作者： Sam（甄峰） sam_code@hotmail.com
1. 解读hiddevice probe程序：
static int hid_probe(struct usb_interface*intf, const struct usb_device_id *id){struct hid_device *hid;char path[64];int i;char *c;
dbg_hid("HID probecalled for ifnum %d\n",intf->altsetting->desc.bInterfaceNumber);
if (!(hid =usb_hid_configure(intf)))return -ENODEV;
usbhid_init_reports(hid);hid_dump_device(hid);if (hid->quirks &HID_QUIRK_RESET_LEDS)usbhid_set_leds(hid);
if(!hidinput_connect(hid))hid->claimed |=HID_CLAIMED_INPUT;if (!hiddev_connect(hid))hid->claimed |=HID_CLAIMED_HIDDEV;
usb_set_intfdata(intf,hid);
if(!hid->claimed) {printk ("HID device not claimedby input or hiddev\n");hid_disconnect(intf);return -ENODEV;}
if((hid->claimed &HID_CLAIMED_INPUT))hid_ff_init(hid);
if(hid->quirks &HID_QUIRK_SONY_PS3_CONTROLLER)hid_fixup_sony_ps3_controller(interface_to_usbdev(intf),intf->cur_altsetting->desc.bInterfaceNumber);
printk(KERN_INFO);
if(hid->claimed &HID_CLAIMED_INPUT)printk("input");if (hid->claimed ==(HID_CLAIMED_INPUT | HID_CLAIMED_HIDDEV))printk(",");if (hid->claimed &HID_CLAIMED_HIDDEV)printk("hiddev%d",hid->minor);
c = "Device";for (i = 0; i <hid->maxcollection; i++) {if(hid->collection[i].type ==HID_COLLECTION_APPLICATION &&(hid->collection[i].usage &HID_USAGE_PAGE) == HID_UP_GENDESK&&(hid->collection[i].usage & 0xffff)< ARRAY_SIZE(hid_types)) {c =hid_types[hid->collection[i].usage &0xffff];break;}}
usb_make_path(interface_to_usbdev(intf),path, 63);
printk(": USB HIDv%x.%02x %s [%s] on %s\n",hid->version>> 8, hid->version& 0xff, c, hid->name,path);
return 0;}
1.1:usb_hid_configure(intf)解读：
从字面来看，它是指配置hid。
static struct hid_device*usb_hid_configure(struct usb_interface *intf){struct usb_host_interface *interface =intf->cur_altsetting;struct usb_device *dev = interface_to_usbdev(intf);struct hid_descriptor *hdesc;struct hid_device *hid;u32 quirks = 0;unsigned rsize = 0;char *rdesc;int n, len, insize = 0;struct usbhid_device *usbhid;
//得到对应vid,pid的quriks.如果没有，则返回0quirks =usbhid_lookup_quirk(le16_to_cpu(dev->descriptor.idVendor),le16_to_cpu(dev->descriptor.idProduct));
//如果为boot设备且为keyboard或mouse.则quirks=HID_QUIRK_NOGET
if(interface->desc.bInterfaceSubClass ==USB_INTERFACE_SUBCLASS_BOOT) {if(interface->desc.bInterfaceProtocol ==USB_INTERFACE_PROTOCOL_KEYBOARD ||interface->desc.bInterfaceProtocol== USB_INTERFACE_PROTOCOL_MOUSE)quirks|= HID_QUIRK_NOGET;}
//如果quirks显示要忽略，则退出probe
if (quirks& HID_QUIRK_IGNORE)return NULL;
//HID_QUIRK_IGNORE_MOUSE表示如果为mouse,则忽略。
if ((quirks& HID_QUIRK_IGNORE_MOUSE)&&(interface->desc.bInterfaceProtocol== USB_INTERFACE_PROTOCOL_MOUSE))returnNULL;
//如果interface扩展描述符中没有类型为HID_DT_HID条目，或者interface包含的endpoint数目为0，又或者interfaceendpoint中扩展描述符中没有类型为HID_DT_HID的条目。则退出。if(usb_get_extra_descriptor(interface, HID_DT_HID,&hdesc) &&(!interface->desc.bNumEndpoints ||usb_get_extra_descriptor(&interface->endpoint[0],HID_DT_HID, &hdesc))) {dbg_hid("class descriptor notpresent\n");return NULL;}
//得到描述符长度：
for (n = 0; n< hdesc->bNumDescriptors; n++)if(hdesc->desc[n].bDescriptorType ==HID_DT_REPORT)rsize =le16_to_cpu(hdesc->desc[n].wDescriptorLength);
//如果描述符长度不对，则退出
if (!rsize || rsize> HID_MAX_DESCRIPTOR_SIZE) {dbg_hid("weird size of reportdescriptor (%u)\n", rsize);return NULL;}
//创建此长度内存空间
if (!(rdesc =kmalloc(rsize, GFP_KERNEL))) {dbg_hid("couldn’t allocaterdesc memory\n");return NULL;}
//向dev的endpoint发送HID_REQ_SET_IDLErequest.
hid_set_idle(dev,interface->desc.bInterfaceNumber, 0, 0);
//取得reportdescription的详细信息,放到rdesc中。
if ((n =hid_get_class_descriptor(dev,interface->desc.bInterfaceNumber, HID_DT_REPORT,rdesc, rsize)) < 0) {dbg_hid("reading reportdescriptor failed\n");kfree(rdesc);return NULL;}
usbhid_fixup_report_descriptor(le16_to_cpu(dev->descriptor.idVendor),le16_to_cpu(dev->descriptor.idProduct),rdesc,rsize,rdesc_quirks_param);
dbg_hid("reportdescriptor (size %u, read %d) = ", rsize, n);for (n = 0; n < rsize; n++)dbg_hid_line(" %02x", (unsignedchar) rdesc[n]);dbg_hid_line("\n");
//解析report。并建立hid_device.返回给hid.
if (!(hid =hid_parse_report(rdesc, n))) {dbg_hid("parsing reportdescriptor failed\n");kfree(rdesc);return NULL;}
kfree(rdesc);hid->quirks = quirks;
if (!(usbhid =kzalloc(sizeof(struct usbhid_device), GFP_KERNEL)))goto fail_no_usbhid;
hid->driver_data =usbhid;usbhid->hid = hid;
usbhid->bufsize =HID_MIN_BUFFER_SIZE;hid_find_max_report(hid, HID_INPUT_REPORT,&usbhid->bufsize);hid_find_max_report(hid, HID_OUTPUT_REPORT,&usbhid->bufsize);hid_find_max_report(hid, HID_FEATURE_REPORT,&usbhid->bufsize);
if(usbhid->bufsize >HID_MAX_BUFFER_SIZE)usbhid->bufsize= HID_MAX_BUFFER_SIZE;
hid_find_max_report(hid,HID_INPUT_REPORT, &insize);
if (insize> HID_MAX_BUFFER_SIZE)insize =HID_MAX_BUFFER_SIZE;
if(hid_alloc_buffers(dev, hid)) {hid_free_buffers(dev,hid);goto fail;}
for (n = 0; n< interface->desc.bNumEndpoints; n++){
structusb_endpoint_descriptor *endpoint;int pipe;int interval;
endpoint =&interface->endpoint[n].desc;if((endpoint->bmAttributes & 3) !=3)continue;
interval =endpoint->bInterval;
if(hid->collection->usage ==HID_GD_MOUSE &&hid_mousepoll_interval > 0)interval =hid_mousepoll_interval;
if(usb_endpoint_dir_in(endpoint)) {if(usbhid->urbin)continue;if(!(usbhid->urbin = usb_alloc_urb(0,GFP_KERNEL)))gotofail;pipe =usb_rcvintpipe(dev,endpoint->bEndpointAddress);usb_fill_int_urb(usbhid->urbin,dev, pipe, usbhid->inbuf, insize,hid_irq_in, hid, interval);usbhid->urbin->transfer_dma= usbhid->inbuf_dma;usbhid->urbin->transfer_flags|= URB_NO_TRANSFER_DMA_MAP;} else {if(usbhid->urbout)continue;if(!(usbhid->urbout = usb_alloc_urb(0,GFP_KERNEL)))gotofail;pipe =usb_sndintpipe(dev,endpoint->bEndpointAddress);usb_fill_int_urb(usbhid->urbout,dev, pipe, usbhid->outbuf, 0,hid_irq_out, hid, interval);usbhid->urbout->transfer_dma= usbhid->outbuf_dma;usbhid->urbout->transfer_flags|= URB_NO_TRANSFER_DMA_MAP;}}
if(!usbhid->urbin) {err_hid("couldn’t find an inputinterrupt endpoint");goto fail;}
init_waitqueue_head(&hid->wait);
INIT_WORK(&usbhid->reset_work,hid_reset);setup_timer(&usbhid->io_retry,hid_retry_timeout, (unsigned long) hid);
spin_lock_init(&usbhid->inlock);spin_lock_init(&usbhid->outlock);spin_lock_init(&usbhid->ctrllock);
hid->version =le16_to_cpu(hdesc->bcdHID);hid->country =hdesc->bCountryCode;hid->dev =&intf->dev;usbhid->intf = intf;usbhid->ifnum =interface->desc.bInterfaceNumber;
hid->name[0] =0;
if(dev->manufacturer)strlcpy(hid->name,dev->manufacturer,sizeof(hid->name));
if(dev->product) {if(dev->manufacturer)strlcat(hid->name," ", sizeof(hid->name));strlcat(hid->name,dev->product,sizeof(hid->name));}
if(!strlen(hid->name))snprintf(hid->name,sizeof(hid->name), "HID %04x:%04x",le16_to_cpu(dev->descriptor.idVendor),le16_to_cpu(dev->descriptor.idProduct));
hid->bus= BUS_USB;hid->vendor =le16_to_cpu(dev->descriptor.idVendor);hid->product =le16_to_cpu(dev->descriptor.idProduct);
usb_make_path(dev,hid->phys, sizeof(hid->phys));strlcat(hid->phys, "/input",sizeof(hid->phys));len = strlen(hid->phys);if (len <sizeof(hid->phys) – 1)snprintf(hid->phys+ len, sizeof(hid->phys) – len, "%d",intf->altsetting[0].desc.bInterfaceNumber);
if (usb_string(dev,dev->descriptor.iSerialNumber,hid->uniq, 64) <= 0)hid->uniq[0] =0;
usbhid->urbctrl =usb_alloc_urb(0, GFP_KERNEL);if (!usbhid->urbctrl)goto fail;
usb_fill_control_urb(usbhid->urbctrl,dev, 0, (void *) usbhid->cr,usbhid->ctrlbuf, 1, hid_ctrl, hid);usbhid->urbctrl->setup_dma= usbhid->cr_dma;usbhid->urbctrl->transfer_dma= usbhid->ctrlbuf_dma;usbhid->urbctrl->transfer_flags|= (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP);hid->hidinput_input_event =usb_hidinput_input_event;hid->hid_open = usbhid_open;hid->hid_close =usbhid_close;#ifdef CONFIG_USB_HIDDEVhid->hiddev_hid_event =hiddev_hid_event;hid->hiddev_report_event =hiddev_report_event;#endifreturn hid;
fail:usb_free_urb(usbhid->urbin);usb_free_urb(usbhid->urbout);usb_free_urb(usbhid->urbctrl);hid_free_buffers(dev, hid);kfree(usbhid);fail_no_usbhid:hid_free_device(hid);
return NULL;}
1.1.1:usbhid_lookup_quirk（pid,vid）解析：
分别使用usbhid_exists_dquirk(pid,vid),usbhid_exists_squirk(pid,vid)来查看动态和静态的quirks-list.如果有，则返回此quirks.没有，则返回0。
1.1.2：usb_get_extra_descriptor（descriptor, type,&hdesc）解析：
它调用__usb_get_extra_descriptor（）来解析参数一（interface或endpoint描述符）中的扩展描述符区–extra。看是否有类型为参数二（type）的条目，然后把地址交给参数三。
Sam未经证明的猜测：HID设备中，interface描述符中包含的这个扩展描述符。其中存放的都是HID信息，以hid_descriptor结构存放。
对于HID设备来说,在interface description之后会附加一个hid description, hiddescription中的最后部份包含有Report description或者PhysicalDescriptors的长度.
hid_descriptor->usb_descriptor_header->bDescriptorType为HID_DT_HID
后面描述符（包括它自己）hid_descriptor->hid_class_descriptor->bDescriptorType为HID_DT_REPORT
1.1.3：hid_set_idle(structusb_device *dev, int ifnum, int report, intidle)：
它简单的调用usb_control_msg() 发送或接收一个usb控制消息。
具体到这个例子中：
usb_control_msg(dev, usb_sndctrlpipe(dev, 0),HID_REQ_SET_IDLE,USB_TYPE_CLASS | USB_RECIP_INTERFACE, (idle<< 8) | report,ifnum, NULL, 0,USB_CTRL_SET_TIMEOUT);
usb_sndctrlpipe(dev,0)：指出将dev中endpoint 0 设为发送control管道。
HID_REQ_SET_IDLE：此控制消息的Request。
USB_TYPE_CLASS |USB_RECIP_INTERFACE：请求类型.
调用成功才会返回。
1.1.4:hid_get_class_descriptor(dev,interface->desc.bInterfaceNumber, HID_DT_REPORT,rdesc, rsize)
也是通过调用usb_control_msg() 发送或接收一个usb控制消息。
发送USB_REQ_GET_DESCRIPTOR，将得到的report descriptor放到rdesc中。
1.1.5: hid_parse_report(__u8*start, unsigned size)
参数一：通过usb_control_msg发送request(USB_REQ_GET_DESCRIPTOR)从设备得到的report descriptor.
参数二：是此report Descriptor的长度。
1）.首先创建hid_device类型设备。
2).将参数一中数据保存在hid_device->rdesc中。长度保存在hid_device->rsize中。
3). 使用fetch_item(__u8 *start, __u8 *end, struct hid_item*item)得到report description的下一项数据。放到item中。
4). 根据不同的item.type.分别调用
hid_parser_main,hid_parser_global,hid_parser_local,hid_parser_reserved
来处理。
人生好如足球赛,看自家总是无奈,对人家总是优待,
