目的：对USB作深入学习，在此留下笔记。欢迎讨论。
[Linux 3.2] [driver/usb/core/devio.c]
定义：usbfs_driver
struct usb_driver usbfs_driver = { .name = "usbfs", .probe = driver_probe, .disconnect = driver_disconnect, .suspend = driver_suspend, .resume = driver_resume, };
[Linux 3.2] [include/linux/usb.h]
函数：usb_register();
/* use a define to avoid include chaining to get THIS_MODULE & friends */ #define usb_register(driver) \ usb_register_driver(driver, THIS_MODULE, KBUILD_MODNAME)
[Linux 3.2] [driver/usb/core/driver.c]
函数：usb_register_driver();
/** * usb_register_driver - register a USB interface driver * @new_driver: USB operations for the interface driver * @owner: module owner of this driver. * @mod_name: module name string * * Registers a USB interface driver with the USB core. The list of * unattached interfaces will be rescanned whenever a new driver is * added, allowing the new driver to attach to any recognized interfaces. * Returns a negative error code on failure and 0 on success. * * NOTE: if you want your driver to use the USB major number, you must call * usb_register_dev() to enable that functionality. This function no longer * takes care of that. */ int usb_register_driver(struct usb_driver *new_driver, struct module *owner, const char *mod_name) { int retval = 0; if (usb_disabled()) return -ENODEV; new_driver->drvwrap.for_devices = 0; new_driver->drvwrap.driver.name = (char *) new_driver->name; new_driver->drvwrap.driver.bus = &usb_bus_type; new_driver->drvwrap.driver.probe = usb_probe_interface; new_driver->drvwrap.driver.remove = usb_unbind_interface; new_driver->drvwrap.driver.owner = owner; new_driver->drvwrap.driver.mod_name = mod_name; spin_lock_init(&new_driver->dynids.lock); INIT_LIST_HEAD(&new_driver->dynids.list); retval = driver_register(&new_driver->drvwrap.driver); if (retval) goto out; usbfs_update_special(); retval = usb_create_newid_file(new_driver); if (retval) goto out_newid; retval = usb_create_removeid_file(new_driver); if (retval) goto out_removeid; pr_info("%s: registered new interface driver %s\n", usbcore_name, new_driver->name); out: return retval; out_removeid: usb_remove_newid_file(new_driver); out_newid: driver_unregister(&new_driver->drvwrap.driver); printk(KERN_ERR "%s: error %d registering interface " " driver %s\n", usbcore_name, retval, new_driver->name); goto out; }
此函数主要功能实现是通过driver_register实现。后面会详细分析。
其余功能如下：
1. usbfs_update_special() ==> 跟usb文件系统相关，暂时不分析。
2. usb_create_newid_file() ==> 创建newid属性文件，在/sys/bus/usb/drivers/usbfs/下面可以看到此文件。
3. usb_create_removeid_file() ==> 创建removeid属性文件，在/sys/bus/usb/drivers/usbfs/下面可以看到此文件。
4. 输出信息：usbcore: registered new interface driver usbfs
问题：newid与removeid属性文件的作用是什么？
回答：等待解答。
现在分析driver_register功能：
1. 首先判断，些驱动所属bus的subsys_private结构有没有初始化。如果没有，报bug信息。
2. 判断需要注册的driver和driver所属的bus是否都有probe, remove, shutdown函数。如有，打印kernel warning信息。
3. 判断此driver已经在driver所属的bus上面注册过了。如果注册过了，打印错误信息，并返回。
4. 调用bus_add_driver来注册driver。
5. 调用driver_add_groups来添加组属性。
6. 返回。
最后对bus_add_driver进行分析。