《Linux总线、设备与驱动》USBHID设备驱动

说明：本分析基于mstar801平台Linux2.6.35.11内核，其他内核版本仅供参考。

一、HID虚拟总线驱动加载

drivers/hid/hid-core.c

module_init(hid_init);
static int __init hid_init(void){
  ret = bus_register(&hid_bus_type);  //注册HID虚拟总线
  ret = hidraw_init();
}
static struct bus_type hid_bus_type = {
  .name       = "hid",
  .match      = hid_bus_match,
  .probe      = hid_device_probe,
  .remove     = hid_device_remove,
  .uevent     = hid_uevent,
};

二、USBHID驱动加载

USBHID驱动同时包含USB总线设备驱动和HID总线设备驱动。

drivers/hid/usbhid/hid-core.c

static int __init hid_init(void){
  retval = hid_register_driver(&hid_usb_driver);  //注册HID总线设备驱动
  retval = usb_register(&hid_driver);  //注册USB总线设备驱动
}
module_init(hid_init);
static struct hid_driver hid_usb_driver = { //一般HID驱动都不实现probe方法
  .name = "generic-usb",
  .id_table = hid_usb_table,
};
static struct usb_driver hid_driver = {  //USB设备驱动方法
  .name =     "usbhid",
  .probe =    usbhid_probe,
  .disconnect =   usbhid_disconnect,
 #ifdef CONFIG_PM
  .suspend =  hid_suspend,
  .resume =   hid_resume,
  .reset_resume = hid_reset_resume,
#endif
  .pre_reset =    hid_pre_reset,
   .post_reset =   hid_post_reset,
  .id_table = hid_usb_ids,
  .supports_autosuspend = 1,
};

三、USBHID设备探测

1.USB总线的设备探测并注册HID设备

USB设备发现机制看如下链接：

《Linux总线、设备与驱动》USB设备发现机制

drivers/hid/usbhid/hid-core.c

static int usbhid_probe(struct usb_interface *intf, const struct usb_device_id *id){
  hid = hid_allocate_device(); //申请HID设备
  hid->ll_driver = &usb_hid_driver; //重要！
  /*
  static struct hid_ll_driver usb_hid_driver = {
    .parse = usbhid_parse,
    .start = usbhid_start,
    .stop = usbhid_stop,
    .open = usbhid_open,
    .close = usbhid_close,
    .power = usbhid_power,
    .hidinput_input_event = usb_hidinput_input_event,
  };
  */
  hid->hiddev_connect = hiddev_connect;
  hid->hiddev_disconnect = hiddev_disconnect;
  hid->hiddev_hid_event = hiddev_hid_event;
  hid->hiddev_report_event = hiddev_report_event;
  usb_make_path(dev, hid->phys, sizeof(hid->phys));
  strlcat(hid->phys, "/input", sizeof(hid->phys));
  if (len < sizeof(hid->phys) - 1)
    snprintf(hid->phys + len, sizeof(hid->phys) - len, "%d", intf->altsetting[0].desc.bInterfaceNumber);
  ret = hid_add_device(hid); //注册HID设备
}

申请HID设备：

drivers/hid/hid-core.c

struct hid_device *hid_allocate_device(void){
  struct hid_device *hdev;
  device_initialize(&hdev->dev);
  hdev->dev.release = hid_device_release;
  hdev->dev.bus = &hid_bus_type;
}
static struct bus_type hid_bus_type = {
  .name       = "hid",
  .match      = hid_bus_match,
  .probe      = hid_device_probe,
  .remove     = hid_device_remove,
  .uevent     = hid_uevent,
};

注册HID设备：

drivers/hid/hid-core.c

int hid_add_device(struct hid_device *hdev){
  ret = device_add(&hdev->dev); //该函数的调用将导致总线对应match和probe的调用
}

2.HID总线的设备探测

参考USB总线探测：http://blog.csdn.net/tankai19880619/article/details/11639185

drivers/hid/hid-core.c

//HID总线match函数
static int hid_bus_match(struct device *dev, struct device_driver *drv){
  if (!hid_match_device(hdev, hdrv)) //匹配VID和PID
    return 0;
  if (!strncmp(hdrv->name, "generic-", 8)) //名字为generic-都匹配
    return !hid_match_id(hdev, hid_have_special_driver);
}
//HID总线的probe函数
static int hid_device_probe(struct device *dev){
  if (hdrv->probe) { //一般HID驱动都没有实现probe方法
    ret = hdrv->probe(hdev, id);
  } else { /* default probe */
     ret = hid_parse(hdev);
     /*
     include/linux/hid.h
     static inline int __must_check hid_parse(struct hid_device *hdev){
       ret = hdev->ll_driver->parse(hdev);
       if (!ret)
         hdev->status |= HID_STAT_PARSED;
       return ret;
     }
     drivers/hid/usbhid/hid-core.c
     static int usbhid_parse(struct hid_device *hid){
       ret = hid_parse_report(hid, rdesc, rsize);
     }
     */
     if (!ret)
       ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
       /*
       include/linux/hid.h
       static inline int __must_check hid_hw_start(struct hid_device *hdev,
unsigned int connect_mask){
         int ret = hdev->ll_driver->start(hdev);
         ret = hid_connect(hdev, connect_mask);
         if (ret)
           hdev->ll_driver->stop(hdev);
       }
       drivers/hid/usbhid/hid-core.c
       static int usbhid_start(struct hid_device *hid){
  
       }
       */
  }
}
int hid_connect(struct hid_device *hdev, unsigned int connect_mask){
  static const char *types[] = { "Device", "Pointer", "Mouse", "Device",
    "Joystick", "Gamepad", "Keyboard", "Keypad",
    "Multi-Axis Controller"
  };
  //HIDINPUT设备
  if ((connect_mask & HID_CONNECT_HIDINPUT) && !hidinput_connect(hdev,connect_mask & HID_CONNECT_HIDINPUT_FORCE))
    hdev->claimed |= HID_CLAIMED_INPUT;
  //HIDDEV设备
  if ((connect_mask & HID_CONNECT_HIDDEV) && hdev->hiddev_connect && !hdev->hiddev_connect(hdev,connect_mask & HID_CONNECT_HIDDEV_FORCE))
    hdev->claimed |= HID_CLAIMED_HIDDEV;
  //HIDRAW设备
  if ((connect_mask & HID_CONNECT_HIDRAW) && !hidraw_connect(hdev))
    hdev->claimed |= HID_CLAIMED_HIDRAW;
}

四、具体设备驱动

1.HIDINPUT设备，如走2.4G的遥控器

drivers/hid/hid-input.c

int hidinput_connect(struct hid_device *hid, unsigned int force){
  //申请设备
  input_dev = input_allocate_device();
  input_dev->event = hid->ll_driver->hidinput_input_event;
  input_dev->open = hidinput_open;
  input_dev->close = hidinput_close;
  input_dev->setkeycode = hidinput_setkeycode;
  input_dev->getkeycode = hidinput_getkeycode;
  input_dev->name = hid->name;
  for (i = 0; i < report->maxfield; i++)
    for (j = 0; j < report->field[i]->maxusage; j++)
      hidinput_configure_usage(hidinput, report->field[i],report->field[i]->usage + j);
  /*
  static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_field *field,
      struct hid_usage *usage){
    switch (usage->hid & HID_USAGE_PAGE) {
      case HID_UP_KEYBOARD:
        set_bit(EV_REP, input->evbit);
        if ((usage->hid & HID_USAGE) < 256) {
          if (!hid_keyboard[usage->hid & HID_USAGE]) goto ignore;
            map_key_clear(hid_keyboard[usage->hid & HID_USAGE]);
            /*
            static const unsigned char hid_keyboard[256] = {
              0,  0,  0,  0, 30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38,
              50, 49, 24, 25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44,  2,  3,
              4,  5,  6,  7,  8,  9, 10, 11, 28,  1, 14, 15, 57, 12, 13, 26,
              27, 43, 43, 39, 40, 41, 51, 52, 53, 58, 59, 60, 61, 62, 63, 64,
              65, 66, 67, 68, 87, 88, 99, 70,119,110,102,104,111,107,109,106,
              105,108,103, 69, 98, 55, 74, 78, 96, 79, 80, 81, 75, 76, 77, 71,
              72, 73, 82, 83, 86,127,116,117,183,184,185,186,187,188,189,190,
              191,192,193,194,134,138,130,132,128,129,131,137,133,135,136,113,
              115,114,unk,172,194,121,229, 89, 93,124, 92, 94, 95,unk,unk,unk,
              122,123, 90, 91, 85,unk,unk,unk,unk,unk,unk,unk,111,unk,unk,unk,
              unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,
              unk,unk,unk,unk,unk,unk,179,180,unk,unk,unk,unk,unk,unk,unk,unk,
              unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,
              unk,unk,unk,unk,unk,unk,unk,unk,111,unk,unk,unk,unk,unk,unk,unk,
              29, 42, 56,125, 97, 54,100,126,164,166,165,163,161,115,114,113,
              150,158,159,128,136,177,178,176,142,152,173,140,unk,unk,unk,unk
            };
            */
          } else
             map_key(KEY_UNKNOWN);
          break;
        }
      }
   }
  */
  //注册设备
  if (hidinput && input_register_device(hidinput->input))
    goto out_cleanup;
}

2.HIDDEV设备

drivers/hid/usbhid/hiddev.c

int hiddev_connect(struct hid_device *hid, unsigned int force){
  retval = usb_register_dev(usbhid->intf, &hiddev_class);
}

3.HIDRAW设备，用来与设备做原始的通讯

这个驱动中不会解析任何数据，只是简单的将设备产生的数据传给应用层。

drivers/hid/hidraw.c

int hidraw_connect(struct hid_device *hid){
  dev->dev = device_create(hidraw_class, &hid->dev, MKDEV(hidraw_major, minor), NULL, "%s%d", "hidraw", minor);
}

五、设备移除部分

1.USB总线设备移除触发USBHID中USB驱动部分调用

drivers/hid/usbhid/hid-core.c

retval = usb_register(&hid_driver);
static struct usb_driver hid_driver = {
  .disconnect =   usbhid_disconnect,
}
static void usbhid_disconnect(struct usb_interface *intf){
  hid_destroy_device(hid); //调用HID总线的设备注销函数
}

2.HID总线驱动

drivers/hid/hid-core.c

void hid_destroy_device(struct hid_device *hdev){
  hid_remove_device(hdev);
}
static void hid_remove_device(struct hid_device *hdev){
  device_del(&hdev->dev);
}
//总线设备注销触发总线函数调用：
static struct bus_type hid_bus_type = {
  .remove     = hid_device_remove,
}
static int hid_device_remove(struct device *dev){
  if (hdrv) {
    if (hdrv->remove)
      hdrv->remove(hdev);
    else /* default remove */
      hid_hw_stop(hdev);
      /*
      include/linux/hid.h
      static inline void hid_hw_stop(struct hid_device *hdev){
        hid_disconnect(hdev);
      }
      */
    hdev->driver = NULL;
  }
}
void hid_disconnect(struct hid_device *hdev){
  device_remove_bin_file(&hdev->dev, &dev_bin_attr_report_desc);
  if (hdev->claimed & HID_CLAIMED_INPUT)
    hidinput_disconnect(hdev); //HIDINPUT设备
  if (hdev->claimed & HID_CLAIMED_HIDDEV)
    hdev->hiddev_disconnect(hdev);  //HIDDEV设备
  if (hdev->claimed & HID_CLAIMED_HIDRAW)
    hidraw_disconnect(hdev);  //HIDRAW设备
}