2 files changed, 20 insertions, 0 deletions
diff --git a/hw/pci.c b/hw/pci.c
index 82c971a17d..63b1857f88 100644
--- a/hw/pci.c
+++ b/hw/pci.c
@@ -1155,6 +1155,24 @@ void pci_device_set_intx_routing_notifier(PCIDevice *dev,
     dev->intx_routing_notifier = notifier;
 }
 
+/*
+ * PCI-to-PCI bridge specification
+ * 9.1: Interrupt routing. Table 9-1
+ *
+ * the PCI Express Base Specification, Revision 2.1
+ * 2.2.8.1: INTx interrutp signaling - Rules
+ *          the Implementation Note
+ *          Table 2-20
+ */
+/*
+ * 0 <= pin <= 3 0 = INTA, 1 = INTB, 2 = INTC, 3 = INTD
+ * 0-origin unlike PCI interrupt pin register.
+ */
+int pci_swizzle_map_irq_fn(PCIDevice *pci_dev, int pin)
+{
+    return (pin + PCI_SLOT(pci_dev->devfn)) % PCI_NUM_PINS;
+}
+
 /***********************************************************/
 /* monitor info on PCI */
 
diff --git a/hw/pci.h b/hw/pci.h
index a852941a5c..241c1d8905 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -318,6 +318,8 @@ void pci_bus_irqs(PCIBus *bus, pci_set_irq_fn set_irq, pci_map_irq_fn map_irq,
                   void *irq_opaque, int nirq);
 int pci_bus_get_irq_level(PCIBus *bus, int irq_num);
 void pci_bus_hotplug(PCIBus *bus, pci_hotplug_fn hotplug, DeviceState *dev);
+/* 0 <= pin <= 3 0 = INTA, 1 = INTB, 2 = INTC, 3 = INTD */
+int pci_swizzle_map_irq_fn(PCIDevice *pci_dev, int pin);
 PCIBus *pci_register_bus(DeviceState *parent, const char *name,
                          pci_set_irq_fn set_irq, pci_map_irq_fn map_irq,
                          void *irq_opaque,