Android 振动器系统架构

平台 MTK6573

Android 振动器系统架构

• 驱动层
• 硬件抽象层
• JNI框架层
• Java应用层
  

一、驱动层

Android修改、新增Linux内核文件

1. /kernel/drivers/staging/android/timed_output.h
   
2. /kernel/drivers/staging/android/timed_output.c

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timed_output.h 定义了timed_output_dev 结构体

1. struct timed_output_dev {
   
2.     const char  *name;
   
3. 
   
4.     /* enable the output and set the timer */
   
5.     void    (*enable)(struct timed_output_dev *sdev, int timeout);
   
6. 
   
7.     /* returns the current number of milliseconds remaining on the timer */
   
8.     int     (*get_time)(struct timed_output_dev *sdev);
   
9. 
   
10.     /* private data */
    
11.     struct device   *dev;
    
12.     int     index;
    
13.     int     state;
    
14. };

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timed_output.c 实现了该结构体，使用函数timed_output_dev_register实现注册，使用timed_output_dev_unregister实现注销。

1. int timed_output_dev_register(struct timed_output_dev *tdev)
   
2. {
   
3.     int ret;
   
4. 
   
5.     if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
   
6.         return -EINVAL;
   
7. 
   
8.     ret = create_timed_output_class();
   
9.     if (ret < 0)
   
10.         return ret;
    
11. 
    
12.     tdev->index = atomic_inc_return(&device_count);
    
13.     tdev->dev = device_create(timed_output_class, NULL,
    
14.         MKDEV(0, tdev->index), NULL, tdev->name);
    
15.     if (IS_ERR(tdev->dev))
    
16.         return PTR_ERR(tdev->dev);
    
17. 
    
18.     ret = device_create_file(tdev->dev, &dev_attr_enable);
    
19.     if (ret < 0)
    
20.         goto err_create_file;
    
21. 
    
22.     dev_set_drvdata(tdev->dev, tdev);
    
23.     tdev->state = 0;
    
24.     return 0;
    
25. 
    
26. err_create_file:
    
27.     device_destroy(timed_output_class, MKDEV(0, tdev->index));
    
28.     printk(KERN_ERR "timed_output: Failed to register driver %s\n",
    
29.             tdev->name);
    
30. 
    
31.     return ret;
    
32. }
    
33. EXPORT_SYMBOL_GPL(timed_output_dev_register);
    
34. 
    
35. void timed_output_dev_unregister(struct timed_output_dev *tdev)
    
36. {
    
37.     device_remove_file(tdev->dev, &dev_attr_enable);
    
38.     device_destroy(timed_output_class, MKDEV(0, tdev->index));
    
39.     dev_set_drvdata(tdev->dev, NULL);
    
40. }
    
41. EXPORT_SYMBOL_GPL(timed_output_dev_unregister);

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驱动实现移植以MTK 6573平台为例 ./mediatek/platform/mt6573/kernel/drivers/vibrator/vibrator.c操作设备首先打开手机调试，连接USB，执行adb shell，进入/sys/devices/timed_output/vibrator/执行 echo "10000" enable 发现手机在震动

1. # echo "10000" enable
   
2. echo "10000" enable
   
3. 10000 enable

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执行 cat enable 可以查看当前震动时间剩余数：

1. # cat enable
   
2. cat enable
   
3. 0

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二、硬件抽象层Android 封装了对底层驱动的调用，成为硬件抽象层。/hardware/libhardware_legacy/vibrator/vibrator.c

1. int vibrator_on(int timeout_ms)
   
2. {
   
3.     /* constant on, up to maximum allowed time */
   
4.     return sendit(timeout_ms);
   
5. }
   
6. 
   
7. int vibrator_off()
   
8. {
   
9.     return sendit(0);
   
10. }

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三、 JNI框架层Android JNI框架层是方便Java调用C/C++方法。./frameworks/base/services/jni/com_android_server_VibratorService.cpp

1. namespace android
   
2. {
   
3.   
   
4. static void vibratorOn(JNIEnv *env, jobject clazz, jlong timeout_ms)
   
5. {
   
6.      // LOGI("vibratorOn\n");
   
7.      vibrator_on(timeout_ms);
   
8. }
   
9. static void vibratorOff(JNIEnv *env, jobject clazz)
   
10. {
    
11.      // LOGI("vibratorOff\n");
    
12.      vibrator_off();
    
13. }
    
14. static JNINativeMethod method_table[] = {
    
15.      { "vibratorOn", "(J)V", (void*)vibratorOn },
    
16.      { "vibratorOff", "()V", (void*)vibratorOff }
    
17. };
    
18. int register_android_server_VibratorService(JNIEnv *env)
    
19. {
    
20.      return jniRegisterNativeMethods(env, "com/android/server/VibratorService",
    
21.              method_table, NELEM(method_table));
    
22. }
    
23. };

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四、Java应用层这层包括Java 应用的调用，Android系统服务Java层./frameworks/base/services/java/com/android/server/VibratorService.java