[03/55] qdev: New qdev_new(), qdev_realize(), etc.

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index b870b27966..fba29308f7 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -57,7 +57,7 @@  typedef void (*BusUnrealize)(BusState *bus);
  * After successful realization, setting static properties will fail.
  *
  * As an interim step, the #DeviceState:realized property can also be
- * set with qdev_init_nofail().
+ * set with qdev_realize() or qdev_init_nofail().
  * In the future, devices will propagate this state change to their children
  * and along busses they expose.
  * The point in time will be deferred to machine creation, so that values
@@ -322,7 +322,13 @@  compat_props_add(GPtrArray *arr,
 
 DeviceState *qdev_create(BusState *bus, const char *name);
 DeviceState *qdev_try_create(BusState *bus, const char *name);
+DeviceState *qdev_new(const char *name);
+DeviceState *qdev_try_new(const char *name);
 void qdev_init_nofail(DeviceState *dev);
+bool qdev_realize(DeviceState *dev, BusState *bus, Error **errp);
+bool qdev_realize_and_unref(DeviceState *dev, BusState *bus, Error **errp);
+void qdev_unrealize(DeviceState *dev);
+
 void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                  int required_for_version);
 HotplugHandler *qdev_get_bus_hotplug_handler(DeviceState *dev);
@@ -411,6 +417,9 @@  typedef int (qdev_walkerfn)(DeviceState *dev, void *opaque);
 void qbus_create_inplace(void *bus, size_t size, const char *typename,
                          DeviceState *parent, const char *name);
 BusState *qbus_create(const char *typename, DeviceState *parent, const char *name);
+bool qbus_realize(BusState *bus, Error **errp);
+void qbus_unrealize(BusState *bus);
+
 /* Returns > 0 if either devfn or busfn skip walk somewhere in cursion,
  *         < 0 if either devfn or busfn terminate walk somewhere in cursion,
  *           0 otherwise. */
diff --git a/hw/core/bus.c b/hw/core/bus.c
index 08c5eab24a..bf622604a3 100644
--- a/hw/core/bus.c
+++ b/hw/core/bus.c
@@ -169,6 +169,20 @@  BusState *qbus_create(const char *typename, DeviceState *parent, const char *nam
     return bus;
 }
 
+bool qbus_realize(BusState *bus, Error **errp)
+{
+    Error *err = NULL;
+
+    object_property_set_bool(OBJECT(bus), true, "realized", &err);
+    error_propagate(errp, err);
+    return !err;
+}
+
+void qbus_unrealize(BusState *bus)
+{
+    object_property_set_bool(OBJECT(bus), true, "realized", &error_abort);
+}
+
 static bool bus_get_realized(Object *obj, Error **errp)
 {
     BusState *bus = BUS(obj);
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index a68ba674db..82deeb7841 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -176,6 +176,32 @@  DeviceState *qdev_try_create(BusState *bus, const char *type)
     return dev;
 }
 
+/*
+ * Create a device on the heap.
+ * A type @name must exist.
+ * This only initializes the device state structure and allows
+ * properties to be set.  The device still needs to be realized.  See
+ * qdev-core.h.
+ */
+DeviceState *qdev_new(const char *name)
+{
+    return DEVICE(object_new(name));
+}
+
+/*
+ * Try to create a device on the heap.
+ * This is like qdev_new(), except it returns %NULL when type @name
+ * does not exist.
+ */
+DeviceState *qdev_try_new(const char *name)
+{
+    if (!object_class_by_name(name)) {
+        return NULL;
+    }
+
+    return DEVICE(object_new(name));
+}
+
 static QTAILQ_HEAD(, DeviceListener) device_listeners
     = QTAILQ_HEAD_INITIALIZER(device_listeners);
 
@@ -427,6 +453,70 @@  void qdev_init_nofail(DeviceState *dev)
     object_unref(OBJECT(dev));
 }
 
+/*
+ * Realize @dev.
+ * @dev must not be plugged into a bus.
+ * Plug @dev into @bus if non-null, else into the main system bus.
+ * This takes a reference to @dev.
+ * If @dev has no QOM parent, make one up, taking another reference.
+ * On success, return true.
+ * On failure, store an error through @errp and return false.
+ */
+bool qdev_realize(DeviceState *dev, BusState *bus, Error **errp)
+{
+    Error *err = NULL;
+
+    assert(!dev->realized && !dev->parent_bus);
+
+    if (!bus) {
+        /*
+         * Assert that the device really is a SysBusDevice before we
+         * put it onto the sysbus.  Non-sysbus devices which aren't
+         * being put onto a bus should be realized with
+         * object_property_set_bool(OBJECT(dev), true, "realized",
+         * errp);
+         */
+        g_assert(object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE));
+        bus = sysbus_get_default();
+    }
+
+    qdev_set_parent_bus(dev, bus);
+
+    object_ref(OBJECT(dev));
+    object_property_set_bool(OBJECT(dev), true, "realized", &err);
+    if (err) {
+        error_propagate_prepend(errp, err,
+                                "Initialization of device %s failed: ",
+                                object_get_typename(OBJECT(dev)));
+    }
+    object_unref(OBJECT(dev));
+    return !err;
+}
+
+/*
+ * Realize @dev and drop a reference.
+ * This is like qdev_realize(), except it steals a reference rather
+ * than take one to plug @dev into @bus.  On failure, it drops that
+ * reference instead.  Intended use:
+ *     dev = qdev_new();
+ *     [...]
+ *     qdev_realize_and_unref(dev, bus, errp);
+ * Now @dev can go away without further ado.
+ */
+bool qdev_realize_and_unref(DeviceState *dev, BusState *bus, Error **errp)
+{
+    bool ret;
+
+    ret = qdev_realize(dev, bus, errp);
+    object_unref(OBJECT(dev));
+    return ret;
+}
+
+void qdev_unrealize(DeviceState *dev)
+{
+    object_property_set_bool(OBJECT(dev), false, "realized", &error_abort);
+}
+
 static int qdev_assert_realized_properly(Object *obj, void *opaque)
 {
     DeviceState *dev = DEVICE(object_dynamic_cast(obj, TYPE_DEVICE));
@@ -1002,6 +1092,10 @@  post_realize_fail:
 fail:
     error_propagate(errp, local_err);
     if (unattached_parent) {
+        /*
+         * Beware, this doesn't just revert
+         * object_property_add_child(), it also runs bus_remove()!
+         */
         object_unparent(OBJECT(dev));
         unattached_count--;
     }