[U-Boot] [PATCH] mx23: Add a README file

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam at freescale.com>

Provide instructions on how to build U-boot and flash the binary into an SD card
for a mx23 based platform.

Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
---
 doc/README.mx23_common |  145 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)
 create mode 100644 doc/README.mx23_common

diff --git a/doc/README.mx23_common b/doc/README.mx23_common
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+Booting U-boot on a MX23 processor
+==================================
+
+This document describes the MX23 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 MX23 based board
+3) Installation of U-Boot for a MX23 based board to SD card
+
+1) Prerequisites
+----------------
+
+To make a MX23 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:
+
+	ftp://ftp.denx.de/pub/tools/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 ftp://ftp.denx.de/pub/tools/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 MX23 based board
+-------------------------------------------
+
+Compiling the U-Boot for a MX23 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 MX23 based board
+
+	$ make <mx23_based_board_name>_config
+
+Examples:
+
+1. For building U-boot for Freescale MX23EVK board:
+
+	$ make mx23evk_config
+
+2. For building U-boot for Olimex MX23 Olinuxino board:
+
+	$ make mx23_olinuxino_config
+
+Lastly, compile U-Boot and prepare a "BootStream". The "BootStream" is a special
+type of file, which the i.MX23 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 MX23 based board to SD card
+-----------------------------------------------------------
+
+To boot a MX23 based board from a SD connected to SSP1 or SSP2, set the boot
+mode DIP switches according to i.MX23 manual section 35.1.2 (Table 35-3).
+
+An SD card the i.MX23 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:
+
+	$ sudo dd if=u-boot.sd of=/dev/mmcblk0p1; sync
+
+Last step is to insert the card into MX23 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.
-- 
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