AP_Compass: detect compasses for minlure

Minlure has an onboard compass (HMC5883L) as slave of MPU-6000, but also
allows the use of an external HMC5883L compass, which should be
connected to the lure's I2C port.

libraries/AP_Compass/AP_Compass.cpp

@@ -1,5 +1,8 @@
 /// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
 #include <AP_HAL/AP_HAL.h>
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+#include <AP_HAL_Linux/I2CDevice.h>
+#endif
 #include <AP_Vehicle/AP_Vehicle.h>
 
 #include "AP_Compass_AK8963.h"
@@ -477,6 +480,16 @@ void Compass::_detect_backends(void)
     } else {
         hal.console->printf("AK8953: External compass not detected\n");
     }
+#elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_MINLURE
+    _add_backend(AP_Compass_HMC5843::probe_mpu6000(*this));
+    _add_backend(AP_Compass_HMC5843::probe(*this,
+        Linux::I2CDeviceManager::from(hal.i2c_mgr)->get_device(
+            { /* UEFI with lpss set to ACPI */
+              "platform/80860F41:05",
+              /* UEFI with lpss set to PCI */
+              "pci0000:00/0000:00:18.6" },
+            HAL_COMPASS_HMC5843_I2C_ADDR),
+        true));
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_AK8963_MPU9250
     _add_backend(AP_Compass_AK8963::probe_mpu9250(*this, 0));
 #elif HAL_COMPASS_DEFAULT == HAL_COMPASS_HMC5843

libraries/AP_HAL/AP_HAL_Boards.h

@@ -260,8 +260,7 @@
 #define HAL_BARO_MS5611_I2C_BUS 10
 #define HAL_BARO_MS5611_I2C_ADDR 0x77
 #define HAL_BARO_MS5611_USE_TIMER true
-#define HAL_COMPASS_DEFAULT HAL_COMPASS_HMC5843_MPU6000
-/* Internal compass */
+/* Internal and external compasses */
 #define HAL_COMPASS_HMC5843_I2C_ADDR 0x1E
 #define HAL_OPTFLOW_ONBOARD_VDEV_PATH "/dev/video0"
 #define HAL_OPTFLOW_ONBOARD_SENSOR_WIDTH 320