AP_Mount: add devid parameter and setter

libraries/AP_Mount/AP_Mount_Backend.cpp

@@ -14,6 +14,12 @@ void AP_Mount_Backend::init()
     _target_sysid = _params.sysid_default.get();
 }
 
+// set device id of this instance, for MNTx_DEVID parameter
+void AP_Mount_Backend::set_dev_id(uint32_t id)
+{
+    _params.dev_id.set_and_save(int32_t(id));
+}
+
 // return true if this mount accepts roll targets
 bool AP_Mount_Backend::has_roll_control() const
 {

libraries/AP_Mount/AP_Mount_Backend.h

@@ -43,6 +43,9 @@ public:
     // init - performs any required initialisation for this instance
     virtual void init();
 
+    // set device id of this instance, for MNTx_DEVID parameter
+    void set_dev_id(uint32_t id);
+
     // update mount position - should be called periodically
     virtual void update() = 0;
 

libraries/AP_Mount/AP_Mount_Params.cpp

@@ -158,6 +158,14 @@ const AP_Param::GroupInfo AP_Mount_Params::var_info[] = {
     // @RebootRequired: True
     // @User: Standard
     AP_GROUPINFO("_SYSID_DFLT", 14, AP_Mount_Params, sysid_default, 0),
+
+    // @Param: _DEVID
+    // @DisplayName: Mount Device ID
+    // @Description: Mount device ID, taking into account its type, bus and instance
+    // @ReadOnly: True
+    // @User: Advanced
+    AP_GROUPINFO_FLAGS("_DEVID", 15, AP_Mount_Params, dev_id, 0, AP_PARAM_FLAG_INTERNAL_USE_ONLY),
+
     AP_GROUPEND
 };
 

libraries/AP_Mount/AP_Mount_Params.h

@@ -30,4 +30,5 @@ public:
     AP_Float    roll_stb_lead;      // roll lead control gain (only used by servo backend)
     AP_Float    pitch_stb_lead;     // pitch lead control gain (only used by servo backend)
     AP_Int8     sysid_default;      // target sysid for mount to follow
+    AP_Int32    dev_id;             // Device id taking into account bus
 };