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This article will explain in detail how to analyze the Android vibrator system. The content of the article is of high quality, so the editor will share it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

Platform MTK6573

Android vibrator system architecture

Driving layer

Hardware abstraction layer

JNI frame layer

Java application layer

1. Driver layer

Android modifies and adds Linux kernel files

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

Timed_output.h defines the timed_output_dev structure

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; int index; int state;}

Timed_output.c implements the structure, using the function timed_output_dev_register to register and timed_output_dev_unregister to log out.

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

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

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)

Driver to achieve migration

Take MTK 6573 platform as an example

. / mediatek/platform/mt6573/kernel/drivers/vibrator/vibrator.c

Operating equipment

First, open the phone to debug, connect to USB, execute adb shell, and enter / sys/devices/timed_output/vibrator/

Execute echo "10000" enable and find the phone is vibrating

# echo "10000" enable echo "10000" enable 10000 enable

Execute cat enable to view the current vibration time remaining:

# cat enable cat enable 0

Second, hardware abstraction layer

Android encapsulates the call to the underlying driver and becomes the hardware abstraction layer.

/ 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);}

Third, JNI framework layer

The Android JNI framework layer makes it easy for Java to call the Cmax Cobb + method.

. / 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));}}

4. Java application layer

This layer includes Java application invocation, Android system service Java layer

. / frameworks/base/services/java/com/android/server/VibratorService.java

On how to analyze the Android vibrator system to share here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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