按键驱动调试总结

今天把6516的按键调试结束总结一下；

本身mtk6516的工程已经整合的很好，客户在修改上很方便，有个专门的工具来修改按键，通过对pcb上的按键进行row colum的定位就知道你需要

修改的按键在什么地方了， 当然这个要根据情况来修改， 说实话，真的太简单了。。

调试后分析了一下，按键的整个调试和驱动的流程。

 \alps\frameworks\base\libs\ui\EventHub.cpp  这个文件就用户输入系统的中枢。 我分析了一下这个文件。

一、Android底层按键事件处理过程

 

   在系统启动后，在文件。。。中，android 会通过

    static const char *device_path = "/dev/input"; 
    bool EventHub::penPlatformInput(void) 
    res = scan_dir(device_path);

    通过下面的函数打开设备。
//从目录下查找设备

int EventHub::scan_dir(const char *dirname)
{
    char devname[PATH_MAX];
    char *filename;
    DIR *dir;
    struct dirent *de;
    dir = opendir(dirname);
    if(dir == NULL)
        return -1;
    strcpy(devname, dirname);
    filename = devname + strlen(devname);
    *filename++ = '/';
    while((de = readdir(dir))) {
        if(de->d_name[0] == '.' &&
           (de->d_name[1] == '\0' ||
            (de->d_name[1] == '.' && de->d_name[2] == '\0')))
            continue;
        strcpy(filename, de->d_name);
        open_device(devname);
    }
    closedir(dir);
    return 0;
}

找到后就调用    int EventHub::open_device(const char *deviceName) 打开设备。    static const char *device_path = "/dev/input"; 这个目录下的都是被搜索到。

 int EventHub::open_device(const char *deviceName)
{
    int version;
    int fd;
    struct pollfd *new_mFDs;
    device_t **new_devices;
    char **new_device_names;
    char name[80];
    char location[80];
    char idstr[80];
    struct input_id id;

    LOGV("Opening device: %s", deviceName);

    AutoMutex _l(mLock);

    fd = open(deviceName, O_RDWR);
    if(fd < 0) {
        LOGE("could not open %s, %s\n", deviceName, strerror(errno));
        return -1;
    }

    if(ioctl(fd, EVIOCGVERSION, &version)) {
        LOGE("could not get driver version for %s, %s\n", deviceName, strerror(errno));
        return -1;
    }
    if(ioctl(fd, EVIOCGID, &id)) {
        LOGE("could not get driver id for %s, %s\n", deviceName, strerror(errno));
        return -1;
    }
    name[sizeof(name) - 1] = '\0';
    location[sizeof(location) - 1] = '\0';
    idstr[sizeof(idstr) - 1] = '\0';
    if(ioctl(fd, EVIOCGNAME(sizeof(name) - 1), &name) < 1) {
        //fprintf(stderr, "could not get device name for %s, %s\n", deviceName, strerror(errno));
        name[0] = '\0';
    }

    // check to see if the device is on our excluded list
    List::iterator iter = mExcludedDevices.begin();
    List::iterator end = mExcludedDevices.end();
    for ( ; iter != end; iter++) {
        const char* test = *iter;
        if (strcmp(name, test) == 0) {
            LOGI("ignoring event id %s driver %s\n", deviceName, test);
            close(fd);
            fd = -1;
            return -1;
        }
    }

    if(ioctl(fd, EVIOCGPHYS(sizeof(location) - 1), &location) < 1) {
        //fprintf(stderr, "could not get location for %s, %s\n", deviceName, strerror(errno));
        location[0] = '\0';
    }
    if(ioctl(fd, EVIOCGUNIQ(sizeof(idstr) - 1), &idstr) < 1) {
        //fprintf(stderr, "could not get idstring for %s, %s\n", deviceName, strerror(errno));
        idstr[0] = '\0';
    }

    int devid = 0;
    while (devid < mNumDevicesById) {
        if (mDevicesById[devid].device == NULL) {
            break;
        }
        devid++;
    }
    if (devid >= mNumDevicesById) {
        device_ent* new_devids = (device_ent*)realloc(mDevicesById,
                sizeof(mDevicesById[0]) * (devid + 1));
        if (new_devids == NULL) {
            LOGE("out of memory");
            return -1;
        }
        mDevicesById = new_devids;
        mNumDevicesById = devid+1;
        mDevicesById[devid].device = NULL;
        mDevicesById[devid].seq = 0;
    }

    mDevicesById[devid].seq = (mDevicesById[devid].seq+(1<> 16, (version >> 8) & 0xff, version & 0xff);
#endif

    device_t* device = new device_t(devid|mDevicesById[devid].seq, deviceName, name);
    if (device == NULL) {
        LOGE("out of memory");
        return -1;
    }

    mFDs[mFDCount].fd = fd;
    mFDs[mFDCount].events = POLLIN;

    // figure out the kinds of events the device reports
    
    // See if this is a keyboard, and classify it.  Note that we only
    // consider up through the function keys; we don't want to include
    // ones after that (play cd etc) so we don't mistakenly consider a
    // controller to be a keyboard.
    uint8_t key_bitmask[(KEY_MAX+7)/8];
    memset(key_bitmask, 0, sizeof(key_bitmask));
    LOGV("Getting keys...");
    if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(key_bitmask)), key_bitmask) >= 0) {
        //LOGI("MAP\n");
        //for (int i=0; i<((KEY_MAX+7)/8); i++) {
        //    LOGI("%d: 0x%02x\n", i, key_bitmask[i]);
        //}
        for (int i=0; i<((BTN_MISC+7)/8); i++) {
            if (key_bitmask[i] != 0) {
                device->classes |= CLASS_KEYBOARD;
                break;
            }
        }
        if ((device->classes & CLASS_KEYBOARD) != 0) {
            device->keyBitmask = new uint8_t[sizeof(key_bitmask)];
            if (device->keyBitmask != NULL) {
                memcpy(device->keyBitmask, key_bitmask, sizeof(key_bitmask));
            } else {
                delete device;
                LOGE("out of memory allocating key bitmask");
                return -1;
            }
        }
    }
    
    // See if this is a trackball.
    if (test_bit(BTN_MOUSE, key_bitmask)) {
        uint8_t rel_bitmask[(REL_MAX+7)/8];
        memset(rel_bitmask, 0, sizeof(rel_bitmask));
        LOGV("Getting relative controllers...");
        if (ioctl(fd, EVIOCGBIT(EV_REL, sizeof(rel_bitmask)), rel_bitmask) >= 0)
        {
            if (test_bit(REL_X, rel_bitmask) && test_bit(REL_Y, rel_bitmask)) {
                device->classes |= CLASS_TRACKBALL;
            }
        }
    }
    
    uint8_t abs_bitmask[(ABS_MAX+7)/8];
    memset(abs_bitmask, 0, sizeof(abs_bitmask));
    LOGV("Getting absolute controllers...");
    ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(abs_bitmask)), abs_bitmask);
    
    // Is this a new modern multi-touch driver?
    if (test_bit(ABS_MT_TOUCH_MAJOR, abs_bitmask)
            && test_bit(ABS_MT_POSITION_X, abs_bitmask)
            && test_bit(ABS_MT_POSITION_Y, abs_bitmask)) {
        device->classes |= CLASS_TOUCHSCREEN | CLASS_TOUCHSCREEN_MT;
        
    // Is this an old style single-touch driver?
    } else if (test_bit(BTN_TOUCH, key_bitmask)
            && test_bit(ABS_X, abs_bitmask) && test_bit(ABS_Y, abs_bitmask)) {
        device->classes |= CLASS_TOUCHSCREEN;
    }

#ifdef EV_SW
    // figure out the switches this device reports
    uint8_t sw_bitmask[(SW_MAX+7)/8];
    memset(sw_bitmask, 0, sizeof(sw_bitmask));
    if (ioctl(fd, EVIOCGBIT(EV_SW, sizeof(sw_bitmask)), sw_bitmask) >= 0) {
        for (int i=0; iid, i, test_bit(i, sw_bitmask));
            if (test_bit(i, sw_bitmask)) {
                if (mSwitches[i] == 0) {
                    mSwitches[i] = device->id;
                }
            }
        }
    }
#endif

    if ((device->classes&CLASS_KEYBOARD) != 0) {
        char tmpfn[sizeof(name)];
        char keylayoutFilename[300];

        // a more descriptive name
        device->name = name;

        // replace all the spaces with underscores
        strcpy(tmpfn, name);
        for (char *p = strchr(tmpfn, ' '); p && *p; p = strchr(tmpfn, ' '))
            *p = '_';

        // find the .kl file we need for this device
        const char* root = getenv("ANDROID_ROOT");//取得root权限
        snprintf(keylayoutFilename, sizeof(keylayoutFilename),
                 "%s/usr/keylayout/%s.kl", root, tmpfn);
        bool defaultKeymap = false;
        if (access(keylayoutFilename, R_OK)) {
            snprintf(keylayoutFilename, sizeof(keylayoutFilename),//不能调用特定的kl文件就要用默认的。
                     "%s/usr/keylayout/%s", root, "qwerty.kl");
            defaultKeymap = true;
        }
        device->layoutMap->load(keylayoutFilename);//交给keylayoutmap 解析，这个是一个内部类

        // tell the world about the devname (the descriptive name)
        if (!mHaveFirstKeyboard && !defaultKeymap && strstr(name, "-keypad")) {
            // the built-in keyboard has a well-known device ID of 0,
            // this device better not go away.
            mHaveFirstKeyboard = true;
            mFirstKeyboardId = device->id;
            property_set("hw.keyboards.0.devname", name);
        } else {
            // ensure mFirstKeyboardId is set to -something-.
            if (mFirstKeyboardId == 0) {
                mFirstKeyboardId = device->id;
            }
        }
        char propName[100];
        sprintf(propName, "hw.keyboards.%u.devname", device->id);
        property_set(propName, name);

        // 'Q' key support = cheap test of whether this is an alpha-capable kbd
        if (hasKeycode(device, kKeyCodeQ)) {
            device->classes |= CLASS_ALPHAKEY;
        }
        
        // See if this has a DPAD.
        if (hasKeycode(device, kKeyCodeDpadUp) &&
                hasKeycode(device, kKeyCodeDpadDown) &&
                hasKeycode(device, kKeyCodeDpadLeft) &&
                hasKeycode(device, kKeyCodeDpadRight) &&
                hasKeycode(device, kKeyCodeDpadCenter)) {
            device->classes |= CLASS_DPAD;
        }
        
        LOGI("New keyboard: device->id=0x%x devname='%s' propName='%s' keylayout='%s'\n",
                device->id, name, propName, keylayoutFilename);
    }

    LOGI("New device: path=%s name=%s id=0x%x (of 0x%x) index=%d fd=%d classes=0x%x\n",
         deviceName, name, device->id, mNumDevicesById, mFDCount, fd, device->classes);
         
    LOGV("Adding device %s %p at %d, id = %d, classes = 0x%x\n",
         deviceName, device, mFDCount, devid, device->classes);

    mDevicesById[devid].device = device;
    device->next = mOpeningDevices;
    mOpeningDevices = device;
    mDevices[mFDCount] = device;

    mFDCount++;
    return 0;
}


 

看到这个一段程序

 // find the .kl file we need for this device
        const char* root = getenv("ANDROID_ROOT");//取得root权限
        snprintf(keylayoutFilename, sizeof(keylayoutFilename),
                 "%s/usr/keylayout/%s.kl", root, tmpfn);
        bool defaultKeymap = false;
        if (access(keylayoutFilename, R_OK)) {
            snprintf(keylayoutFilename, sizeof(keylayoutFilename),//不能调用特定的kl文件就要用默认的。
                     "%s/usr/keylayout/%s", root, "qwerty.kl");
            defaultKeymap = true;
        }
        device->layoutMap->load(keylayoutFilename);//交给keylayoutmap 解析，这个是一个内部类

还有一个消息获取函数

//获取事件，无限循环得到事件，调用阻塞函数等待
bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
        int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
        int32_t* outValue, nsecs_t* outWhen)
{
    *outDeviceId = 0;
    *outType = 0;
    *outScancode = 0;
    *outKeycode = 0;
    *outFlags = 0;
    *outValue = 0;
    *outWhen = 0;

    status_t err;

    fd_set readfds;
    int maxFd = -1;
    int cc;
    int i;
    int res;
    int pollres;
    struct input_event iev;

    // Note that we only allow one caller to getEvent(), so don't need
    // to do locking here...  only when adding/removing devices.

    if (!mOpened) {
        mError = openPlatformInput() ? NO_ERROR : UNKNOWN_ERROR;
        mOpened = true;
    }

    while(1) {

        // First, report any devices that had last been added/removed.
        if (mClosingDevices != NULL) {
            device_t* device = mClosingDevices;
            LOGV("Reporting device closed: id=0x%x, name=%s\n",
                 device->id, device->path.string());
            mClosingDevices = device->next;
            *outDeviceId = device->id;
            if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
            *outType = DEVICE_REMOVED;
            delete device;
            return true;
        }
        if (mOpeningDevices != NULL) {
            device_t* device = mOpeningDevices;
            LOGV("Reporting device opened: id=0x%x, name=%s\n",
                 device->id, device->path.string());
            mOpeningDevices = device->next;
            *outDeviceId = device->id;
            if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
            *outType = DEVICE_ADDED;
            return true;
        }

        release_wake_lock(WAKE_LOCK_ID);
// 阻塞等待！！！！！
        pollres = poll(mFDs, mFDCount, -1);

        acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_ID);

        if (pollres <= 0) {
            if (errno != EINTR) {
                LOGW("select failed (errno=%d)\n", errno);
                usleep(100000);
            }
            continue;
        }

        //printf("poll %d, returned %d\n", mFDCount, pollres);

        // mFDs[0] is used for inotify, so process regular events starting at mFDs[1]
        for(i = 1; i < mFDCount; i++) {
            if(mFDs[i].revents) {
                LOGV("revents for %d = 0x%08x", i, mFDs[i].revents);
                if(mFDs[i].revents & POLLIN) {
                    res = read(mFDs[i].fd, &iev, sizeof(iev));//读取信息！！事件代码
                    if (res == sizeof(iev)) {
                        LOGV("%s got: t0=%d, t1=%d, type=%d, code=%d, v=%d",
                             mDevices[i]->path.string(),
                             (int) iev.time.tv_sec, (int) iev.time.tv_usec,
                             iev.type, iev.code, iev.value);
                        *outDeviceId = mDevices[i]->id;
                        if (*outDeviceId == mFirstKeyboardId) *outDeviceId = 0;
                        *outType = iev.type;
                        *outScancode = iev.code;
                        if (iev.type == EV_KEY) {
                            err = mDevices[i]->layoutMap->map(iev.code, outKeycode, outFlags);
                            LOGV("iev.code=%d outKeycode=%d outFlags=0x%08x err=%d\n",
                                iev.code, *outKeycode, *outFlags, err);
                            if (err != 0) {
                                *outKeycode = 0;
                                *outFlags = 0;
                            }
#ifdef HAVE_AEE_FEATURE
#ifdef AEE_MANUAL_DB_DUMP
                            aee_aed_dump_db((unsigned int)iev.code, 
                                (signed int)iev.value, 0);
#endif
#endif
                        } else {
                            *outKeycode = iev.code;
                        }
                        *outValue = iev.value;
                        *outWhen = s2ns(iev.time.tv_sec) + us2ns(iev.time.tv_usec);
                        return true;
                    } else {
                        if (res<0) {
                            LOGW("could not get event (errno=%d)", errno);
                        } else {
                            LOGE("could not get event (wrong size: %d)", res);
                        }
                        continue;
                    }
                }
            }
        }
        
        // read_notify() will modify mFDs and mFDCount, so this must be done after
        // processing all other events.
        if(mFDs[0].revents & POLLIN) {
            read_notify(mFDs[0].fd);
        }
    }
}

  打开设备的时候，如果 device->classes&CLASS_KEYBOARD 不等于 0 表明是键盘。 
  常用输入设备的定义有： 
  enum { 
        CLASS_KEYBOARD      = 0x00000001, //键盘 
        CLASS_ALPHAKEY      = 0x00000002, // 
        CLASS_TOUCHSCREEN   = 0x00000004, //触摸屏 
        CLASS_TRACKBALL     = 0x00000008  //轨迹球 
  };

  打开键盘设备的时候通过上面的 ioctl 获得设备名称，命令字 EVIOCGNAME 的定义在文件：  

  kernel/include/linux/input.h 中。
  对于按键事件，调用mDevices->layoutMap->map进行映射，调用的是文件 KeyLayoutMap.cpp

  (frameworks\base\libs\ui)中的函数：
  status_t KeyLayoutMap::load(const char* filename)通过解析 .kl 把按键的

  映射关系保存在 ：KeyedVector m_keys; 中。

  当获得按键事件以后调用： status_t KeyLayoutMap::map(int32_t scancode, int32_t

  *keycode, uint32_t *flags)
  由映射关系 KeyedVector m_keys 把扫描码转换成andorid上层可以识别的按键。

二、按键映射

 

  Key layout maps的路径是 /system/usr/keylayout，第一个查找的名字是按键驱动的名字，例如

  mxckpd.kl。如果没有的话，默认为qwerty.kl。
  Key character maps的路径是 /system/usr/keychars，第一个查找的名字是按键驱动的名字，例如

  mxckpd.kcm。如果没有的话，默认为qwerty.kl。
  
  qwerty.kl是 UTF-8类型的，格式为：key SCANCODE KEYCODE [FLAGS...]。
  
  SCANCODE表示按键扫描码；
  KEYCODE表示键值，例如HOME,BACK,1,2,3...
  FLAGS有如下定义：
    SHIFT: While pressed, the shift key modifier is set 
    ALT: While pressed, the alt key modifier is set 
    CAPS: While pressed, the caps lock key modifier is set 
    WAKE: When this key is pressed while the device is asleep, the device will

                  wake up and the key event gets sent to the app. 
    WAKE_DROPPED: When this key is pressed while the device is asleep, the device

                  will wake up and the key event does not get sent to the app
  
  qwerty.kcm文件为了节省空间，在编译过程中会用工具makekcharmap转化为二进制文件qwerty.bin。

三、按键分发

 

  1、输入事件分发线程
  
    在frameworks/base/services/java/com/android/server/WindowManagerService.java里创

    建了一个输入事件分发线程，它负责把事件分发到相应的窗口上去。
    
    在WindowManagerService类的构造函数WindowManagerService()中：
        mQueue = new KeyQ(); //读取按键
        mInputThread = new InputDispatcherThread();  //创建分发线程     
        ...     
        mInputThread.start();
      
    在启动的线程InputDispatcherThread中：
        run() 
        process(); 
        QueuedEvent ev = mQueue.getEvent(...) 
      
      在process() 方法中进行处理事件：
        switch (ev.classType) 
          case RawInputEvent.CLASS_KEYBOARD: 
             ... 
             dispatchKey((KeyEvent)ev.event, 0, 0); 
             mQueue.recycleEvent(ev); 
             break; 
          case RawInputEvent.CLASS_TOUCHSCREEN: 
             //Log.i(TAG, "Read next event " + ev); 
             dispatchPointer(ev, (MotionEvent)ev.event, 0, 0); 
             break; 
 　       case RawInputEvent.CLASS_TRACKBALL:
             dispatchTrackball(ev, (MotionEvent)ev.event, 0, 0);
             break;
             
  2、上层读取按键的流程

 

    WindowManagerService()  //(frameworks\base\services\java\com\android\server

                                                    \WindowManagerService.java)
      |
    KeyQ()  //KeyQ 是抽象类 KeyInputQueue 的实现
      |
    InputDeviceReader //在 KeyInputQueue 类中创建的线程 
     |
    readEvent()  //
     |
    android_server_KeyInputQueue_readEvent() //frameworks\base\services\jni\

                                              com_android_server_KeyInputQueue.cpp
     |
    hub->getEvent()
     |
    EventHub::getEvent() //frameworks\base\libs\ui\EventHub.cpp
     |
    res = read(mFDs.fd, &iev, sizeof(iev)); //

摘取网上的一段资料

键盘消息是window manager从驱动里面获取的，然后分发给应用程序框架的

具体参考如下：
2.1 第一步:用户数据收集及其初步判定
     KeyInputQ在WindowMangerService中建立一个独立的线程InputDeviceReader，使用Native函数readEvent来读取Linux Driver的数据构建RawEvent，放入到KeyQ消息队列中。

preProcessEvent()@[email protected]这个是在输入系统中的第一个拦截函数原型。KeyQ重载了preProcessEvent()@WindowManagerService.java。在该成员函数中进行如下动作：
（1） 根据PowerManager获取的Screen on,Screen off状态来判定用户输入的是否WakeUPScreen。
（2） 如果按键式应用程序切换按键，则切换应用程序。
（3） 根据WindowManagerPolicy觉得该用户输入是否投递。
2.2 第二步 消息分发第一层面
InputDispatcherThread从KeyQ中读取Events，找到Window Manager中的Focus Window，通过Focus Window记录的mClient接口，将Events专递到Client端。

如何将KeyEvent对象传到Client端：
在前面的章节（窗口管理ViewRoot，Window Manager Proxy）我们已经知道：在客户端建立Window Manager Proxy后，添加窗口到Window Manager service时，带了一个跟客户ViewRoot相关的IWindow接口实例过去，记录在WindowState中的mClient成员变量中。通过IWindow这个AIDL接口实例，Service可以访问客户端的信息，IWindow是Service连接View桥梁。

看看在Client ViewRootKeyEvent的分发过程
IWindow：dispatchKey(event)
dispatchKey(event)@W@[email protected]
       ViewRoot.dispatchKey(event)@ViewRoot.java
                     message>
                     sendMessageAtTime(msg)@[email protected]
至此我们通过前面的Looper，Handler详解章节的分析结论，我们可以知道Key Message已经放入到应用程序的消息队列。
2.3第三步：应用消息队列分发
   消息的分发,在Looper，Handler详解章节我们分析了Looper.loop()在最后后面调用了handleMesage.
          …
           ActivityThread.main()
                Looper.loop()
                  ViewRoot$RootHandler().dispatch()
                      handleMessage
                          ....
      注意到在分发的调用msg.target.dispatch()，而这个target在第二层将消息sendMessageAtTime到消息队列时填入了mag.target=this即为msg.target=ViewRoot实例。所有此时handleMessage就是ViewRoot重载的handleMessage函数。
handlerMessage@[email protected]
       deliverkeyEvent
            如果输入法存在，dispatchKey到输入法服务。
            否则[email protected]
     在这里需要强调的是，输入法的KeyEvent的拦截并没有放入到Window Manager Service中，而是放入到了客户端的RootView中来处理。
2.4第四步：向焦点进发，完成焦点路径的遍历。

分发函数调用栈
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mView.dispatchKeyEvent：mView是与ViewRoot相对应的Top-Level View.如果mView是一个ViewGroup则分发消息到他的mFocus。
mView.dispatchKeyEvent @ViewGroup  （ViewRoot@root）
               Event.dispatch
                        mFocus.dispatchKeyEevnet
    如果此时的mFocu还是一个ViewGroup，这回将事件专递到下一层的焦点，直到mFocus为一个View。通过这轮调用，就遍历了焦点Path，至此，用户事件传递完成一个段落。
2.5第五步 缺省处理
如果事件在上述Focus View没有处理掉，并且为方向键之类的焦点转换相关按键，则转移焦点到下一个View。

转载于:https://www.cnblogs.com/yuzaipiaofei/archive/2011/08/04/4124422.html