用sysfs查看linux下usb设备的描述符
/sys/bus/usb/devices/下的路径命名规则
roothub-port[.port]：configuration：interface
一般，1-0是根hub自身信息，当hub上有插入设备时，就会出现1-1、1-2了。
1.查看目录：
ls /sys/bus/usb/devices/
1-0:1.0 1-1.1:1.0 2-1 4-0:1.0 usb1 usb4
1-1 1-1:1.0 2-1:1.0 5-0:1.0 usb2 usb5
1-1.1 2-0:1.0 3-0:1.0 6-0:1.0 usb3 usb6
这是什么鬼东西？
2.别急，再详细看看。
ls /sys/bus/usb/devices/usb1/
1-0:1.0 bcdDevice manufacturer
1-1 bmAttributes maxchild
authorized busnum power
authorized_default configuration product
avoid_reset_quirk descriptors quirks
bConfigurationValue dev removable
bDeviceClass devnum remove
bDeviceProtocol devpath serial
bDeviceSubClass driver speed
bMaxPacketSize0 ep_00 subsystem
bMaxPower idProduct uevent
bNumConfigurations idVendor urbnum
bNumInterfaces ltm_capable version
可以直接看到描述符？
3.子目录呢？
ls /sys/bus/usb/devices/usb1/1-0\:1.0/
bAlternateSetting bNumEndpoints power
bInterfaceClass driver subsystem
bInterfaceNumber ep_81 supports_autosuspend
bInterfaceProtocol modalias uevent
bInterfaceSubClass port1
接口描述符？好家伙！
4.看看是啥设备：
cat /sys/bus/usb/devices/usb1/1-0\:1.0/bInterfaceClass
09
哇哦，是hub！
5.那1-1是啥东西？
cat /sys/bus/usb/devices/usb1/1-1/1-1.1/bDeviceClass
00
是一个设备，我刚刚插进去的安卓手机
于是可以得到：
接口描述符：
cat /sys/bus/usb/devices/usb1/1-1/1-1.1/1-1.1\:1.0/
bAlternateSetting driver/ subsystem/
bInterfaceClass ep_02/ supports_autosuspend
bInterfaceNumber ep_81/ uevent
bInterfaceProtocol interface usbmisc/
bInterfaceSubClass modalias
bNumEndpoints power/
往上是配置和设备描述符：
cat /sys/bus/usb/devices/usb1/1-1/1-1.1/
1-1.1:1.0/ busnum port/
authorized configuration power/
avoid_reset_quirk descriptors product
bConfigurationValue dev quirks
bDeviceClass devnum removable
bDeviceProtocol devpath remove
bDeviceSubClass driver/ serial
bMaxPacketSize0 ep_00/ speed
bMaxPower idProduct subsystem/
bNumConfigurations idVendor uevent
bNumInterfaces ltm_capable urbnum
bcdDevice manufacturer version
bmAttributes maxchild
再往上：
cat /sys/bus/usb/devices/usb1/1-1/
1-1.1/ bmAttributes port/
1-1:1.0/ busnum power/
authorized configuration product
avoid_reset_quirk descriptors quirks
bConfigurationValue dev removable
bDeviceClass devnum remove
bDeviceProtocol devpath speed
bDeviceSubClass driver/ subsystem/
bMaxPacketSize0 ep_00/ uevent
bMaxPower idProduct urbnum
bNumConfigurations idVendor version
bNumInterfaces ltm_capable
bcdDevice maxchild
这个好像没有区别。
6.回到主目录：
ls /sys/bus/usb/devices/
1-0:1.0 1-1.1:1.0 2-1 4-0:1.0 usb1 usb4
1-1 1-1:1.0 2-1:1.0 5-0:1.0 usb2 usb5
1-1.1 2-0:1.0 3-0:1.0 6-0:1.0 usb3 usb6
一共3个接口，为啥有6个usb呢？追溯一下：
ls -al /sys/bus/usb/devices/
total 0
drwxr-xr-x 2 root root 0 Jan 1 06:59 .
drwxr-xr-x 4 root root 0 Jan 1 06:59 ..
lrwxrwxrwx 1 root root 0 Jan 1 06:59 1-0:1.0 -> ../../../devices/soc/5200000.ehci1-controller/usb1/1-0:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 1-1 -> ../../../devices/soc/5200000.ehci1-controller/usb1/1-1
lrwxrwxrwx 1 root root 0 Jan 1 08:46 1-1.1 -> ../../../devices/soc/5200000.ehci1-controller/usb1/1-1/1-1.1
lrwxrwxrwx 1 root root 0 Jan 1 08:46 1-1.1:1.0 -> ../../../devices/soc/5200000.ehci1-controller/usb1/1-1/1-1.1/1-1.1:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 1-1:1.0 -> ../../../devices/soc/5200000.ehci1-controller/usb1/1-1/1-1:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 2-0:1.0 -> ../../../devices/soc/5310000.ehci2-controller/usb2/2-0:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 2-1 -> ../../../devices/soc/5310000.ehci2-controller/usb2/2-1
lrwxrwxrwx 1 root root 0 Jan 1 06:59 2-1:1.0 -> ../../../devices/soc/5310000.ehci2-controller/usb2/2-1/2-1:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 3-0:1.0 -> ../../../devices/soc/5311000.ehci3-controller/usb3/3-0:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 4-0:1.0 -> ../../../devices/soc/5200000.ohci1-controller/usb4/4-0:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 5-0:1.0 -> ../../../devices/soc/5310000.ohci2-controller/usb5/5-0:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 6-0:1.0 -> ../../../devices/soc/5311000.ohci3-controller/usb6/6-0:1.0
lrwxrwxrwx 1 root root 0 Jan 1 06:59 usb1 -> ../../../devices/soc/5200000.ehci1-controller/usb1
lrwxrwxrwx 1 root root 0 Jan 1 06:59 usb2 -> ../../../devices/soc/5310000.ehci2-controller/usb2
lrwxrwxrwx 1 root root 0 Jan 1 06:59 usb3 -> ../../../devices/soc/5311000.ehci3-controller/usb3
lrwxrwxrwx 1 root root 0 Jan 1 06:59 usb4 -> ../../../devices/soc/5200000.ohci1-controller/usb4
lrwxrwxrwx 1 root root 0 Jan 1 06:59 usb5 -> ../../../devices/soc/5310000.ohci2-controller/usb5
lrwxrwxrwx 1 root root 0 Jan 1 06:59 usb6 -> ../../../devices/soc/5311000.ohci3-controller/usb6
看到了，ehci和ohci是分开的，所以一共有6个控制器。
void checkUSBDevice()
{
bool ret = false;
#define USB1_PATH "/sys/bus/usb/devices/usb1/1-1/1-1.1/product"
#define USB2_PATH "/sys/bus/usb/devices/usb1/1-1/1-1.2/product"
int fd = open(USB1_PATH,O_RDONLY);
if(fd>0)
{
printf("usb 1 is exist!\n");
char product[BUF_LEN] = {'\0'};
int seekLen = lseek(fd,0,SEEK_END);
lseek(fd,0,SEEK_SET);
int ret = read(fd,product,seekLen);
close(fd);
}
else
{
printf("usb 1 is not exist!\n");
}
fd = open(USB2_PATH,O_RDONLY);
if(fd>0)
{
printf("usb 2 is exist!\n");
char product[BUF_LEN] = {'\0'};
int seekLen = lseek(fd,0,SEEK_END);
lseek(fd,0,SEEK_SET);
int ret = read(fd,product,seekLen);
printf("usb1 name:%s,strlen=%d,seekLen=%d,reedlen=%d\n",product,strlen(product),seekLen,ret);
close(fd);
}
else
{
printf("usb 2 is not exist!\n");
}
}