android中Sensor工作流程(6)

      /**
       * Set the delay between sensor events in ms
       *
       * @return 0 if successful, < 0 on error
       */
     int (*set_delay)(struct sensors_control_device_t *dev, int32_t ms);
     /**
       * Causes sensors_data_device_t.poll() to return -EWOULDBLOCK immediately.
       */
     int (*wake)(struct sensors_control_device_t *dev);
};
struct sensors_data_device_t {
     struct hw_device_t common;
     /**
       * Prepare to read sensor data.
       *
       * This routine does NOT take ownership of the fd
       * and must not close it. Typically this routine would
       * use a duplicate of the fd parameter.
       *
       * @param fd from sensors_control_open.
       *
       * @return 0 if successful, < 0 on error
       */
     int (*data_open)(struct sensors_data_device_t *dev, int fd);
     /**
       * Caller has completed using the sensor data.
       * The caller will not be blocked in sensors_data_poll
       * when this routine is called.
       *
       * @return 0 if successful, < 0 on error
       */
     int (*data_close)(struct sensors_data_device_t *dev);
     /**
       * Return sensor data for one of the enabled sensors.
       *
       * @return sensor handle for the returned data, 0x7FFFFFFF when
       * sensors_control_device_t.wake() is called and -errno on error
       *
        */
      int (*poll)(struct sensors_data_device_t *dev,
                 sensors_data_t* data);
};
最后一组函数
/** convenience API for opening and closing a device */
static inline int sensors_control_open(const struct hw_module_t* module,