Writing a basic Linux device driver when you know nothing about Linux drivers

10 months ago

The author purchased a Nanoleaf Pegboard Desk Dock, which only supports Windows and macOS, prompting the development of a Linux driver.
After reverse-engineering the device's protocol and receiving official documentation from Nanoleaf, the author decided to write a Linux driver.
The device was identified using `lsusb`, revealing it as a Human Interface Device (HID) with a generic USB driver in the Linux kernel.
Two options were considered for the driver: a kernel driver or a userspace driver via `libusb`. The author chose the latter for simplicity.
A `udev` rule was created to allow non-root users to access the device, with specific instructions for NixOS users.
The driver was written in Rust using the `rusb` crate, starting with basic device enumeration and interface claiming.
The author encountered and resolved issues with the kernel driver holding the device open, requiring manual detachment.
Data was sent to the device using interrupt endpoints, with initial success in changing the device's LED color.
The driver was improved to handle interrupts properly, including polling for device responses in a background thread.
The final proof-of-concept demonstrated that writing a simple USB device driver is feasible with minimal code.

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