[U-Boot] [PATCH v2] README.mx28: add

[Otavio Salvador]

This is mainline a copy of README.m28 changing the references to the
mx28 counterpart but it makes easy for people looking for information
about mx28 based boards.

Signed-off-by: Otavio Salvador <otavio at ossystems.com.br>
Cc: Fabio Estevam <fabio.estevam at freescale.com>
---
 doc/README.mx28 |  152 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 152 insertions(+), 0 deletions(-)
 create mode 100644 doc/README.mx28

diff --git a/doc/README.mx28 b/doc/README.mx28
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+Freescale MX28EVK
+=================
+
+This document describes the Freescale MX28EVK 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
+--------
+
+0) Files of the MX28EVK port
+1) Prerequisites
+2) Compiling U-Boot for MX28EVK
+3) Installation of U-Boot for MX28EVK to SD card
+
+0) Files of the MX28EVK port
+----------------------------
+
+arch/arm/cpu/arm926ejs/mx28/	- The CPU support code for the Freescale i.MX28
+arch/arm/include/asm/arch-mx28/	- Header files for the Freescale i.MX28
+board/denx/mx28evk/		- MX28EVK board specific files
+include/configs/mx28evk.h	- MX28EVK configuration file
+
+1) Prerequisites
+----------------
+
+To make the MX28EVK board bootable, some tools are necessary. The first one is
+the "elftosb" tool distributed by Freescale Semiconductor. The other tool 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 MX28
+----------------------------
+
+Compiling the U-Boot for MX28 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 MX28EVK:
+
+	$ 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 MX28EVK to SD card
+------------------------------------------------
+
+To boot an MX28 from SD, set the boot mode DIP switches as:
+
+   * Boot Mode Select: 1 0 0 1 (Boot from SD card Slot 0 - U42)
+   * JTAG PSWITCH RESET: To the left (reset enabled)
+   * Battery Source: Down
+   * Wall 5V: Up
+   * VDD 5V: To the left (off)
+   * Hold Button: Down (off)
+
+Full reference at i.MX28 manual chapter 12.2.1 (Table 12-2).
+
+An SD card that can be used to boot U-Boot on a i.MX28 CPU 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 MX28EVK 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.
-- 
1.7.9.1