Difference between revisions of "BeagleBoard/GSoC/2023 Proposal/AyushSingh"

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I have been studying up on [https://www.youtube.com/watch?v=JPXw5Hw--4M OpenThread] since it is supported by cc1352 and was suggested in slack by @jkridner.
  
 
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Revision as of 12:33, 25 March 2023


BeagleBoard/GSoC/2023 Proposal/AyushSingh

About Student: Ayush Singh
Mentors: Jason Kridner, Vaishnav
Wiki: BeagleConnect
GSoC: TBD

Status

This project is currently just a proposal.

Proposal

  • Completed All the requirements listed on the ideas page.
  • The PR request for cross-compilation task: #170

About you

IRC: @ayush1325:matrix.org
Github: Ayush1325
Blog: Programmer's Hideaway
Slack: Ayush1325
Gitlab: ayush1325
Discourse: ayush1325
School: Indian Institute of Technology (ISM), Dhanbad
Country: India
Primary language: English, Hindi
Typical work hours: 12PM - 01AM Indian Standard Time<be>

Previous GSoC participation: I have previously participated in GSoC 2022 for Tianocore Organization. I have been quite interested in working on the Linux Kernel, the biggest Open-Source project in the world, for a long time. While I have worked on low-level stuff like UEFI, I still haven’t contributed to upstream Linux. Initially, the barrier of entry was simply too high for me. After completing the GSoC 2022 project, I was more confident about working on upstream Linux. However, I couldn’t find strong enough motivation to drop my other open-source projects to work on Linux Kernel. With this project, I hope to change this and start contributing to upstream Linux. I am also quite interested in BeagleConnect and its implications in the Internet of Things applications. Thus I would like to help improve it.

About your project

Project name: Replace GBridge

Description

Overview

The goal of the project is to eliminate the need for GBridge completely and simplify the architecture of BeagleConnect. The current architecture is as follows:

Greybus <--Netlink--> GBridge <--wpanusb--> cc1532 <--6lowpan--> BeagleConnect

The new architecture will look as follows:

Greybus <--Platform Driver--> cc1532 <--6lowpan--> BeagleConnect

The subtasks I have identified are the following:

  1. Allow the Greybus Linux driver to directly communicate with cc1352
  2. Move SVC and APBridge roles into cc1352
  3. Eliminate the need for GBridge

GBridge Overview

To eliminate GBridge, we must first understand it's different parts. Thus I will discuss each part here in brief.

SVC

It is in charge of module hot plug / hot unplug detection, create / destroy connections, etc.

Netlink

GBridge is using netlink to communicate with Greybus.

Controller

The controller is actually the link between the SVC, netlink and all the modules. There are 4 main controllers present in GBridge currently:

  1. Bluetooth Controller: It scans continuously to detect new bluetooth module. When a Bluetooth module with the "GREYBUS" string in its name show up, the controller will generate an hotplug event and create a connection.
  2. TCP/IP: It use avahi to detect a new module.
  3. GBSHIM: It provides a way to test quickly and easily Greybus, Greybus netlink and gbridge.
  4. UART: This does not seem to be in the README, but is being registered if a `p` option is supplied.

Greybus Driver

Currently, the upstream Greybus driver uses netlink (which is added using a patch). However, netlink will not be needed since GBridge is being removed. Instead, a platform driver will be used to communicate directly with cc1352.

The actual types that are used in communication can be found at include/linux/greybus/greybus_protocols.h` in upstream Linux kernel. While there are many request and response types, all of them have a header with the following signature:

struct gb_operation_msg_hdr {
	__le16	size;		/* Size in bytes of header + payload */
	__le16	operation_id;	/* Operation unique id */
	__u8	type;		/* E.g GB_I2C_TYPE_* or GB_GPIO_TYPE_* */
	__u8	result;		/* Result of request (in responses only) */
	__u8	pad[2];		/* must be zero (ignore when read) */
};

Depending on the driver's choice, the data might need to be formatted in some specific way.

Platform Driver

This new driver will be responsible for communication between Greybus and cc1352. Since this will be a Platform Driver, it will follow the standard convention:

struct platform_driver {
      int (*probe)(struct platform_device *);
      int (*remove)(struct platform_device *);
      void (*shutdown)(struct platform_device *);
      int (*suspend)(struct platform_device *, pm_message_t state);
      int (*suspend_late)(struct platform_device *, pm_message_t state);
      int (*resume_early)(struct platform_device *);
      int (*resume)(struct platform_device *);
      struct device_driver driver;
};

I have been studying up on OpenThread since it is supported by cc1352 and was suggested in slack by @jkridner.

cc1352 Firmware

Most of the heavy lifting will be done by the cc1352 firmware. It now needs to take care of both the SVC and APBridge roles.

SVC Role

The cc1352 firmware will need to detect the hotplug and removal of modules. In the current architecture, each controller runs an event_loop in a pthread to carry out its functionality. In zephyr, I can see 2 ways to achieve something similar:

  1. Use threads: Since we can use compile parameters to determine which controllers to use, we can use K_THREAD_DEFINE to define the required threads at compile time. However, since zephyr is more constrained than a Linux host, I am not sure if this is the best implementation.
  2. Use Polling API: The hotplug detection portion of the controllers can be moved to a Polling API, which can be more efficient.

Currently, I will be focussing on TCPIP controller. I have been studying up on Multicast DNS since that is currently being used in the form of avahi. However, I will try to find if there is a better (more efficient) solution for a constrained system.

APBridge Role

This role involves converting UART to something like TCP/IP, which can be implemented in cc1352. The actual communication between Host and BeagleConnect can be implemented using Message Queues + Events.

I think using Message Queues might be better than pipes and/or directly sending messages from the controller since the asynchronous operation of Message Queues in a multi-controller architecture might be more efficient.

Timeline

Date Status Details
Presubmission
  • Setup zephyr environment and build a board for native POSIX execution
  • Blink an LED using Linux, Zephyr and Greybus
May 4 - May 28 Community Bonding

I will be having exams till May 10th, so I will start being active after that,

May 28 Milestone #1
  • Required hardware will be available to me, and I will start flashing Zephyr on Beagleconnect Freedom
  • Start going through the documentation and datasheet of the hardware available.
June 4th Milestone #2
  • Introduction Video
  • Start work on platform driver for communication between Greybus and cc1352.
June 11th Milestone #3
  • Start testing communication between Greybus and cc1352 using new platform driver.
  • Start with Module Insert Event.
June 18th Milestone #4
  • Implement APBridge role for cc1352.
June 25th Milestone #5
  • Write tests that APBridge role is working as intended
July 2nd Milestone #6
  • Start work on implementing the SVC role for cc1352.
  • Write generic code used by all controllers.
July 9th Milestone #7
  • Make avahi or its alternative run on cc1352.
July 14th Milestone #8 (Mid-term Evaluation)
  • Implement TCPIP controller.
July 23th Milestone #9
  • Start testing all the 3 components (Greybus Linux driver, cc1352 and BeagleConnect) together.
  • Iron out bugs.
July 30th Milestone #10
  • Submit upstream PR for the new Platform Driver.
August 6th Milestone #11
  • Test the completed setup and make some performance optimizations.
August 13th Milestone #12
  • Make any suggested changes to different PRs.
August 21th to 28th Final Week
  • Submit final work product and final mentor evaluation
  • Complete YouTube video
August 28 to September 4 End of competition

Mentors submit final student evaluations

Experience and approach

I have a very good knowledge of Rust programming language in firmware development. I work a lot on `no_std` environments, i.e. environments where Rust standard library is not available due to some reason. I also have experience with Rust FFI for things like UEFI specification. I have some experience with C and C++ as well. Some of my previous projects include

  1. Rust UEFI std: PR for implementation of Rust std for UEFI. This project was initially done as a part of the Google Summer of Code 2022. However, at this point it has evolved into its own thing and I am still actively working on it.
  2. r-efi: UEFI Reference Specification Protocol Constants and Definitions in Rust. I am just one of the frequent contributors. This project requires deep knowledge of Rust FFI.
  3. kconfig-rs: Rust bindings for KConfig KDE Framework. This project was done as a part of the Season of KDE 2022.
  4. Qmetaobject: I am one of the collaborators in this project. It allows the creation of Qt applications in Rust.

I also regularly contribute to other open-source projects I am using at the time.

Contingency

If I get stuck on my project and my mentor isn’t around, I will use the following resources:

Benefit

The completed project would allow using BeagleConnect without requiring an intermediary (GBridge). Also, due to the presence of GBridge, the upstream Greybus drivers need to be patched for netlink support, which will be eliminated by this project. Thus, it will eventually be possible to just use mainline Linux kernel for BeagleConnect. This should help increase the adoption of BeagleConnect as an industry standard.