TS-7970 U-boot Sections

This platform uses U-Boot as the bootloader to launch the full operating system. The i.MX6 processor loads U-Boot from the on-board 8 MiB SPI flash. U-Boot provides support for loading data from various mediums; this allows booting a kernel from SD, eMMC, SATA, NFS, or USB. U-Boot is a general purpose bootloader that is capable of booting into common Linux distributions, Android, Windows, or custom software OSes.

On a normal boot the output should be similar to the output below:

U-Boot 2014.10-gee73348 (Oct 07 2015 - 11:12:20)

I2C:   ready
DRAM:  1 GiB
MMC:   FSL_SDHC: 0, FSL_SDHC: 1
SF: Detected N25Q64 with page size 256 Bytes, erase size 4 KiB, total 8 MiB
In:    serial
Out:   serial
Err:   serial
Net:   using phy at 7
FEC [PRIME]

By default the device will boot to SD or eMMC depending on the status of the "SD Boot" jumper on startup.

To break into the U-Boot console, press and hold the SW1 button while the unit is being powered up. This mode will also check for a USB mass storage device to use for production purposes.

U-Boot Environment

The eMMC flash contains both the U-Boot executable binary and U-Boot environment. Our default build has 2 MiB of environment space which can be used for variables and boot scripts. The following commands are examples of how to manipulate the U-Boot environment:

# Print all environment variables
env print -a

# Sets the variable bootdelay to 5 seconds
env set bootdelay 5;

# Variables can also contain commands
env set hellocmd 'led red on; echo Hello world; led green on;'

# Execute commands saved in a variable
env run hellocmd;

# Commit environment changes to the SPI flash
# Otherwise changes are lost
env save

# Restore environment to default
env default -a

# Remove a variable
env delete emmcboot

U-Boot Commands

# The most important command is 
help
# This can also be used to see more information on a specific command
help i2c

# This is a command added to U-Boot by TS to read the baseboard ID on our 
# System on Module devices
bbdetect
echo ${baseboard} ${baseboardid} 
# The echo will return something similar to:
# TS-8390 2

# Boots into the binary at $loadaddr.  The loaded file needs to have
# the U-Boot header from mkimage.  A uImage already contains this.
bootm
# Boots into the binary at $loadaddr, skips the initrd, specifies
# the FDT addrress so Linux knows where to find the device tree
bootm ${loadaddr} - ${fdtaddr}

# Boot a Linux zImage loaded at $loadaddr
bootz
# Boot in to a Linux zImage at $loadaddr, skip initrd, specifies
# the FDT address to Linux knows where to find the device tree
bootz ${loadaddr} - ${fdtaddr}

# Get a DHCP address
dhcp
# This sets ${ipaddr}, ${dnsip}, ${gatewayip}, ${netmask}
# and ${ip_dyn} which can be used to check if the dhcp was successful

# These commands are used for scripting:
false # do nothing, unsuccessfully
true # do nothing, successfully

# This command can set fuses in the processor
# Setting fuses can brick the unit, will void the warranty,
# and should not be done in most cases
fuse

# GPIO can be manipulated from U-Boot.  Keep in mind that the IOMUX 
# in U-Boot is only setup enough to boot the device, so not all pins will
# be set to GPIO mode out of the box.  Boot to the full operating system
# for more GPIO support.
# GPIO are specified in bank and IO in this manual.  U-Boot uses a flat numberspace,
# so for bank 2 DIO 25, this would be number (32*1)+25=89
# The formula thus being (32*(bank-1)+dio)=flattened_dio
# Note that on some products, bank 1 is the first bank
# Set 2_25 low
gpio clear 83
# Set 2_25 high
gpio set 83
# Read 2_25
gpio input 83

# Control LEDs
led red on
led green on
led all off
led red toggle

# This command is used to copy a file from most devices
# Load kernel from SD
load mmc 0:1 ${loadaddr} /boot/uImage
# Load Kernel from eMMC
load mmc 1:1 ${loadaddr} /boot/uImage
# Load kernel from USB
usb start
load usb 0:1 ${loadaddr} /boot/uImage
# Load kernel from SATA
sata init
load sata 0:1 ${loadaddr} /boot/uImage

# View the FDT from U-Boot
load mmc 0:1 ${fdtaddr} /boot/imx6q-ts4900.dtb
fdt addr ${fdtaddr}
fdt print

# It is possible to blindly jump to any memory location
# This is similar to bootm, but it does not require
# the use of the U-Boot header
load mmc 0:1 ${loadaddr} /boot/custombinary
go ${loadaddr}

# Browse fat, ext2, ext3, or ext4 filesystems:
ls mmc 0:1 /

# Access memory like devmem in Linux, read/write arbitrary memory
# using mw and md
# write
mw 0x10000000 0xc0ffee00 1
# read
md 0x10000000 1

# Test memory.
mtest

# Check for new SD card
mmc rescan
# Read SD card size
mmc dev 0
mmcinfo
# Read eMMC Size
mmc dev 1
mmcinfo

# The NFS command is like 'load', but used over the network
dhcp
env set serverip 192.168.0.11
nfs ${loadaddr} 192.168.0.11:/path/to/somefile

# Test ICMP
dhcp
ping 192.168.0.11

# Reboot
reset

# SPI access is through the SF command
# Be careful with sf commands since
# this is where U-Boot and the FPGA bitstream exist
# Improper use can render the board unbootable
sf probe

# Delay in seconds
sleep 10

# Load HUSH scripts that have been created with mkimage
load mmc 0:1 ${loadaddr} /boot/ubootscript
source ${loadaddr}

# Most commands have return values that can be used to test
# success, and HUSH scripting supports comparisons like
# test in Bash, but much more minimal
if load mmc 1:1 ${fdtaddr} /boot/uImage;
	then echo Loaded Kernel
else
	echo Could not find kernel
fi

# Commands can be timed with "time"
time sf probe

# Print U-Boot version/build information
version

Modify Linux Kernel cmdline

The Linux kernel cmdline can be customized by modifying the cmdline_append variable. The variable contents are clobbered when set, so be sure to specify the full desired cmdline string.

env set cmdline_append console=ttymxc0,115200 init=/sbin/init quiet
env save

The kernel command line can also be modified from from the on-board Linux. Debian (and other distributions) provide a U-Boot utilities package that contains the tools necessary to create a U-Boot script:

apt-get update && apt-get install u-boot-tools -y
echo "env set cmdline_append console=ttymxc0,115200 init=/sbin/init quiet" > /boot/boot.scr
mkimage -A arm -T script -C none -n 'tsimx6 boot script' -d /boot/boot.scr /boot/boot.ub

The boot.scr includes the plain text commands to be run in U-Boot on startup. The mkimage tool adds a checksum and header to this file which can be loaded by U-Boot. The .ub file should not be edited directly.

U-boot Recovery

U-Boot itself handles CPU and RAM setup/configuration that needs to be run every boot. Therefore separate binaries are maintained for each CPU grade, RAM part, and RAM size; and the proper binary must be used for the device configuration. On a functional unit, run 'env print imx_type' in U-Boot and it will return the correct device variant.

On startup, the TS-7970 checks the SPI flash for a valid boot header in SPI flash. If it is unable to locate a valid boot header, the CPU falls back to the "serial downloader" which allows the CPU to execute code sent via USB. If the board has a valid boot header, but a damaged or invalid U-Boot binary located in SPI; an RMA return or a TS-9468 development board will be required in order to properly recover the unit. Please contact us for assistance with this.

1) Download u-boot for the correct imx_type variant from the list here: ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7970-linux/u-boot/. See the U-Boot Changelog for information on the changes between released versions.

2) Download and build/install the "imx_usb" loader: https://community.freescale.com/docs/DOC-94117

3) Disconnect power from the device.

4) Remove the "CON EN" jumper.

5) Apply power to the device.

6) Plug a USB type B cable into the P2 connector on the device and connect it to a host PC.

7) Check 'dmesg' or 'lsusb' on the host PC for a new USB connection. This should show a HID device listing NXP or Freescale as the manufacturer. For example:

hid-generic 0003:15A2:0054.0006: hiddev0,hidraw3: USB HID v1.10 Device [Freescale SemiConductor Inc  SE Blank ARIK] on usb-0000:00:14.0-6.4.2/input0

If it does not show the above output, an RMA return or TS-9468 development board will be required in order to properly recover the unit. Please contact us for assistance with this.

8) Hold down SW1.

9) Run 'imx_usb path/to/u-boot.imx' on the host PC while still holding down SW1. Continue holding SW1 for a few seconds after the command is run.

10) Disconnect the USB cable on P2.

11) Set the "CON EN" jumper.

12) Re-insert the USB cable into P2.

At this point, the USB serial device should show up on the host, opening it will reveal that the unit is stopped at the U-Boot prompt. Follow the steps in Update U-Boot to reinstall U-Boot on the SPI flash.

Linux NFS Boot

U-Boot's NFS support can be used to load a kernel, device tree binary, and root filesystem over the network. The default scripts include an example NFS boot script.

# Set this to your NFS root path.  The server root should be accessible at this path.
env set nfsroot 192.168.0.36:/mnt/storage/imx6/
env save

To boot to an NFS root:

# Boot to NFS once
run nfsboot;

# To make the NFS boot the persistent default
env set bootcmd run nfsboot;
env save

Update U-Boot

WARNING:

Installing a custom U-Boot is not recommended and may cause the device to fail to boot.

U-Boot requires a different build for Quad/Dual and Solo/Duallite. When booted to the U-Boot shell, run 'env print imx_type' and it will return the correct U-Boot build that should be used. Copy the built u-boot.imx file or the pre-built binary from our FTP site to the SD card as "/u-boot.imx", and run the following U-Boot commands:

mmc dev 0
load mmc 0:1 ${loadaddr} /u-boot.imx
sf probe
sf erase 0 0x80000
sf write ${loadaddr} 0x400 $filesize