platform-bus-device: use device plug callback instead of machine_done notifier

platform-bus were using machine_done notifier to get and map
(assign irq/mmio resources) dynamically added sysbus devices
after all '-device' options had been processed.
That however creates non obvious dependencies on ordering of
machine_done notifiers and requires carefull line juggling
to keep it working. For example see comment above
create_platform_bus() and 'straitforward' arm_load_kernel()
had to converted to machine_done notifier and that lead to
yet another machine_done notifier to keep it working
arm_register_platform_bus_fdt_creator().

Instead of hiding resource assignment in platform-bus-device
to magically initialize sysbus devices, use device plug
callback and assign resources explicitly at board level
at the moment each -device option is being processed.

That adds a bunch of machine declaration boiler plate to
e500plat board, similar to ARM/x86 but gets rid of hidden
machine_done notifier and would allow to remove the dependent
notifiers in ARM code simplifying it and making code flow
easier to follow.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Message-id: 1525691524-32265-3-git-send-email-imammedo@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 31 insertions, 3 deletions

diff --git a/hw/arm/sysbus-fdt.c b/hw/arm/sysbus-fdt.c
index d68e3dcdbd..80ff70e1ed 100644
--- a/hw/arm/sysbus-fdt.c
+++ b/hw/arm/sysbus-fdt.c
@@ -506,9 +506,6 @@ static void add_all_platform_bus_fdt_nodes(ARMPlatformBusFDTParams *fdt_params)
     dev = qdev_find_recursive(sysbus_get_default(), TYPE_PLATFORM_BUS_DEVICE);
     pbus = PLATFORM_BUS_DEVICE(dev);
 
-    /* We can only create dt nodes for dynamic devices when they're ready */
-    assert(pbus->done_gathering);
-
     PlatformBusFDTData data = {
         .fdt = fdt,
         .irq_start = irq_start,
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 11b9f599ca..1f54223f19 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1150,6 +1150,7 @@ static void create_platform_bus(VirtMachineState *vms, qemu_irq *pic)
     qdev_prop_set_uint32(dev, "mmio_size",
         platform_bus_params.platform_bus_size);
     qdev_init_nofail(dev);
+    vms->platform_bus_dev = dev;
     s = SYS_BUS_DEVICE(dev);
 
     for (i = 0; i < platform_bus_params.platform_bus_num_irqs; i++) {
@@ -1627,9 +1628,33 @@ static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
     return ms->possible_cpus;
 }
 
+static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
+                                        DeviceState *dev, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
+
+    if (vms->platform_bus_dev) {
+        if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
+            platform_bus_link_device(PLATFORM_BUS_DEVICE(vms->platform_bus_dev),
+                                     SYS_BUS_DEVICE(dev));
+        }
+    }
+}
+
+static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine,
+                                                        DeviceState *dev)
+{
+    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
+        return HOTPLUG_HANDLER(machine);
+    }
+
+    return NULL;
+}
+
 static void virt_machine_class_init(ObjectClass *oc, void *data)
 {
     MachineClass *mc = MACHINE_CLASS(oc);
+    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
 
     mc->init = machvirt_init;
     /* Start max_cpus at the maximum QEMU supports. We'll further restrict
@@ -1648,6 +1673,8 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     mc->cpu_index_to_instance_props = virt_cpu_index_to_props;
     mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
     mc->get_default_cpu_node_id = virt_get_default_cpu_node_id;
+    mc->get_hotplug_handler = virt_machine_get_hotplug_handler;
+    hc->plug = virt_machine_device_plug_cb;
 }
 
 static const TypeInfo virt_machine_info = {
@@ -1657,6 +1684,10 @@ static const TypeInfo virt_machine_info = {
     .instance_size = sizeof(VirtMachineState),
     .class_size    = sizeof(VirtMachineClass),
     .class_init    = virt_machine_class_init,
+    .interfaces = (InterfaceInfo[]) {
+         { TYPE_HOTPLUG_HANDLER },
+         { }
+    },
 };
 
 static void machvirt_machine_init(void)