MTK USB 子系统

一、USB 子系统初始化

1. kernel/drivers/usb/core/usb.c

 subsys_initcall(usb_init);

 static int __init usb_init(void)
 {
     int retval;
     if (nousb) {
         pr_info("%s: USB support disabled\n", usbcore_name);
         return ;
     }

     usb_init_pool_max();

     retval = usb_debugfs_init();
     if (retval)
         goto out;

     usb_acpi_register();
     retval = bus_register(&usb_bus_type);
     if (retval)
         goto bus_register_failed;
     retval = bus_register_notifier(&usb_bus_type, &usb_bus_nb);
     if (retval)
         goto bus_notifier_failed;
     retval = usb_major_init();
     if (retval)
         goto major_init_failed;
     retval = usb_register(&usbfs_driver);
     if (retval)
         goto driver_register_failed;
     retval = usb_devio_init();
     if (retval)
         goto usb_devio_init_failed;
     retval = usb_hub_init();
     if (retval)
         goto hub_init_failed;
     retval = usb_register_device_driver(&usb_generic_driver, THIS_MODULE);
     if (!retval)
         goto out;

     usb_hub_cleanup();
 hub_init_failed:
     usb_devio_cleanup();
 usb_devio_init_failed:
     usb_deregister(&usbfs_driver);
 driver_register_failed:
     usb_major_cleanup();
 major_init_failed:
     bus_unregister_notifier(&usb_bus_type, &usb_bus_nb);
 bus_notifier_failed:
     bus_unregister(&usb_bus_type);
 bus_register_failed:
     usb_acpi_unregister();
     usb_debugfs_cleanup();
 out:
     return retval;
 }