Find an extended capability
int pci_find_next_ext_capability(struct pci_dev * dev, int start, int cap);
dev
PCI device to query
start
address at which to start looking (0 to start at beginning of list)
cap
capability code
Returns the address of the next matching extended capability structure within the device's PCI configuration space or 0 if the device does not support it. Some capabilities can occur several times, e.g., the vendor-specific capability, and this provides a way to find them all.