pci_config_offset
static int pci_config_offset(pcitag_t);
data = *(uint32_t *)(pci_conf_addr + pci_config_offset(tag) + reg);
*((uint32_t *)(pci_conf_addr + pci_config_offset(tag) + reg))
uint64_t pci_config_offset, uint64_t size,
uint64_t pci_config_offset, uint64_t size, uint64_t data,