Linux那些事儿之我是EHCI(3) pci match 和 probe

pci_bus_type 定义如下，




struct bus_type pci_bus_type = ...{


.name = "pci",


.match = pci_bus_match,


.uevent = pci_uevent,


.probe = pci_device_probe,


.remove = pci_device_remove,


.suspend = pci_device_suspend,


.suspend_late = pci_device_suspend_late,


.resume_early = pci_device_resume_early,


.resume = pci_device_resume,


.shutdown = pci_device_shutdown,


.dev_attrs = pci_dev_attrs,


};


static int pci_bus_match(struct device *dev, struct device_driver *drv)




...{


struct pci_dev *pci_dev = to_pci_dev(dev);


struct pci_driver *pci_drv = to_pci_driver(drv);


const struct pci_device_id *found_id;




found_id = pci_match_device(pci_drv, pci_dev);


if (found_id)


return 1;




return 0;


}

总的来说，判断一个设备和驱动是否匹配，是看设备的描述符是否和驱动所支持的一样。pci_match_device()分别在driver->dynid，driver->id_table这两个列表(由一系列的pci_device_id构成)里面查找。找到则返回这个设备的pci_device_id。(不妨比较一下pci_bus_type->match 和 usb_bus_type->match)




struct pci_device_id ...{




__u32 vendor, device; /**//* Vendor and device ID or PCI_ANY_ID*/




__u32 subvendor, subdevice; /**//* Subsystem ID's or PCI_ANY_ID */




__u32 class, class_mask; /**//* (class,subclass,prog-if) triplet */




kernel_ulong_t driver_data; /**//* Data private to the driver */


};

注意，pci_device_id->driver_data指向了每个pci设备驱动所特有的数据结构，比如ehci来说：.driver_data = (unsigned long) &ehci_pci_hc_driver。

另外就是，


static int pci_device_probe(struct device * dev)




...{


int error = 0;


struct pci_driver *drv;


struct pci_dev *pci_dev;




drv = to_pci_driver(dev->driver);


pci_dev = to_pci_dev(dev);


pci_dev_get(pci_dev);


error = __pci_device_probe(drv, pci_dev);


if (error)


pci_dev_put(pci_dev);




return error;


}



pci_device_probe() ---> __pci_device_probe() ---> pci_call_probe() ---> ( pci_driver->probe() )

而ehci_pci_driver->probe = usb_hcd_pci_probe()。像pci_device_probe的外包函数，就是一种面向对象的设计。不管怎样，经历了千辛万苦，咱终于绕到usb了。