AP_Compass: add and use AP_COMPASS_MAG3110_ENABLED

libraries/AP_Compass/AP_Compass.h

@@ -453,7 +453,9 @@ private:
 #if AP_COMPASS_SITL_ENABLED
         DRIVER_SITL     =13,
 #endif
+#if AP_COMPASS_MAG3110_ENABLED
         DRIVER_MAG3110  =14,
+#endif
 #if AP_COMPASS_IST8308_ENABLED
         DRIVER_IST8308  =15,
 #endif

libraries/AP_Compass/AP_Compass_MAG3110.cpp

@@ -12,14 +12,16 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#include "AP_Compass_MAG3110.h"
+
+#if AP_COMPASS_MAG3110_ENABLED
+
 #include <utility>
 
 #include <AP_HAL/AP_HAL.h>
 #include <AP_Math/AP_Math.h>
 #include <stdio.h>
 
-#include "AP_Compass_MAG3110.h"
-
 extern const AP_HAL::HAL &hal;
 
 
@@ -219,3 +221,5 @@ void AP_Compass_MAG3110::read()
 
     drain_accumulated_samples(_compass_instance);
 }
+
+#endif  // AP_COMPASS_MAG3110_ENABLED

libraries/AP_Compass/AP_Compass_MAG3110.h

@@ -1,5 +1,9 @@
 #pragma once
 
+#include "AP_Compass_config.h"
+
+#if AP_COMPASS_MAG3110_ENABLED
+
 #include <AP_Common/AP_Common.h>
 #include <AP_HAL/AP_HAL.h>
 #include <AP_HAL/Device.h>
@@ -44,3 +48,5 @@ private:
     uint8_t _compass_instance;
     bool _initialised;
 };
+
+#endif  // AP_COMPASS_MAG3110_ENABLED

libraries/AP_Compass/AP_Compass_config.h

@@ -83,6 +83,10 @@
 #define AP_COMPASS_LSM9DS1_ENABLED AP_COMPASS_I2C_BACKEND_DEFAULT_ENABLED
 #endif
 
+#ifndef AP_COMPASS_MAG3110_ENABLED
+#define AP_COMPASS_MAG3110_ENABLED AP_COMPASS_I2C_BACKEND_DEFAULT_ENABLED
+#endif
+
 #ifndef AP_COMPASS_MMC3416_ENABLED
 #define AP_COMPASS_MMC3416_ENABLED AP_COMPASS_I2C_BACKEND_DEFAULT_ENABLED
 #endif