pci: introduce pci_swizzle_map_irq_fn() for standardized interrupt pin swizzle

Introduce pci_swizzle_map_irq_fn() for interrupt pin swizzle which is
standardized. PCI bridge swizzle is common logic, by introducing
this function duplicated swizzle logic will be avoided later.

[jbaron@redhat.com: drop opaque argument]
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 18 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 */