142 lines
5.0 KiB
Plaintext
142 lines
5.0 KiB
Plaintext
With this approach, we don't need the UBL any more on DaVinci boards.
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A "make boardname" will compile a u-boot.ubl, with UBL Header, which is
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needed for the RBL to find the "UBL", which actually is a UBL-compatible
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header, nand spl code and u-boot code.
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As the RBL uses another read function as the "standard" u-boot,
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we need a command, which switches between this two read/write
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functions, so we can write the UBL header and the spl
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code in a format, which the RBL can read. This is realize
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(at the moment in board specific code) in the u-boot command
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nandrbl
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nandrbl without arguments returns actual mode (rbl or uboot).
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with nandrbl mode (mode = "rbl" or "uboot") you can switch
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between the two NAND read/write modes.
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To set up mkimage you need a config file for mkimage, example:
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board/ait/cam_enc_4xx/ublimage.cfg
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For information about the configuration please see:
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doc/README.ublimage
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Example for the cam_enc_4xx board:
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On the cam_enc_4xx board we have a NAND flash with blocksize = 0x20000 and
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pagesize = 0x800, so the u-boot.ubl image (which you get with:
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"make cam_enc_4xx") looks like this:
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00000000 00 ed ac a1 20 00 00 00 06 00 00 00 05 00 00 00 |.... ...........|
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00000010 00 00 00 00 20 00 00 00 ff ff ff ff ff ff ff ff |.... ...........|
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00000020 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
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*
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00000800 14 00 00 ea 14 f0 9f e5 10 f0 9f e5 0c f0 9f e5 |................|
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00000810 08 f0 9f e5 04 f0 9f e5 00 f0 9f e5 04 f0 1f e5 |................|
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00000820 00 01 00 00 78 56 34 12 78 56 34 12 78 56 34 12 |....xV4.xV4.xV4.|
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[...]
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*
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00001fe0 00 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff |................|
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00001ff0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................|
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*
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00003800 14 00 00 ea 14 f0 9f e5 14 f0 9f e5 14 f0 9f e5 |................|
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00003810 14 f0 9f e5 14 f0 9f e5 14 f0 9f e5 14 f0 9f e5 |................|
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00003820 80 01 08 81 e0 01 08 81 40 02 08 81 a0 02 08 81 |........@.......|
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In the first "page" of the image, we have the UBL Header, needed for
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the RBL to find the spl code.
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The spl code starts in the second "page" of the image, with a size
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defined by:
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#define CONFIG_SYS_NROF_PAGES_NAND_SPL 6
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After the spl code, there comes the "real" u-boot code
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@ (6 + 1) * pagesize = 0x3800
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------------------------------------------------------------------------
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Setting up spl code:
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/*
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* RBL searches from Block n (n = 1..24)
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* so we can define, how many UBL Headers
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* we write before the real spl code
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*/
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#define CONFIG_SYS_NROF_UBL_HEADER 5
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#define CONFIG_SYS_NROF_PAGES_NAND_SPL 6
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#define CONFIG_SYS_NAND_U_BOOT_OFFS ((CONFIG_SYS_NROF_UBL_HEADER * \
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CONFIG_SYS_NAND_BLOCK_SIZE) + \
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(CONFIG_SYS_NROF_PAGES_NAND_SPL) * \
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CONFIG_SYS_NAND_PAGE_SIZE)
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------------------------------------------------------------------------
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Burning into NAND:
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step 1:
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The RBL searches from Block n ( n = 1..24) on page 0 for valid UBL
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Headers, so you have to burn the UBL header page from the u-boot.ubl
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image to the blocks, you want to have the UBL header.
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!! Don;t forget to switch to rbl nand read/write functions with
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"nandrbl rbl"
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step 2:
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You need to setup in the ublimage.cfg, where the RBL can find the spl
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code, and how big it is.
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!! RBL always starts reading from page 0 !!
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For the AIT board, we have:
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PAGES 6
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START_BLOCK 5
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So we need to copy the spl code to block 5 page 0
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!! Don;t forget to switch to rbl nand read/write functions with
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"nandrbl rbl"
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step 3:
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You need to copy the u-boot image to the block/page
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where the spl code reads it (CONFIG_SYS_NAND_U_BOOT_OFFS)
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!! Don;t forget to switch to rbl nand read/write functions with
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"nandrbl uboot", which is default.
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On the cam_enc_4xx board it is:
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#define CONFIG_SYS_NAND_U_BOOT_OFFS (0xc0000)
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-> this results in following NAND usage on the cam_enc_4xx board:
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addr
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20000 possible UBL Header
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40000 possible UBL Header
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60000 possible UBL Header
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80000 possilbe UBL Header
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a0000 spl code
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c0000 u-boot code
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The above steps are executeed through the following environment vars:
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(using 80000 as address for the UBL header)
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pagesz=800
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uboot=/tftpboot/cam_enc_4xx/u-boot.ubl
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load=tftp 80000000 ${uboot}
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writeheader nandrbl rbl;nand erase 80000 ${pagesz};nand write 80000000 80000 ${pagesz};nandrbl uboot
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writenand_spl nandrbl rbl;nand erase a0000 3000;nand write 80000800 a0000 3000;nandrbl uboot
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writeuboot nandrbl uboot;nand erase c0000 5d000;nand write 80003800 c0000 5d000
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update=run load writeheader writenand_spl writeuboot
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If you do a "run load update" u-boot, spl + ubl header
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are magically updated ;-)
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Note:
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- There seem to be a bug in the RBL code (at least on my HW),
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In the UBL block, I can set the page to values != 0, so it
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is possible to burn step 1 and step 2 in one step into the
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flash, but the RBL ignores the page settings, so I have to
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burn the UBL Header to a page 0 and the spl code to
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a page 0 ... :-(
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- If we make the nand read/write functions in the RBL equal to
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the functions in u-boot (as I have no RBL code, it is only
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possible in u-boot), we could burn the complete image in
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one step ... that would be nice ...
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