USB Card Scanner Driver

Patrick TullySteven Bronson

Motivation

Monitors in Majors Lab scan FSU cards using a USB card reader

USB card reader generates keystrokes Program must have focus at all times, in the correct textbox

Pre-existing Projects

Read from /dev/usb/hiddev Only works for the USB HID card scanner

Write a userspace program using libusb or PyUSB Requires root privileges each time Depends on deprecated (obsolete?) usbfs

Contribution

Used a small part (boilerplate) of the usbkbd driver as a starting point.

Most of the work went into implementing read, which did not exist in usbkbd.

Create /dev/cardscanner that can be opened and read.

Challenges

USB probe order Determined by module insertion order Fixed with USB quirks

Kernel circular buffer implementation is not really Record API makes more sense, but Unix loves byte

streams (why pass records when you can design ambiguous grammars?)