Back in 2002 I developed my first evaluation board with the Cypress EZ-USB AN2131 microcontroller. Since then I developed several projects using this microcontroller. Each time a dedicated firmware was necessary.
In 2011 a student used one of my firmware projects to develop a firmware for the Keil ULink JTAG adapter, which also has an EZ-USB microcontroller. Unfortunately my firmware had a few files with unclear license conditions, so he re-implemented most files. His work was published as OpenULINK as part of the OpenOCD JTAG driver.
I used his improved firmware as starting point for the development of a firmware skeleton for the Cypress EZ-USB microcontroller. Please find the source code at https://github.com/hansiglaser/ezusb-firmware.