Linux USB Gadget custom configuration

2
votes

I am using a i.Mx6 Sabre Lite board running Linux Kernel 3.14.18 and board is supposed to act as a USB Device (USB Gadget). One Vendor specific interface need to be added into CDC/NCM Configuration. CDC/NCM Configuration by default has two standard interfaces - Communication & Data. I have added third interface (Vendor specific) to CDC/NCM Configuration. This interface has two Bulk (IN & OUT) Endpoints. I can verify this newly added interface once board is connected to PC using "lsusb".

Problem:

  1. I cannot see the newly added interface getting exposed to user-space on i.Mx Board or PC, like standard NCM interfaces can be seen as usb0 (Ethernet device) on i.Mx Board as well as on PC and I can PING to/from board using usb0.

  2. If I have to hookup this newly added interface with some g_"driver" (just like standard NCM interfaces are hooked to g_ether); then what is the best choice for BULK I/O?

  3. How to make this newly added vendor specific interface available to i.MX6 user space so as to do read/write on it from Linux Application? I came to know about GadgetFS; but any example would be

Hope someone must have tried similar thing in Linux-USB and can guide.

1
linux-kernelusbembedded-linuxusb-descriptor

1 Answers

2
votes

A vendor-specific interface does not use a standard protocol, so it is not possible to use one of the standard drivers. (And bulk is not a protocol, it is a mechanism to implement your own protocol.)

To access such an interface, you have to use the low-level functions from something like libusb.