qdev: Introduce PropertyInfo.create

This allows property implementation to provide a specialized property
creation method.

Update conditions guarding property types accordingly.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170714021509.23681-3-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/core/qdev.c

@@ -744,6 +744,10 @@ static void qdev_property_add_legacy(DeviceState *dev, Property *prop,
         return;
     }
 
+    if (prop->info->create) {
+        return;
+    }
+
     name = g_strdup_printf("legacy-%s", prop->name);
     object_property_add(OBJECT(dev), name, "str",
                         prop->info->print ? qdev_get_legacy_property : prop->info->get,
@@ -770,20 +774,23 @@ void qdev_property_add_static(DeviceState *dev, Property *prop,
     Error *local_err = NULL;
     Object *obj = OBJECT(dev);
 
-    /*
-     * TODO qdev_prop_ptr does not have getters or setters.  It must
-     * go now that it can be replaced with links.  The test should be
-     * removed along with it: all static properties are read/write.
-     */
-    if (!prop->info->get && !prop->info->set) {
-        return;
+    if (prop->info->create) {
+        prop->info->create(obj, prop, &local_err);
+    } else {
+        /*
+         * TODO qdev_prop_ptr does not have getters or setters.  It must
+         * go now that it can be replaced with links.  The test should be
+         * removed along with it: all static properties are read/write.
+         */
+        if (!prop->info->get && !prop->info->set) {
+            return;
+        }
+        object_property_add(obj, prop->name, prop->info->name,
+                            prop->info->get, prop->info->set,
+                            prop->info->release,
+                            prop, &local_err);
     }
 
-    object_property_add(obj, prop->name, prop->info->name,
-                        prop->info->get, prop->info->set,
-                        prop->info->release,
-                        prop, &local_err);
-
     if (local_err) {
         error_propagate(errp, local_err);
         return;

include/hw/qdev-core.h

@@ -241,6 +241,7 @@ struct PropertyInfo {
     const char * const *enum_table;
     int (*print)(DeviceState *dev, Property *prop, char *dest, size_t len);
     void (*set_default_value)(Object *obj, const Property *prop);
+    void (*create)(Object *obj, Property *prop, Error **errp);
     ObjectPropertyAccessor *get;
     ObjectPropertyAccessor *set;
     ObjectPropertyRelease *release;

qmp.c

@@ -480,7 +480,7 @@ static DevicePropertyInfo *make_device_property_info(ObjectClass *klass,
              * for removal.  This conditional should be removed along with
              * it.
              */
-            if (!prop->info->set) {
+            if (!prop->info->set && !prop->info->create) {
                 return NULL;           /* no way to set it, don't show */
             }