1. dwc3 and dummy gadget

debug：

ls /sys/class/udc        //查看系统注册了的udc驱动

1.1 gadegt 初始化

1.1.1 dwc3 gadget 初始化

== dwc3_gadget_init(struct dwc3 *dwc);== dwc3_gadget_init_endpoints(dwc, dwc->num_eps);   // num_eps 从设备硬件中读取== dwc3_gadget_init_endpoint(dwc, epnum);      // 初始化端点==    struct dwc3_ep          *dep;           // 对usb_ep 封装成dwc3_epdep->number = epnum;                   // dep 数量最多32 个dep->regs = dwc->regs + DWC3_DEP_BASE(epnum);    // 对应寄存器地址dwc->eps[epnum] = dep;== dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep);== dep->endpoint.ops = &dwc3_gadget_ep_ops;        //usb_ep 的ops== usb_add_gadget(dwc->gadget);       //gadget设备：struct usb_gadget *gadget; == device_add(&gadget->dev);  // 注册gadget 设备== list_add_tail(&udc->list, &udc_list); //将该udc 添加到udc_list 链表，与后期gadget 匹配== device_add(&udc->dev);        // 注册udc 设备

1.1.2 dummy gadget 初始化

== dummy_udc_probe(struct platform_device *pdev);== dum->gadget.ops = &dummy_ops;== init_dummy_udc_hw(dum);== struct dummy_ep    *ep = &dum->ep[i];      // 对usb_ep 封装成dummy_epep->ep.ops = &dummy_ep_ops;               // usb_ep 的opsdum->gadget.ep0 = &dum->ep[0].ep;      // 端点0 比较特殊== usb_add_gadget_udc(&pdev->dev, &dum->gadget);== usb_add_gadget_udc_release(parent, gadget, NULL);== usb_initialize_gadget(parent, gadget, release);== usb_add_gadget(gadget);

1.1.3 端点 ep

usb_gadget 结构体为共有信息，含有端点0（ep0），所有设备都必须含有端点0，用于控制传输。

struct usb_gadget {struct usb_udc            *udc;/* readonly to gadget driver */const struct usb_gadget_ops *ops;struct usb_ep          *ep0;struct list_head       ep_list;    /* of usb_ep */enum usb_device_speed        speed;enum usb_device_speed     max_speed;enum usb_device_state     state;const char            *name;struct device         dev;
}

dwc3 属于私有设备信息，包含usb_gadget 信息，并含有其他端点的信息dw3_ep（封装的usb_ep）。

struct dwc3 {struct device       *dev;struct device      *sysdev;struct platform_device  *xhci;struct resource       xhci_resources[DWC3_XHCI_RESOURCES_NUM];struct dwc3_ep      *eps[DWC3_ENDPOINTS_NUM];struct usb_gadget  *gadget;
}

同样的，dummy 属于私有设备信息，包含usb_gadget 信息，并含有其他端点的信息dummy_ep（封装的usb_ep）。

struct dummy {// DEVICE/GADGET side supportstruct dummy_ep           ep[DUMMY_ENDPOINTS];int             address;int             callback_usage;struct usb_gadget        gadget;struct usb_gadget_driver *driver;struct dummy_request        fifo_req;u8             fifo_buf[FIFO_SIZE];u16             devstatus;// HOST side supportstruct dummy_hcd      *hs_hcd;struct dummy_hcd        *ss_hcd;
}

1.2 gadget 发送数据(dwc3)

1.2.1 function 向gadget 申请req

\drivers\usb\gadget\function\f_fs.c
（1）申请req：

ffs->ep0req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);     //端点0 的传输
ffs->ep0req->complete = ffs_ep0_complete;    // req的完成函数

ep = usb_ep_autoconfig(func->gadget, ds);        // 从gadget 获取与description 对应的端点
req = usb_ep_alloc_request(ep, GFP_KERNEL);

（2）将req 提交到dwc3 gadget core：

== usb_ep_queue(ffs->gadget->ep0, req, GFP_ATOMIC);      //提交到ep0
== ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC);           //提交到非0 端点== ret = ep->ops->queue(ep, req, gfp_flags);== dwc3_gadget_ep_queue();

1.2.2 dwc3 gadget core 处理req （写寄存器）

== dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request, gfp_t gfp_flags)== __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)== __dwc3_gadget_start_isoc(struct dwc3_ep *dep)== __dwc3_gadget_kick_transfer(struct dwc3_ep *dep)== dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd, struct dwc3_gadget_ep_cmd_params *params)     // This function will issue @cmd with given @params to @dep and wait for its completion.== dwc3_writel(void __iomem *base, u32 offset, u32 value)

1.2.3 core 返回req （中断回调函数）

== udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)== usb_gadget_udc_start(struct usb_udc *udc);udc->gadget->ops->udc_start(udc->gadget, udc->driver);== dwc3_gadget_start(struct usb_gadget *g, struct usb_gadget_driver *driver)  //注册中断== request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt, IRQF_SHARED, "dwc3", dwc->ev_buf);== dwc3_thread_interrupt(int irq, void *_evt)     //中断产生，调用回调函数== dwc3_process_event_buf(struct dwc3_event_buffer *evt)      //处理中断事件buf== dwc3_process_event_entry(struct dwc3 *dwc, const union dwc3_event *event)== dwc3_endpoint_interrupt(struct dwc3 *dwc, const struct dwc3_event_depevt *event)== dwc3_gadget_endpoint_transfer_complete()     //调用req完成函数== dwc3_gadget_endpoint_trbs_complete()== dwc3_gadget_ep_cleanup_completed_requests()== dwc3_gadget_giveback(dep, req, status);                //数据返回== usb_gadget_giveback_request()    // give the request back to the gadget layer== req->complete(ep, req);== ffs_ep0_complete(struct usb_ep *ep, struct usb_request *req)    // function的完成函数

1.3 gadget 发送数据（dummy）

1.2.1 function 向gadget 申请req

与dwc3 一样。

1.2.2 dummy gadget core 处理req （memcpy）

== dummy_queue(struct usb_ep *_ep, struct usb_request *_req, gfp_t mem_flags)；/* implement an emulated single-request FIFO */== memcpy(dum->fifo_buf, _req->buf, _req->length);  == req->req.context = dum;== req->req.complete = fifo_complete;         //完成函数== list_add_tail(&req->queue, &ep->queue);== usb_gadget_giveback_request(_ep, _req);        //返回req，调用完成函数== req->complete(ep, req);

1.4 usb_gadget_ops

usb_gadget_ops函数集，这些函数主要是操作UDC设备的一些特性（针对设备）。
当enable/disable gadget 的时候，会调用到相关接口。

1.4.1 dwc3

== dwc3_gadget_init(struct dwc3 *dwc)== dwc->gadget->ops       = &dwc3_gadget_ops;        //初始化static const struct usb_gadget_ops dwc3_gadget_ops = {.get_frame      = dwc3_gadget_get_frame,.wakeup            = dwc3_gadget_wakeup,.set_selfpowered  = dwc3_gadget_set_selfpowered,.pullup          = dwc3_gadget_pullup,.udc_start        = dwc3_gadget_start,.udc_stop      = dwc3_gadget_stop,.udc_set_speed      = dwc3_gadget_set_speed,.udc_set_ssp_rate  = dwc3_gadget_set_ssp_rate,.get_config_params  = dwc3_gadget_config_params,.vbus_draw     = dwc3_gadget_vbus_draw,.check_config      = dwc3_gadget_check_config,.udc_async_callbacks    = dwc3_gadget_async_callbacks,
};

1.4.2 dummy

static const struct usb_gadget_ops dummy_ops = {.get_frame  = dummy_g_get_frame,.wakeup        = dummy_wakeup,.set_selfpowered = dummy_set_selfpowered,.pullup       = dummy_pullup,.udc_start  = dummy_udc_start,.udc_stop    = dummy_udc_stop,.udc_set_speed    = dummy_udc_set_speed,
};

1.5 usb_ep_ops

1.5.1 dwc3

== dwc3_gadget_init(struct dwc3 *dwc)== dwc3_gadget_init_endpoint(struct dwc3 *dwc, u8 epnum)== dwc3_gadget_init_in_endpoint(struct dwc3_ep *dep)== dep->endpoint.ops = &dwc3_gadget_ep_ops;static const struct usb_ep_ops dwc3_gadget_ep_ops = {.enable        = dwc3_gadget_ep_enable,.disable   = dwc3_gadget_ep_disable,.alloc_request    = dwc3_gadget_ep_alloc_request,.free_request   = dwc3_gadget_ep_free_request,.queue       = dwc3_gadget_ep_queue,.dequeue    = dwc3_gadget_ep_dequeue,.set_halt = dwc3_gadget_ep_set_halt,.set_wedge   = dwc3_gadget_ep_set_wedge,
};

1.5.2 dummy

static const struct usb_ep_ops dummy_ep_ops = {.enable      = dummy_enable,.disable    = dummy_disable,.alloc_request = dummy_alloc_request,.free_request    = dummy_free_request,.queue        = dummy_queue,.dequeue = dummy_dequeue,.set_halt  = dummy_set_halt,.set_wedge    = dummy_set_wedge,
};

2. dummy hcd

== dummy_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags)== usb_hcd_link_urb_to_ep(hcd, urb);== timer_pending(&dum_hcd->timer)timer_setup(&dum_hcd->timer, dummy_timer, 0);== dummy_timer(struct timer_list *t)== handle_control_request(dum_hcd, urb, &setup, &status);       //handle control requests== transfer(dum_hcd, urb, ep, limit, &status);       //non-control requests == dummy_perform_transfer(urb, req, len);== memcpy(ubuf, rbuf, len);                 //拷贝数据== usb_gadget_giveback_request(&ep->ep, &req->req);== req->complete(ep, req);== usb_hcd_unlink_urb_from_ep(dummy_hcd_to_hcd(dum_hcd), urb);        //return urb== usb_hcd_giveback_urb(dummy_hcd_to_hcd(dum_hcd), urb, status);

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1. dwc3 and dummy gadget

1.1 gadegt 初始化

1.1.1 dwc3 gadget 初始化

1.1.2 dummy gadget 初始化

1.1.3 端点 ep

1.2 gadget 发送数据(dwc3)

1.2.1 function 向gadget 申请req

1.2.2 dwc3 gadget core 处理req （写寄存器）

1.2.3 core 返回req （中断回调函数）

1.3 gadget 发送数据（dummy）

1.2.1 function 向gadget 申请req

1.2.2 dummy gadget core 处理req （memcpy）

1.4 usb_gadget_ops

1.4.1 dwc3

1.4.2 dummy

1.5 usb_ep_ops

1.5.1 dwc3

1.5.2 dummy

2. dummy hcd

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