hardware/usb/UsbManager.java

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package android.hardware.usb;

import android.app.PendingIntent;
import android.content.Context;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.util.Log;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.HashMap;

/**
 * This class allows you to access the state of USB.
 *
 * <p>You can obtain an instance of this class by calling
 * {@link android.content.Context#getSystemService(java.lang.String) Context.getSystemService()}.
 *
 * {@samplecode
 * UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
 * }
 * @hide
 */
public class UsbManager {
    private static final String TAG = "UsbManager";

   /**
     * Broadcast Action:  A sticky broadcast for USB state change events when in device mode.
     *
     * This is a sticky broadcast for clients that includes USB connected/disconnected state,
     * <ul>
     * <li> {@link #USB_CONNECTED} boolean indicating whether USB is connected or disconnected.
     * <li> {@link #USB_CONFIGURATION} a Bundle containing name/value pairs where the name
     * is the name of a USB function and the value is either {@link #USB_FUNCTION_ENABLED}
     * or {@link #USB_FUNCTION_DISABLED}.  The possible function names include
     * {@link #USB_FUNCTION_MASS_STORAGE}, {@link #USB_FUNCTION_ADB}, {@link #USB_FUNCTION_RNDIS},
     * {@link #USB_FUNCTION_MTP} and {@link #USB_FUNCTION_ACCESSORY}.
     * </ul>
     */
    public static final String ACTION_USB_STATE =
            "android.hardware.usb.action.USB_STATE";

   /**
     * Broadcast Action:  A broadcast for USB accessory attached event.
     *
     * This intent is sent when a USB accessory is attached.
     * <ul>
     * <li> {@link #EXTRA_ACCESSORY} containing the {@link android.hardware.usb.UsbAccessory}
     * for the attached accessory
     * </ul>
     */
    public static final String ACTION_USB_ACCESSORY_ATTACHED =
            "android.hardware.usb.action.USB_ACCESSORY_ATTACHED";

   /**
     * Broadcast Action:  A broadcast for USB accessory detached event.
     *
     * This intent is sent when a USB accessory is detached.
     * <ul>
     * <li> {@link #EXTRA_ACCESSORY} containing the {@link UsbAccessory}
     * for the attached accessory that was detached
     * </ul>
     */
    public static final String ACTION_USB_ACCESSORY_DETACHED =
            "android.hardware.usb.action.USB_ACCESSORY_DETACHED";

    /**
     * Boolean extra indicating whether USB is connected or disconnected.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast.
     */
    public static final String USB_CONNECTED = "connected";

    /**
     * Integer extra containing currently set USB configuration.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast.
     */
    public static final String USB_CONFIGURATION = "configuration";

    /**
     * Name of the USB mass storage USB function.
     * Used in extras for the {@link #ACTION_USB_STATE} broadcast
     */
    public static final String USB_FUNCTION_MASS_STORAGE = "mass_storage";

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

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

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

    /**
     * Value indicating that a USB function is enabled.
     * Used in {@link #USB_CONFIGURATION} extras bundle for the
     * {@link #ACTION_USB_STATE} broadcast
     */
    public static final String USB_FUNCTION_ENABLED = "enabled";

    /**
     * Value indicating that a USB function is disabled.
     * Used in {@link #USB_CONFIGURATION} extras bundle for the
     * {@link #ACTION_USB_STATE} broadcast
     */
    public static final String USB_FUNCTION_DISABLED = "disabled";

    /**
     * Name of extra for {@link #ACTION_USB_ACCESSORY_ATTACHED} and
     * {@link #ACTION_USB_ACCESSORY_DETACHED} broadcasts
     * containing the UsbAccessory object for the accessory.
     */
    public static final String EXTRA_ACCESSORY = "accessory";

    /**
     * Name of extra added to the {@link android.app.PendingIntent}
     * passed into {@link #requestPermission(UsbDevice, PendingIntent)}
     * or {@link #requestPermission(UsbAccessory, PendingIntent)}
     * containing a boolean value indicating whether the user granted permission or not.
     */
    public static final String EXTRA_PERMISSION_GRANTED = "permission";

    private final Context mContext;
    private final IUsbManager mService;

    /**
     * {@hide}
     */
    public UsbManager(Context context, IUsbManager service) {
        mContext = context;
        mService = service;
    }

    /**
     * Returns a list of currently attached USB accessories.
     * (in the current implementation there can be at most one)
     *
     * @return list of USB accessories, or null if none are attached.
     */
    public UsbAccessory[] getAccessoryList() {
        try {
            UsbAccessory accessory = mService.getCurrentAccessory();
            if (accessory == null) {
                return null;
            } else {
                return new UsbAccessory[] { accessory };
            }
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in getAccessoryList", e);
            return null;
        }
    }

    /**
     * Opens a file descriptor for reading and writing data to the USB accessory.
     *
     * @param accessory the USB accessory to open
     * @return file descriptor, or null if the accessor could not be opened.
     */
    public ParcelFileDescriptor openAccessory(UsbAccessory accessory) {
        try {
            return mService.openAccessory(accessory);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in openAccessory", e);
            return null;
        }
    }

    /**
     * Returns true if the caller has permission to access the accessory.
     * Permission might have been granted temporarily via
     * {@link #requestPermission(UsbAccessory, PendingIntent)} or
     * by the user choosing the caller as the default application for the accessory.
     *
     * @param accessory to check permissions for
     * @return true if caller has permission
     */
    public boolean hasPermission(UsbAccessory accessory) {
        try {
            return mService.hasAccessoryPermission(accessory);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in hasPermission", e);
            return false;
        }
    }

    /**
     * Requests temporary permission for the given package to access the accessory.
     * This may result in a system dialog being displayed to the user
     * if permission had not already been granted.
     * Success or failure is returned via the {@link android.app.PendingIntent} pi.
     * If successful, this grants the caller permission to access the accessory only
     * until the device is disconnected.
     *
     * The following extras will be added to pi:
     * <ul>
     * <li> {@link #EXTRA_ACCESSORY} containing the accessory passed into this call
     * <li> {@link #EXTRA_PERMISSION_GRANTED} containing boolean indicating whether
     * permission was granted by the user
     * </ul>
     *
     * @param accessory to request permissions for
     * @param pi PendingIntent for returning result
     */
    public void requestPermission(UsbAccessory accessory, PendingIntent pi) {
        try {
            mService.requestAccessoryPermission(accessory, mContext.getPackageName(), pi);
        } catch (RemoteException e) {
            Log.e(TAG, "RemoteException in requestPermission", e);
        }
    }

    private static File getFunctionEnableFile(String function) {
        return new File("/sys/class/usb_composite/" + function + "/enable");
    }

    /**
     * Returns true if the specified USB function is supported by the kernel.
     * Note that a USB function maybe supported but disabled.
     *
     * @param function name of the USB function
     * @return true if the USB function is supported.
     */
    public static boolean isFunctionSupported(String function) {
        return getFunctionEnableFile(function).exists();
    }

    /**
     * Returns true if the specified USB function is currently enabled.
     *
     * @param function name of the USB function
     * @return true if the USB function is enabled.
     */
    public static boolean isFunctionEnabled(String function) {
        try {
            FileInputStream stream = new FileInputStream(getFunctionEnableFile(function));
            boolean enabled = (stream.read() == '1');
            stream.close();
            return enabled;
        } catch (IOException e) {
            return false;
        }
    }

    /**
     * Enables or disables a USB function.
     *
     * @hide
     */
    public static boolean setFunctionEnabled(String function, boolean enable) {
        try {
            FileOutputStream stream = new FileOutputStream(getFunctionEnableFile(function));
            stream.write(enable ? '1' : '0');
            stream.close();
            return true;
        } catch (IOException e) {
            return false;
        }
    }
}