Android振动器系统是Android其他系统中相对简单的系统。 振动器系统用来启动电话的震动功能。比如闹钟、振动模式都需要用到振动器系统。
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
/kernel/drivers/staging/android/timed_output.h
/kernel/drivers/staging/android/timed_output.c
timed_output.h 定义了timed_output_dev 结构体
struct timed_output_dev {
const char*name;
/* enable the output and set the timer */
void(*enable)(struct timed_output_dev *sdev, int timeout);
/* returns the current number of milliseconds remaining on the timer */
int(*get_time)(struct timed_output_dev *sdev);
/* private data */
struct device*dev;
intindex;
intstate;
};
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。
int timed_output_dev_register(struct timed_output_dev *tdev)
{
int ret;
if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
return -EINVAL;
ret = create_timed_output_class();
if (ret < 0)
return ret;
tdev->index = atomic_inc_return(&device_count);
tdev->dev = device_create(timed_output_class, NULL,
MKDEV(0, tdev->index), NULL, tdev->name);
if (IS_ERR(tdev->dev))
return PTR_ERR(tdev->dev);
ret = device_create_file(tdev->dev, &dev_attr_enable);
if (ret < 0)
goto err_create_file;
dev_set_drvdata(tdev->dev, tdev);
tdev->state = 0;
return 0;
err_create_file:
device_destroy(timed_output_class, MKDEV(0, tdev->index));
printk(KERN_ERR "timed_output: Failed to register driver %s\n",
tdev->name);
return ret;
}
EXPORT_SYMBOL_GPL(timed_output_dev_register);
void timed_output_dev_unregister(struct timed_output_dev *tdev)
{
device_remove_file(tdev->dev, &dev_attr_enable);
device_destroy(timed_output_class, MKDEV(0, tdev->index));
dev_set_drvdata(tdev->dev, NULL);
}
EXPORT_SYMBOL_GPL(timed_output_dev_unregister);
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
# echo "10000" enable
echo "10000" enable
10000 enable
执行 cat enable 可以查看当前震动时间剩余数：
# cat enable
cat enable
0
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
int vibrator_on(int timeout_ms)
{
/* constant on, up to maximum allowed time */
return sendit(timeout_ms);
}
int vibrator_off()
{
return sendit(0);
}
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
namespace android
{
static void vibratorOn(JNIEnv *env, jobject clazz, jlong timeout_ms)
{
// LOGI("vibratorOn\n");
vibrator_on(timeout_ms);
}
static void vibratorOff(JNIEnv *env, jobject clazz)
{
// LOGI("vibratorOff\n");
vibrator_off();
}
static JNINativeMethod method_table[] = {
{ "vibratorOn", "(J)V", (void*)vibratorOn },
{ "vibratorOff", "()V", (void*)vibratorOff }
};
int register_android_server_VibratorService(JNIEnv *env)
{
return jniRegisterNativeMethods(env, "com/android/server/VibratorService",
method_table, NELEM(method_table));
}
};
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
