pcspk: convert "pit" property type from ptr to link

The speaker device needs pointer to ISA PIT device to operate. But according to
qdev-properties.h, properties of pointer type should be avoided. It seems a
link type property is a good substitution.
Signed-off-by: NEfimov Vasily <real@ispras.ru>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/audio/pcspk.c

@@ -31,6 +31,7 @@
 #include "qemu/timer.h"
 #include "hw/timer/i8254.h"
 #include "hw/audio/pcspk.h"
+#include "qapi/error.h"
 
 #define PCSPK_BUF_LEN 1792
 #define PCSPK_SAMPLE_RATE 32000
@@ -169,6 +170,11 @@ static void pcspk_initfn(Object *obj)
     PCSpkState *s = PC_SPEAKER(obj);
 
     memory_region_init_io(&s->ioport, OBJECT(s), &pcspk_io_ops, s, "pcspk", 1);
+
+    object_property_add_link(obj, "pit", TYPE_I8254,
+                             (Object **)&s->pit,
+                             qdev_prop_allow_set_link_before_realize,
+                             0, &error_abort);
 }
 
 static void pcspk_realizefn(DeviceState *dev, Error **errp)
@@ -183,7 +189,6 @@ static void pcspk_realizefn(DeviceState *dev, Error **errp)
 
 static Property pcspk_properties[] = {
     DEFINE_PROP_UINT32("iobase", PCSpkState, iobase,  -1),
-    DEFINE_PROP_PTR("pit", PCSpkState, pit),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -194,7 +199,7 @@ static void pcspk_class_initfn(ObjectClass *klass, void *data)
     dc->realize = pcspk_realizefn;
     set_bit(DEVICE_CATEGORY_SOUND, dc->categories);
     dc->props = pcspk_properties;
-    /* Reason: pointer property "pit", realize sets global pcspk_state */
+    /* Reason: realize sets global pcspk_state */
     dc->cannot_instantiate_with_device_add_yet = true;
 }
 

include/hw/audio/pcspk.h

@@ -38,7 +38,7 @@ static inline ISADevice *pcspk_init(ISABus *bus, ISADevice *pit)
     isadev = isa_create(bus, TYPE_PC_SPEAKER);
     dev = DEVICE(isadev);
     qdev_prop_set_uint32(dev, "iobase", 0x61);
-    qdev_prop_set_ptr(dev, "pit", pit);
+    object_property_set_link(OBJECT(dev), OBJECT(pit), "pit", NULL);
     qdev_init_nofail(dev);
 
     return isadev;