tillitis-key/doc/system_description/firmware.md

Tillitis Key firmware

Build the firmware

You need Clang with 32 bit RISC-V support. You can check this with:

$ llc --version | grep riscv32
    riscv32    - 32-bit RISC-V

or just try building.

Build the FPGA bitstream with the firmware using make in the hw/application_fpga directory.

If your available objcopy and size commands is anything other than the default llvm-objcopy and llvm-size define OBJCOPY and SIZE to whatever they're called on your system.

Using QEMU

Checkout the tk1 branch of our version of the qemu and build:

$ git clone -b tk1 https://github.com/tillitis/qemu
$ mkdir qemu/build
$ cd qemu/build
$ ../configure --target-list=riscv32-softmmu --disable-werror
$ make -j $(nproc)

(Built with warnings-as-errors disabled, see this issue.)

Run it like this:

$ /path/to/qemu/build/qemu-system-riscv32 -nographic -M tk1,fifo=chrid -bios firmware.elf \
  -chardev pty,id=chrid

This attaches the FIFO to a tty, something like /dev/pts/16 which you can use with host software to talk to the firmware.

To quit QEMU you can use: Ctrl-a x (see Ctrl-a ? for other commands).

Debugging? Use the HTIF console by removing -DNOCONSOLE from the CFLAGS and using the helper functions in lib.c for printf-like debugging.

You can also use the qemu monitor for debugging, e.g. info registers, or run qemu with -d in_asm or -d trace:riscv_trap.

Happy hacking!