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diff --git a/doc/README.mx28_common b/doc/README.mx28_common new file mode 100644 index 0000000..448d221 --- /dev/null +++ b/doc/README.mx28_common @@ -0,0 +1,226 @@ +Booting U-boot on a MX28 processor +================================== + +This document describes the MX28 U-Boot port. This document mostly +covers topics related to making the module/board bootable. + +Terminology +----------- + +The dollar symbol ($) introduces a snipped of shell code. This shall be typed +into the unix command prompt in U-Boot source code root directory. + +The (=>) introduces a snipped of code that should by typed into U-Boot command +prompt + +Contents +-------- + +1) Prerequisites +2) Compiling U-Boot for a MX28 based board +3) Installation of U-Boot for a MX28 based board to SD card + +1) Prerequisites +---------------- + +To make a MX28 based board bootable, some tools are necessary. The first one +is the "elftosb" tool distributed by Freescale Semiconductor. The other one +is the "mxsboot" tool found in U-Boot source tree. + +Firstly, obtain the elftosb archive from the following location: + + http://foss.doredevelopment.dk/mirrors/imx/elftosb-10.12.01.tar.gz + +We use a $VER variable here to denote the current version. At the time of +writing of this document, that is "10.12.01". To obtain the file from command +line, use: + + $ VER="10.12.01" + $ wget http://foss.doredevelopment.dk/mirrors/imx/elftosb-${VER}.tar.gz + +Extract the file: + + $ tar xzf elftosb-${VER}.tar.gz + +Compile the file. We need to manually tell the linker to use also libm: + + $ cd elftosb-${VER}/ + $ make LIBS="-lstdc++ -lm" elftosb + +Optionally, remove debugging symbols from elftosb: + + $ strip bld/linux/elftosb + +Finally, install the "elftosb" binary. The "install" target is missing, so just +copy the binary by hand: + + $ sudo cp bld/linux/elftosb /usr/local/bin/ + +Make sure the "elftosb" binary can be found in your $PATH, in this case this +means "/usr/local/bin/" has to be in your $PATH. + +2) Compiling U-Boot for a MX28 based board +------------------------------------------- + +Compiling the U-Boot for a MX28 board is straightforward and done as compiling U-Boot +for any other ARM device. For cross-compiler setup, please refer to ELDK5.0 +documentation. First, clean up the source code: + + $ make mrproper + +Next, configure U-Boot for a MX28 based board + + $ make <mx28_based_board_name>_config + +Examples: + +1. For building U-boot for Denx M28EVK board: + + $ make m28evk_config + +2. For building U-boot for Freescale MX28EVK board: + + $ make mx28evk_config + +Lastly, compile U-Boot and prepare a "BootStream". The "BootStream" is a special +type of file, which the i.MX28 CPU can boot. This is handled by the following +command: + + $ make u-boot.sb + +HINT: To speed-up the build process, you can add -j<N>, where N is number of + compiler instances that'll run in parallel. + +The code produces "u-boot.sb" file. This file needs to be augmented with a +proper header to allow successful boot from SD or NAND. Adding the header is +discussed in the following chapters. + +3) Installation of U-Boot for a MX28 based board to SD card +----------------------------------------------------------- + +To boot a MX28 based board from SD, set the boot mode DIP switches according +to i.MX28 manual chapter 12.2.1 (Table 12-2), PORT=SSP0, SD/MMC master on +SSP0, 3.3V. + + +An SD card the i.MX28 CPU can use to boot U-Boot must contain a DOS partition +table, which in turn carries a partition of special type and which contains a +special header. The rest of partitions in the DOS partition table can be used +by the user. + +To prepare such partition, use your favourite partitioning tool. The partition +must have the following parameters: + + * Start sector .......... sector 2048 + * Partition size ........ at least 1024 kb + * Partition type ........ 0x53 (sometimes "OnTrack DM6 Aux3") + +For example in Linux fdisk, the sequence for a clear card follows. Be sure to +run fdisk with the option "-u=sectors" to set units to sectors: + + * o ..................... create a clear partition table + * n ..................... create new partition + * p ............. primary partition + * 1 ............. first partition + * 2048 .......... first sector is 2048 + * +1M ........... make the partition 1Mb big + * t 1 ................... change first partition ID + * 53 ............ change the ID to 0x53 (OnTrack DM6 Aux3) + * <create other partitions> + * w ..................... write partition table to disk + +The partition layout is ready, next the special partition must be filled with +proper contents. The contents is generated by running the following command +(see chapter 2)): + + $ ./tools/mxsboot sd u-boot.sb u-boot.sd + +The resulting file, "u-boot.sd", shall then be written to the partition. In this +case, we assume the first partition of the SD card is /dev/mmcblk0p1: + + $ dd if=u-boot.sd of=/dev/mmcblk0p1 + +Last step is to insert the card into MX28 based board and boot. + +NOTE: If the user needs to adjust the start sector, the "mxsboot" tool contains + a "-p" switch for that purpose. The "-p" switch takes the sector number as + an argument. + +4) Installation of U-Boot for NAND flash +----------------------------------------------- + +To boot a MX28 based board from NAND, set the boot mode DIP switches according to i.MX28 +manual chapter 12.2.1 (Table 12-2), PORT=GPMI, NAND 1.8 V. + +There are two possibilities when preparing an image writable to NAND flash. + + I) The NAND wasn't written at all yet or the BCB is broken + ---------------------------------------------------------- + In this case, both BCB (FCB and DBBT) and firmware needs to be + written to NAND. To generate NAND image containing all these, + there is a tool called "mxsboot" in the "tools/" directory. The tool + is invoked on "u-boot.sb" file from chapter 2): + + $ ./tools/mxsboot nand u-boot.sb u-boot.nand + + NOTE: The above invokation works for NAND flash with geometry of + 2048b per page, 64b OOB data, 128kb erase size. If your chip + has a different geometry, please use: + + -w <size> change page size (default 2048 b) + -o <size> change oob size (default 64 b) + -e <size> change erase size (default 131072 b) + + The geometry information can be obtained from running U-Boot + on the MX28 board by issuing the "nand info" command. + + The resulting file, "u-boot.nand" can be written directly to NAND + from the U-Boot prompt. To simplify the process, the U-Boot default + environment contains script "update_nand_full" to update the system. + + This script expects a working TFTP server containing the file + "u-boot.nand" in it's root directory. This can be changed by + adjusting the "update_nand_full_filename" varible. + + To update the system, run the following in U-Boot prompt: + + => run update_nand_full + + In case you would only need to update the bootloader in future, + see II) below. + + II) The NAND was already written with a good BCB + ------------------------------------------------ + This part applies after the part I) above was done at least once. + + If part I) above was done correctly already, there is no need to + write the FCB and DBBT parts of NAND again. It's possible to upgrade + only the bootloader image. + + To simplify the process of firmware update, the U-Boot default + environment contains script "update_nand_firmware" to update only + the firmware, without rewriting FCB and DBBT. + + This script expects a working TFTP server containing the file + "u-boot.sb" in it's root directory. This can be changed by + adjusting the "update_nand_firmware_filename" varible. + + To update the system, run the following in U-Boot prompt: + + => run update_nand_firmware + + III) Special settings for the update scripts + -------------------------------------------- + There is a slight possibility of the user wanting to adjust the + STRIDE and COUNT options of the NAND boot. For description of these, + see i.MX28 manual section 12.12.1.2 and 12.12.1.3. + + The update scripts take this possibility into account. In case the + user changes STRIDE by blowing fuses, the user also has to change + "update_nand_stride" variable. In case the user changes COUNT by + blowing fuses, the user also has to change "update_nand_count" + variable for the update scripts to work correctly. + + In case the user needs to boot a firmware image bigger than 1Mb, the + user has to adjust the "update_nand_firmware_maxsz" variable for the + update scripts to work properly. |