How to use U-BOOT on SeeedStudio NPI-IMX6ULL Single Board Computer
------------------------------------------------------------------

- Configure and build U-Boot for NPI-IMX6ULL:

    $ export ARCH=arm
    $ export CROSS_COMPILE=arm-none-linux-gnueabihf-
    $ make seeed_npi_imx6ull_defconfig
    $ make

This will generate SPL and u-boot-dtb.img images.

Boot from MMC/SD:
- The SPL and u-boot-dtb.img images need to be flashed into the micro SD card:

    $ sudo dd if=SPL of=/dev/mmcblk0 bs=1k seek=1; sync
    $ sudo dd if=u-boot-dtb.img of=/dev/mmcblk0 bs=1k seek=69; sync

- Boot mode settings:

  Boot switch position: SW1 -> 0
			SW2 -> 1
			SW3 -> 0
			SW4 -> 0
			SW5 -> 1
			SW6 -> 0
			SW7 -> 0
			SW8 -> 1

Boot from NAND:
- Boot the board using SD/MMC or Serial download and load the SPL into memory
either from SD/MMC or TFTP.

Default MTD layout is 512k(spl),1m(uboot),1m(uboot-dup),-(ubi)

Flash SPL to NAND from SD/MMC,

    $ ext4load mmc 0:2 $loadaddr SPL
    $ nand erase.part spl
    $ nandbcb init $loadaddr 0x0 $filesize

Flash u-boot image to NAND from SD/MMC,

    $ ext4load mmc 0:2 $loadaddr u-boot-dtb.img
    $ nand erase.part uboot
    $ nand write $loadaddr uboot $filesize

- Boot mode settings:

  Boot switch position: SW1 -> 0
			SW2 -> 1
			SW3 -> 1
			SW4 -> 0
			SW5 -> 0
			SW6 -> 1
			SW7 -> 0
			SW8 -> 0

- Connect the Serial cable to UART0 and the PC for the console.

- Reset the board using reset button and U-Boot should boot from NAND.