hw/riscv: virt: Add device plug support

Add support for plugging in devices, this was tested with the TPM
device.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20220427234146.1130752-6-alistair.francis@opensource.wdc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

hw/riscv/virt.c

@@ -1569,10 +1569,37 @@ static void virt_set_aclint(Object *obj, bool value, Error **errp)
     s->have_aclint = value;
 }
 
+static HotplugHandler *virt_machine_get_hotplug_handler(MachineState *machine,
+                                                        DeviceState *dev)
+{
+    MachineClass *mc = MACHINE_GET_CLASS(machine);
+
+    if (device_is_dynamic_sysbus(mc, dev)) {
+        return HOTPLUG_HANDLER(machine);
+    }
+    return NULL;
+}
+
+static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
+                                        DeviceState *dev, Error **errp)
+{
+    RISCVVirtState *s = RISCV_VIRT_MACHINE(hotplug_dev);
+
+    if (s->platform_bus_dev) {
+        MachineClass *mc = MACHINE_GET_CLASS(s);
+
+        if (device_is_dynamic_sysbus(mc, dev)) {
+            platform_bus_link_device(PLATFORM_BUS_DEVICE(s->platform_bus_dev),
+                                     SYS_BUS_DEVICE(dev));
+        }
+    }
+}
+
 static void virt_machine_class_init(ObjectClass *oc, void *data)
 {
     char str[128];
     MachineClass *mc = MACHINE_CLASS(oc);
+    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
 
     mc->desc = "RISC-V VirtIO board";
     mc->init = virt_machine_init;
@@ -1584,6 +1611,10 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
     mc->get_default_cpu_node_id = riscv_numa_get_default_cpu_node_id;
     mc->numa_mem_supported = true;
     mc->default_ram_id = "riscv_virt_board.ram";
+    assert(!mc->get_hotplug_handler);
+    mc->get_hotplug_handler = virt_machine_get_hotplug_handler;
+
+    hc->plug = virt_machine_device_plug_cb;
 
     machine_class_allow_dynamic_sysbus_dev(mc, TYPE_RAMFB_DEVICE);
 
@@ -1614,6 +1645,10 @@ static const TypeInfo virt_machine_typeinfo = {
     .class_init = virt_machine_class_init,
     .instance_init = virt_machine_instance_init,
     .instance_size = sizeof(RISCVVirtState),
+    .interfaces = (InterfaceInfo[]) {
+         { TYPE_HOTPLUG_HANDLER },
+         { }
+    },
 };
 
 static void virt_machine_init_register_types(void)