[Qemu-devel] [PATCH RFC V2 15/17] hw/pxb: add map_irq func

[Marcel Apfelbaum <marcel@redhat.com>]

The bios does not index the pxb slot number when
it computes the IRQ because it resides on bus 0
and not on the current bus.
However Qemu routes the irq through bus 0 and adds
the pxb slot to the IRQ computation.

Synchronize between bios and Qemu by canceling
pxb's effect.

Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
---
 hw/pci-bridge/pci_expander_bridge.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
index 941f3c8..1126841 100644
--- a/hw/pci-bridge/pci_expander_bridge.c
+++ b/hw/pci-bridge/pci_expander_bridge.c
@@ -92,6 +92,24 @@ static const TypeInfo pxb_host_info = {
     .class_init    = pxb_host_class_init,
 };
 
+
+static int pxb_map_irq_fn(PCIDevice *pci_dev, int pin)
+{
+    PCIDevice *pxb = pci_dev->bus->parent_dev;
+
+    /*
+     * The bios does not index the pxb slot number when
+     * it computes the IRQ because it resides on bus 0
+     * and not on the current bus.
+     * However Qemu routes the irq through bus 0 and adds
+     * the pxb slot to the IRQ computation.
+     *
+     * Synchronize between bios and Qemu by canceling
+     * pxb's effect.
+     */
+    return pin - PCI_SLOT(pxb->devfn);
+}
+
 static int pxb_dev_initfn(PCIDevice *dev)
 {
     PXBDev *pxb = PXB_DEV(dev);
@@ -118,7 +136,7 @@ static int pxb_dev_initfn(PCIDevice *dev)
     bus->parent_dev = dev;
     bus->address_space_mem = dev->bus->address_space_mem;
     bus->address_space_io = dev->bus->address_space_io;
-    bus->map_irq = pci_swizzle_map_irq_fn;
+    bus->map_irq = pxb_map_irq_fn;
 
     bds = qdev_create(BUS(bus), "pci-bridge");
     bds->id = dev_name;
-- 
2.1.0