driver/sensor: gets the capacity of the hardware fifo

to hold the number of events

Change-Id: I58a9ad07913c7b189e1fd229ab22e91e220e01f6
Signed-off-by: Jiuzhu Dong <dongjiuzhu1@xiaomi.com>

drivers/sensors/sensor.c

@@ -419,7 +419,7 @@ static int sensor_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
       case SNIOC_GET_NEVENTBUF:
         {
-          *val = lower->buffer_number;
+          *val = lower->buffer_number + lower->batch_number;
         }
         break;
 

include/nuttx/sensors/sensor.h

@@ -584,6 +584,13 @@ struct sensor_lowerhalf_s
 
   uint32_t buffer_number;
 
+  /* The number of events that hardware fifo hold maximum number of samples,
+   * must be aligned with size of struct sensor_event_xxx.
+   * If sensor don't hardware fifo, you don't need to care about fifo_size.
+   */
+
+  uint32_t batch_number;
+
   /* The uncalibrated use to describe whether the sensor event is
    * uncalibrated. True is uncalibrated data, false is calibrated data,
    * default false.