pcibios_map_irq
bridge->map_irq = pcibios_map_irq;
extern int pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin);
bridge->map_irq = pcibios_map_irq;
irq = pcibios_map_irq(dev, PCI_SLOT(dev->devfn), 1); /* INTA */