| ================================================================================ |
| Useful notes on bulding and using of U-Boot on |
| ARC EM Software Development Platform (AKA EMSDP) |
| ================================================================================ |
| |
| BOARD OVERVIEW |
| |
| The DesignWare ARC EM Software Development Platform is FPGA-bases platform |
| for rapid software development on the ARC EM family of processors. |
| |
| Since this board is based on FPGA it's possible to load and use different |
| versions of ARC EM CPUs. U-Boot is built to be run on the simplest |
| possible configuration which means the same one binary will work on more |
| advanced configurations as well. |
| |
| The board 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 |
| user applications, data files etc. |
| |
| * 256 KiB of "ROM" |
| - This so-called "ROM" is a part of FPGA image and even though it |
| might be unlocked for writes its initial content will be restored |
| on the next power-on. |
| |
| |
| BUILDING U-BOOT |
| |
| 1. Configure U-Boot: |
| ------------------------->8---------------------- |
| make emsdp_defconfig |
| ------------------------->8---------------------- |
| |
| 2. To build Elf file (for example to be used with host debugger via JTAG |
| connection to the target board): |
| ------------------------->8---------------------- |
| make mdbtrick |
| ------------------------->8---------------------- |
| |
| This will produce `u-boot` Elf file. |
| |
| 3. To build binary image to be put in "ROM": |
| ------------------------->8---------------------- |
| make u-boot.bin |
| ------------------------->8---------------------- |
| |
| |
| EXECUTING U-BOOT |
| |
| 1. The EMSDP board is supposed to auto-start U-Boot image stored in ROM on |
| power-on. For that make sure VCCIO DIP-switches are all in "off" state. |
| |
| 2. Though it is possible to load U-Boot as a simple Elf file via JTAG right |
| in "ROM" and start it from the debugger. One important note here we first |
| need to enable writes into "ROM" by writing 1 to 0xf0001000. |
| |
| 2.1. In case of proprietary MetaWare debugger run: |
| ------------------------->8---------------------- |
| mdb -dll=opxdarc.so -OK -preloadexec="eval *(int*)0xf0001000=0" u-boot |
| ------------------------->8---------------------- |
