[Qemu-devel] [PATCH 1/2 RFC] pci: detangle Sysbus PCI bridge from PCIBus

[Frank Blaschka <blaschka@linux.vnet.ibm.com>]

This patch detangle Sysbus PCI bridge from PCIBus. The pci host
bridge is derived from sysbus device and therefore it is not possible
to hotplug a host bridge. This change makes it possible to develop
hotplugable devices creating a pci bus on the fly.

Signed-off-by: Frank Blaschka <blaschka@linux.vnet.ibm.com>
---
 hw/pci/pci.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index cc5d946..553a130 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -253,9 +253,11 @@ static void pcibus_reset(BusState *qbus)
 
 static void pci_host_bus_register(PCIBus *bus, DeviceState *parent)
 {
-    PCIHostState *host_bridge = PCI_HOST_BRIDGE(parent);
-
-    QLIST_INSERT_HEAD(&pci_host_bridges, host_bridge, next);
+    PCIHostState *host_bridge = (PCIHostState *)object_dynamic_cast(
+                                OBJECT(parent), TYPE_PCI_HOST_BRIDGE);
+    if (host_bridge) {
+        QLIST_INSERT_HEAD(&pci_host_bridges, host_bridge, next);
+    }
 }
 
 PCIBus *pci_find_primary_bus(void)
@@ -288,14 +290,20 @@ PCIBus *pci_device_root_bus(const PCIDevice *d)
 const char *pci_root_bus_path(PCIDevice *dev)
 {
     PCIBus *rootbus = pci_device_root_bus(dev);
-    PCIHostState *host_bridge = PCI_HOST_BRIDGE(rootbus->qbus.parent);
-    PCIHostBridgeClass *hc = PCI_HOST_BRIDGE_GET_CLASS(host_bridge);
+    PCIHostState *host_bridge;
+    PCIHostBridgeClass *hc;
+
+    host_bridge = (PCIHostState *)object_dynamic_cast(
+                  OBJECT(rootbus->qbus.parent), TYPE_PCI_HOST_BRIDGE);
 
     assert(!rootbus->parent_dev);
-    assert(host_bridge->bus == rootbus);
 
-    if (hc->root_bus_path) {
-        return (*hc->root_bus_path)(host_bridge, rootbus);
+    if (host_bridge) {
+        assert(host_bridge->bus == rootbus);
+        hc = PCI_HOST_BRIDGE_GET_CLASS(host_bridge);
+        if (hc->root_bus_path) {
+            return (*hc->root_bus_path)(host_bridge, rootbus);
+        }
     }
 
     return rootbus->qbus.name;
-- 
2.1.4