Introduce machine property "audiodev"

Many machine types have default audio devices with no way to set the underlying
audiodev.  Instead of adding an option for each and every one of them, this new
property can be used as a default during machine initialisation when creating
such devices.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
[Make the property optional, instead of including it in all machines. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/core/machine.c

@@ -39,6 +39,7 @@
 #include "hw/virtio/virtio.h"
 #include "hw/virtio/virtio-pci.h"
 #include "hw/virtio/virtio-net.h"
+#include "audio/audio.h"
 
 GlobalProperty hw_compat_8_1[] = {};
 const size_t hw_compat_8_1_len = G_N_ELEMENTS(hw_compat_8_1);
@@ -686,6 +687,26 @@ bool device_type_is_dynamic_sysbus(MachineClass *mc, const char *type)
     return allowed;
 }
 
+static char *machine_get_audiodev(Object *obj, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    return g_strdup(ms->audiodev);
+}
+
+static void machine_set_audiodev(Object *obj, const char *value,
+                                 Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    if (!audio_state_by_name(value, errp)) {
+        return;
+    }
+
+    g_free(ms->audiodev);
+    ms->audiodev = g_strdup(value);
+}
+
 HotpluggableCPUList *machine_query_hotpluggable_cpus(MachineState *machine)
 {
     int i;
@@ -931,6 +952,17 @@ out_free:
     qapi_free_BootConfiguration(config);
 }
 
+void machine_add_audiodev_property(MachineClass *mc)
+{
+    ObjectClass *oc = OBJECT_CLASS(mc);
+
+    object_class_property_add_str(oc, "audiodev",
+                                  machine_get_audiodev,
+                                  machine_set_audiodev);
+    object_class_property_set_description(oc, "audiodev",
+                                          "Audiodev to use for default machine devices");
+}
+
 static void machine_class_init(ObjectClass *oc, void *data)
 {
     MachineClass *mc = MACHINE_CLASS(oc);
@@ -1136,6 +1168,7 @@ static void machine_finalize(Object *obj)
     g_free(ms->device_memory);
     g_free(ms->nvdimms_state);
     g_free(ms->numa_state);
+    g_free(ms->audiodev);
 }
 
 bool machine_usb(MachineState *machine)

include/hw/boards.h

@@ -24,6 +24,7 @@ OBJECT_DECLARE_TYPE(MachineState, MachineClass, MACHINE)
 
 extern MachineState *current_machine;
 
+void machine_add_audiodev_property(MachineClass *mc);
 void machine_run_board_init(MachineState *machine, const char *mem_path, Error **errp);
 bool machine_usb(MachineState *machine);
 int machine_phandle_start(MachineState *machine);
@@ -358,6 +359,14 @@ struct MachineState {
     MemoryRegion *ram;
     DeviceMemoryState *device_memory;
 
+    /*
+     * Included in MachineState for simplicity, but not supported
+     * unless machine_add_audiodev_property is called.  Boards
+     * that have embedded audio devices can call it from the
+     * machine init function and forward the property to the device.
+     */
+    char *audiodev;
+
     ram_addr_t ram_size;
     ram_addr_t maxram_size;
     uint64_t   ram_slots;