18433df357
We introduce an explicit state machine (see README). With the new states we: - combine setting size and USS to a single command. - start the device app immediatiely when having receceived the last data chunk and returning the digest. - Loop forever and wait for the stick to be removed if we end up in unknown state. Signed-off-by: Michael Cardell Widerkrantz <mc@tillitis.se>
3.0 KiB
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.
Firmware state machine
States:
initial- At start.init_loading- Reset app digest, size,USSand load address.loading- Expect more app data or a reset byLoadApp().run- Computes CDI and starts the device app.
Commands in state initial:
| command | next state |
|---|---|
| NameVersion() | unchanged |
| GetUDI() | unchanged |
| LoadApp(size, uss) | init_loading |
Commands in init_loading:
| command | next state |
|---|---|
| NameVersion() | unchanged |
| GetUDI() | unchanged |
| LoadApp(size, uss) | init_loading |
| LoadAppData(data) | loading |
Commands in loading:
| command | next state |
|---|---|
| NameVersion() | unchanged |
| GetUDI() | unchanged |
| LoadApp(size, uss) | init_loading |
| LoadAppData(data) | loading or run on last chunk |
Behaviour:
- NameVersion: identifies stick.
- GetUDI: returns the Unique Device ID with vendor id, product id, revision, serial number.
- LoadApp(size, uss): Start loading an app with this size and user supplied secret.
- LoadAppData(data): Load chunk of data of app. When last data chunk is received we compute and return the digest.
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!