Locate pci device for a given pci domain (segment), bus, and slot
struct pci_dev * pci_get_domain_bus_and_slot(int domain, unsigned int bus, unsigned int devfn);
domain
PCI domain/segment on which the PCI device resides.
bus
PCI bus on which desired PCI device resides
devfn
encodes number of PCI slot in which the desired PCI device resides and the logical device number within that slot in case of multi-function devices.
Given a PCI domain, bus, and slot/function number, the desired PCI device is located in the list of PCI devices. If the device is found, its reference count is increased and this function returns a pointer to its data structure. The caller must decrement the reference count by calling pci_dev_put. If no device is found, NULL is returned.