cc216f0ab1
This patch allows the administrator to configure the interface name of a function using u_ether (e.g., eem, ncm, rndis). Currently, all such interfaces, regardless of function type, are always called usb0, usb1, etc. This makes it very cumbersome to use more than one such type at a time, because userspace cannnot easily tell the interfaces apart and apply the right configuration to each one. Interface renaming in userspace based on driver doesn't help, because the interfaces all have the same driver. Without this patch, doing this require hacks/workarounds such as setting fixed MAC addresses on the functions, and then renaming by MAC address, or scraping configfs after each interface is created to find out what it is. Setting the interface name is done by writing to the same "ifname" configfs attribute that reports the interface name after the function is bound. The write must contain an interface pattern such as "usb%d" (which will cause the net core to pick the next available interface name starting with "usb"). This patch does not allow writing an exact interface name (as opposed to a pattern) because if the interface already exists at bind time, the bind will fail and the whole gadget will fail to activate. This could be allowed in a future patch. For compatibility with current userspace, when reading an ifname that has not currently been set, the result is still "(unnamed net_device)". Once a write to ifname happens, then reading ifname will return whatever was last written. Tested by configuring an rndis function and an ncm function on the same gadget, and writing "rndis%d" to ifname on the rndis function and "ncm%d" to ifname on the ncm function. When the gadget was bound, the rndis interface was rndis0 and the ncm interface was ncm0. Signed-off-by: Lorenzo Colitti <lorenzo@google.com> (cherry picked from commit 63d152149b2d0860ccf8c4e6596b6175b2b7ace6 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-next) Link: https://lore.kernel.org/r/20210113234222.3272933-1-lorenzo@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lorenzo Colitti <lorenzo@google.com> Change-Id: I04deb6cc1d8a5b8ee82404940de2a79c06fbafe7 Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("hub_wq").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.