbManager.USB_FUNCTION_EEM) ) {mDefaultFunctions = mSettingFunction;}}// Do not update persystent.sys.usb.config if the device is booted up// with OEM specific mode.if (functions != null && makeDefault && !needsOemUsbOverride() && !mIsUsbBicrEvo) {if(bEvdoDtViaSupport == true) {//VIA-START VIA USBif(Settings.Secure.getInt(mContentResolver,Settings.Secure.ADB_ENABLED, 0) > 0){mAdbEnabled = true;updateAdbNotification();}//VIA-END VIA USB}mSettingFunction = functions;if (mAdbEnabled && !mSettingUsbCharging) {functions = addFunction(functions, UsbManager.USB_FUNCTION_ADB);} else {functions = removeFunction(functions, UsbManager.USB_FUNCTION_ADB);}String acm_idx = SystemProperties.get("sys.usb.acm_idx", "");Slog.d(TAG, "sys.usb.acm_idx=" + acm_idx + ",mAcmPortIdx=" + mAcmPortIdx);if ((mAcmEnabled || ((acm_idx!=null) && !acm_idx.isEmpty()) ||((mAcmPortIdx!=null) && !mAcmPortIdx.isEmpty())) &&!mSettingUsbCharging && !mSettingUsbBicr) {int port_num = 0;String port_str = "";if(!acm_idx.isEmpty()) {port_num = validPortNum(acm_idx);if(port_num > 0 ) {port_str = acm_idx;mAcmPortIdx = acm_idx;}} else if(!mAcmPortIdx.isEmpty()) {port_num = validPortNum(mAcmPortIdx);if(port_num > 0 )port_str = mAcmPortIdx;}Slog.d(TAG, "port_num=" + port_num);if (port_num > 0) {Slog.d(TAG, "Write port_str=" + port_str);writeFile(ACM_PORT_INDEX_PATH, port_str);}/*Add ACM or Dual ACM at the tail. Even with ADB.*/functions = removeFunction(functions, UsbManager.USB_FUNCTION_ACM);functions = removeFunction(functions, UsbManager.USB_FUNCTION_DUAL_ACM);String tmp = ( (port_num == 2) ? UsbManager.USB_FUNCTION_DUAL_ACM : UsbManager.USB_FUNCTION_ACM);functions = addFunction(functions, tmp);//Slog.d(TAG, "set persist.sys.port_index=" + port_str);/*Keep the port info. We need it when reboot.*///SystemProperties.set("persist.sys.port_index", port_str);} else {functions = removeFunction(functions, UsbManager.USB_FUNCTION_ACM);functions = removeFunction(functions, UsbManager.USB_FUNCTION_DUAL_ACM);SystemProperties.set("persist.sys.port_index", "");}Slog.d(TAG, "setEnabledFunctions - functions: " + functions);if (!mDefaultFunctions.equals(functions) || containsFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_BICR) || containsFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_RNDIS)) {if (!setUsbConfig("none")) {Slog.e(TAG, "Failed to disable USB");// revert to previous configuration if we failsetUsbConfig(mCurrentFunctions);return;}// setting this property will also change the current USB state// via a property triggerSystemProperties.set("persist.sys.usb.config", functions);if (mSettingFunction.equals(UsbManager.USB_FUNCTION_CHARGING_ONLY)) {if (mAdbEnabled) {SystemProperties.set("persist.service.adb.enable", "1");} else {SystemProperties.set("persist.service.adb.enable", "0");}} else {SystemProperties.set("persist.service.adb.enable", "");}if (waitForState(functions)) {mCurrentFunctions = functions;mDefaultFunctions = functions;} else {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);}} else {//VIA-START VIA USBif(bEvdoDtViaSupport == true) {if(mDefaultFunctions.equals(functions) &&(mCurrentFunctions.contains(UsbManager.USB_FUNCTION_VIA_CDROM)||mCurrentFunctions.contains(Bypass.USB_FUNCTION_BYPASS))){Slog.i(TAG, "reset DefaultFunctions!");if (!setUsbConfig("none")) {Slog.e(TAG, "Failed to disable USB");// revert to previous configuration if we failsetUsbConfig(mCurrentFunctions);return;}if (setUsbConfig(functions)) {mCurrentFunctions = functions;} else {Slog.e(TAG, "Failed to switch USB config to " + functions);// revert to previous configuration if we failsetUsbConfig(mCurrentFunctions);}}}//VIA-END VIA USB}} else {if (functions == null) {functions = mDefaultFunctions;if(bEvdoDtViaSupport == true){mUsbSetBypassWithTether=false ;}}//VIA-START VIA USBif(bEvdoDtViaSupport == true) {//adb can't be open with bypass and via cdromif(Settings.Secure.getInt(mContentResolver,Settings.Secure.ADB_ENABLED, 0) > 0){mAdbEnabled = true;updateAdbNotification();}}//VIA-END VIA USB// Override with bootmode specific usb mode if neededfunctions = processOemUsbOverride(functions);mSettingFunction = functions;if(bEvdoDtViaSupport == true){if ((containsFunction(functions, UsbManager.USB_FUNCTION_RNDIS) || containsFunction(functions, UsbManager.USB_FUNCTION_EEM)) && mUsbSetBypassWithTether){					functions = addFunction(functions, Bypass.USB_FUNCTION_BYPASS);Slog.d(TAG, "add the bypass functions to tethering : " + functions);}}if (mIsUsbBicrEvo && !mIsPcKnowMe && !mSettingUsbCharging) {functions = UsbManager.USB_FUNCTION_BICR;mSettingFunction = functions;}if (mAdbEnabled && !mSettingUsbCharging) {functions = addFunction(functions, UsbManager.USB_FUNCTION_ADB);} else {functions = removeFunction(functions, UsbManager.USB_FUNCTION_ADB);}String acm_idx = SystemProperties.get("sys.usb.acm_idx", "");Slog.d(TAG, "sys.usb.acm_idx=" + acm_idx);if ((mAcmEnabled || ((acm_idx!=null) && !acm_idx.isEmpty()) ||((mAcmPortIdx!=null) && !mAcmPortIdx.isEmpty())) &&!mSettingUsbCharging && !mSettingUsbBicr) {int port_num = 0;String port_str = "";if(!acm_idx.isEmpty()) {port_num = validPortNum(acm_idx);if(port_num > 0 ) {port_str = acm_idx;mAcmPortIdx = acm_idx;}} else if(!mAcmPortIdx.isEmpty()) {port_num = validPortNum(mAcmPortIdx);if(port_num > 0 )port_str = mAcmPortIdx;}Slog.d(TAG, "port_num=" + port_num);if (port_num > 0) {Slog.d(TAG, "Write port_str=" + port_str);writeFile(ACM_PORT_INDEX_PATH, port_str);}/*Add ACM or Dual ACM at the tail. Even with ADB.*/functions = removeFunction(functions, UsbManager.USB_FUNCTION_ACM);functions = removeFunction(functions, UsbManager.USB_FUNCTION_DUAL_ACM);String tmp = ( (port_num == 2) ? UsbManager.USB_FUNCTION_DUAL_ACM : UsbManager.USB_FUNCTION_ACM);functions = addFunction(functions, tmp);} else {functions = removeFunction(functions, UsbManager.USB_FUNCTION_ACM);functions = removeFunction(functions, UsbManager.USB_FUNCTION_DUAL_ACM);}Slog.d(TAG, "else setEnabledFunctions, functions: " + functions + ", mCurrentFunctions: " + mCurrentFunctions);if (!mCurrentFunctions.equals(functions) || containsFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_BICR) || (mIsUsbBicrEvo && !mIsPcKnowMe) || mMtpAskDisconnect) {if (mIsUsbBicrEvo) {Slog.w(TAG, "====mIsPcKnowMe:" + mIsPcKnowMe + ", mIsBicrSet:" + mIsBicrSet + ", mHwDisconnected:" + mHwDisconnected);if (mIsBicrSet && !mIsPcKnowMe && mHwDisconnected && mCurrentFunctions.equals(functions) && containsFunction(mCurrentFunctions, UsbManager.USB_FUNCTION_BICR)) {Slog.e(TAG, "Do not do setUsbConfig() again!!!");return;} else {mIsBicrSet = true;}}if (!setUsbConfig("none")) {Slog.e(TAG, "Failed to disable USB");// revert to previous configuration if we failsetUsbConfig(mCurrentFunctions);return;}if (setUsbConfig(functions)) {mCurrentFunctions = functions;} else {Slog.e(TAG, "Failed to switch USB config to " + functions);// revert to previous configuration if we failsetUsbConfig(mCurrentFunctions);}}}/* reset this value after trigger setconfig, i.e. one time JOB */	if(bEvdoDtViaSupport == true){mUsbSetBypassWithTether=false ;}}

下面我们来看下init.usb.rc

on property:sys.usb.config=nonestop adbdwrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/bDeviceClass 0setprop sys.usb.state ${sys.usb.config}# adb only USB configuration
# This is the fallback configuration if the
# USB manager fails to set a standard configuration
on property:sys.usb.config=adbwrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/idVendor 18d1write /sys/class/android_usb/android0/idProduct 4EE7write /sys/class/android_usb/android0/functions ${sys.usb.config}write /sys/class/android_usb/android0/enable 1start adbdsetprop sys.usb.state ${sys.usb.config}# USB accessory configuration
on property:sys.usb.config=accessorywrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/idVendor 18d1write /sys/class/android_usb/android0/idProduct 2d00write /sys/class/android_usb/android0/functions ${sys.usb.config}write /sys/class/android_usb/android0/enable 1setprop sys.usb.state ${sys.usb.config}# USB accessory configuration, with adb
on property:sys.usb.config=accessory,adbwrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/idVendor 18d1write /sys/class/android_usb/android0/idProduct 2d01write /sys/class/android_usb/android0/functions ${sys.usb.config}write /sys/class/android_usb/android0/enable 1start adbdsetprop sys.usb.state ${sys.usb.config}# audio accessory configuration
on property:sys.usb.config=audio_sourcewrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/idVendor 18d1write /sys/class/android_usb/android0/idProduct 2d02write /sys/class/android_usb/android0/functions ${sys.usb.config}write /sys/class/android_usb/android0/enable 1setprop sys.usb.state ${sys.usb.config}# audio accessory configuration, with adb
on property:sys.usb.config=audio_source,adbwrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/idVendor 18d1write /sys/class/android_usb/android0/idProduct 2d03write /sys/class/android_usb/android0/functions ${sys.usb.config}write /sys/class/android_usb/android0/enable 1start adbdsetprop sys.usb.state ${sys.usb.config}# USB and audio accessory configuration
on property:sys.usb.config=accessory,audio_sourcewrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/idVendor 18d1write /sys/class/android_usb/android0/idProduct 2d04write /sys/class/android_usb/android0/functions ${sys.usb.config}write /sys/class/android_usb/android0/enable 1setprop sys.usb.state ${sys.usb.config}# USB and audio accessory configuration, with adb
on property:sys.usb.config=accessory,audio_source,adbwrite /sys/class/android_usb/android0/enable 0write /sys/class/android_usb/android0/idVendor 18d1write /sys/class/android_usb/android0/idProduct 2d05write /sys/class/android_usb/android0/functions ${sys.usb.config}write /sys/class/android_usb/android0/enable 1start adbdsetprop sys.usb.state ${sys.usb.config}# 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}

从上面可以看出，设置persist.sys.usb.config后sys.usb,config跟着改变，然后向节点写入数据改变状态