Let's start simple and put qdev_new() to use.  Coccinelle script:

    @ depends on !(file in "hw/core/qdev.c")@
    expression type_name;
    @@
    -    DEVICE(object_new(type_name))
    +    qdev_new(type_name)

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 hw/block/nand.c  | 2 +-
 hw/misc/auxbus.c | 2 +-
 qdev-monitor.c   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/block/nand.c b/hw/block/nand.c
index bba89688ba..cdf3429ce6 100644
--- a/hw/block/nand.c
+++ b/hw/block/nand.c
@@ -644,7 +644,7 @@ DeviceState *nand_init(BlockBackend *blk, int manf_id, int chip_id)
     if (nand_flash_ids[chip_id].size == 0) {
         hw_error("%s: Unsupported NAND chip ID.\n", __func__);
     }
-    dev = DEVICE(object_new(TYPE_NAND));
+    dev = qdev_new(TYPE_NAND);
     qdev_prop_set_uint8(dev, "manufacturer_id", manf_id);
     qdev_prop_set_uint8(dev, "chip_id", chip_id);
     if (blk) {
diff --git a/hw/misc/auxbus.c b/hw/misc/auxbus.c
index 5e4794f0ac..7fb020086f 100644
--- a/hw/misc/auxbus.c
+++ b/hw/misc/auxbus.c
@@ -273,7 +273,7 @@ DeviceState *aux_create_slave(AUXBus *bus, const char *type)
 {
     DeviceState *dev;
 
-    dev = DEVICE(object_new(type));
+    dev = qdev_new(type);
     assert(dev);
     qdev_set_parent_bus(dev, &bus->qbus);
     return dev;
diff --git a/qdev-monitor.c b/qdev-monitor.c
index 07f78e9f5d..bbbbf3d907 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -652,7 +652,7 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
     }
 
     /* create device */
-    dev = DEVICE(object_new(driver));
+    dev = qdev_new(driver);
 
     /* Check whether the hotplug is allowed by the machine */
     if (qdev_hotplug && !qdev_hotplug_allowed(dev, &err)) {
-- 
2.21.1