这个是PCI的关键结构体。
static const struct file_operations proc_bus_pci_operations = {
.owner = THIS_MODULE,
.llseek = proc_bus_pci_lseek,
.read = proc_bus_pci_read,
.write = proc_bus_pci_write,
.unlocked_ioctl = proc_bus_pci_ioctl,
.compat_ioctl = proc_bus_pci_ioctl,
#ifdef HAVE_PCI_MMAP
.open = proc_bus_pci_open,
.release = proc_bus_pci_release,
.mmap = proc_bus_pci_mmap,
#ifdef HAVE_ARCH_PCI_GET_UNMAPPED_AREA
.get_unmapped_area = get_pci_unmapped_area,
#endif /* HAVE_ARCH_PCI_GET_UNMAPPED_AREA */
#endif /* HAVE_PCI_MMAP */
};