usb hub 2

linux的usb hub之usb hub的设备驱动

       hub的设备出生后，就要找驱动；哪里找呢？看关键字<usb_device_type,for_devices>
看代码很多后，才发现，所谓usb驱动分为接口驱动和设备驱动，大多时候，网友口口相传驱动都指定为接口驱动；而我们这里讲的是设备驱动，据我对代码的查看，在usb hub驱动时找到一例；至于其他地方，我们不要去理会了，少则得，多则惑；

     后来，我界定，这种驱动还只是属于设备创建的一部分，它只是创建接口设备；
代码的起始点：retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE);

struct usb_device_driver usb_generic_driver = {
    .name = "usb",
    .probe = generic_probe,
    .disconnect = generic_disconnect,
#ifdef    CONFIG_PM
    .suspend = generic_suspend,
    .resume = generic_resume,
#endif
    .supports_autosuspend = 1,
}

/**
 * usb_register_device_driver - register a USB device (not interface) driver
 * @new_udriver: USB operations for the device driver
 * @owner: module owner of this driver.
 *
 * Registers a USB device driver with the USB core. The list of
 * unattached devices will be rescanned whenever a new driver is
 * added, allowing the new driver to attach to any recognized devices.
 * Returns a negative error code on failure and 0 on success.
 */
int usb_register_device_driver(struct usb_device_driver *new_udriver,
        struct module *owner)
{
    int retval = 0;

    if (usb_disabled())
        return -ENODEV;
//对devices；主要是Mark一下，引起注意；
//在总线匹配中，区分接口设备和usb设备<usb_device_type,>；
    new_udriver->drvwrap.for_devices = 1;
    new_udriver->drvwrap.driver.name = (char *) new_udriver->name;
    new_udriver->drvwrap.driver.bus = &usb_bus_type;//所属总线；
    new_udriver->drvwrap.driver.probe = usb_probe_device;
    new_udriver->drvwrap.driver.remove = usb_unbind_device;
    new_udriver->drvwrap.driver.owner = owner;
//通用设备驱动的注册
    retval = driver_register(&new_udriver->drvwrap.driver);

    if (!retval) {
        pr_info("%s: registered new device driver %s\n",
            usbcore_name, new_udriver->name);
        usbfs_update_special();
    } else {
        printk(KERN_ERR "%s: error %d registering device "
            "    driver %s\n",
            usbcore_name, retval, new_udriver->name);
    }

    return retval;
}

      上面就是usb设备类型的驱动，只要是满足{usb_device_type,for_devices==1}的设备，都会来找他配对；然后生出{usb_if_device_type,for_devices==0}这样的设备；
usb_device_type，usb_if_device_type为usb设备的类型，用来总线匹配驱动。for_devices是驱动中设置，用来总线匹配匹配。
需要牢记一点，出生的设备最新还是需要在那根红线usb_bus_type上仔细找usb_device_match驱动usb_generic_driver；


     下一篇，就是讲usb_device_type设备的驱动匹配和函数调用；