spapr, xics, xive: Introduce SpaprInterruptController QOM interface

The SpaprIrq structure is used to represent ths spapr machine's irq
backend.  Except that it kind of conflates two concepts: one is the
backend proper - a specific interrupt controller that we might or
might not be using, the other is the irq configuration which covers
the layout of irq space and which interrupt controllers are allowed.

This leads to some pretty confusing code paths for the "dual"
configuration where its hooks redirect to other SpaprIrq structures
depending on the currently active irq controller.

To clean this up, we start by introducing a new
SpaprInterruptController QOM interface to represent strictly an
interrupt controller backend, not counting anything configuration
related.  We implement this interface in the XICs and XIVE interrupt
controllers, and in future we'll move relevant methods from SpaprIrq
into it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>

hw/intc/spapr_xive.c

@@ -519,6 +519,10 @@ static const TypeInfo spapr_xive_info = {
     .instance_init = spapr_xive_instance_init,
     .instance_size = sizeof(SpaprXive),
     .class_init = spapr_xive_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_SPAPR_INTC },
+        { }
+    },
 };
 
 static void spapr_xive_register_types(void)

hw/intc/xics_spapr.c

@@ -343,6 +343,10 @@ static const TypeInfo ics_spapr_info = {
     .name = TYPE_ICS_SPAPR,
     .parent = TYPE_ICS,
     .class_init = ics_spapr_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_SPAPR_INTC },
+        { }
+    },
 };
 
 static void xics_spapr_register_types(void)

hw/ppc/spapr_irq.c

@@ -23,6 +23,12 @@
 
 #include "trace.h"
 
+static const TypeInfo spapr_intc_info = {
+    .name = TYPE_SPAPR_INTC,
+    .parent = TYPE_INTERFACE,
+    .class_size = sizeof(SpaprInterruptControllerClass),
+};
+
 void spapr_irq_msi_init(SpaprMachineState *spapr, uint32_t nr_msis)
 {
     spapr->irq_map_nr = nr_msis;
@@ -762,3 +768,10 @@ SpaprIrq spapr_irq_xics_legacy = {
     .set_irq     = spapr_irq_set_irq_xics,
     .init_kvm    = spapr_irq_init_kvm_xics,
 };
+
+static void spapr_irq_register_types(void)
+{
+    type_register_static(&spapr_intc_info);
+}
+
+type_init(spapr_irq_register_types)

include/hw/ppc/spapr_irq.h

@@ -31,6 +31,20 @@
 
 typedef struct SpaprMachineState SpaprMachineState;
 
+typedef struct SpaprInterruptController SpaprInterruptController;
+
+#define TYPE_SPAPR_INTC "spapr-interrupt-controller"
+#define SPAPR_INTC(obj)                                     \
+    INTERFACE_CHECK(SpaprInterruptController, (obj), TYPE_SPAPR_INTC)
+#define SPAPR_INTC_CLASS(klass)                                     \
+    OBJECT_CLASS_CHECK(SpaprInterruptControllerClass, (klass), TYPE_SPAPR_INTC)
+#define SPAPR_INTC_GET_CLASS(obj)                                   \
+    OBJECT_GET_CLASS(SpaprInterruptControllerClass, (obj), TYPE_SPAPR_INTC)
+
+typedef struct SpaprInterruptControllerClass {
+    InterfaceClass parent;
+} SpaprInterruptControllerClass;
+
 void spapr_irq_msi_init(SpaprMachineState *spapr, uint32_t nr_msis);
 int spapr_irq_msi_alloc(SpaprMachineState *spapr, uint32_t num, bool align,
                         Error **errp);