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Useful notes on bulding and using of U-Boot on ARC HS Development Kit (AKA HSDK)
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BOARD OVERVIEW
The DesignWare ARC HS Development Kit is a ready-to-use platform for rapid
software development on the ARC HS3x family of processors.
For more information please visit:
https://www.synopsys.com/dw/ipdir.php?ds=arc-hs-development-kit
User guide is availalble here:
https://github.com/foss-for-synopsys-dwc-arc-processors/ARC-Development-Systems-Forum/wiki/docs/ARC_HSDK_User_Guide.pdf
It has the following features useful for U-Boot:
* On-board 2-channel FTDI TTL-to-USB converter
- The first channel is used for serial debug port (which makes it possible
to use a serial connection on pretty much any host machine be it
Windows, Linux or Mac).
On Linux machine typucally FTDI serial port would be /dev/ttyUSB0.
There's no HW flow-control and baud-rate is 115200.
- The second channel is used for built-in Digilent USB JTAG probe.
That means no extra hardware is required to access ARC core from a
debugger on development host. Both proprietary MetaWare debugger and
open source OpenOCD + GDB client are supported.
- Also with help of this FTDI chip it is possible to reset entire
board with help of a special `rff-ftdi-reset` utility, see:
https://github.com/foss-for-synopsys-dwc-arc-processors/rff-ftdi-reset
* Micro SD-card slot
- U-Boot expects to see the very first partition on the card formatted as
FAT file-system and uses it for keeping its environment in `uboot.env`
file. Note uboot.env is not just a text file but it is auto-generated
file created by U-Boot on invocation of `saveenv` command.
It contains a checksum which makes this saved environment invalid in
case of maual modification.
- There might be more useful files on that first FAT partition like
Linux kernl image in form of uImage (with or without built-in
initramfs), device tree blob (.dtb) etc.
- Except FAT partition there might be others following the first FAT one
like Ext file-system with rootfs etc.
* 1 Gb Ethernet socket
- U-Boot might get payload from TFTP server. This might be uImage, rootfs
image and anything else.
* 2 MiB of SPI-flash
- SPI-flahs is used as a storage for image of an application auto-executed
by bootROM on power-on. Typically U-Boot gets programmed there but
there might be other uses. But note bootROM expects to find a special
header preceeding application image itself so before flashing anything
make sure required image is prepended. In case of U-Boot this is done
by invocation of `headerize-hsdk.py` with `make bsp-generate` command.
BUILDING U-BOOT
1. Configure U-Boot:
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make hsdk_defconfig
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2. To build Elf file (for example to be used with host debugger via JTAG
connection to the target board):
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make mdbtrick
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This will produce `u-boot` Elf file.
3. To build artifacts required for U-Boot update in n-board SPI-flash:
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make bsp-generate
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This will produce `u-boot.head` and `u-boot-update.scr` which should
be put on the first FAT partition of micro SD-card to be inserted in the
HSDK board.
Note that Python3 script is used for generation of a header, thus
to get that done it's required to have Python3 with "pyelftools" installed.
"pyelftools" could be installed with help of "pip" even w/o root rights:
------------------------->8----------------------
python3 -m pip install --user pyelftools
------------------------->8----------------------
EXECUTING U-BOOT
1. The HSDK board is supposed to auto-start U-Boot image stored in on-board
SPI-flash on power-on. For that make sure DIP-switches in the corner of
the board are in their default positions: BIM in 1:off, 2:on state
while both BMC and BCS should be in 1:on, 2:on state.
2. Though it is possible to load U-Boot as a simple Elf file via JTAG right
in DDR and start it from the debugger.
2.1. In case of proprietary MetaWare debugger run:
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mdb -digilent -run -cl u-boot
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UPDATION U-BOOT IMAGE IN ON-BOARD SPI-FLASH
1. Create `u-boot.head` and `u-boot-update.scr` as discribed above with
`make bsp-generate` command.
2. Copy `u-boot.head` and `u-boot-update.scr` to the first FAT partition
of micro SD-card.
3. Connect USB cable from the HSDK board to the developemnt host and
fire-up serial terminal.
3. Insert prepared micro SD-card in the HSDK board, press reset button
and stop auto-execution of existing `bootcmd` pressing any key in serial
terminal and enter the following command:
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mmc rescan && fatload mmc 0:1 ${loadaddr} u-boot-update.scr && source ${loadaddr}
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Wait before you see "u-boot update: OK" message.
4. Press RESET button and enjoy updated U-Boot version.
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