pseries: Refactor spapr irq allocation

Paulo Bonzini changed the original spapr code, which manually assigned irq
numbers for each virtual device, to allocate them automatically from the
device initialization. That allowed spapr virtual devices to be constructed
with -device, which is a good start.  However, the way that patch worked
doesn't extend nicely for the future when we want to support devices other
than sPAPR VIO devices (e.g. virtio and PCI).

This patch rearranges the irq allocation to be global across the sPAPR
environment, so it can be used by other bus types as well.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

hw/spapr.c

@@ -61,6 +61,30 @@
 
 sPAPREnvironment *spapr;
 
+qemu_irq spapr_allocate_irq(uint32_t hint, uint32_t *irq_num)
+{
+    uint32_t irq;
+    qemu_irq qirq;
+
+    if (hint) {
+        irq = hint;
+        /* FIXME: we should probably check for collisions somehow */
+    } else {
+        irq = spapr->next_irq++;
+    }
+
+    qirq = xics_find_qirq(spapr->icp, irq);
+    if (!qirq) {
+        return NULL;
+    }
+
+    if (irq_num) {
+        *irq_num = irq;
+    }
+
+    return qirq;
+}
+
 static void *spapr_create_fdt_skel(const char *cpu_model,
                                    target_phys_addr_t initrd_base,
                                    target_phys_addr_t initrd_size,
@@ -372,6 +396,7 @@ static void ppc_spapr_init(ram_addr_t ram_size,
 
     /* Set up Interrupt Controller */
     spapr->icp = xics_system_init(XICS_IRQS);
+    spapr->next_irq = 16;
 
     /* Set up VIO bus */
     spapr->vio_bus = spapr_vio_bus_init();

hw/spapr.h

@@ -17,6 +17,7 @@ typedef struct sPAPREnvironment {
     long rtas_size;
     void *fdt_skel;
     target_ulong entry_point;
+    int next_irq;
 } sPAPREnvironment;
 
 #define H_SUCCESS         0
@@ -281,11 +282,7 @@ void spapr_register_hypercall(target_ulong opcode, spapr_hcall_fn fn);
 target_ulong spapr_hypercall(CPUState *env, target_ulong opcode,
                              target_ulong *args);
 
-static inline qemu_irq spapr_find_qirq(sPAPREnvironment *spapr,
-                                        int irq_num)
-{
-    return xics_find_qirq(spapr->icp, irq_num);
-}
+qemu_irq spapr_allocate_irq(uint32_t hint, uint32_t *irq_num);
 
 static inline uint32_t rtas_ld(target_ulong phys, int n)
 {

hw/spapr_vio.c

@@ -600,7 +600,6 @@ static int spapr_vio_busdev_init(DeviceState *qdev, DeviceInfo *qinfo)
 {
     VIOsPAPRDeviceInfo *info = (VIOsPAPRDeviceInfo *)qinfo;
     VIOsPAPRDevice *dev = (VIOsPAPRDevice *)qdev;
-    VIOsPAPRBus *bus = DO_UPCAST(VIOsPAPRBus, bus, dev->qdev.parent_bus);
     char *id;
 
     if (asprintf(&id, "%s@%x", info->dt_name, dev->reg) < 0) {
@@ -608,10 +607,11 @@ static int spapr_vio_busdev_init(DeviceState *qdev, DeviceInfo *qinfo)
     }
 
     dev->qdev.id = id;
-    if (!dev->vio_irq_num) {
-        dev->vio_irq_num = bus->irq++;
+
+    dev->qirq = spapr_allocate_irq(dev->vio_irq_num, &dev->vio_irq_num);
+    if (!dev->qirq) {
+        return -1;
     }
-    dev->qirq = spapr_find_qirq(spapr, dev->vio_irq_num);
 
     rtce_init(dev);
 
@@ -666,7 +666,6 @@ VIOsPAPRBus *spapr_vio_bus_init(void)
 
     qbus = qbus_create(&spapr_vio_bus_info, dev, "spapr-vio");
     bus = DO_UPCAST(VIOsPAPRBus, bus, qbus);
-    bus->irq = 16;
 
     /* hcall-vio */
     spapr_register_hypercall(H_VIO_SIGNAL, h_vio_signal);

hw/spapr_vio.h

@@ -67,7 +67,6 @@ typedef struct VIOsPAPRDevice {
 
 typedef struct VIOsPAPRBus {
     BusState bus;
-    int irq;
 } VIOsPAPRBus;
 
 typedef struct {