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