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Diffstat (limited to 'doc/README.davinci.nand_spl')
| -rw-r--r-- | doc/README.davinci.nand_spl | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/doc/README.davinci.nand_spl b/doc/README.davinci.nand_spl new file mode 100644 index 0000000..f46721a --- /dev/null +++ b/doc/README.davinci.nand_spl @@ -0,0 +1,141 @@ +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 ... |