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https://github.com/brain-hackers/u-boot-brain
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![Stefano Babic](/assets/img/avatar_default.png)
The patch adds suupport for the Freescale's mx35pdk board (known as well as mx35_3stack). The board boots from the NOR flash. Following devices are supported: - two ethernet devices (FEC and SMC911x on debug board) - I2C - PMIC (MC13892) via I2C interface - UART - NOR flash (64MB) - NAND flash (2GB) - basic access to mc9sdz60 registers via I2C interface Signed-off-by: Stefano Babic <sbabic@denx.de>
189 lines
5.9 KiB
Plaintext
189 lines
5.9 KiB
Plaintext
Overview
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--------------
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mx35pdk (known als as mx35_3stack) is a development board by Freescale.
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It consists of three pluggable board:
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- CPU module, with CPU, RAM, flash
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- Personality board, with most interfaces (USB, Network,..)
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- Debug board with JTAG header.
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The board is usually delivered with redboot. This howto explains how to boot
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a linux kernel and how to replace the original bootloader with U-Boot.
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The board is delivered with Redboot on the NAND flash. It is possible to
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switch the boot device with the switches SW1-SW2 on the Personality board,
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and with SW5-SW10 on the Debug board.
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Delivered Redboot script to start the kernel
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---------------------------------------------------
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In redboot the following script is stored:
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fis load kernel
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exec -c "noinitrd console=ttymxc0,115200 root=/dev/mtdblock8 rw rootfstype=jffs2 ip=dhcp fec_mac=00:04:9F:00:E7:76"
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Kernel is taken from flash. The image is in zImage format.
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Booting from NET, rootfs on NFS:
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-----------------------------------
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To change the script in redboot:
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load -r -b 0x100000 <path_to_zImage>
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exec -c "noinitrd console=ttymxc0,115200 root=/dev/nfsroot rootfstype=nfsroot nfsroot=192.168.1.1:/opt/eldk-4.2-arm/armVFP rw ip=dhcp"
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If the ip address is not set, you can set it with :
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ip_address -l <board_ip/netmask> -h <server_ip>
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Linux partitions:
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---------------------------
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As default, the board is shipped with these partition tables for NAND
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and for NOR:
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Creating 5 MTD partitions on "NAND 2GiB 3,3V 8-bit":
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0x00000000-0x00100000 : "nand.bootloader"
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0x00100000-0x00600000 : "nand.kernel"
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0x00600000-0x06600000 : "nand.rootfs"
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0x06600000-0x06e00000 : "nand.configure"
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0x06e00000-0x80000000 : "nand.userfs"
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Creating 6 MTD partitions on "mxc_nor_flash.0":
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0x00000000-0x00080000 : "Bootloader"
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0x00080000-0x00480000 : "nor.Kernel"
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0x00480000-0x02280000 : "nor.userfs"
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0x02280000-0x03e80000 : "nor.rootfs"
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0x01fe0000-0x01fe3000 : "FIS directory"
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0x01fff000-0x04000000 : "Redboot config"
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NAND partitions can be recognized enabling in kernel CONFIG_MTD_REDBOOT_PARTS.
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For this board, CONFIG_MTD_REDBOOT_DIRECTORY_BLOCK should be set to 2.
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However, the setup in redboot is not correct and does not use the whole flash.
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Better solution is to use the kernel parameter mtdparts.
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Here the resulting script to be defined in RedBoot with fconfig:
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load -r -b 0x100000 sbabic/mx35pdk/zImage.2.6.37
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exec -c "noinitrd console=ttymxc0,115200 root=/dev/nfsroot rootfstype=nfsroot nfsroot=192.168.1.1:/opt/eldk-4.2-arm/arm rw ip=dhcp mtdparts=mxc_nand:1m(boot),5m(linux),96m(root),8m(cfg),1938m(user);physmap-flash.0:512k(b),4m(k),30m(u),28m(r)"
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Flashing U-Boot
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--------------------------------
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There are two options: the original bootloader in NAND can be replaced with
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u-boot, or u-boot can be stored on the NOR flash without erasing
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the delivered bootloader.
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The boot storage can be select using the switches on the personality board
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(SW1-SW2) and on the DEBUG board (SW4-SW10).
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The second option is to be preferred if you have not a JTAG debugger.
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If something goes wrong flashing the bootloader, it is always possible to
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recover the board booting from the other device.
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Replacing the bootloader on the NAND
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--------------------------------------
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To replace RedBoot with U-Boot, the easy way is to do this in linux.
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Start the kernel with the suggested options. Make sure to have set the
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mtdparts exactly as described, because this matches the layout on the
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mx35pdk.
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You should see in your boot log the following entries for the NAND
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flash:
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5 cmdlinepart partitions found on MTD device mxc_nand
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Creating 5 MTD partitions on "mxc_nand":
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0x000000000000-0x000000100000 : "boot"
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0x000000100000-0x000000600000 : "linux"
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0x000000600000-0x000006600000 : "root"
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0x000006600000-0x000006e00000 : "cfg"
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0x000006e00000-0x000080000000 : "user"
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You can use the utilities flash_eraseall and nandwrite to put
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u-boot on the NAND. The bootloader is marked as "boot", and 1MB is
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reserved. If everything is correct, this partition is accessed as
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/dev/mtd4. However, check if it is correct with "cat /proc/mtd" and
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get the device node from the partition name:
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$ cat /proc/mtd | grep boot
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I suggest you try the utilities on a different partition to be sure
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if everything works correctly. If not, and you remove RedBoot, you have to
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reinstall it using the ATK tool as suggested by Freescale, or using a
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JTAG debugger.
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I report the versions of the utilities I used (they are provided with ELDK):
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-bash-3.2# nandwrite --version
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nandwrite $Revision: 1.32 $
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flash_eraseall --version
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flash_eraseall $Revision: 1.22 $
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nandwrite reports a warning if the file to be saved is not sector aligned.
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This should have no consequences, but I preferred to pad u-boot.bin
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to get no problem at all.
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$ dd if=/dev/zero of=zeros bs=1 count=74800
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$ cat u-boot.bin zeros > u-boot-padded.bin
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To erase the partition:
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$ flash_eraseall /dev/mtd4
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Writing u-boot:
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$ nandwrite /dev/mtd4 u-boot-padded.bin
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Now U-Boot is stored on the booting partition.
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To boot from NAND, you have to select the switches as follows:
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Personality board
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SW2 1, 4, 5 on
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2, 3, 6, 7, 8 off
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SW1 all off
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Debug Board:
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SW5 0
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SW6 0
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SW7 0
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SW8 1
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SW9 1
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SW10 0
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Saving U-Boot in the NOR flash
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---------------------------------
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The procedure to save in the NOR flash is quite the same as to write into the NAND.
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Check the partition for boot in the NOR flash. Setting the mtdparts as reported,
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the boot partition should be /dev/mtd0.
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Creating 6 MTD partitions on "mxc_nor_flash.0":
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0x00000000-0x00080000 : "Bootloader"
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0x00080000-0x00480000 : "nor.Kernel"
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0x00480000-0x02280000 : "nor.userfs"
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0x02280000-0x03e80000 : "nor.rootfs"
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0x01fe0000-0x01fe3000 : "FIS directory"
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0x01fff000-0x04000000 : "Redboot config"
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To erase the whole partition:
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$ flash_eraseall /dev/mtd0
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Writing u-boot:
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dd if=u-boot.bin of=/dev/mtd0
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To boot from NOR, you have to select the switches as follows:
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Personality board
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SW2 all off
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SW1 all off
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Debug Board:
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SW5 0
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SW6 0
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SW7 0
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SW8 1
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SW9 1
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SW10 0
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