[sensor] sensor service & hal

hardware/sensor/hwmsen/sensors_hwmsen.c

static int open_sensors(const struct hw_module_t* module, const char* name,
        struct hw_device_t** device)
{
    int status = -EINVAL;
    LOGD("%s: name: %s!\r\n", __func__, name);
    
    struct sensors_data_context_t *dev;
    dev = malloc(sizeof(*dev));
    memset(dev, 0, sizeof(*dev));
    dev->events_fd = open_input(O_RDONLY);
    if (dev->events_fd < 0)  
    {   
        LOGE("%s: Open input device error!",__func__);
        return -1; 
    }   
    dev->device_io_fd = -1; 
    if(dev->device_io_fd <= 0)
    {   
        dev->device_io_fd = open(HWM_SENSOR_DEV, O_RDONLY);
        LOGD("%s: device handle %d",__func__, dev->device_io_fd);
    }   
    dev->activate =  hwm__activate;
    dev->set_delay = hwm__set_delay;
    dev->poll = hwm__poll;
    
    dev->device.common.tag = HARDWARE_DEVICE_TAG;
    dev->device.common.version  = 0;
    dev->device.common.module   = (struct hw_module_t*)module;
    dev->device.common.close    = data__close;
    dev->device.activate        = control__activate;
    dev->device.setDelay        = control__setDelay;
    dev->device.poll            = data__poll;

    *device = &dev->device.common;
    status = 0;
    return status;
}

frameworks/base/services/sensorservice/SensorDevice.cpp

ANDROID_SINGLETON_STATIC_INSTANCE(SensorDevice)

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);
            }
        }
    }
}

mSensorDevice->activate()调用的就是hwm_activate().