Getting Interface Numbers

If you are using a multiple-interface device where the usb_mid(7D) driver is making only one of its interfaces available to the calling driver, you might need to know the number of the interface to which the calling driver is bound. Use the usb_get_if_number(9F) function to do any of the following tasks:

• Return the number of the interface to which the calling driver is bound. The usb_get_if_number(9F) function returns an interface number greater than zero in this case.

• Discover that the calling driver manages an entire multi-interface device. The driver is bound at the device level so that usb_mid has not split it. The usb_get_if_number(9F) function returns USB_DEVICE_NODE in this case.

• Discover that the calling driver manages an entire device by managing the only interface that device offers in its current configuration. The usb_get_if_number(9F) function returns USB_COMBINED_NODE in this case.