mirror of
https://github.com/brain-hackers/u-boot-brain
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f4e2c10a71
This drops assigning bi_arch_number on LEGO MINDSTORMS EV3. This board never had its own unique number and since we are using device tree, we no longer need to pass an arch number to Linux. Signed-off-by: David Lechner <david@lechnology.com> |
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| .. | ||
| Kconfig | ||
| legoev3.c | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Summary ======= LEGO MINDSTORMS EV3 is a toy robot produced by the LEGO Group. It is based on the davinci da850 evm. The EV3 has a 16MB spi flash and a SDHC microSD card reader. Booting ======= The EV3 contains a bootloader in EEPROM that loads u-boot.bin from address 0x0 of the SPI flash memory (with a size of 256KiB!). Because the EEPROM is read- only and it takes care of low level configuration (PLL and DDR), we don't use U-Boot to produce an SPL image. Using the default configuration, U-Boot had a boot scrips that works as follows: * Check to see if microSD card is present * If it is, try to load boot.scr from the first FAT partition * If loading boot.scr was successful, run it * Otherwise, try loading uEnv.txt * If loading uEnv.txt was successful, import it * If there is a uenvcmd variable (from uEnv.txt), run it * Try to load uImage from the first FAT partition * If it was successful, try to load da850-lego-ev3.dtb * If loading uImage was successful, boot it (DT is optional) * If none of the above was successful, try booting from flash Suggested Flash Memory Layout ============================= The following is based on the default U-Boot configuration: | Image (file) | Start Addr. | Max. Size | +--------------------+-------------+-------------------+ | u-boot.bin | 0x0 | 0x40000 (256KiB) | | da850-lego-ev3.dtb | 0x40000 | 0x10000 (64KiB) | | uImage | 0x50000 | 0x400000 (4MiB) | | rootfs (squashfs) | 0x450000 | 0xa00000 (10MiB) | Writing image to flash ====================== The EEPROM contains a program for uploading an image file to the flash memory. The program is started by holding down the right button on the EV3 when powering it on. You can also `run fwupdateboot` in the u-boot shell to reboot into this mode. The image can then be uploaded using the official LEGO MINDSTORMS EV3 software or a 3rd party program capable of uploading a firmware file. If you are booting from the microSD card, it is enough to just write uboot.bin to the flash. If you are not using a microSD card, you will need to create an image file using the layout described above. IMPORTANT: The EEPROM bootloader only copies 256k, so u-boot.img must not exceed that size!