[Qemu-devel] Internship idea: I2C passthrough

[Stefan Hajnoczi <stefanha@gmail.com>]

Hi folks,
You may be interested in I2C passthrough support in QEMU.  Paolo and I
brainstormed the idea and I've written up a rough project summary
below.  It still needs some work to make this a solid internship
project idea.

Any thoughts?  Would you like to co-mentor this summer?

=== I2C Passthrough ===

'''Summary:''' Implement I2C bus passthrough on Linux hosts so that
emulated Raspberry Pi or micro:bit boards can talk to real I2C
devices.

QEMU emulates I2C devices in software but currently cannot pass
through real I2C devices from the host to the guest.  It would be
useful to access real I2C devices from inside the guest, for example
for developers writing and testing software under QEMU on their
computer.

The project consists of the following tasks:
* Implement -object i2c-bus-passthrough,adapter=N,id=my-i2c-bus
* Add i2c-bus-passthrough support to at least 1 existing emulated I2C controller
* Implement micro:bit TWI controller emulation on the nRF51 system-on-chip

This project will allow you to learn about the I2C bus and how to
write device emulation code in QEMU.  You will enjoy it if you like
working with physical hardware.

'''Links:'''
* [https://en.wikipedia.org/wiki/I%C2%B2C I2C wikipedia page]
* [https://elinux.org/Interfacing_with_I2C_Devices Overview of Linux
I2C programming interfaces]
* [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/Documentation/i2c/dev-interface
Linux I2C userspace interface documentation]

'''Details:'''
* Skill level: intermediate
* Language: C
* Mentor: Paolo Bonzini <pbonzini@redhat.com> ("bonzini" on IRC),
Stefan Hajnoczi <stefanha@redhat.com> ("stefanha" on IRC)