Query for devices capabilities
int pci_bus_find_capability(struct pci_bus * bus, unsigned int devfn, int cap);
bus
the PCI bus to query
devfn
PCI device to query
cap
capability code
Like pci_find_capability but works for pci devices that do not have a pci_dev structure set up yet.
Returns the address of the requested capability structure within the device's PCI configuration space or 0 in case the device does not support it.