mirror of
https://github.com/AsahiLinux/u-boot
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69 lines
2.6 KiB
Text
69 lines
2.6 KiB
Text
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Summary
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=======
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The README is for the boot procedure used for various DA850 (or compatible
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parts such as the AM1808) based boards.
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In the context of U-Boot, the board is booted in three stages. The initial
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bootloader which executes upon reset is the ROM Boot Loader (RBL) and sits
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in the internal ROM. The RBL initializes the internal memory and then
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depending on the exact board and pin configurations will initialize another
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controller (such as SPI or NAND) to continue the boot process by loading
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the secondary program loader (SPL). The SPL will initialize the system
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further (some clocks, SDRAM) and then load the full u-boot from a
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predefined location in persistent storage to DDR and jumps to the u-boot
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entry point.
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AIS is an image format defined by TI for the images that are to be loaded
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to memory by the RBL. The image is divided into a series of sections and
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the image's entry point is specified. Each section comes with meta data
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like the target address the section is to be copied to and the size of the
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section, which is used by the RBL to load the image. At the end of the
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image the RBL jumps to the image entry point. The AIS format allows for
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other things such as programming the clocks and SDRAM if the header is
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programmed for it. We do not take advantage of this and instead use SPL as
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it allows for additional flexibility (run-time detect of board revision,
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loading the next image from a different media, etc).
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Compilation
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===========
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The exact build target you need will depend on the board you have. For
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Logic PD boards, or other boards which store the ethernet MAC address at
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the end of SPI flash, run 'make da850evm'. For boards which store the
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ethernet MAC address in the i2c EEPROM located at 0x50, run
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'make da850_am18xxevm'. Once this build completes you will have a
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u-boot.ais file that needs to be written to the correct persistent
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storage.
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Flashing the images to SPI
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==========================
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The AIS image can be written to SPI flash using the following commands.
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Assuming that the network is configured and enabled and the u-boot.ais file
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is tftp'able.
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U-Boot > sf probe 0
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U-Boot > sf erase 0 +320000
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U-Boot > tftp u-boot.ais
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U-Boot > sf write c0700000 0 $filesize
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Recovery
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========
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In the case of a "bricked" board, you need to use the TI tools found
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here[1] to write the u-boot.ais file. An example of recovering to the SPI
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flash of an AM1808 would be:
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$ mono sfh_OMAP-L138.exe -targetType AM1808 -p /dev/ttyUSB0 \
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-flash_noubl /path/to/u-boot.ais
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For other target types and flash locations:
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$ mono sfh_OMAP-L138.exe -h
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Links
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=====
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[1]
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http://processors.wiki.ti.com/index.php/Serial_Boot_and_Flash_Loading_Utility_for_OMAP-L138
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