USB Card Scanner Driver
Patrick Tully
Steven Bronson
Motivation
Monitors in Majors Lab scan FSU cards using a USB
card reader
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
USB card reader generates keystrokes
Program must have focus at all times, in the correct
textbox
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Pre-existing Projects
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Read from /dev/usb/hiddev
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Only works for the USB HID card scanner
Write a userspace program using libusb or PyUSB
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Requires root privileges each time

Depends on deprecated (obsolete?) usbfs
Contribution
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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
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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?)