pcibios_read_config_word
pcibios_read_config_word(p->bus, p->devfn, PCI_COMMAND, &pci_command);
extern int pcibios_read_config_word(unsigned int bus, unsigned int device_fn, unsigned int where, uint16_t *value);
return pcibios_read_config_word(dev->bus, dev->devfn, where, value);