hw/core/sysbus: Add a function for creating and attaching an object

A lot of functions are initializing an object and attach it immediately
afterwards to the system bus. Provide a common function for this, which
also uses object_initialize_child() to make sure that the reference
counter is correctly initialized to 1 afterwards.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 1531745974-17187-3-git-send-email-thuth@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/core/sysbus.c

@@ -376,6 +376,14 @@ BusState *sysbus_get_default(void)
     return main_system_bus;
 }
 
+void sysbus_init_child_obj(Object *parent, const char *childname, void *child,
+                           size_t childsize, const char *childtype)
+{
+    object_initialize_child(parent, childname, child, childsize, childtype,
+                            &error_abort, NULL);
+    qdev_set_parent_bus(DEVICE(child), sysbus_get_default());
+}
+
 static void sysbus_register_types(void)
 {
     type_register_static(&system_bus_info);

include/hw/sysbus.h

@@ -96,6 +96,23 @@ void sysbus_add_io(SysBusDevice *dev, hwaddr addr,
                    MemoryRegion *mem);
 MemoryRegion *sysbus_address_space(SysBusDevice *dev);
 
+/**
+ * sysbus_init_child_obj:
+ * @parent: The parent object
+ * @childname: Used as name of the "child<>" property in the parent
+ * @child: A pointer to the memory to be used for the object.
+ * @childsize: The maximum size available at @child for the object.
+ * @childtype: The name of the type of the object to instantiate.
+ *
+ * This function will initialize an object and attach it to the main system
+ * bus. The memory for the object should have already been allocated. The
+ * object will then be added as child to the given parent. The returned object
+ * has a reference count of 1 (for the "child<...>" property from the parent),
+ * so the object will be finalized automatically when the parent gets removed.
+ */
+void sysbus_init_child_obj(Object *parent, const char *childname, void *child,
+                           size_t childsize, const char *childtype);
+
 /* Call func for every dynamically created sysbus device in the system */
 void foreach_dynamic_sysbus_device(FindSysbusDeviceFunc *func, void *opaque);