高通985处理器(高通8676)

作者:庄泽斌

写一个文档，总结一下在msm8916平台上移植一个自己写的简单字符设备驱动的全过程。这个小项目的主要功能是开发一个简单的APP，通过JNI调用位于内核的字符设备驱动。

一、APP的设计，开发平台Android Studio

主要文件有以下三个文件:

MainActivity.java文件内容如下:

包com . example . administrator . myled；导入Android . NFC . tag；导入Android . support . V7 . app . app compat activity；导入Android . OS . bundle；导入Android . util . log；导入Android . view . view；导入Android . widget . button；导入Android . widget . toast；导入com . zba Huang . led . low level . led native；公共类MainActivity扩展AppCompatActivity实现视图。onclick listener { private final static String TAG = & # 34；zbzhuang & # 34；按钮btn _ led _ on按钮btn _ led _ offLedNative myled@ Override protected void onCreate(Bundle savedInstanceState){ super . onCreate(savedInstanceState)；setContentView(r . layout . activity _ main)；initUI()；myled = new led native()；myled . opendev()；Log.d(标签，& # 34；应用程序:打开开发& # 34；);} private void initUI(){ BTN _ led _ on =(Button)findViewById(r . id . BTN _ led _ on)；BTN _ led _ on . setonclicklistener(this)；BTN _ led _ off =(Button)findViewById(r . id . BTN _ led _ off)；BTN _ led _ off . setonclicklistener(this)；} @ Override public void onClick(View v){ switch(v . getid()){ case r . id . BTN _ led _ on:toast . make text(main activity . this，& # 34；拉灯-& gt；"，吐司。LENGTH_SHORT)。show()；Log.d(标签，& # 34；app:LED亮& # 34；);myled . Devon()；打破；case r . id . BTN _ led _ off:toast . make text(main activity . this，& # 34；关灯-& gt；"，吐司。LENGTH_SHORT)。show()；Log.d(标签，& # 34；app:LED关闭& # 34；);myled . devoff()；打破；默认:break} } @覆盖受保护的void on destroy(){ super . on destroy()；myled . closedev()；Log.d(标签，& # 34；应用程序:关闭开发& # 34；);} } } led native . Java文件的内容如下:

这个文件中声明的方法是在jni中实现的。特殊关键字的使用表明这种方法在JNI实施。

包com . zba Huang . led . low level；/** *由管理员于2017/3/29 0029创建。*/public class led native { static { system . loadlibrary(& # 34；led _ jni & # 34);} public native int openDev()；public native int devOn()；public native int devOff()；public native int closeDev()；}包com . zbahuang . led . low level；/** *由管理员于2017/3/29 0029创建。*/public class led native { static { system . loadlibrary(& # 34；led _ jni & # 34);} public native int openDev()；public native int devOn()；public native int devOff()；public native int closeDev()；}activity_main.xml文件的内容如下:

& lt？xml版本= & # 34；1.0"编码= & # 34；utf-8 & # 34；？& gt& ltAndroid . support . constraint . constraint layout xmlns:Android = & # 34；http://schemas.android.com/apk/res/android" xmlns:app = & # 34；http://schemas.android.com/apk/res-auto" xmlns:tools = & # 34；http://schemas.android.com/tools"安卓:layout _ width = & # 34match _ parent & # 34Android:layout _ height = & # 34；match _ parent & # 34工具:上下文= & # 34；com . example . administrator . myled . main activity & # 34；& gt& ltrelative layout Android:layout _ width = & # 34；394dp & # 34Android:layout _ height = & # 34；520dp & # 34工具:layout _ editor _ absoluteX = & # 34-5dp & # 34；tools:layout _ editor _ absolute y = & # 34；-10dp & # 34；& gt& lt按钮Android:id = & # 34；@+id/BTN _ led _ on & # 34；Android:layout _ width = & # 34；wrap _ content & # 34Android:layout _ height = & # 34；wrap _ content & # 34Android:layout _ alignParentStart = & # 34；真& # 34；Android:layout _ alignParentTop = & # 34；真& # 34；Android:layout _ margin start = & # 34；56dp & # 34Android:layout _ margin top = & # 34；109dp & # 34Android:text = & # 34；拉灯& # 34；/& gt；& lt按钮Android:id = & # 34；@+id/BTN _ led _ off & # 34；Android:layout _ width = & # 34；wrap _ content & # 34Android:layout _ height = & # 34；wrap _ content & # 34Android:layout _ align baseline = & # 34；@+id/BTN _ led _ on & # 34；Android:layout _ align bottom = & # 34；@+id/BTN _ led _ on & # 34；Android:layout _ margin start = & # 34；81dp & # 34Android:layout _ toEndOf = & # 34；@+id/BTN _ led _ on & # 34；Android:text = & # 34；关上灯& # 34；/& gt；& lt/relative layout & gt；& lt/Android . support . constraint . constraint layout & gt；JNI文件:

led_jni.cpp

# include & ltsys/types . h & gt；# include & ltsys/stat . h & gt；# include & ltfcntl.h & gt# include & ltunistd.h & gt# include & lt错误号& gt# include & ltstring.h & gt#定义LOG _ TAG & # 34zbzhuang & # 34# include & ltutils/log . h & gt；#包括& # 34；jni.h & # 34静态jint fdstatic jint open_led(JNIEnv *env，jobobject thiz){ a logd(& # 34；JNI:-% s-& # 34；，_ _ FUNCTION _ _)；FD = open(& # 34；/dev/led 1 & # 34；，O _ RDWR)；if(FD & lt；0){ a logd(& # 34；JNI:打开错误:% s \ n & # 34，strerror(errno))；return-1；}返回0；}static jint led_on(JNIEnv *env，job object thiz){ a logd(& # 34；JNI:-% s-& # 34；，_ _ FUNCTION _ _)；jint retjint on = 1；ret = write(fd，&on，4)；if(ret & lt；0){ a logd(& # 34；JNI:注销错误:% s \ n & # 34，strerror(errno))；return-1；}返回0；}static jint led_off(JNIEnv *env，job object thiz){ a logd(& # 34；JNI:-% s-& # 34；，_ _ FUNCTION _ _)；jint retjint off = 0；ret = write(fd，&off，4)；if(ret & lt；0){ a logd(& # 34；JNI:注销错误:% s \ n & # 34，strerror(errno))；return-1；}返回0；} static jint close _ led(JNIEnv * env，job object thiz){ a logd(& # 34；JNI:-% s-& # 34；，_ _ FUNCTION _ _)；关闭(FD)；返回0；} const jnitivemethod led _ JNI _ methods[]= { { & # 34；openDev & # 34,"()我& # 34；，(void *)open_led}，{ & # 34；德文郡& # 34；,"()我& # 34；、(void *)led_on}、{ & # 34；德沃夫& # 34；,"()我& # 34；、(void *)led_off}、{ & # 34；closeDev & # 34,"()我& # 34；，(void *)close_led}，}；金特JNI_OnLoad(JavaVM * vm，void * reserved){ JNIEnv * env = NULL；jint reta logd(& # 34；% s[% s:% d]JNI:-^_&-\ n & # 34；、__func__、__FILE__、_ _ LINE _ _)；ret = VM-& gt；GetEnv((void * *)&env，JNI _版本_ 1 _ 4)；如果(ret！= JNI _ OK){ ALOGE(& # 34；JNI:VM-& gt；GetEnv错误& # 34；);return-1；} jclass clz = env-& gt；find class(& # 34；com/zba Huang/led/low level/led native & # 34；);if(clz = = NULL){ ALOGE(& # 34；% s[% s:% d]JNI:env-& gt；FindClass错误& # 34；、__func__、__FILE__、_ _ LINE _ _)；return-1；} ret = env-& gt；RegisterNatives(clz，led_jni_methods，sizeof(led _ JNI _ methods)/sizeof(led _ JNI _ methods[0])；if(ret & lt；0){ ALOGE(& # 34；% s[% s:% d]JNI:env-& gt；RegisterNatives错误\ n & # 34、__func__、__FILE__、_ _ LINE _ _)；return-1；}返回JNI _版本_ 1 _ 4；}Android.mk

LOCAL _ PATH:= $(call my-dir)include $(CLEAR _ VARS)LOCAL _ MODULE _ TAGS:= option allocal _ MODULE:= lib led _ JNI . cpplocal _ SHARED _ LIBRARIES:= \ libutils liblogLOCAL _ C _ INCLUDES+= \执行$(JNI _ h _ include)include $(build _ SHARED _ library)后:mmmmmytest/led _ JNI/，会生成一个动态库并放入out/target/product/MSM 8911

把这个库推送到平板电脑上，就可以通过这个库调用驱动了。

内核的驱动文件:kernel/drivers/input/misc/led . c

/*1.头文件*/# include；val，buf，count)；if(ret & gt；0){ printk(KERN _ ERR & # 34；zb庄###从用户复制失败！\ n & # 34);返回ret} if(s5pv _ led _ dev-& gt；Val) {/*点亮LED *//* GPC 0dat | = ((0x1表示如果分配不成功，则休眠*/s5pv _ LED _ dev = kmalloc(sizeof(structed LED _ device)，GFP _ kernel)；如果(！s5pv _ led _ dev){ printk(KERN _ ERR & # 34；zbzhuang对malloc没有记忆！\ n & # 34);ret =-eno mem；goto out _ err _ 1；} /*3.construct cdev structure */setup _ led _ cdev()；/*4.创建设备文件*/* * param 1:struct class * * param 2:parent class，一般为null * * param 3:dev _ t-->表示一个设备号，是一个无符号的32位整数* *其中高12位为主设备号，低20位为从设备号* *如何操作设备号:MKDEV(major，minor)根据主设备号和从设备号组成一个设备号*/s5pv _ led _ dev-& gt；led _ class = class _ create(THIS _ MODULE，& # 34；led _ class & # 34);if(IS _ ERR(s5pv _ led _ dev-& gt；{ printk(KERN _ ERR & # 34；led_class的zb庄class_create()失败\ n & # 34);ret =-EINVAL；goto out _ err _ 2；} s5pv _ led _ dev-& gt；led _ device = device _ create(s5pv _ led _ dev-& gt；led_class，NULL，MKDEV(led_major，0)，NULL，& # 34；led1 & # 34);//创建设备文件/dev/led1f(is _ err(s5pv _ led _ dev-->；led _ device)){ printk(KERN _ ERR & # 34；led_device的zb庄device_create失败\ n & # 34);ret =-eno dev；goto out _ err _ 3；}返回0；out _ err _ 3:class _ destroy(s5pv _ led _ dev-& gt；led _ class)；out _ err _ 2:cdev _ del(s5pv _ led _ dev-& gt；led _ cdev)；kfree(s5pv _ led _ dev)；out _ err _ 1:unregister _ chr dev _ region(MKDEV(led _ major，0)，1)；返回ret}/*3.实现模块卸载函数*/static void _ _ exit led _ exit(void){ unregister _ chrdev _ region(mkdev(led _ major，0)，1)；device _ destroy(s5pv _ led _ dev-& gt；led_class，MKDEV(led_major，0))；class _ destroy(s5pv _ led _ dev-& gt；led _ class)；cdev _ del(s5pv _ led _ dev-& gt；led _ cdev)；kfree(s5pv _ led _ dev)；}/*4.模块许可声明*/模块_初始化(led _ init)；模块_出口(led _出口)；模块许可证(& # 34；GPL & # 34);修改kconfig和makefile，并添加:

生成文件

kconfig:

修改此文件以将驱动程序编译到内核中:kernel/arch/arm 64/configs/MSM _ def config和msm-perf_deconfig。

之后使用adb工具将重新编译的boot.imge镜像重新烧录就可以了啊。然后用adb工具重新刻录重新编译的boot.imge镜像。

查看日志的输出以验证结果:

Android studio查看日志结果:

Adb查看日志结果:

从app到jni再到内核，整个调用过程是成功的。

如果打开设备出现故障，只需在system/core/rootdir/uevent.rc中添加设备节点的权限777即可。

觉得好，就给我一点支持。