BeagleBoard/GSoC/2021 Proposal/usb configfs in device tree

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Proposal for Device Tree Improvement


  • Pre-application phase


  • Completed all the general requirements
  • Completed "Hello Wolrd" of cross compilation mentioned in the requirements list.
  • Sent a PR to the mentioned upstream #145

About You

About Your Project

  • Project name: USB configfs in device tree


  • ConfigFS which along with libcomposite allows to set up custom gadget. This can be achieved using simple, command-line file system operation like mkdir, rmdir, ln -s, read and write. It is possible to configure USB gadget using only the command line but each time after reboot user needs to recreate all gadgets once again. This means that after each reboot user needs to use commands.
  • Also scripts can be edited and are obviously less secure.
  • Secondly it's really hard to modify such a script because many calls have a hard-coded path where for example echo should be done. There is a lot of simple, but low-level operations which can cause a lot of confusion for a beginner.
  • This leads us to another solution : libusbgx which is a userspace library to configure USB gadgets
  • However a better solution to this could be using device trees for configuration. The idea with this GSoC project is to create a device-tree node that could specify the USB gadget through libcomposite on bootup. Thus users of USB gadget wouldn’t have to rely on custom boot scripts or libusbgX.
  • Goal: USB configfs in device tree such that they can be configured statically in device tree ahead of boot and speed the boot process.

Implementation Details

A device tree is a tree data structure with nodes that describe the physical devices in a system. From wiki we can see the basic usage guide of device tree. We can look at the bindings here.

               USB:&USB {
                               compatible = "chip,subset";
                               reg = <USB_hub_port_HEX>;
                               reset-gpios = <&gpio1 NUM GPIO_ACTIVE_LOW>;
                               vendor-id = /bits/ 16 <0x0000>;
                               product-id = /bits/ 16 <0x0000>;
                               manufacturer = "Foo";
                               product = "Foo-Bar";
                               serial = "1234567890A";
                               configs: configs{
                                      configuration = "BeagleBone Composite";
                                      max_power = 500;
                                      sub-class = <04>;
                                      protocol = <01>;
                               symlink = "functions/acm.usb0";


Date Status Details
13/04/2021 to 17/05/2021 Application Review Period Right After submitting the application I will go through rigorous set of reference materials udemy course which has practical implementation with device tree. Resource 1 Resource 2 Resource 3 Resource 4
17/05/2021 to 07/06/2021 Community Bonding
  • Complete College exams , vivas, practicals and stuff
  • Make sure that stuff for project is available
  • Coding Begins
14/06/2021 Milestone #1
  • Introductory Video
  • Build and test the already present device tree files
  • Update as per mentioned kernel version and bindings as necessary
21/06/2021 Milestone #2
  • Build and Test A prototype of Device Tree
  • This will allow me to get more info on the process of setting up the device trees for future reference.
28/06/2021 Milestone #3
  • Implement a generic usb node in device tree
  • Create child nodes with configurations
  • Test the configurations thoroughly
05/07/2021 - 10/07/2021 Milestone #4
  • Eliminate the boot scripts for usb-gadget configuration
  • Review the configurations for errors
  • Documentation for everything till now
17/07/2021 Milestone #5
  • Add USB functions and test for Abstract Control Model or ACM
  • Verify the USB functionality
24/07/2021 Milestone #6
  • Build and test functionality on all Beagle Devices
  • Implement examples for USB configurations
31/07/2021 - 03/07/2021 Milestone #7
  • Documentation of everything till now
  • Brief overview and discussion with mentor
  • Bring in required changes
10/08/2021 Milestone #8
  • Compile with other latest kernels
  • Test the kernel modules for mass storage and Verify the functionality
17/08/2021 Milestone #9
  • Document If anything remaining
  • If finished early solve the kernel bugs
24/08/2021 Milestone #10
  • Students submit final work product and final mentor evaluation
  • Completion of youtube video
31/08/2021 Milestone #11 Completion of GSoC

Experience and approach

  • Previously I have worked with Qt and Boost.ASIO . PID-Tuning-GUI is an application that sends data to ESP32 micro controller which supports WiFi connectivity. Handled Application threads and Plotting of data as well as sending user input to microcontroller.
  • kernel learn is a repository I had created for kernel learning purpose in which I had learned several Kernel development Basics .
  • I have played with Pocketbeagle for a month and learned a lot about u-boot, device trees and Loadable Kernel Modules.
  • This gives me best of both the worlds embedded as well as a bit in frontend (Qt).


  • There is a good documentation of FXTUI and Qt
  • Plenty of examples to get me through if I am stuck.
  • Past experience regarding Qt and DOM manipulation combined with experience in embedded and loadable kernel modules development will pay off in this duration .


  • Having a seamless one-click experience to configure is enjoyed by any user, be it production or a robotics team.
  • Provides a configuration file to the users. Remembers defaults and helps in accidental modification to low level configurations.



  • For hello_world of cross-compilation , sent a PR to the mentioned upstream #145