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前面，帶著大家一起寫了一個temperature sensor的驅(qū)動，已經(jīng)一個測試tool來測試這個驅(qū)動，基本功能已經(jīng)ok，若還有問題的可以參考前面2篇文章，在這里我們要在HAL層中添加我們的設(shè)備，來跟framework中的代碼連接起來。 在開始擺代碼之前我覺得有必要啰嗦幾句，HAL層我個人覺得是個比較重要的東西，雖然這邊現(xiàn)在還不是很成熟，還不是很規(guī)范，但是google還是做了很大力氣針對HAL的。 首先來介紹一下android HAL 層， Android的硬件抽象層，簡單來說，就是對Linux內(nèi)核驅(qū)動程序的封裝，向上提供接口，屏蔽低層的實現(xiàn)細(xì)節(jié)。也就是說，把對硬件的支持分成了兩層，一層放在用戶空間（User Space），一層放在內(nèi)核空間（Kernel Space），其中，硬件抽象層運行在用戶空間，而Linux內(nèi)核驅(qū)動程序運行在內(nèi)核空間。 下圖為整個android 架構(gòu)：  這個是google定義的android整個系統(tǒng)的架構(gòu)，大家可以看到HAL層起了一個承上啟下的作用，HAL層主要是針對一些傳感器和一些個硬件而存在的，其實也可以繞過HAL層直接使用JNI來實現(xiàn)從驅(qū)動到framework這個過程，但是我們這里主要是講android中的sensor，針對標(biāo)準(zhǔn)的android而言，sensor都是在HAL中添加的，個人理解還是呼應(yīng)硬件廠商的建議吧，畢竟這部分代碼還可以不開源的。 好了，開源不開源什么的，我是不去關(guān)心，對我影響不大，我們還是接著看HAL。 Android硬件抽象層，從下到上涉及到了Android系統(tǒng)的硬件驅(qū)動層、硬件抽象層、運行時庫和應(yīng)用程序框架層等等，下圖描述了硬件抽象層在Android系統(tǒng)中的位置，以及它和其它層的關(guān)系：  現(xiàn)在的libhardware 作法，使用了stub的概念。stub 雖然仍是以*.so 檔的形式存在，但HAL 已經(jīng)將*.so 檔隱藏起來了。Stub 向HAL提供操作函數(shù)（operations），而runtime 則是向HAL 取得特定模塊（stub）的operations，再callback 這些操作函數(shù)。 HAL的實現(xiàn)主要在hardware.c和hardware.h文件中。實質(zhì)也是通過加載*.so 庫。從而呼叫*.so 里的符號（symbol）實現(xiàn)。 -------------------------------------------------------------------------------------------------------------------------------------------------------------- 到此，都是些理論的東西，實在是不想講這些條條杠杠的，從小語文就不好的我，最討厭的就是這些理論的東西了，實踐才是真理呢。。。 好了接下來輪到我們的sensor的HAL層了，這里先列出來主要用到的代碼： 。。。。。。 講漏了，這邊sensor的HAL層代碼我參考的是freescale的BSP，因為個人感覺比較容易懂，哈哈。 先給下載鏈接，不然大家看不到完整的代碼。 http://download.csdn.net/detail/zhangjie201412/4039312 代碼目錄如下： sensor/ ├──AccelSensor.cpp ├──AccelSensor.h ├──Android.mk ├──InputEventReader.cpp ├──InputEventReader.h ├──LightSensor.cpp ├──LightSensor.h ├──SensorBase.cpp ├──SensorBase.h ├──sensors.cpp ├──sensors.h ├──TemperatureSensor.cpp └──TemperatureSensor.h 這里我們要修改以及添加的是三個文件： sensor.cpp TemperatureSensor.cpp TemperatureSensor.h 好了，接下來就帶大家分析下android sensor的HAL層！?。?br> 先看一下/hardware/libhareware/hardware.c和/hardware/libhardware/include/hardware/hardware.h 這2個文件是android hal層最重要的兩個文件，其中定義了hal層主要要實現(xiàn)的3個結(jié)構(gòu)體， struct hw_module_t; struct hw_module_methods_t; struct hw_device_t; /** * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM * and the fields of this data structure must begin with hw_module_t * followed by module specific information. */ typedef struct hw_module_t { /** tag must be initialized to HARDWARE_MODULE_TAG */ uint32_t tag; /** major version number for the module */ uint16_t version_major; /** minor version number of the module */ uint16_t version_minor; /** Identifier of module */ const char *id; /** Name of this module */ const char *name; /** Author/owner/implementor of the module */ const char *author; /** Modules methods */ struct hw_module_methods_t* methods; /** module's dso */ void* dso; /** padding to 128 bytes, reserved for future use */ uint32_t reserved[32-7]; } hw_module_t; typedef struct hw_module_methods_t { /** Open a specific device */ int (*open)(const struct hw_module_t* module, const char* id, struct hw_device_t** device); } hw_module_methods_t; /** * Every device data structure must begin with hw_device_t * followed by module specific public methods and attributes. */ typedef struct hw_device_t { /** tag must be initialized to HARDWARE_DEVICE_TAG */ uint32_t tag; /** version number for hw_device_t */ uint32_t version; /** reference to the module this device belongs to */ struct hw_module_t* module; /** padding reserved for future use */ uint32_t reserved[12]; /** Close this device */ int (*close)(struct hw_device_t* device); } hw_device_t; struct hw_module_t; struct hw_module_methods_t; struct hw_device_t; /** * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM * and the fields of this data structure must begin with hw_module_t * followed by module specific information. */ typedef struct hw_module_t { /** tag must be initialized to HARDWARE_MODULE_TAG */ uint32_t tag; /** major version number for the module */ uint16_t version_major; /** minor version number of the module */ uint16_t version_minor; /** Identifier of module */ const char *id; /** Name of this module */ const char *name; /** Author/owner/implementor of the module */ const char *author; /** Modules methods */ struct hw_module_methods_t* methods; /** module's dso */ void* dso; /** padding to 128 bytes, reserved for future use */ uint32_t reserved[32-7]; } hw_module_t; typedef struct hw_module_methods_t { /** Open a specific device */ int (*open)(const struct hw_module_t* module, const char* id, struct hw_device_t** device); } hw_module_methods_t; /** * Every device data structure must begin with hw_device_t * followed by module specific public methods and attributes. */ typedef struct hw_device_t { /** tag must be initialized to HARDWARE_DEVICE_TAG */ uint32_t tag; /** version number for hw_device_t */ uint32_t version; /** reference to the module this device belongs to */ struct hw_module_t* module; /** padding reserved for future use */ uint32_t reserved[12]; /** Close this device */ int (*close)(struct hw_device_t* device); } hw_device_t; 其實標(biāo)準(zhǔn)的android hal就是實現(xiàn)這3個結(jié)構(gòu)體，然后設(shè)置一些回調(diào)函數(shù)，最后把數(shù)據(jù)poll到framework中。 好，接下來看下sensor中是怎么封裝的： 在/hardware/libhardware/include/hardware/sensors.h 中定義了幾個結(jié)構(gòu)體，其中都包含了上面的3個結(jié)構(gòu)體，所以我們sensor module只需要去實現(xiàn)sensor.h中的這幾個就OK了。 下面提一下如何添加我們的temperature sensor，首先是hardware/libhardware/modules/sensor/sensors.cpp 中sensor list中添加我們的sensor的信息， /* The SENSORS Module */ static const struct sensor_t sSensorList[] = { { "Analog Devices ADXL345/6 3-axis Accelerometer", "ADI", 1, SENSORS_ACCELERATION_HANDLE, SENSOR_TYPE_ACCELEROMETER, RANGE_A, CONVERT_A, 0.145f, 200, { } }, //20000 { "Android Light sensor", "Android", 1, SENSORS_LIGHT_HANDLE, SENSOR_TYPE_LIGHT, 16000.0f, 1.0f, 0.35f, 0, { } }, //++++++add by Jay for temperature sensor { "Android Temperature Sensor", "Android", 1, SENSORS_TEMPERATURE_HANDLE, SENSOR_TYPE_TEMPERATURE, 100.0f, 1.0f, 1.0f,0, { }}, //----------- }; /* The SENSORS Module */ static const struct sensor_t sSensorList[] = { { "Analog Devices ADXL345/6 3-axis Accelerometer", "ADI", 1, SENSORS_ACCELERATION_HANDLE, SENSOR_TYPE_ACCELEROMETER, RANGE_A, CONVERT_A, 0.145f, 200, { } }, //20000 { "Android Light sensor", "Android", 1, SENSORS_LIGHT_HANDLE, SENSOR_TYPE_LIGHT, 16000.0f, 1.0f, 0.35f, 0, { } }, //++++++add by Jay for temperature sensor { "Android Temperature Sensor", "Android", 1, SENSORS_TEMPERATURE_HANDLE, SENSOR_TYPE_TEMPERATURE, 100.0f, 1.0f, 1.0f,0, { }}, //----------- };這里面的Android Temperature Sensor就是我們自己添加的sensor，然后我們?nèi)崿F(xiàn)我們的temperature sensor的功能，也就是填充一些結(jié)構(gòu)體和實現(xiàn)一些回調(diào)函數(shù)，這里我挑重要的講。 int TemperatureSensor::readEvents(sensors_event_t* data, int count) { if(count<1) return -EINVAL; if(mHasPendingEvent){ mHasPendingEvent = false; mPendingEvent.timestamp = getTimestamp(); *data = mPendingEvent; return mEnabled ? 1:0; } ssize_t n = mInputReader.fill(data_fd); if(n<0) return n; int numEventReceived = 0; input_event const* event; DEBUG("count: %d\n",count); while(count && mInputReader.readEvent(&event)){ int fd=open("/dev/input/event1", O_RDONLY); if(fd<0){ DEBUG("readEvents: open event2 failed...\n"); return fd; } int ret=read(fd,&event,sizeof(event)); if(ret<sizeof(event)){ DEBUG("readEvent read failed....\n"); return ret; } close(fd); int type=event->type; if(type == EV_ABS){ DEBUG("Current Temp: %d\n",event->value); mPendingEvent.temperature = (float)(event->value); }else if(type==EV_SYN){ mPendingEvent.timestamp = timevalToNano(event->time); if(/*mEnabled &&*/ (mPendingEvent.temperature != mPreviousTemperature)){ *data++ = mPendingEvent; count--; numEventReceived++; mPreviousTemperature = mPendingEvent.temperature; DEBUG("Current Temp: %d\n",(int)mPendingEvent.temperature); } }else DEBUG("temperature : unknow event...\n"); mInputReader.next(); } return numEventReceived; } int TemperatureSensor::readEvents(sensors_event_t* data, int count) { if(count<1) return -EINVAL; if(mHasPendingEvent){ mHasPendingEvent = false; mPendingEvent.timestamp = getTimestamp(); *data = mPendingEvent; return mEnabled ? 1:0; } ssize_t n = mInputReader.fill(data_fd); if(n<0) return n; int numEventReceived = 0; input_event const* event; DEBUG("count: %d\n",count); while(count && mInputReader.readEvent(&event)){ int fd=open("/dev/input/event1", O_RDONLY); if(fd<0){ DEBUG("readEvents: open event2 failed...\n"); return fd; } int ret=read(fd,&event,sizeof(event)); if(ret<sizeof(event)){ DEBUG("readEvent read failed....\n"); return ret; } close(fd); int type=event->type; if(type == EV_ABS){ DEBUG("Current Temp: %d\n",event->value); mPendingEvent.temperature = (float)(event->value); }else if(type==EV_SYN){ mPendingEvent.timestamp = timevalToNano(event->time); if(/*mEnabled &&*/ (mPendingEvent.temperature != mPreviousTemperature)){ *data++ = mPendingEvent; count--; numEventReceived++; mPreviousTemperature = mPendingEvent.temperature; DEBUG("Current Temp: %d\n",(int)mPendingEvent.temperature); } }else DEBUG("temperature : unknow event...\n"); mInputReader.next(); } return numEventReceived; }大家看了Temperature.cpp就應(yīng)該知道我這里實現(xiàn)HAL層poll數(shù)據(jù)最主要的就是上面這個函數(shù)，這邊其實就是linux的應(yīng)用層的寫法，open input 節(jié)點，然后read data，在poll給framework層。 這里我要提醒大家，如果對自己不夠有信心的話第一次寫hal層代碼的時候最好多加點debug message，因為在hal層的調(diào)試比較麻煩，出現(xiàn)的錯誤會直接導(dǎo)致系統(tǒng)不斷重啟，不會告訴你錯哪，所以，最好自己加debug message來調(diào)試。 代碼方面大家可以看下Temperature.h和sensor.cpp這兩個文件里面要實現(xiàn)的一些類和結(jié)構(gòu)體，按照規(guī)范寫好回調(diào)函數(shù)就ok了，大家自行分析綽綽有余。 還有就是這里的makefile，會把module編譯成sensor.goldfish.so，給framework調(diào)用，ok來講一下framework是如何調(diào)用HAL層里面的API的， 大家可以看下android源碼下面的frameworks/base/services/sensorservice/SensorDevice.cpp SensorDevice::SensorDevice() : mSensorDevice(0), mSensorModule(0) { status_t err = hw_get_module(SENSORS_HARDWARE_MODULE_ID, (hw_module_t const**)&mSensorModule); LOGE_IF(err, "couldn't load %s module (%s)", SENSORS_HARDWARE_MODULE_ID, strerror(-err)); if (mSensorModule) { err = sensors_open(&mSensorModule->common, &mSensorDevice); LOGE_IF(err, "couldn't open device for module %s (%s)", SENSORS_HARDWARE_MODULE_ID, strerror(-err)); if (mSensorDevice) { sensor_t const* list; ssize_t count = mSensorModule->get_sensors_list(mSensorModule, &list); mActivationCount.setCapacity(count); Info model; for (size_t i=0 ; i<size_t(count) ; i++) { mActivationCount.add(list[i].handle, model); mSensorDevice->activate(mSensorDevice, list[i].handle, 0); } } } } SensorDevice::SensorDevice() : mSensorDevice(0), mSensorModule(0) { status_t err = hw_get_module(SENSORS_HARDWARE_MODULE_ID, (hw_module_t const**)&mSensorModule); LOGE_IF(err, "couldn't load %s module (%s)", SENSORS_HARDWARE_MODULE_ID, strerror(-err)); if (mSensorModule) { err = sensors_open(&mSensorModule->common, &mSensorDevice); LOGE_IF(err, "couldn't open device for module %s (%s)", SENSORS_HARDWARE_MODULE_ID, strerror(-err)); if (mSensorDevice) { sensor_t const* list; ssize_t count = mSensorModule->get_sensors_list(mSensorModule, &list); mActivationCount.setCapacity(count); Info model; for (size_t i=0 ; i<size_t(count) ; i++) { mActivationCount.add(list[i].handle, model); mSensorDevice->activate(mSensorDevice, list[i].handle, 0); } } } } 這里調(diào)用了status_t err = hw_get_module(SENSORS_HARDWARE_MODULE_ID, (hw_module_t const**)&mSensorModule); status_t err = hw_get_module(SENSORS_HARDWARE_MODULE_ID, (hw_module_t const**)&mSensorModule); 這個函數(shù)在哪呢？在這： hardware/libhardware/hardware.c里的 int hw_get_module(const char *id, const struct hw_module_t **module) { int status; int i; const struct hw_module_t *hmi = NULL; char prop[PATH_MAX]; char path[PATH_MAX]; /* * Here we rely on the fact that calling dlopen multiple times on * the same .so will simply increment a refcount (and not load * a new copy of the library). * We also assume that dlopen() is thread-safe. */ /* Loop through the configuration variants looking for a module */ for (i=0 ; i<HAL_VARIANT_KEYS_COUNT+1 ; i++) { if (i < HAL_VARIANT_KEYS_COUNT) { if (property_get(variant_keys[i], prop, NULL) == 0) { continue; } snprintf(path, sizeof(path), "%s/%s.%s.so", HAL_LIBRARY_PATH1, id, prop); if (access(path, R_OK) == 0) break; snprintf(path, sizeof(path), "%s/%s.%s.so", HAL_LIBRARY_PATH2, id, prop); if (access(path, R_OK) == 0) break; } else { snprintf(path, sizeof(path), "%s/%s.default.so", HAL_LIBRARY_PATH1, id); if (access(path, R_OK) == 0) break; } } status = -ENOENT; if (i < HAL_VARIANT_KEYS_COUNT+1) { /* load the module, if this fails, we're doomed, and we should not try * to load a different variant. */ status = load(id, path, module); } return status; } int hw_get_module(const char *id, const struct hw_module_t **module) { int status; int i; const struct hw_module_t *hmi = NULL; char prop[PATH_MAX]; char path[PATH_MAX]; /* * Here we rely on the fact that calling dlopen multiple times on * the same .so will simply increment a refcount (and not load * a new copy of the library). * We also assume that dlopen() is thread-safe. */ /* Loop through the configuration variants looking for a module */ for (i=0 ; i<HAL_VARIANT_KEYS_COUNT+1 ; i++) { if (i < HAL_VARIANT_KEYS_COUNT) { if (property_get(variant_keys[i], prop, NULL) == 0) { continue; } snprintf(path, sizeof(path), "%s/%s.%s.so", HAL_LIBRARY_PATH1, id, prop); if (access(path, R_OK) == 0) break; snprintf(path, sizeof(path), "%s/%s.%s.so", HAL_LIBRARY_PATH2, id, prop); if (access(path, R_OK) == 0) break; } else { snprintf(path, sizeof(path), "%s/%s.default.so", HAL_LIBRARY_PATH1, id); if (access(path, R_OK) == 0) break; } } status = -ENOENT; if (i < HAL_VARIANT_KEYS_COUNT+1) { /* load the module, if this fails, we're doomed, and we should not try * to load a different variant. */ status = load(id, path, module); } return status; } 這里首先把要get的module的名字傳進(jìn)去，然后找到sensor.goldfish.so，但是怎么去加載這個binary呢？ 看下這里的load函數(shù)： /** * Load the file defined by the variant and if successful * return the dlopen handle and the hmi. * @return 0 = success, !0 = failure. */ static int load(const char *id, const char *path, const struct hw_module_t **pHmi) { int status; void *handle; struct hw_module_t *hmi; /* * load the symbols resolving undefined symbols before * dlopen returns. Since RTLD_GLOBAL is not or'd in with * RTLD_NOW the external symbols will not be global */ handle = dlopen(path, RTLD_NOW); if (handle == NULL) { char const *err_str = dlerror(); LOGE("load: module=%s\n%s", path, err_str?err_str:"unknown"); status = -EINVAL; goto done; } /* Get the address of the struct hal_module_info. */ const char *sym = HAL_MODULE_INFO_SYM_AS_STR; hmi = (struct hw_module_t *)dlsym(handle, sym); if (hmi == NULL) { LOGE("load: couldn't find symbol %s", sym); status = -EINVAL; goto done; } /* Check that the id matches */ if (strcmp(id, hmi->id) != 0) { LOGE("load: id=%s != hmi->id=%s", id, hmi->id); status = -EINVAL; goto done; } hmi->dso = handle; /* success */ status = 0; done: if (status != 0) { hmi = NULL; if (handle != NULL) { dlclose(handle); handle = NULL; } } else { LOGV("loaded HAL id=%s path=%s hmi=%p handle=%p", id, path, *pHmi, handle); } *pHmi = hmi; return status; } /** * Load the file defined by the variant and if successful * return the dlopen handle and the hmi. * @return 0 = success, !0 = failure. */ static int load(const char *id, const char *path, const struct hw_module_t **pHmi) { int status; void *handle; struct hw_module_t *hmi; /* * load the symbols resolving undefined symbols before * dlopen returns. Since RTLD_GLOBAL is not or'd in with * RTLD_NOW the external symbols will not be global */ handle = dlopen(path, RTLD_NOW); if (handle == NULL) { char const *err_str = dlerror(); LOGE("load: module=%s\n%s", path, err_str?err_str:"unknown"); status = -EINVAL; goto done; } /* Get the address of the struct hal_module_info. */ const char *sym = HAL_MODULE_INFO_SYM_AS_STR; hmi = (struct hw_module_t *)dlsym(handle, sym); if (hmi == NULL) { LOGE("load: couldn't find symbol %s", sym); status = -EINVAL; goto done; } /* Check that the id matches */ if (strcmp(id, hmi->id) != 0) { LOGE("load: id=%s != hmi->id=%s", id, hmi->id); status = -EINVAL; goto done; } hmi->dso = handle; /* success */ status = 0; done: if (status != 0) { hmi = NULL; if (handle != NULL) { dlclose(handle); handle = NULL; } } else { LOGV("loaded HAL id=%s path=%s hmi=%p handle=%p", id, path, *pHmi, handle); } *pHmi = hmi; return status; } handle = dlopen(path, RTLD_NOW)；這個函數(shù)是用來打開找到的sensor.goldfish.so這個動態(tài)庫的，然后找到這個庫里的一些回調(diào)函數(shù)，怎么找呢？ handle = dlopen(path, RTLD_NOW)；這個函數(shù)是用來打開找到的sensor.goldfish.so這個動態(tài)庫的，然后找到這個庫里的一些回調(diào)函數(shù)，怎么找呢？看下這句話： 看下這句話：<pre name="code" class="cpp" style="background-color: rgb(255, 255, 255); "><pre name="code" class="cpp"> /* Get the address of the struct hal_module_info. */ const char *sym = HAL_MODULE_INFO_SYM_AS_STR; <pre name="code" class="cpp" style="background-color: rgb(255, 255, 255); "><pre name="code" class="cpp"> /* Get the address of the struct hal_module_info. */ const char *sym = HAL_MODULE_INFO_SYM_AS_STR; HAL_MODULE_INFO_SYM_AS_STR;是一個宏，被定義在hardware.h中： HAL_MODULE_INFO_SYM_AS_STR;是一個宏，被定義在hardware.h中：<pre name="code" class="cpp">#define HAL_MODULE_INFO_SYM_AS_STR "HMI" <pre name="code" class="cpp">#define HAL_MODULE_INFO_SYM_AS_STR "HMI"好了，就是找HMI這個字串，我們可以用readelf命令查看下sensor.glodfish.so里面的symbol： <pre name="code" class="cpp">root@jay:/home/jay/android/android2.3.3# readelf -s out/target/product/generic/system/lib/hw/sensors.goldfish.so Symbol table '.dynsym' contains 118 entries: Num: Value Size Type Bind Vis Ndx Name 0: 00000000 0 NOTYPE LOCAL DEFAULT UND 1: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr0 2: 00001a29 44 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 3: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_f2iz 4: 00001a5d 364 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 5: 00000000 0 FUNC GLOBAL DEFAULT UND poll 6: 00000000 0 FUNC GLOBAL DEFAULT UND __errno 7: 00000000 0 FUNC GLOBAL DEFAULT UND strerror 8: 00000000 0 FUNC GLOBAL DEFAULT UND __android_log_print 9: 00000000 0 FUNC GLOBAL DEFAULT UND read 10: 00001bd1 120 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 11: 00000000 0 FUNC GLOBAL DEFAULT UND write 12: 00001c51 42 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 13: 00000000 0 FUNC GLOBAL DEFAULT UND close 14: 00000000 0 FUNC GLOBAL DEFAULT UND _ZdlPv 15: 00001c95 42 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 16: 00001cc1 216 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 17: 00000000 0 FUNC GLOBAL DEFAULT UND _Znwj 18: 00002455 124 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorC1Ev 19: 00002af1 288 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorC1Ev 20: 00002fd5 108 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorC1E 21: 00000000 0 FUNC GLOBAL DEFAULT UND pipe 22: 00000000 0 FUNC GLOBAL DEFAULT UND fcntl 23: 00000000 0 FUNC GLOBAL DEFAULT UND memset 24: 00001ded 216 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 25: 0000432c 132 OBJECT GLOBAL DEFAULT 16 HMI 26: 00001ec5 24 FUNC GLOBAL DEFAULT 7 _ZNK10SensorBase5getFdEv 27: 00001edd 4 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase8setDelayE 28: 00001ee1 4 FUNC GLOBAL DEFAULT 7 _ZNK10SensorBase16hasPend 29: 00001ee5 32 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase12close_de 30: 00001f05 60 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseD1Ev 31: 000040e8 36 OBJECT GLOBAL DEFAULT 13 _ZTV10SensorBase 32: 00001f41 60 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseD2Ev 33: 00001f7d 312 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase9openInput 34: 00000000 0 FUNC GLOBAL DEFAULT UND opendir 35: 00000000 0 FUNC GLOBAL DEFAULT UND strcpy 36: 00000000 0 FUNC GLOBAL DEFAULT UND strlen 37: 00000000 0 FUNC GLOBAL DEFAULT UND open 38: 00000000 0 FUNC GLOBAL DEFAULT UND ioctl 39: 00000000 0 FUNC GLOBAL DEFAULT UND strcmp 40: 00000000 0 FUNC GLOBAL DEFAULT UND readdir 41: 00000000 0 FUNC GLOBAL DEFAULT UND closedir 42: 00000000 0 FUNC GLOBAL DEFAULT UND __stack_chk_fail 43: 00000000 0 OBJECT GLOBAL DEFAULT UND __stack_chk_guard 44: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr1 45: 000020b5 68 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseC1EPKcS1_ 46: 000020f9 68 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseC2EPKcS1_ 47: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_lmul 48: 00002141 56 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase12getTimes 49: 00000000 0 FUNC GLOBAL DEFAULT UND clock_gettime 50: 00002179 80 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase11open_dev 51: 000021c9 18 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseD0Ev 52: 00000000 0 FUNC GLOBAL DEFAULT UND __cxa_pure_virtual 53: 000021dd 4 FUNC GLOBAL DEFAULT 7 _ZN11LightSensor8setDelay 54: 000021e1 24 FUNC GLOBAL DEFAULT 7 _ZN11LightSensor6enableEi 55: 000021f9 12 FUNC GLOBAL DEFAULT 7 _ZNK11LightSensor16hasPen 56: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_i2f 57: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_fcmpeq 58: 00002209 432 FUNC GLOBAL DEFAULT 7 _ZN11LightSensor10readEve 59: 00000000 0 FUNC GLOBAL DEFAULT UND memcpy 60: 000030dd 96 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 61: 000030c5 24 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 62: 000030ad 22 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 63: 000023b9 68 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorD1Ev 64: 0000313d 18 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 65: 00004110 36 OBJECT GLOBAL DEFAULT 13 _ZTV11LightSensor 66: 000023fd 18 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorD0Ev 67: 00002411 68 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorD2Ev 68: 00003165 30 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 69: 000024d1 124 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorC2Ev 70: 0000254d 48 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor6enableEi 71: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_fmul 72: 0000257d 120 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor12process 73: 000025f9 308 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor10readEve 74: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_ldivmod 75: 00002731 216 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor8setDelay 76: 00000000 0 FUNC GLOBAL DEFAULT UND fopen 77: 00000000 0 FUNC GLOBAL DEFAULT UND snprintf 78: 00000000 0 FUNC GLOBAL DEFAULT UND fwrite 79: 00000000 0 FUNC GLOBAL DEFAULT UND fclose 80: 00002809 628 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor11getPoll 81: 00000000 0 FUNC GLOBAL DEFAULT UND strncmp 82: 00000000 0 FUNC GLOBAL DEFAULT UND strcat 83: 00000000 0 FUNC GLOBAL DEFAULT UND fread 84: 00000000 0 FUNC GLOBAL DEFAULT UND strtol 85: 00002a7d 48 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorD1Ev 86: 00004138 36 OBJECT GLOBAL DEFAULT 13 _ZTV11AccelSensor 87: 00002aad 18 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorD0Ev 88: 00002ac1 48 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorD2Ev 89: 00002c11 288 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorC2Ev 90: 00002d31 4 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensor8se 91: 00002d35 24 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensor6en 92: 00002d4d 12 FUNC GLOBAL DEFAULT 7 _ZNK17TemperatureSensor16 93: 00002d59 488 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensor10r 94: 00002f41 64 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorD1E 95: 00004160 36 OBJECT GLOBAL DEFAULT 13 _ZTV17TemperatureSensor 96: 00002f81 18 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorD0E 97: 00002f95 64 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorD2E 98: 00003041 108 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorC2E 99: 00000000 0 FUNC GLOBAL DEFAULT UND _ZdaPv 100: 00003151 18 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 101: 00000000 0 FUNC GLOBAL DEFAULT UND _Znaj 102: 00003185 30 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 103: 00000000 0 FUNC GLOBAL DEFAULT UND __cxa_finalize 104: 000043c0 0 NOTYPE GLOBAL DEFAULT 17 __dso_handle 105: 00004000 0 NOTYPE GLOBAL DEFAULT 11 __INIT_ARRAY__ 106: 00004008 0 NOTYPE GLOBAL DEFAULT 12 __FINI_ARRAY__ 107: 000035dc 0 NOTYPE GLOBAL DEFAULT ABS __exidx_start 108: 0000371c 0 NOTYPE GLOBAL DEFAULT ABS __exidx_end 109: 0000432c 0 NOTYPE GLOBAL DEFAULT 16 __data_start 110: 000043b4 0 NOTYPE GLOBAL DEFAULT ABS _edata 111: 000043b4 0 NOTYPE GLOBAL DEFAULT ABS __bss_start 112: 000043b4 0 NOTYPE GLOBAL DEFAULT ABS __bss_start__ 113: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS _bss_end__ 114: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS __bss_end__ 115: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS __end__ 116: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS _end 117: 00080000 0 NOTYPE GLOBAL DEFAULT ABS _stack <pre name="code" class="cpp">root@jay:/home/jay/android/android2.3.3# readelf -s out/target/product/generic/system/lib/hw/sensors.goldfish.so Symbol table '.dynsym' contains 118 entries: Num: Value Size Type Bind Vis Ndx Name 0: 00000000 0 NOTYPE LOCAL DEFAULT UND 1: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr0 2: 00001a29 44 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 3: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_f2iz 4: 00001a5d 364 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 5: 00000000 0 FUNC GLOBAL DEFAULT UND poll 6: 00000000 0 FUNC GLOBAL DEFAULT UND __errno 7: 00000000 0 FUNC GLOBAL DEFAULT UND strerror 8: 00000000 0 FUNC GLOBAL DEFAULT UND __android_log_print 9: 00000000 0 FUNC GLOBAL DEFAULT UND read 10: 00001bd1 120 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 11: 00000000 0 FUNC GLOBAL DEFAULT UND write 12: 00001c51 42 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 13: 00000000 0 FUNC GLOBAL DEFAULT UND close 14: 00000000 0 FUNC GLOBAL DEFAULT UND _ZdlPv 15: 00001c95 42 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 16: 00001cc1 216 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 17: 00000000 0 FUNC GLOBAL DEFAULT UND _Znwj 18: 00002455 124 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorC1Ev 19: 00002af1 288 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorC1Ev 20: 00002fd5 108 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorC1E 21: 00000000 0 FUNC GLOBAL DEFAULT UND pipe 22: 00000000 0 FUNC GLOBAL DEFAULT UND fcntl 23: 00000000 0 FUNC GLOBAL DEFAULT UND memset 24: 00001ded 216 FUNC GLOBAL DEFAULT 7 _ZN22sensors_poll_context 25: 0000432c 132 OBJECT GLOBAL DEFAULT 16 HMI 26: 00001ec5 24 FUNC GLOBAL DEFAULT 7 _ZNK10SensorBase5getFdEv 27: 00001edd 4 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase8setDelayE 28: 00001ee1 4 FUNC GLOBAL DEFAULT 7 _ZNK10SensorBase16hasPend 29: 00001ee5 32 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase12close_de 30: 00001f05 60 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseD1Ev 31: 000040e8 36 OBJECT GLOBAL DEFAULT 13 _ZTV10SensorBase 32: 00001f41 60 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseD2Ev 33: 00001f7d 312 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase9openInput 34: 00000000 0 FUNC GLOBAL DEFAULT UND opendir 35: 00000000 0 FUNC GLOBAL DEFAULT UND strcpy 36: 00000000 0 FUNC GLOBAL DEFAULT UND strlen 37: 00000000 0 FUNC GLOBAL DEFAULT UND open 38: 00000000 0 FUNC GLOBAL DEFAULT UND ioctl 39: 00000000 0 FUNC GLOBAL DEFAULT UND strcmp 40: 00000000 0 FUNC GLOBAL DEFAULT UND readdir 41: 00000000 0 FUNC GLOBAL DEFAULT UND closedir 42: 00000000 0 FUNC GLOBAL DEFAULT UND __stack_chk_fail 43: 00000000 0 OBJECT GLOBAL DEFAULT UND __stack_chk_guard 44: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_unwind_cpp_pr1 45: 000020b5 68 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseC1EPKcS1_ 46: 000020f9 68 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseC2EPKcS1_ 47: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_lmul 48: 00002141 56 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase12getTimes 49: 00000000 0 FUNC GLOBAL DEFAULT UND clock_gettime 50: 00002179 80 FUNC GLOBAL DEFAULT 7 _ZN10SensorBase11open_dev 51: 000021c9 18 FUNC GLOBAL DEFAULT 7 _ZN10SensorBaseD0Ev 52: 00000000 0 FUNC GLOBAL DEFAULT UND __cxa_pure_virtual 53: 000021dd 4 FUNC GLOBAL DEFAULT 7 _ZN11LightSensor8setDelay 54: 000021e1 24 FUNC GLOBAL DEFAULT 7 _ZN11LightSensor6enableEi 55: 000021f9 12 FUNC GLOBAL DEFAULT 7 _ZNK11LightSensor16hasPen 56: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_i2f 57: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_fcmpeq 58: 00002209 432 FUNC GLOBAL DEFAULT 7 _ZN11LightSensor10readEve 59: 00000000 0 FUNC GLOBAL DEFAULT UND memcpy 60: 000030dd 96 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 61: 000030c5 24 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 62: 000030ad 22 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 63: 000023b9 68 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorD1Ev 64: 0000313d 18 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 65: 00004110 36 OBJECT GLOBAL DEFAULT 13 _ZTV11LightSensor 66: 000023fd 18 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorD0Ev 67: 00002411 68 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorD2Ev 68: 00003165 30 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 69: 000024d1 124 FUNC GLOBAL DEFAULT 7 _ZN11LightSensorC2Ev 70: 0000254d 48 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor6enableEi 71: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_fmul 72: 0000257d 120 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor12process 73: 000025f9 308 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor10readEve 74: 00000000 0 FUNC GLOBAL DEFAULT UND __aeabi_ldivmod 75: 00002731 216 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor8setDelay 76: 00000000 0 FUNC GLOBAL DEFAULT UND fopen 77: 00000000 0 FUNC GLOBAL DEFAULT UND snprintf 78: 00000000 0 FUNC GLOBAL DEFAULT UND fwrite 79: 00000000 0 FUNC GLOBAL DEFAULT UND fclose 80: 00002809 628 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensor11getPoll 81: 00000000 0 FUNC GLOBAL DEFAULT UND strncmp 82: 00000000 0 FUNC GLOBAL DEFAULT UND strcat 83: 00000000 0 FUNC GLOBAL DEFAULT UND fread 84: 00000000 0 FUNC GLOBAL DEFAULT UND strtol 85: 00002a7d 48 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorD1Ev 86: 00004138 36 OBJECT GLOBAL DEFAULT 13 _ZTV11AccelSensor 87: 00002aad 18 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorD0Ev 88: 00002ac1 48 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorD2Ev 89: 00002c11 288 FUNC GLOBAL DEFAULT 7 _ZN11AccelSensorC2Ev 90: 00002d31 4 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensor8se 91: 00002d35 24 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensor6en 92: 00002d4d 12 FUNC GLOBAL DEFAULT 7 _ZNK17TemperatureSensor16 93: 00002d59 488 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensor10r 94: 00002f41 64 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorD1E 95: 00004160 36 OBJECT GLOBAL DEFAULT 13 _ZTV17TemperatureSensor 96: 00002f81 18 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorD0E 97: 00002f95 64 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorD2E 98: 00003041 108 FUNC GLOBAL DEFAULT 7 _ZN17TemperatureSensorC2E 99: 00000000 0 FUNC GLOBAL DEFAULT UND _ZdaPv 100: 00003151 18 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 101: 00000000 0 FUNC GLOBAL DEFAULT UND _Znaj 102: 00003185 30 FUNC GLOBAL DEFAULT 7 _ZN24InputEventCircularRe 103: 00000000 0 FUNC GLOBAL DEFAULT UND __cxa_finalize 104: 000043c0 0 NOTYPE GLOBAL DEFAULT 17 __dso_handle 105: 00004000 0 NOTYPE GLOBAL DEFAULT 11 __INIT_ARRAY__ 106: 00004008 0 NOTYPE GLOBAL DEFAULT 12 __FINI_ARRAY__ 107: 000035dc 0 NOTYPE GLOBAL DEFAULT ABS __exidx_start 108: 0000371c 0 NOTYPE GLOBAL DEFAULT ABS __exidx_end 109: 0000432c 0 NOTYPE GLOBAL DEFAULT 16 __data_start 110: 000043b4 0 NOTYPE GLOBAL DEFAULT ABS _edata 111: 000043b4 0 NOTYPE GLOBAL DEFAULT ABS __bss_start 112: 000043b4 0 NOTYPE GLOBAL DEFAULT ABS __bss_start__ 113: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS _bss_end__ 114: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS __bss_end__ 115: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS __end__ 116: 000043d0 0 NOTYPE GLOBAL DEFAULT ABS _end 117: 00080000 0 NOTYPE GLOBAL DEFAULT ABS _stack 大家可以看到這里的第25行，OK 找到了，這里找到了這個動態(tài)庫的地址，然后就可以一次找到這個動態(tài)庫中的函數(shù)，最終可以被調(diào)用。 結(jié)束語： 這里我只是大致分析了一下這個流程，對于代碼是如何編寫的，大家可以參考我提供的下載，其實android hal層就是填充一些“規(guī)則”。 這里我只是大致分析了一下這個流程，對于代碼是如何編寫的，大家可以參考我提供的下載，其實android hal層就是填充一些“規(guī)則”。下面一節(jié)我們來編寫一個測試apk來抓我們的溫度，之后再來分析framework層，因為到這里我們sensor的移植就結(jié)束了，framework層中android已經(jīng)幫我們把a(bǔ)pi都寫好了，也就是說sensor是android的標(biāo)準(zhǔn)api，我們不需要自己去搭建。 摘自 zhangjie201412的專欄 |
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