LINUX USB gadget

Linux 3.0新的USB gadget configfs.c驱动的用法如下所示：

挂载configfs文件系统：

# mount -t configfs none /sys/kernel/config

# cd /sys/kernel/config

# ls

usb_gadget

# cd usb_gadget

创建g1目录，实例化一个新的gadget模板：

# mkdir g1

# cd g1

# ls

UDC bDeviceProtocol bMaxPacketSize0 bcdUSB functions idVendor

bDeviceClass bDeviceSubClass bcdDevice configs idProduct strings

定义产品的VendorID和ProductID

# echo "0xabcd" > idVendor

# echo "0x1234" > idProduct

实例化英语ID：

# mkdir strings/0x409

# ls strings/0x409

manufacturer product serialnumber

将开发商、产品和序列号字符串写入内核：

# echo "0123456789ABCDEF" > strings/0x409/serialnumber

# echo "Master" > strings/0x409/manufacturer

# echo "Demo" > strings/0x409/product

创建功能实例，需要注意的是，一个功能如果有多个实例的话，扩展名必须用数字编号：

# mkdir functions/acm.GS0

# mkdir functions/acm.GS1

# mkdir functions/ecm.usb0

创建一个USB配置实例：

# mkdir configs/c.1

# ls configs/c.1

MaxPower bmAttributes strings

定义配置描述符使用的字符串

# mkdir configs/c.1/strings/0x409

# ls configs/c.1/strings/0x409/

configuration

# echo "2XACM+ECM" > configfs/c.1/strings/0x409/configuration

捆绑功能实例到配置c.1

# ln -s functions/acm.GS0 configs/c.1

# ln -s functions/acm.GS1 configs/c.1

# ln -s functions/ecm.usb0 configs/c.1

查找本机可获得的UDC实例

# ls /sys/class/udc/

msm_hsusb

将gadget驱动注册到UDC上，插上USB线到电脑上，电脑就会枚举USB设备。

# echo "msm_hsusb" > UDC