操作系统： debian 7.4(linux 3.2.54）
硬件： 一个无线鼠标、一个有线鼠标、usb集线器。
从淘宝上花了15块钱买了个无线鼠标，很好奇它的驱动程序是如何执行的。
首先将usb集线器插入到pc的usb口，然后将无线鼠标插入到usb集线器的一个usb口上。
执行下面命令来捕获uevent事件：
sudo udevadm monitor
然后插入和移除再插入无线鼠标的nano接收器(为了完整的查看信息才操作这么多次)，可以在控制台下查看到下面的信息：
$ sudo udevadm monitor
monitor will print the received events for:
UDEV - the event which udev sends out after rule processing
KERNEL - the kernel uevent
KERNEL[22375.667072] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1 (usb)
KERNEL[22375.667421] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0 (usb)
KERNEL[22375.667470] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006 (hid)
KERNEL[22375.668613] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9 (input)
KERNEL[22375.668769] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/mouse0 (input)
KERNEL[22375.668899] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/event0 (input)
KERNEL[22375.669151] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006/hidraw/hidraw0 (hidraw)
UDEV [22375.693845] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1 (usb)
UDEV [22375.701112] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0 (usb)
UDEV [22375.714647] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9 (input)
UDEV [22375.716553] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/mouse0 (input)
UDEV [22375.719153] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006 (hid)
UDEV [22375.719712] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006/hidraw/hidraw0 (hidraw)
UDEV [22375.729434] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/event0 (input)
KERNEL[22456.752414] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/mouse0 (input)
UDEV [22456.752961] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/mouse0 (input)
KERNEL[22456.776217] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/event0 (input)
UDEV [22456.776626] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9/event0 (input)
KERNEL[22456.785326] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9 (input)
KERNEL[22456.785501] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006/hidraw/hidraw0 (hidraw)
KERNEL[22456.785523] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006 (hid)
KERNEL[22456.785541] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0 (usb)
KERNEL[22456.785616] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1 (usb)
UDEV [22456.786670] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input9 (input)
UDEV [22456.786699] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006/hidraw/hidraw0 (hidraw)
UDEV [22456.786842] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0006 (hid)
UDEV [22456.786940] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0 (usb)
UDEV [22456.794130] remove /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1 (usb）
KERNEL[22562.038737] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1 (usb)
KERNEL[22562.039577] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0 (usb)
KERNEL[22562.039748] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0007 (hid)
KERNEL[22562.040809] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input10 (input)
KERNEL[22562.040953] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input10/mouse0 (input)
KERNEL[22562.041206] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input10/event0 (input)
KERNEL[22562.041400] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0007/hidraw/hidraw0 (hidraw)
UDEV [22562.070879] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1 (usb)
UDEV [22562.077647] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0 (usb)
UDEV [22562.084927] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0007 (hid)
UDEV [22562.086144] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/0003:1D57:0016.0007/hidraw/hidraw0 (hidraw)
UDEV [22562.089305] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input10 (input)
UDEV [22562.089350] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input10/mouse0 (input)
UDEV [22562.089384] add /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input10/event0 (input)
输出信息中add对应行是插入时候产生的uevent,remove对应行是移除nano接收器时产生的uevent。
最后一次插入时在/sys文件夹下添加了很多目录，可以用下面命令查看：
$ cat /sys/devices/pci0000:/::1d./usb1/-/-1.1/-1.1:1.0/input/input10/mouse0/device/id/vendor
1d57
$ cat /sys/devices/pci0000:/::1d./usb1/-/-1.1/-1.1:1.0/input/input10/mouse0/device/id/product
这与lsusb命令获取的信息一致：
$ lsusb
Bus Device : ID 1d6b: Linux Foundation 2.0 root hub
Bus Device : ID 1d6b: Linux Foundation 1.1 root hub
Bus Device : ID 1d6b: Linux Foundation 1.1 root hub
Bus Device : ID 1d6b: Linux Foundation 1.1 root hub
Bus Device : ID 1d6b: Linux Foundation 1.1 root hub
Bus Device : ID 1a40: * Technology Inc. -Port HUB
Bus 001 Device 010: ID 1d57:0016 Xenta
Bus Device : ID 046d:c05a Logitech, Inc. Optical Mouse M90
Bus Device : ID 413c: Dell Computer Corp. Keyboard
Bus Device : ID 0a12: Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode) $ lsusb -s 001:010 -v Bus 001 Device 010: ID 1d57:0016 Xenta
Couldn't open device, some information will be missing
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x1d57 Xenta
idProduct 0x0016
bcdDevice 11.10
iManufacturer 1
iProduct 2
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 34
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xa0
(Bus Powered)
Remote Wakeup
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 3 Human Interface Device
bInterfaceSubClass 1 Boot Interface Subclass
bInterfaceProtocol 2 Mouse
iInterface 0
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.10
bCountryCode 0 Not supported
bNumDescriptors 1
bDescriptorType 34 Report
wDescriptorLength 65
Report Descriptors:
** UNAVAILABLE **
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 2
这个nano接收器的vendorID和productID分别是0x1d57和0x0016。
执行dmesg查看插入nano接收器的输入信息：
dmesg | tail -n
[22375.556155] usb -1.1: new full-speed USB device number using ehci_hcd
[22375.666762] usb -1.1: New USB device found, idVendor=1d57, idProduct=
[22375.666769] usb -1.1: New USB device strings: Mfr=, Product=, SerialNumber=
[22375.666773] usb -1.1: Product: HID Wireless Mouse
[22375.666777] usb -1.1: Manufacturer: HID Wireless Mouse
[22375.668566] input: HID Wireless Mouse HID Wireless Mouse as /devices/pci0000:/::1d./usb1/-/-1.1/-1.1:1.0/input/input9
[22375.668979] generic-usb :1D57:0016.0006: input,hidraw0: USB HID v1. Mouse [HID Wireless Mouse HID Wireless Mouse] on usb-::1d.-1.1/input0
[22456.751805] usb -1.1: USB disconnect, device number
[22561.928127] usb 1-1.1: new full-speed USB device number 10 using ehci_hcd
[22562.038482] usb 1-1.1: New USB device found, idVendor=1d57, idProduct=0016
[22562.038489] usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[22562.038493] usb 1-1.1: Product: HID Wireless Mouse
[22562.038497] usb 1-1.1: Manufacturer: HID Wireless Mouse
[22562.040767] input: HID Wireless Mouse HID Wireless Mouse as /devices/pci0000:00/0000:00:1d.7/usb1/1-1/1-1.1/1-1.1:1.0/input/input10
[22562.041276] generic-usb 0003:1D57:0016.0007: input,hidraw0: USB HID v1.10 Mouse [HID Wireless Mouse HID Wireless Mouse] on usb-0000:00:1d.7-1.1/input0
只有最后7行输出信息与最后一次插入nano接收器有关。
下面获取当前linux的内核源码，我使用的是debian 7.4,使用下面命令查看内核信息：
host@debian:~/soft/mini2440/linux-2.6.32.2$ uname -a
Linux debian 3.2.---pae # SMP Debian 3.2.- i686 GNU/Linux
当前内核版本是linux 3.2.54, 因为我已经下载了3.2.57的内核，就直接使用该版本的内核源代码（这两个版本源码差别很小，我只是查看源代码，所以就不想重新下载了）。
如果没有内核源代码，可以参考我的博文《编译debian内核》下载内核源码。
内核源代码下载后，执行解压缩，然后进入该文件夹.
鼠标属于hid(human interface device)，而nano接收器使用了usb口，所以其对应驱动所在位置很可能是在drivers/hid或者drivers/usb下。
为了确保能找到所有相关代码，我在drivers文件夹执行搜索：
$ find drivers/ -name '*.[ch]' -exec grep -rnHi 'full-speed' {} \; | grep USB
drivers/usb/usb-common.c:: [USB_SPEED_FULL] = "full-speed",
可以看到该行源代码位于usb_speed_string。在vim下执行"make cscope"、"cs add cscope.out"、"cs f s usb_speed_string"可以搜索到所有使用usb_speed_string的代码。
其中最可能相关联的是hub_port_init函数中调用usb_speed_string的代码。
而hub_port_init又被hub_port_connect_change函数所调用。
当前情况下是将nano接收器插入到usb口，确实满足port连接状况改变的情况。
继续查找信息，使用下面命令：
$ find drivers/ -name '*.[ch]' -exec grep -rnHi 'idVendor=' {} \;
drivers/usb/core/hub.c:: dev_info(&udev->dev, "New USB device found, idVendor=%04x, idProduct=%04x\n",
该行代码位于annouce_device函数，annouce_device函数内容如下：
static void announce_device(struct usb_device *udev)
{
dev_info(&udev->dev, "New USB device found, idVendor=%04x, idProduct=%04x\n",
le16_to_cpu(udev->descriptor.idVendor),
le16_to_cpu(udev->descriptor.idProduct));
dev_info(&udev->dev,
"New USB device strings: Mfr=%d, Product=%d, SerialNumber=%d\n",
udev->descriptor.iManufacturer,
udev->descriptor.iProduct,
udev->descriptor.iSerialNumber);
show_string(udev, "Product", udev->product);
show_string(udev, "Manufacturer", udev->manufacturer);
show_string(udev, "SerialNumber", udev->serial);
}
而annouce_device被usb_new_device调用，usb_new_device又被hub_port_connect_change函数所调用。
倒数第二行的输出信息中不容易用grep搜索到，直接搜索最后一行输出信息中的"generic-usb":
$ find drivers/ -name '*.[ch]' -exec grep -rnHi 'generic-usb' {} \;
drivers/hid/usbhid/hid-core.c:: .name = "generic-usb",
这行输出信息很可能是初始化hid(对应于hid_init函数）时得到的输出信息。
稍微整理一下代码的执行流程（参考《essential linux device drivers》）。
usb代码架构中包含有三个重要的组成部分:usbcore, usb host controller driver, usb client driver.
其中usb host controller driver是比较靠近内核的一部分功能，此处不需要考虑。
usbcore中创建了一个khubd线程（位于usb_hub_init函数中）监控端口（port）的状态，当端口(port)状态改变时，会调用hub_port_connect_change函数。
hub_port_connect_change中调用hub_port_init对port进行初始化（包括获取设备描述符，这样能得到所有该设备相关信息），
然后调用usb_new_device调用device_add添加新的usb设备（此处即nano接收器）。
device_add添加该设备(nano接收器）时,主要是创建设备和sysfs文件夹以及添加相应的设备驱动,
中间经过漫长的调用（具体执行过程比较复杂，我还没有好好分析）后会执行hid_bus_match对总线匹配，
匹配成功后执行hid_device_probe->hid_hw_start->hid_connect输出信息。
我手中还有个有线鼠标，插入该鼠标得到的输出信息如下：
[ 7029.876038] usb -: new low-speed USB device number using uhci_hcd
[ 7030.051078] usb -: New USB device found, idVendor=046d, idProduct=c05a
[ 7030.051085] usb -: New USB device strings: Mfr=, Product=, SerialNumber=
[ 7030.051090] usb -: Product: USB Optical Mouse
[ 7030.051093] usb -: Manufacturer: Logitech
[ 7030.067358] input: Logitech USB Optical Mouse as /devices/pci0000:/::1d./usb2/-/-:1.0/input/input7
[ 7030.067521] generic-usb :046D:C05A.: input,hidraw0: USB HID v1. Mouse [Logitech USB Optical Mouse] on usb-::1d.-/input0
从输出信息上看，二者输出信息是相当类似的，其驱动执行过程也应该大致相似。
在写博客之前，我猜想无线鼠标可能会用到和有线鼠标不同的驱动程序，但是从整个分析过程看来二者用的驱动程序基本上是差不多的（都是用到usbcore和usbhid）。