Linux下 USB HID device driver研究（三）--probe

时间：2019-09-02 15:26:01

关键字： Linux descriptor

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[导读]作者： Sam（甄峰） sam_code@hotmail.com 1. 解读hiddevice probe程序： static int hid_probe(struct usb_interface

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 %dn",
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 hiddevn");
  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 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 %sn",
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0
quirks =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 notpresentn");
  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 memoryn");
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 failedn");
  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 failedn");
  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 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_HIDDEV
hid->hiddev_hid_event =hiddev_hid_event;
hid->hiddev_report_event =hiddev_report_event;
#endif
return 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。