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72 lines
2.2 KiB
Markdown
72 lines
2.2 KiB
Markdown
# Foboot: The Bootloader for Fomu
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Foboot is a failsafe bootloader for Fomu. It exposes a DFU interface to the host. Foboot comes in two halves: A Software half and a Hardware half. These two halves are integrated into a single "bitstream" that is directly loaded onto an ICE40UP5k board, such as Fomu.
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## Requirements
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To build the hardware, you need:
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* Python 3.5+
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* Nextpnr
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* Icestorm
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* Yosys
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* Git
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Subproject hardware dependencies will be taken care of with `lxbuildenv`.
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To build the software, you need:
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* RISC-V toolchain
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## Building the project
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The hardware half will take care of building the software half, if it is run with `--boot-source bios` (which is the default). Therefore, to build Foboot, enter the `hw/` directory and run:
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```
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$ python3 foboot-bitstream.py --revision hacker
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```
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This will verify you have the correct dependencies installed, compile the Foboot software, then synthesize the Foboot bitstream. The resulting output will be in `build/gateware/`. You should write `build/gateware/top-multiboot.bin` to your Fomu device in order to get basic bootloader support.
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### Usage
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You can write the bitstream to your SPI flash. If you're using `fomu-flash`, you would run the following:
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```sh
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$ fomu-flash -w build/gateware/top-multiboot.bin
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Erasing @ 018000 / 01973a Done
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Programming @ 01973a / 01973a Done
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$ fomu-flash -r
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resetting fpga
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$
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```
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Fomu should now show up when you connect it to your machine:
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```
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[172294.296354] usb 1-1.3: new full-speed USB device number 33 using dwc_otg
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[172294.445661] usb 1-1.3: New USB device found, idVendor=1209, idProduct=70b1
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[172294.445675] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
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[172294.445684] usb 1-1.3: Product: Fomu Bootloader (0)
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[172294.445692] usb 1-1.3: Manufacturer: Kosagi
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```
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To load a new bitstream, use the `dfu-util -D` command. For example:
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```sh
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$ dfu-util -D blink.bin
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```
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This will reflash the SPI beginning at offset 262144.
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To exit DFU and run the bitstream at offset 262144, run:
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```sh
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$ dfu-util -e
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```
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**Note that, unlike Toboot, Foboot requires you to issue `dfu-util -e` in order to start the program.**
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## Building the Software
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Software is contained in the `sw/` directory. |