mirror of
https://github.com/brain-hackers/u-boot-brain
synced 2024-06-09 23:36:03 +09:00
a1c6aed1de
Enable CONFIG_SPL_DM_SPI_FLASH to be able to boot from SPI NOR, modify the offset of U-boot proper in the SPI NOR, so the difference in offset matches between SPL and U-boot matches that of the SD Card, allowing u-boot-with-spl.imx to also be copied to SPI NOR at an offset of 0x400. Update the README to reflect this change. Signed-off-by: Niel Fourie <lusus@denx.de> Cc: Stefano Babic <sbabic@denx.de>
91 lines
3.3 KiB
Plaintext
91 lines
3.3 KiB
Plaintext
Board information
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-----------------
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The SBC produced by Phytec has a SOM based on a i.MX6Q.
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The SOM is sold in two versions, with eMMC or with NAND. Support
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here is for the SOM with NAND.
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The evaluation board "phyBoard-Mira" is thought to be used
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together with the SOM.
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More information on the board can be found on manufacturer's
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website:
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http://www.phytec.de/produkt/single-board-computer/phyboard-mira/
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http://www.phytec.de/fileadmin/user_upload/images/content/1.Products/SOMs/phyCORE-i.MX6/L-808e_1.pdf
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Building U-Boot
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-------------------------------
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$ make pcm058_defconfig
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$ make
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This generates the artifacts SPL and u-boot.img.
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The SOM can boot from NAND or from SD-Card, having the SPI-NOR
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as second option.
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The dip switch "DIP-1" on the board let choose between
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NAND and SD.
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DIP-1 set to off: Boot first from NAND, then try SPI
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DIP-1 set to on: Boot first from SD, then try SPI
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The bootloader was tested with DIP-1 set to on. If a SD-card
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is present, then the RBL tries to load SPL from the SD Card, if not,
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RBL loads from SPI-NOR. The SPL tries then to load from the same
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device where SPL was loaded (SD or SPI). Booting from NAND is
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not supported.
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Flashing U-Boot onto an SD card
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-------------------------------
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After a successful build, the generated SPL and U-boot binaries can be copied
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to an SD card. Adjust the SD card device as necessary:
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$ sudo dd if=u-boot-with-spl.imx of=/dev/mmcblk0 bs=1k seek=1
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This is equivalent to separately copying the SPL and U-boot using:
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$ sudo dd if=SPL of=/dev/mmcblk0 bs=1k seek=1
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$ sudo dd if=u-boot-dtb.img of=/dev/mmcblk0 bs=1k seek=197
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The default bootscripts expect a kernel fit-image file named "fitImage" in the
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first partition and Linux ext4 rootfs in the second partition.
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Flashing U-boot to the SPI Flash, for booting Linux from NAND
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-------------------------------------------------------------
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The SD card created above can also be used to install the SPL and U-boot into
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the SPI flash. Boot U-boot from the SD card as above, and stop at the autoboot.
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Then, clear the SPI flash:
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=> sf probe
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=> sf erase 0x0 0x1000000
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Load the equivalent of u-boot-with-spl.imx from the raw MMC into memory and
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copy to the SPI. The SPL is expected at an offset of 0x400, and its size is
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maximum 392*512-byte blocks in size, therefore 0x188 blocks, totaling 0x31000
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bytes. Assume U-boot should fit into 640KiB, therefore 0x500 512-byte blocks,
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totalling 0xA0000 bytes. Adding these together:
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=> mmc read ${loadaddr} 0x2 0x688
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=> sf write ${loadaddr} 0x400 0xD1000
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The SPL is located at offset 0x400, and U-boot at 0x31400 in SPI flash, as to
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match the SD Card layout. This would allow, instead of reading from the SD Card
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above, with networking and TFTP correctly configured, the equivalent of:
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=> tftp u-boot-with-spl.imx
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=> sf write ${fileaddr} 0x400 ${filesize}
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The default NAND bootscripts expect a single MTD partition named "rootfs",
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which in turn contains the UBI volumes "fit" (which contains the kernel fit-
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image) and "root" (which contains a ubifs root filesystem).
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The "bootm_size" variable in the environment
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--------------------------------------------
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By default, U-boot relocates the device tree towards the upper end of the RAM,
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which kernels using CONFIG_HIGHMEM=y may not be able to access during early
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boot. With the bootm_size variable set to 0x30000000, U-boot relocates the
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device tree to below this address instead.
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