drivers/sensors: Add Velocity sensor type to UORB

This patch adds support for velocity measurement sensors.
I plan to use it as a generic velocity type to be used for
Renesas FS3000 (Air Velocity Flow).

Signed-off-by: Alan C. Assis <acassis@gmail.com>

drivers/sensors/sensor.c

@@ -214,6 +214,7 @@ static const struct sensor_meta_s g_sensor_meta[] =
   {sizeof(struct sensor_gnss_measurement),    "gnss_measurement"},
   {sizeof(struct sensor_gnss_clock),          "gnss_clock"},
   {sizeof(struct sensor_gnss_geofence_event), "gnss_geofence_event"},
+  {sizeof(struct sensor_velocity),            "velocity"},
 };
 
 static const struct file_operations g_sensor_fops =

include/nuttx/uorb.h

@@ -467,9 +467,18 @@
 
 #define SENSOR_TYPE_GNSS_GEOFENCE                   52
 
-/* The total number of sensor */
+/* Velocity Sensor
+ * A sensor of this type measures the velocity as it is moving.
+ * The default unit velocity is meter by seconds m/s (SI).
+ */
 
-#define SENSOR_TYPE_COUNT                           53
+#define SENSOR_TYPE_VELOCITY                        53
+
+/* The total number of sensor
+ * please increase it if you added a new sensor type!
+ */
+
+#define SENSOR_TYPE_COUNT                           54
 
 /* The additional sensor open flags */
 
@@ -747,6 +756,12 @@ struct sensor_force         /* Type: Force */
   int32_t event;            /* Force event */
 };
 
+struct sensor_velocity      /* Type: Velocity */
+{
+  uint64_t timestamp;       /* Unit is microseconds */
+  float velocity;           /* Velocity value, units is m/s (SI) */
+};
+
 struct sensor_hall          /* Type: HALL */
 {
   uint64_t timestamp;       /* Units is microseconds */