[15/21] qom: add Device class

diff --git a/Makefile.qom b/Makefile.qom
index 34f1f91..c694cbb 100644
--- a/Makefile.qom
+++ b/Makefile.qom
@@ -13,3 +13,6 @@  common-obj-y += $(addprefix qapi/,$(qapi-obj-y))
 include $(SRC_PATH)/qom/Makefile
 common-obj-y += $(addprefix qom/,$(qom-obj-y))
 
+include $(SRC_PATH)/devices/Makefile
+common-obj-y += $(addprefix devices/,$(devices-obj-y))
+
diff --git a/Qconfig b/Qconfig
index 889dfa6..03f2a87 100644
--- a/Qconfig
+++ b/Qconfig
@@ -1,2 +1,3 @@ 
 source qapi/Qconfig
 source qom/Qconfig
+source devices/Qconfig
diff --git a/configure b/configure
index 93e5e97..6ec1020 100755
--- a/configure
+++ b/configure
@@ -3516,7 +3516,7 @@  DIRS="$DIRS pc-bios/spapr-rtas"
 DIRS="$DIRS roms/seabios roms/vgabios"
 DIRS="$DIRS fsdev ui"
 DIRS="$DIRS qapi"
-DIRS="$DIRS qga qom"
+DIRS="$DIRS qga qom devices"
 FILES="Makefile tests/Makefile"
 FILES="$FILES tests/cris/Makefile tests/cris/.gdbinit"
 FILES="$FILES pc-bios/optionrom/Makefile pc-bios/keymaps"
diff --git a/devices/Makefile b/devices/Makefile
new file mode 100644
index 0000000..fbb0b82
--- /dev/null
+++ b/devices/Makefile
@@ -0,0 +1 @@ 
+devices-obj-$(CONFIG_DEVICE) := device.o
diff --git a/devices/Qconfig b/devices/Qconfig
new file mode 100644
index 0000000..6a06417
--- /dev/null
+++ b/devices/Qconfig
@@ -0,0 +1,6 @@ 
+config DEVICE
+       bool "QOM based device model"
+       default y
+       depends on QOM && QAPI_QMP
+       help
+         Device model
diff --git a/devices/device.c b/devices/device.c
new file mode 100644
index 0000000..5d289fc
--- /dev/null
+++ b/devices/device.c
@@ -0,0 +1,125 @@ 
+#include "qemu/device.h"
+#include "qapi/qmp-output-visitor.h"
+#include "qapi/qmp-input-visitor.h"
+
+static void device_state_accessor(Plug *plug, const char *name, Visitor *v, void *opaque, Error **errp)
+{
+    DeviceClass *class = DEVICE_GET_CLASS(DEVICE(plug));
+    return class->visit(DEVICE(plug), v, name, errp);
+}
+
+static void device_initfn(TypeInstance *obj)
+{
+    Device *device = DEVICE(obj);
+
+    plug_add_property_full(PLUG(device), "state",
+                           device_state_accessor,
+                           device_state_accessor,
+                           NULL,
+                           NULL,
+                           type_get_type(obj),
+                           PROP_F_READWRITE);
+}
+
+void device_visit(Device *device, Visitor *v, const char *name, Error **errp)
+{
+    visit_start_struct(v, (void **)&device, "Device", name, 0, errp);
+    visit_end_struct(v, errp);
+}
+
+static void device_visit_properties(Device *device, bool is_input, const char *name, Visitor *v, Error **errp);
+
+typedef struct DeviceVisitPropertyData
+{
+    Visitor *v;
+    Error **errp;
+    bool is_input;
+} DeviceVisitPropertyData;
+
+static void device_visit_property(Plug *plug, const char *name, const char *typename, int flags, void *opaque)
+{
+    DeviceVisitPropertyData *data = opaque;
+
+    if (strcmp(name, "state") == 0 || strcmp(name, "realized") == 0) {
+        return;
+    }
+
+    if (strstart(typename, "plug<", NULL)) {
+        Device *value = DEVICE(plug_get_property_plug(plug, NULL, name));
+        device_visit_properties(value, data->is_input, name, data->v, data->errp);
+    } else if (data->is_input) {
+        if ((flags & PROP_F_READ) && (flags & PROP_F_WRITE)) {
+            plug_set_property(plug, name, data->v, data->errp);
+        }
+    } else {
+        if (flags & PROP_F_READ) {
+            plug_get_property(plug, name, data->v, data->errp);
+        }
+    }
+}
+
+static void device_visit_properties(Device *device, bool is_input, const char *name, Visitor *v, Error **errp)
+{
+    DeviceVisitPropertyData data = {
+        .v = v,
+        .errp = errp,
+        .is_input = is_input,
+    };
+
+    visit_start_struct(v, (void **)&device, "Device", name, sizeof(Device), errp);
+    plug_foreach_property(PLUG(device), device_visit_property, &data);
+    visit_end_struct(v, errp);
+}
+
+static void device_unrealize(Plug *plug)
+{
+    Device *device = DEVICE(plug);
+    const char *typename;
+    char id[MAX_ID];
+    QmpOutputVisitor *qov;
+    QmpInputVisitor *qiv;
+    Error *local_err = NULL; // FIXME
+
+    snprintf(id, sizeof(id), "%s", type_get_id(TYPE_INSTANCE(device)));
+    typename = type_get_type(TYPE_INSTANCE(device));
+
+    qov = qmp_output_visitor_new();
+
+    device_visit_properties(device, false, id, qmp_output_get_visitor(qov), &local_err);
+
+    type_finalize(device);
+    type_initialize(device, typename, id);
+
+    qiv = qmp_input_visitor_new(qmp_output_get_qobject(qov));
+
+    device_visit_properties(device, true, id, qmp_input_get_visitor(qiv), &local_err);
+
+    qmp_input_visitor_cleanup(qiv);
+    qmp_output_visitor_cleanup(qov);
+}
+
+static void device_class_initfn(TypeClass *type_class)
+{
+    PlugClass *plug_class = PLUG_CLASS(type_class);
+    DeviceClass *class = DEVICE_CLASS(type_class);
+
+    plug_class->unrealize = device_unrealize;
+    class->visit = device_visit;
+}
+
+static const TypeInfo device_type_info = {
+    .name = TYPE_DEVICE,
+    .parent = TYPE_PLUG,
+    .instance_size = sizeof(Device),
+    .class_size = sizeof(DeviceClass),
+    .class_init = device_class_initfn,
+    .instance_init = device_initfn,
+    .abstract = true,
+};
+
+static void register_devices(void)
+{
+    type_register_static(&device_type_info);
+}
+
+device_init(register_devices);
diff --git a/include/qemu/device.h b/include/qemu/device.h
new file mode 100644
index 0000000..8e15232
--- /dev/null
+++ b/include/qemu/device.h
@@ -0,0 +1,28 @@ 
+#ifndef DEVICE_H
+#define DEVICE_H
+
+#include "qemu/plug.h"
+
+typedef struct Device
+{
+    Plug parent;
+} Device;
+
+typedef void (DeviceVisitor)(Device *device, Visitor *v, const char *name, Error **errp);
+
+typedef struct DeviceClass
+{
+    PlugClass parent_class;
+
+    /* public */
+    DeviceVisitor *visit;
+} DeviceClass;
+
+#define TYPE_DEVICE "device"
+#define DEVICE(obj) TYPE_CHECK(Device, obj, TYPE_DEVICE)
+#define DEVICE_CLASS(class) TYPE_CLASS_CHECK(DeviceClass, class, TYPE_DEVICE)
+#define DEVICE_GET_CLASS(obj) TYPE_GET_CLASS(DeviceClass, obj, TYPE_DEVICE)
+
+void device_visit(Device *device, Visitor *v, const char *name, Error **errp);
+
+#endif