qdev: reset qdev along with qdev tree

This patch changes the reset handling so that qdev has no knowledge of the
global system reset.  Instead, a new bus/device level function is introduced
that allows all devices/buses on the bus/device to be reset using a depth
first transversal.

N.B. we have to expose the implicit system bus because we have various hacks
that result in an implicit system bus existing.  Instead, we ought to have an
explicitly created system bus that we can trigger reset from.  That's a topic
for a future patch though.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NIsaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/qdev.c

@@ -257,13 +257,6 @@ DeviceState *qdev_device_add(QemuOpts *opts)
     return qdev;
 }
 
-static void qdev_reset(void *opaque)
-{
-    DeviceState *dev = opaque;
-    if (dev->info->reset)
-        dev->info->reset(dev);
-}
-
 /* Initialize a device.  Device properties should be set before calling
    this function.  IRQs and MMIO regions should be connected/mapped after
    calling this function.
@@ -279,7 +272,6 @@ int qdev_init(DeviceState *dev)
         qdev_free(dev);
         return rc;
     }
-    qemu_register_reset(qdev_reset, dev);
     if (dev->info->vmsd) {
         vmstate_register_with_alias_id(dev, -1, dev->info->vmsd, dev,
                                        dev->instance_id_alias,
@@ -308,6 +300,25 @@ int qdev_unplug(DeviceState *dev)
     return dev->info->unplug(dev);
 }
 
+static int qdev_reset_one(DeviceState *dev, void *opaque)
+{
+    if (dev->info->reset) {
+        dev->info->reset(dev);
+    }
+
+    return 0;
+}
+
+BusState *sysbus_get_default(void)
+{
+    return main_system_bus;
+}
+
+void qbus_reset_all(BusState *bus)
+{
+    qbus_walk_children(bus, qdev_reset_one, NULL, NULL);
+}
+
 /* can be used as ->unplug() callback for the simple cases */
 int qdev_simple_unplug_cb(DeviceState *dev)
 {
@@ -351,7 +362,6 @@ void qdev_free(DeviceState *dev)
         if (dev->opts)
             qemu_opts_del(dev->opts);
     }
-    qemu_unregister_reset(qdev_reset, dev);
     QLIST_REMOVE(dev, sibling);
     for (prop = dev->info->props; prop && prop->name; prop++) {
         if (prop->info->free) {

hw/qdev.h

@@ -187,10 +187,14 @@ int qbus_walk_children(BusState *bus, qdev_walkerfn *devfn,
                        qbus_walkerfn *busfn, void *opaque);
 int qdev_walk_children(DeviceState *dev, qdev_walkerfn *devfn,
                        qbus_walkerfn *busfn, void *opaque);
+void qbus_reset_all(BusState *bus);
 void qbus_free(BusState *bus);
 
 #define FROM_QBUS(type, dev) DO_UPCAST(type, qbus, dev)
 
+/* This should go away once we get rid of the NULL bus hack */
+BusState *sysbus_get_default(void);
+
 /*** monitor commands ***/
 
 void do_info_qtree(Monitor *mon);

vl.c

@@ -2976,6 +2976,7 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
+    qemu_register_reset((void *)qbus_reset_all, sysbus_get_default());
     qemu_system_reset();
     if (loadvm) {
         if (load_vmstate(loadvm) < 0) {