USB stack implementation using ChibiOS

Notes

• To use, unpack or symlink ChibiOS here, to chibios.
• For gcc options, inspect chibios.mk. For instance, I enabled -Wno-missing-field-initializers, because TMK common bits generated a lot of hits on that. Also pay attention to -O0 (enabled for debugging); for deployment use -O2.
• USB string descriptors are a mess. I did not find a way to cleanly generate the right structures from actual strings, so the definitions in individual keyboards’ config.h are ugly as heck.
• There are some random constants left so far, e.g. 5ms sleep between calling keyboard_task in main.c. There should be no such in usb_main.c. Everything is based on timers/interrupts/kernel scheduling (well except keyboard_task), so no periodically called things (again, except keyboard_task, which is just how TMK is designed).
• It is easy to add some code for testing (e.g. blink LED, do stuff on button press, etc…) - just create another thread in main.c, it will run independently of the keyboard business.
• The USB stack works pretty completely; however there are bits of other TMK stuff that are not done yet:

Immediate todo

• suspend / sleep led

Missing / not working (TMK vs ChibiOS bits)

• eeprom / bootmagic (will be chip dependent)
• bootloader jump (chip dependent)

Tried with

• ChibiOS 3.0.1 and ST F072RB DISCOVERY board.
• Need to test on other STM32 chips (F3, F4) to make it as much chip-independent as possible.