sclp/s390: rework sclp cpu hotplug device notification

Let's get rid of this strange local variable + irq logic and
work directly on the QOM. (hint: what happens if two such devices
are created?)

We could introduce proper QOM class + state for the cpu hotplug device,
however that would result in too much overhead for a simple
"trigger_signal" function.

Also remove one unnecessary class function initialization.

Reviewed-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

hw/s390x/sclpcpu.c

@@ -25,13 +25,16 @@ typedef struct ConfigMgtData {
     uint8_t event_qualifier;
 } QEMU_PACKED ConfigMgtData;
 
-static qemu_irq *irq_cpu_hotplug; /* Only used in this file */
-
 #define EVENT_QUAL_CPU_CHANGE  1
 
 void raise_irq_cpu_hotplug(void)
 {
-    qemu_irq_raise(*irq_cpu_hotplug);
+    Object *obj = object_resolve_path_type("", TYPE_SCLP_CPU_HOTPLUG, NULL);
+
+    SCLP_EVENT(obj)->event_pending = true;
+
+    /* Trigger SCLP read operation */
+    sclp_service_interrupt(0);
 }
 
 static unsigned int send_mask(void)
@@ -70,31 +73,14 @@ static int read_event_data(SCLPEvent *event, EventBufferHeader *evt_buf_hdr,
     return 1;
 }
 
-static void trigger_signal(void *opaque, int n, int level)
-{
-    SCLPEvent *event = opaque;
-    event->event_pending = true;
-
-    /* Trigger SCLP read operation */
-    sclp_service_interrupt(0);
-}
-
-static int irq_cpu_hotplug_init(SCLPEvent *event)
-{
-    irq_cpu_hotplug = qemu_allocate_irqs(trigger_signal, event, 1);
-    return 0;
-}
-
 static void cpu_class_init(ObjectClass *oc, void *data)
 {
     SCLPEventClass *k = SCLP_EVENT_CLASS(oc);
     DeviceClass *dc = DEVICE_CLASS(oc);
 
-    k->init = irq_cpu_hotplug_init;
     k->get_send_mask = send_mask;
     k->get_receive_mask = receive_mask;
     k->read_event_data = read_event_data;
-    k->write_event_data = NULL;
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 }