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diff --git a/doc/README.ublimage b/doc/README.ublimage new file mode 100644 index 0000000..add24d6 --- /dev/null +++ b/doc/README.ublimage @@ -0,0 +1,141 @@ +--------------------------------------------- +UBL image Boot Image generation using mkimage +--------------------------------------------- + +This document describes how to set up an U-Boot image that can be directly +booted by a DaVinci processor via NAND boot mode, using an UBL header, +but without need for UBL. + +For more details see section 11.2 "ARM ROM Boot Modes" of +http://focus.ti.com/lit/ug/sprufg5a/sprufg5a.pdf + +Command syntax: +-------------- +./tools/mkimage -l <u-boot_file> + to list the UBL image file details + +./tools/mkimage -T ublimage \ + -n <board specific configuration file> \ + -d <u-boot binary> <output image file> + +For example, for the davinci dm365evm board: +./tools/mkimage -n ./board/davinci/dm365evm/ublimage.cfg \ + -T ublimage \ + -d u-boot-nand.bin u-boot.ubl + +You can generate the image directly when you compile u-boot with: + +$ make u-boot.ubl + +The output image can be flashed into the NAND. + +Please check the DaVinci documentation for further details. + +Board specific configuration file specifications: +------------------------------------------------- +1. This file must present in the $(BOARDDIR) and the name should be + ublimage.cfg (since this is used in Makefile). +2. This file can have empty lines and lines starting with "#" as first + character to put comments. +3. This file can have configuration command lines as mentioned below, + any other information in this file is treated as invalid. + +Configuration command line syntax: +--------------------------------- +1. Each command line must have two strings, first one command or address + and second one data string +2. Following are the valid command strings and associated data strings:- + Command string data string + -------------- ----------- + MODE UBL special mode, on of: + safe + Example: + MODE safe + + ENTRY Entry point address for the user + bootloader (absolute address) = TEXT_BASE + nand_spl loader. + Example: + ENTRY 0x00000020 + + PAGES Number of pages (size of user bootloader + in number of pages) + Example: + PAGES 27 + + START_BLOCK Block number where user bootloader is present + Example: + START_BLOCK 5 + + START_PAGE Page number where user bootloader is present + (for RBL always 0) + Example: + START_PAGE 0 + +------------------------------------------------ + +Structure of the u-boot.ubl binary: + +compile steps: + +1) nand_spl code compile, with pad_to = (TEXT_BASE + + (CONFIG_SYS_NROF_PAGES_NAND_SPL * pagesize)) + Example: cam_enc_4xx pad_to = 0x20 + (6 * 0x800) = 0x3020 = 12320 + -> u-boot-spl-16k.bin + + !! TEXT_BASE = 0x20, as the RBL starts at 0x20 + +2) compile u-boot.bin ("normal" u-boot) + -> u-boot.bin + +3) create u-boot-nand.bin = u-boot-spl-16k.bin + u-boot.bin + +4) create u-boot.ubl, size = 1 page size NAND + create UBL header and paste it before u-boot.bin + +This steps are done automagically if you do a "make all" + +-> You get an u-boot.ubl binary, which you can flash + into your NAND. + +Structure of this binary (Example for the cam_enc_4xx board with a NAND +page size = 0x800): + +offset : 0x00000 | 0x800 | 0x3800 +content: UBL | nand_spl | u-boot code + Header | code | + +The NAND layout looks for example like this: + +(Example for the cam_enc_4xx board with a NAND page size = 0x800, block +size = 0x20000 and CONFIG_SYS_NROF_UBL_HEADER 5): + +offset : 0x80000 | 0xa0000 | 0xa3000 +content: UBL | nand_spl | u-boot code + Header | code | + ^ ^ + ^ 0xa0000 = CONFIG_SYS_NROF_UBL_HEADER * 0x20000 + ^ + 0x80000 = Block 4 * 0x20000 + +If the cpu starts in NAND boot mode, it checks the UBL descriptor +starting with block 1 (page 0). When a valid UBL signature is found, +the corresponding block number (from 1 to 24) is written to the last 32 +bits of ARM internal memory (0x7ffc-0x8000). This feature is provided +as a basic debug mechanism. If not found, it continues with block 2 +... last possible block is 24 + +If a valid UBL descriptor is found, the UBL descriptor is read and +processed. The descriptor gives the information required for loading +and control transfer to the nand_spl code. The nand_spl code is then +read and processed. + +Once the user-specified start-up conditions are set, the RBL copies the +nand_spl into ARM internal RAM, starting at address 0x0000: 0020. + ^^^^ + +The nand_spl code itself now does necessary intializations, and at least, +copies the u-boot code from NAND into RAM, and jumps to it ... + +------------------------------------------------ +Author: Heiko Schocher <hs@denx.de> |