U盘使用的是drivers/usb/storage/usb.c驱动

讯享网

#define DRV_NAME "usb-storage" //插入U盘时一般会打印usb-storage 1-1:1.0: USB Mass Storage device detected static struct usb_driver usb_storage_driver = { .name = DRV_NAME, .probe = storage_probe, .disconnect = usb_stor_disconnect, .suspend = usb_stor_suspend, .resume = usb_stor_resume, .reset_resume = usb_stor_reset_resume, .pre_reset = usb_stor_pre_reset, .post_reset = usb_stor_post_reset, .id_table = usb_storage_usb_ids, .supports_autosuspend = 1, .soft_unbind = 1, }; module_usb_stor_driver(usb_storage_driver, usb_stor_host_template, DRV_NAME);

讯享网/* The main probe routine for standard devices */ static int storage_probe(struct usb_interface *intf, const struct usb_device_id *id) { struct us_unusual_dev *unusual_dev; struct us_data *us; int result; int size; /* If uas is enabled and this device can do uas then ignore it. */ #if IS_ENABLED(CONFIG_USB_UAS) if (uas_use_uas_driver(intf, id, NULL)) return -ENXIO; #endif /* * If the device isn't standard (is handled by a subdriver * module) then don't accept it. */ if (usb_usual_ignore_device(intf)) //检测匹配 return -ENXIO; /* * Call the general probe procedures. * * The unusual_dev_list array is parallel to the usb_storage_usb_ids * table, so we use the index of the id entry to find the * corresponding unusual_devs entry. */ size = ARRAY_SIZE(us_unusual_dev_list); if (id >= usb_storage_usb_ids && id < usb_storage_usb_ids + size) { unusual_dev = (id - usb_storage_usb_ids) + us_unusual_dev_list; } else { unusual_dev = &for_dynamic_ids; dev_dbg(&intf->dev, "Use Bulk-Only transport with the Transparent SCSI protocol for dynamic id: 0x%04x 0x%04x\n", id->idVendor, id->idProduct); } result = usb_stor_probe1(&us, intf, id, unusual_dev, &usb_stor_host_template);//probe的第一部分 if (result) return result; /* No special transport or protocol settings in the main module */ result = usb_stor_probe2(us);//probe的第二部分 return result; } /* First part of general USB mass-storage probing */ int usb_stor_probe1(struct us_data pus, struct usb_interface *intf, const struct usb_device_id *id, struct us_unusual_dev *unusual_dev, struct scsi_host_template *sht) { struct Scsi_Host *host; struct us_data *us; int result; dev_info(&intf->dev, "USB Mass Storage device detected\n"); /* * Ask the SCSI layer to allocate a host structure, with extra * space at the end for our private us_data structure. */ host = scsi_host_alloc(sht, sizeof(*us));//分配Scsi_Host结构体 if (!host) { dev_warn(&intf->dev, "Unable to allocate the scsi host\n"); return -ENOMEM; } /* * Allow 16-byte CDBs and thus > 2TB */ host->max_cmd_len = 16; host->sg_tablesize = usb_stor_sg_tablesize(intf); *pus = us = host_to_us(host);//从host结构体中提取出us_data结构体 mutex_init(&(us->dev_mutex)); us_set_lock_class(&us->dev_mutex, intf); init_completion(&us->cmnd_ready);//初始化完成量 init_completion(&(us->notify)); init_waitqueue_head(&us->delay_wait);//初始化等待队列头 INIT_DELAYED_WORK(&us->scan_dwork, usb_stor_scan_dwork); /* Associate the us_data structure with the USB device */ result = associate_dev(us, intf);//将us_data与USB设备相关联 if (result) goto BadDevice; /* Get the unusual_devs entries and the descriptors */ result = get_device_info(us, id, unusual_dev);//获取设备信息 if (result) goto BadDevice; /* Get standard transport and protocol settings */ get_transport(us);//获取传输方式 get_protocol(us);//获取传输协议 /* * Give the caller a chance to fill in specialized transport * or protocol settings. */ return 0; BadDevice: usb_stor_dbg(us, "storage_probe() failed\n"); release_everything(us); return result; } /* Second part of general USB mass-storage probing */ int usb_stor_probe2(struct us_data *us) { int result; struct device *dev = &us->pusb_intf->dev; /* Make sure the transport and protocol have both been set */ if (!us->transport || !us->proto_handler) { result = -ENXIO; goto BadDevice; } usb_stor_dbg(us, "Transport: %s\n", us->transport_name); usb_stor_dbg(us, "Protocol: %s\n", us->protocol_name); if (us->fflags & US_FL_SCM_MULT_TARG) { /* * SCM eUSCSI bridge devices can have different numbers * of LUNs on different targets; allow all to be probed. */ us->max_lun = 7; /* The eUSCSI itself has ID 7, so avoid scanning that */ us_to_host(us)->this_id = 7; /* max_id is 8 initially, so no need to set it here */ } else { /* In the normal case there is only a single target */ us_to_host(us)->max_id = 1; /* * Like Windows, we won't store the LUN bits in CDB[1] for * SCSI-2 devices using the Bulk-Only transport (even though * this violates the SCSI spec). */ if (us->transport == usb_stor_Bulk_transport) us_to_host(us)->no_scsi2_lun_in_cdb = 1; } /* fix for single-lun devices */ if (us->fflags & US_FL_SINGLE_LUN) us->max_lun = 0; /* Find the endpoints and calculate pipe values */ result = get_pipes(us);//获得管道 if (result) goto BadDevice; /* * If the device returns invalid data for the first READ(10) * command, indicate the command should be retried. */ if (us->fflags & US_FL_INITIAL_READ10) set_bit(US_FLIDX_REDO_READ10, &us->dflags); /* Acquire all the other resources and add the host */ result = usb_stor_acquire_resources(us);//获取资源 if (result) goto BadDevice; usb_autopm_get_interface_no_resume(us->pusb_intf); snprintf(us->scsi_name, sizeof(us->scsi_name), "usb-storage %s", dev_name(&us->pusb_intf->dev)); result = scsi_add_host(us_to_host(us), dev);//添加scsi if (result) { dev_warn(dev, "Unable to add the scsi host\n"); goto HostAddErr; } /* Submit the delayed_work for SCSI-device scanning */ set_bit(US_FLIDX_SCAN_PENDING, &us->dflags); if (delay_use > 0) //delay_use秒后如果U盘没拔出则继续执行，否则执行disconnect dev_dbg(dev, "waiting for device to settle before scanning\n"); queue_delayed_work(system_freezable_wq, &us->scan_dwork, delay_use * HZ); return 0; /* We come here if there are any problems */ HostAddErr: usb_autopm_put_interface_no_suspend(us->pusb_intf); BadDevice: usb_stor_dbg(us, "storage_probe() failed\n"); release_everything(us); return result; }

        U盘驱动程序大概就是如此，其中probe1和probe2中还设计很多细节的内容，比如端点设置、urb控制等内容，这些内容和USB协议有很大关系，过于晦涩，所以暂时不做进一步研究。