Uboot porting with NXP MX serie

12 Jun 2020

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Linux Uboot

Some previous knowledge about U-boot has been discussed in another blog.

1. Files need to be configured

THe following files are needed to be created and configured before doing further modifications.

/configs/<board_name>_defconfig

/include/configs/<board_name>.h

/arch/arm/cpu/armv7/mash-imx/mx6/Kconfig //adding config TARGET and source “board/<vendor>/<board_name>”

/board/<vendor>/<board_name>/ 
                        ...Kconfig
                        ...<board_name>.c
                        ...MAINTAINERS

2. Add or modify devices support

One of the most important file will need to modify is /board/<vendor>/<board_name>/<board_name>.c, which

2.1 Add LCD support

A. Uboot command

A.1 Network commands

Basically, network connections can be very useful in debugging drivers and testing a system.

A.1.1 ping and network configuration

ping and configuration Before we use the network. There are some configurations have to be done first.

  • setenv ipaddr 192.168.0.209 (Or using dhcp for dynamically allocate ip address)
  • setenv ethaddr 08:00:00:00:22:02 (Depend on the ethernet port for eth-0 ethaddr, eth-1 eth1addr, eth-2 eth2addr)
  • setenv gatewayip 192.168.0.1
  • setenv netmask 255.255.255.0
  • setenv serverip 192.168.1.250
  • saveenv

A.1.2 nfs

nfs service can be very useful when we debug the rootsf or kernel.

1. nfs server setup (pc)

  1. sudo apt install nfs-kernel-server install nfs-server
  2. configuration of nfs:
    sudo vim /etc/exports
    adding following content to the end of /etc/exports
    /home/jie/workdir 192.168.0.0/24(rw,sync,all_squash,anonuid=998,anongid=998,no_subtree_check)
Note: anonuid=, anongid= related with the uid and gid of PC which can be obtained by `id` command in terminal.
192.168.0.0/24 is the netmask and network of host PC. This `/home/jie/workdir` path, which can be modified , will be used to share files.

2. nfs client operation(embedded device)

nfs 80800000 192.168.0.188:/home/jie/workdir/zImage

A.1.3 tftp

tftp command is very similar with nfs command.

sudo apt-get install tftp-hpa tftpd-hpa sudo apt-get install xinetd mkdir /home/zuozhongkai/linux/tftpboot chmod 777 /home/zuozhongkai/linux/tftpboot ` touch /etc/xinetd.d/tftp ` write following content into tftp:

server tftp
 {
  socket_type = dgram
  protocol = udp
  wait = yes
  user = root
  server = /usr/sbin/in.tftpd
  server_args = -s /home/jie/linux/tftpboot/
  disable = no
  per_source = 11
  cps = 100 2
  flags = IPv4
 }

vim /etc/default.tftp-hpa sudo service tftpd-hpa start

# /etc/default/tftpd-hpa
2
3 TFTP_USERNAME="tftp"
4 TFTP_DIRECTORY="/home/zuozhongkai/linux/tftpboot"
5 TFTP_ADDRESS=":69"
6 TFTP_OPTIONS="-l -c -s"

sudo service tftpd-hpa restart

A.2 boot command

A.2.1 bootz

A.2.2 go

By using go command, we can run the bare-metal program at assigned address. It is a convenient way to test bare-metal program.

tftp 87800000 printf.bin
go 87800000

B Usage of U-boot

B.1 Boot from network

  • bootcmd ‘tftp 80800000 zImage;tftp 83000000 imx6ull-14x14-evk.dtb;bootz 80800000 - 83000000’
  • bootargs ‘console=ttymxc0,115200 root=/dev/mmcblk1p2’

    B.1.1. bootcmd & bootargs

  • bootcmd can save those default command and execute it when bringup.
  • bootargs is one of the crucial arguments which save environment features

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Linux Uboot