gadget usb 增加端点

实现在gadget中添加一个新的in端点进行数据传输

主要是这个函数，函数的说明

/**
* usb_ep_autoconfig - choose an endpoint matching the descriptor
* @gadget: The device to which the endpoint must belong.
* @desc: Endpoint descriptor, with endpoint direction and transfer mode
* initialized. For periodic transfers, the maximum packet
* size must also be initialized. This is modified on success.
*
* By choosing an endpoint to use with the specified descriptor, this
* routine simplifies writing gadget drivers that work with multiple
* USB device controllers. The endpoint would be passed later to
* usb_ep_enable(), along with some descriptor.
*
* That second descriptor won't always be the same as the first one.
* For example, isochronous endpoints can be autoconfigured for high
* bandwidth, and then used in several lower bandwidth altsettings.
* Also, high and full speed descriptors will be different.
*
* Be sure to examine and test the results of autoconfiguration on your
* hardware. This code may not make the best choices about how to use the
* USB controller, and it can't know all the restrictions that may apply.
* Some combinations of driver and hardware won't be able to autoconfigure.
*
* On success, this returns an un-claimed usb_ep, and modifies the endpoint
* descriptor bEndpointAddress. For bulk endpoints, the wMaxPacket value
* is initialized as if the endpoint were used at full speed. To prevent
* the endpoint from being returned by a later autoconfig call, claim it
* by assigning ep->driver_data to some non-null value.
*
* On failure, this returns a null endpoint descriptor.
*/

0、在f_sourcesink结构体里加上新的端点指针，与新的请求指针

struct usb_ep *in_ep1;
struct usb_request *in_req1;

1、定义端点描述符

static struct usb_endpoint_descriptor fs_source_desc1 = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,

.bEndpointAddress = 0x83,
.bmAttributes = USB_ENDPOINT_XFER_BULK,
};

2、配置的描述符

static struct usb_descriptor_header *fs_source_sink_descs[] = {
   (struct usb_descriptor_header *) &source_sink_intf,
   (struct usb_descriptor_header *) &fs_source_desc,
   (struct usb_descriptor_header *) &fs_source_desc1,
   (struct usb_descriptor_header *) &fs_sink_desc,
   NULL,
};

3、将端点的描述符fs_source_desc1与定义的端点匹配

in_ep1是增加的端点

ss->in_ep = usb_ep_autoconfig(cdev->gadget, &fs_source_desc);
ss->in_ep1 = usb_ep_autoconfig(cdev->gadget, &fs_source_desc1);/

4、给端点分配请求

ss->in_req = alloc_ep_req(ss->in_ep, TX_REQ_LEN);
if(ss->in_req == NULL){
DBG_PRT("Alloc_ep_req for write in failed.\n");
return -EFAULT;
}
ss->in_req->complete = source_sink_complete;

ss->in_req1 = alloc_ep_req(ss->in_ep1, TX_REQ_LEN);
   if(ss->in_req1 == NULL){
       DBG_PRT("Alloc_ep_req for write in failed.\n");
       return -EFAULT;
   }
   ss->in_req1->complete = source_sink_complete;

5、在写函数中将原端点未写完的数据通过新端点写

ret = usb_ep_queue(ss->in_ep1, ss->in_req1, GFP_ATOMIC);

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