tree b0de88bd611e1e8ac6cdb6ce82d8593e3f43cfa8
parent b68e2285f2ebab000f3d0d7d7cdc6693b09c7e93
author Igor Kononenko <i.kononenko.e@gmail.com> 1702560426 +0300
committer i.kononenko.e <i.kononenko.e@gmail.com> 1732575066 +0000

usb-ctrl: add a way to mount composite gdts

The usb-vhub has a limited number of usb-gadget ports. The BMC features
might want to attach usb-device count greater than the aspeed-vhub
contains ports. One of the ways to solve the issue could be by attaching
usb-gadget functions to a composite usb interface.

The change brings a way to mount mass_storage and cdc-based devices
under composite device configuration (VID/PID: 1D6B:0104)

This make possible to mount bouth device functions under single
vhub-port.

Tested:
* Insert usb-gadget:mass-storage device is success:
  ```bash
  #: usb-ctrl insert usb0 /tmp/image.iso cdrom
  ```
* Insert usb-gadget:usb-ecm device for same port is success:
  ```bash
  #: usb-ctrl ecm usb0 on A0:C5:F2:15:B5:89 A0:C5:F2:15:B5:88
  ```
* the sysfs displays function-descriptors for both interfaces:
  ```bash
  #: root@vegman-r120-020323000A:~# cd /sys/kernel/config/usb_gadget
  #: root@vegman-r120-020323000A:~# ls -la ./usb0/functions/
     drwxr-xr-x 4 root root 0 Dec 14 12:13 .
     drwxr-xr-x 6 root root 0 Dec 14 12:14 ..
     drwxr-xr-x 2 root root 0 Dec 14 12:13 ecm.usb0
     drwxr-xr-x 3 root root 0 Dec 14 12:11 mass_storage.usb0
  ```
* eject one of the mounted device works properly, another one stay
  online:
  ```bash
  #: usb-ctrl ecm usb0 off
  #: ls -la /sys/kernel/config/usb_gadget/usb0/functions/
     drwxr-xr-x 3 root root 0 Dec 14 12:19 .
     drwxr-xr-x 6 root root 0 Dec 14 12:19 ..
     drwxr-xr-x 3 root root 0 Dec 14 12:11 mass_storage.usb0
  ```

* output on the host side
  ```bash
  #: root@ubuntu:/home/ubuntu# lsusb -d 1d6b:0104 -v

     Bus 001 Device 003: ID 1d6b:0104 Linux Foundation Multifunction ...
     Device Descriptor:
     ...
       idVendor 0x1d6b Linux Foundation
       idProduct 0x0104 Multifunction Composite Gadget
     ...
       Interface Descriptor:
       ...
            bInterfaceClass 8 Mass Storage
            bInterfaceSubClass 6 SCSI
            bInterfaceProtocol 80 Bulk-Only
            iInterface 5 Mass Storage
       ...
       Interface Descriptor:
       ...
            bInterfaceClass 2 Communications
            bInterfaceSubClass 6 Ethernet Networking
            bInterfaceProtocol 0
            iInterface 7 CDC Ethernet Control Model (ECM)
       ...

  ```

Change-Id: I6f54ac5c116ee0bb08e9d18c33267f5b401c2c00
Signed-off-by: Igor Kononenko <i.kononenko.e@gmail.com>