AP_Compass: add option to selectively disable Compass I2C backend

libraries/AP_Compass/AP_Compass.cpp

@@ -1014,6 +1014,8 @@ bool Compass::_have_i2c_driver(uint8_t bus, uint8_t address) const
 void Compass::_probe_external_i2c_compasses(void)
 {
     bool all_external = (AP_BoardConfig::get_board_type() == AP_BoardConfig::PX4_BOARD_PIXHAWK2);
+
+#if !defined(HAL_DISABLE_I2C_MAGS_BY_DEFAULT) || defined(HAL_USE_I2C_MAG_HMC5843)
     // external i2c bus
     FOREACH_I2C_EXTERNAL(i) {
         ADD_BACKEND(DRIVER_HMC5843, AP_Compass_HMC5843::probe(GET_I2C_DEVICE(i, HAL_COMPASS_HMC5843_I2C_ADDR),
@@ -1028,7 +1030,9 @@ void Compass::_probe_external_i2c_compasses(void)
                         all_external, all_external?ROTATION_ROLL_180:ROTATION_YAW_270));
         }
     }
+#endif
 
+#if !defined(HAL_DISABLE_I2C_MAGS_BY_DEFAULT) || defined(HAL_USE_I2C_MAG_QMC5883L)
     //external i2c bus
     FOREACH_I2C_EXTERNAL(i) {
         ADD_BACKEND(DRIVER_QMC5883L, AP_Compass_QMC5883L::probe(GET_I2C_DEVICE(i, HAL_COMPASS_QMC5883L_I2C_ADDR),
@@ -1044,6 +1048,7 @@ void Compass::_probe_external_i2c_compasses(void)
                         all_external?HAL_COMPASS_QMC5883L_ORIENTATION_EXTERNAL:HAL_COMPASS_QMC5883L_ORIENTATION_INTERNAL));
         }
     }
+#endif
 
 #ifndef HAL_BUILD_AP_PERIPH
     // AK09916 on ICM20948
@@ -1060,6 +1065,7 @@ void Compass::_probe_external_i2c_compasses(void)
     }
 #endif // HAL_BUILD_AP_PERIPH
 
+#if !defined(HAL_DISABLE_I2C_MAGS_BY_DEFAULT) || defined(HAL_USE_I2C_MAG_LIS3MDL)
     // lis3mdl on bus 0 with default address
     FOREACH_I2C_INTERNAL(i) {
         ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR),
@@ -1083,7 +1089,9 @@ void Compass::_probe_external_i2c_compasses(void)
         ADD_BACKEND(DRIVER_LIS3MDL, AP_Compass_LIS3MDL::probe(GET_I2C_DEVICE(i, HAL_COMPASS_LIS3MDL_I2C_ADDR2),
                     true, ROTATION_YAW_90));
     }
+#endif
 
+#if !defined(HAL_DISABLE_I2C_MAGS_BY_DEFAULT) || defined(HAL_USE_I2C_MAG_AK09916)
     // AK09916. This can be found twice, due to the ICM20948 i2c bus pass-thru, so we need to be careful to avoid that
     FOREACH_I2C_EXTERNAL(i) {
         ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
@@ -1093,7 +1101,9 @@ void Compass::_probe_external_i2c_compasses(void)
         ADD_BACKEND(DRIVER_AK09916, AP_Compass_AK09916::probe(GET_I2C_DEVICE(i, HAL_COMPASS_AK09916_I2C_ADDR),
                     all_external, all_external?ROTATION_YAW_270:ROTATION_NONE));
     }
+#endif
 
+#if !defined(HAL_DISABLE_I2C_MAGS_BY_DEFAULT) || defined(HAL_USE_I2C_MAG_IST8310)
     // IST8310 on external and internal bus
     if (AP_BoardConfig::get_board_type() != AP_BoardConfig::PX4_BOARD_FMUV5 &&
         AP_BoardConfig::get_board_type() != AP_BoardConfig::PX4_BOARD_FMUV6) {
@@ -1118,13 +1128,17 @@ void Compass::_probe_external_i2c_compasses(void)
             }
         }
     }
+#endif
 
+#if !defined(HAL_DISABLE_I2C_MAGS_BY_DEFAULT) || defined(HAL_USE_I2C_MAG_IST8308)
     // external i2c bus
     FOREACH_I2C_EXTERNAL(i) {
         ADD_BACKEND(DRIVER_IST8308, AP_Compass_IST8308::probe(GET_I2C_DEVICE(i, HAL_COMPASS_IST8308_I2C_ADDR),
                     true, ROTATION_NONE));
     }
+#endif
 
+#if !defined(HAL_DISABLE_I2C_MAGS_BY_DEFAULT) || defined(HAL_USE_I2C_MAG_RM3100)
 #ifdef HAL_COMPASS_RM3100_I2C_ADDR
     const uint8_t rm3100_addresses[] = { HAL_COMPASS_RM3100_I2C_ADDR };
 #else
@@ -1140,11 +1154,13 @@ void Compass::_probe_external_i2c_compasses(void)
             ADD_BACKEND(DRIVER_RM3100, AP_Compass_RM3100::probe(GET_I2C_DEVICE(i, rm3100_addresses[j]), true, ROTATION_NONE));
         }
     }
+
     FOREACH_I2C_INTERNAL(i) {
         for (uint8_t j=0; j<ARRAY_SIZE(rm3100_addresses); j++) {
             ADD_BACKEND(DRIVER_RM3100, AP_Compass_RM3100::probe(GET_I2C_DEVICE(i, rm3100_addresses[j]), all_external, ROTATION_NONE));
         }
     }
+#endif
 }
 
 /*