Understanding Linux Network Internals

Example of PCI NIC Driver Registration

Let's use the Intel PRO/100 Ethernet driver in drivers/net/e100.c to illustrate a driver registration:

#define INTEL_8255X_ETHERNET_DEVICE(device_id, ich) {\
     PCI_VENDOR_ID_INTEL, device_id, PCI_ANY_ID, PCI_ANY_ID, \
     PCI_CLASS_NETWORK_ETHERNET << 8, 0xFFFF00, ich }
static struct pci_device_id e100_id_table[] = {
     INTEL_8255X_ETHERNET_DEVICE(0x1029, 0),
     INTEL_8255X_ETHERNET_DEVICE(0x1030, 0),
     ...
}

We saw in the section "Registering a PCI NIC Device Driver" that a PCI NIC device driver registers with the kernel a vector of pci_device_id structures that lists the devices it can handle. e100_id_table is, for instance, the structure used by the e100.c driver. Note that:

• The first field (which corresponds to vendor in the structure's definition) has the fixed value of PCI_VENDOR_ID_INTEL which is initialized to the vendor ID assigned to Intel.^[*]

• The third and fourth fields (subvendor and subdevice) are often initialized to the wildcard value PCI_ANY_ID, because the first two fields (vendor and device) are sufficient to identify the devices.

• Many devices use the macro _ _devinitdata on the table of devices to mark it as initialization data, although e100_id_table does not. You will see in Chapter 7 exactly what that macro is used for.

The module is initialized by e100_init_module, as specified by the module_init macro.^[*] When the function is executed by the kernel at boot time or at module loading time, it calls pci_module_init, the function introduced ...