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f203a479e7
This updates the LEGO MINDSTORMS EV3 boot script to try loading a uEnv.txt file and a da850-lego-ev3.dtb device tree during boot. 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.