419ea2d84a
Split the README into a common part and a m28 specific part. This will make things easier when adding new README files for other mx28 based boards. Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> Acked-by: Marek Vasut <marex@denx.de>
227 lines
8.1 KiB
Plaintext
227 lines
8.1 KiB
Plaintext
Booting U-boot on a MX28 processor
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==================================
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This document describes the MX28 U-Boot port. This document mostly
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covers topics related to making the module/board bootable.
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Terminology
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-----------
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The dollar symbol ($) introduces a snipped of shell code. This shall be typed
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into the unix command prompt in U-Boot source code root directory.
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The (=>) introduces a snipped of code that should by typed into U-Boot command
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prompt
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Contents
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--------
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1) Prerequisites
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2) Compiling U-Boot for a MX28 based board
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3) Installation of U-Boot for a MX28 based board to SD card
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1) Prerequisites
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----------------
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To make a MX28 based board bootable, some tools are necessary. The first one
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is the "elftosb" tool distributed by Freescale Semiconductor. The other one
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is the "mxsboot" tool found in U-Boot source tree.
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Firstly, obtain the elftosb archive from the following location:
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http://foss.doredevelopment.dk/mirrors/imx/elftosb-10.12.01.tar.gz
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We use a $VER variable here to denote the current version. At the time of
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writing of this document, that is "10.12.01". To obtain the file from command
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line, use:
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$ VER="10.12.01"
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$ wget http://foss.doredevelopment.dk/mirrors/imx/elftosb-${VER}.tar.gz
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Extract the file:
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$ tar xzf elftosb-${VER}.tar.gz
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Compile the file. We need to manually tell the linker to use also libm:
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$ cd elftosb-${VER}/
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$ make LIBS="-lstdc++ -lm" elftosb
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Optionally, remove debugging symbols from elftosb:
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$ strip bld/linux/elftosb
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Finally, install the "elftosb" binary. The "install" target is missing, so just
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copy the binary by hand:
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$ sudo cp bld/linux/elftosb /usr/local/bin/
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Make sure the "elftosb" binary can be found in your $PATH, in this case this
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means "/usr/local/bin/" has to be in your $PATH.
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2) Compiling U-Boot for a MX28 based board
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-------------------------------------------
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Compiling the U-Boot for a MX28 board is straightforward and done as compiling U-Boot
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for any other ARM device. For cross-compiler setup, please refer to ELDK5.0
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documentation. First, clean up the source code:
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$ make mrproper
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Next, configure U-Boot for a MX28 based board
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$ make <mx28_based_board_name>_config
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Examples:
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1. For building U-boot for Denx M28EVK board:
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$ make m28evk_config
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2. For building U-boot for Freescale MX28EVK board:
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$ make mx28evk_config
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Lastly, compile U-Boot and prepare a "BootStream". The "BootStream" is a special
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type of file, which the i.MX28 CPU can boot. This is handled by the following
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command:
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$ make u-boot.sb
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HINT: To speed-up the build process, you can add -j<N>, where N is number of
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compiler instances that'll run in parallel.
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The code produces "u-boot.sb" file. This file needs to be augmented with a
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proper header to allow successful boot from SD or NAND. Adding the header is
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discussed in the following chapters.
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3) Installation of U-Boot for a MX28 based board to SD card
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-----------------------------------------------------------
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To boot a MX28 based board from SD, set the boot mode DIP switches according
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to i.MX28 manual chapter 12.2.1 (Table 12-2), PORT=SSP0, SD/MMC master on
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SSP0, 3.3V.
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An SD card the i.MX28 CPU can use to boot U-Boot must contain a DOS partition
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table, which in turn carries a partition of special type and which contains a
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special header. The rest of partitions in the DOS partition table can be used
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by the user.
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To prepare such partition, use your favourite partitioning tool. The partition
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must have the following parameters:
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* Start sector .......... sector 2048
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* Partition size ........ at least 1024 kb
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* Partition type ........ 0x53 (sometimes "OnTrack DM6 Aux3")
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For example in Linux fdisk, the sequence for a clear card follows. Be sure to
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run fdisk with the option "-u=sectors" to set units to sectors:
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* o ..................... create a clear partition table
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* n ..................... create new partition
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* p ............. primary partition
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* 1 ............. first partition
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* 2048 .......... first sector is 2048
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* +1M ........... make the partition 1Mb big
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* t 1 ................... change first partition ID
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* 53 ............ change the ID to 0x53 (OnTrack DM6 Aux3)
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* <create other partitions>
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* w ..................... write partition table to disk
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The partition layout is ready, next the special partition must be filled with
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proper contents. The contents is generated by running the following command
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(see chapter 2)):
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$ ./tools/mxsboot sd u-boot.sb u-boot.sd
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The resulting file, "u-boot.sd", shall then be written to the partition. In this
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case, we assume the first partition of the SD card is /dev/mmcblk0p1:
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$ dd if=u-boot.sd of=/dev/mmcblk0p1
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Last step is to insert the card into MX28 based board and boot.
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NOTE: If the user needs to adjust the start sector, the "mxsboot" tool contains
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a "-p" switch for that purpose. The "-p" switch takes the sector number as
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an argument.
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4) Installation of U-Boot for NAND flash
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-----------------------------------------------
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To boot a MX28 based board from NAND, set the boot mode DIP switches according to i.MX28
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manual chapter 12.2.1 (Table 12-2), PORT=GPMI, NAND 1.8 V.
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There are two possibilities when preparing an image writable to NAND flash.
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I) The NAND wasn't written at all yet or the BCB is broken
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----------------------------------------------------------
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In this case, both BCB (FCB and DBBT) and firmware needs to be
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written to NAND. To generate NAND image containing all these,
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there is a tool called "mxsboot" in the "tools/" directory. The tool
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is invoked on "u-boot.sb" file from chapter 2):
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$ ./tools/mxsboot nand u-boot.sb u-boot.nand
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NOTE: The above invokation works for NAND flash with geometry of
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2048b per page, 64b OOB data, 128kb erase size. If your chip
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has a different geometry, please use:
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-w <size> change page size (default 2048 b)
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-o <size> change oob size (default 64 b)
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-e <size> change erase size (default 131072 b)
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The geometry information can be obtained from running U-Boot
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on the MX28 board by issuing the "nand info" command.
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The resulting file, "u-boot.nand" can be written directly to NAND
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from the U-Boot prompt. To simplify the process, the U-Boot default
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environment contains script "update_nand_full" to update the system.
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This script expects a working TFTP server containing the file
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"u-boot.nand" in it's root directory. This can be changed by
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adjusting the "update_nand_full_filename" varible.
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To update the system, run the following in U-Boot prompt:
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=> run update_nand_full
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In case you would only need to update the bootloader in future,
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see II) below.
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II) The NAND was already written with a good BCB
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------------------------------------------------
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This part applies after the part I) above was done at least once.
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If part I) above was done correctly already, there is no need to
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write the FCB and DBBT parts of NAND again. It's possible to upgrade
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only the bootloader image.
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To simplify the process of firmware update, the U-Boot default
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environment contains script "update_nand_firmware" to update only
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the firmware, without rewriting FCB and DBBT.
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This script expects a working TFTP server containing the file
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"u-boot.sb" in it's root directory. This can be changed by
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adjusting the "update_nand_firmware_filename" varible.
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To update the system, run the following in U-Boot prompt:
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=> run update_nand_firmware
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III) Special settings for the update scripts
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--------------------------------------------
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There is a slight possibility of the user wanting to adjust the
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STRIDE and COUNT options of the NAND boot. For description of these,
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see i.MX28 manual section 12.12.1.2 and 12.12.1.3.
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The update scripts take this possibility into account. In case the
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user changes STRIDE by blowing fuses, the user also has to change
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"update_nand_stride" variable. In case the user changes COUNT by
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blowing fuses, the user also has to change "update_nand_count"
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variable for the update scripts to work correctly.
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In case the user needs to boot a firmware image bigger than 1Mb, the
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user has to adjust the "update_nand_firmware_maxsz" variable for the
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update scripts to work properly.
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