**************This code is based on the code from internet.
**************contact: Du, Changbin <changbin.du@gmail.com>

1. build and install
=====================
	$ make
	$ sudo make install

2. dnw tool usage 
=====================
Connect board to PC and open minicom. Boot board and enter U-Boot command line mode.
Then run command "dnw <download address>" in U-Boot. U-Boot may print bellow message:
	Insert a OTG cable into the connector!
	OTG cable Connected!
	Now, Waiting for DNW to transmit data

Now, you can download your file to board by follow command on PC end:
	$ sudo dnw <file_to_download>

Note: If your board isn't FL Ok6410, please set right load-address via "a" option.
      Above steps have only download file to board's RAM, so you need  flash
      it to nand via U-Boot command "nand write".

If above doesn't work, pls check if you can see bellow message in `dmesg`.
	usb 1-1: new full speed USB device using uhci_hcd and address 2
	usb 1-1: configuration #1 chosen from 1 choice
	secbulk:secbulk probing...
	secbulk:bulk out endpoint found!

===============================================
some U-Boot commands special for FL Ok6410
   (1) download U-Boot
	$dnw 50008000
	$nand erase 0 100000
	$nand write.uboot 50008000 0 100000
	#dnw default load address is 0xc0000000
	all in one:
	$dnw 50008000 && nand erase 0 100000 && nand write.uboot 50008000 0 100000
   (2) download kernel
	$dnw 50008000
	$nand erase 100000 500000
	$nand write.e 50008000 100000 500000
	all in one:
	$dnw 50008000 && nand erase 100000 500000 && nand write.e 50008000 100000 500000
   (3) download yaffs2 root file system
	$dnw 50008000
	$nand erase 600000 #erase mtdblock2 partition
	$nand write.yaffs2 50008000 600000 8000000 #instead 8000000 of real image size
	all in one:
	$dnw 50008000 && nand erase 600000 && nand write.yaffs2 50008000 600000 8000000
   (4) download ubifs/cramfs root file system
	$dnw 50008000
	$nand erase 600000 #erase mtdblock2 partition
	$nand write.e 50008000 600000 8000000 #instead 8000000 of real image size
	all in one:
	$dnw 50008000 && nand erase 600000 && nand write.e 50008000 600000 8000000
   (5) download jffs2 root file system
	$dnw 50008000
	$nand erase 600000 #erase mtdblock2 partition
	$nand write.jffs2 50008000 600000 8000000 #instead 8000000 of real image size
	all in one:
	$dnw 50008000 && nand erase 600000 && nand write.jffs2 50008000 600000 8000000
   (6) deal with bad blocks
	$nand scrub
   (7) set kernel arguments
	To boot using ubi image:
		$setenv bootargs console=ttySAC0,115200 ubi.mtd=rootfs root=ubi0:rootfs rootfstype=ubifs rw init=/linuxrc debug
		$save
		$reset
	To boot using cramfs image:
		$setenv bootargs console=ttySAC0,115200 root=/dev/mtdblock2 rootfstype=cramfs init=/linuxrc debug
		$save
		$reset
	To boot using yaffs2 image:
		$setenv bootargs "root=/dev/mtdblock2 rootfstype=yaffs2 console=ttySAC0,115200" 
		$save
		$reset
        To boot from NFS
		$setenv bootargs "root=/dev/nfs nfsroot=192.168.0.231:/FileSystem-Yaffs2 \
		 ip=192.168.0.232:192.168.0.231:192.168.0.201:255.255.255.0:8.8.8.8:eth0:off \
		 console=ttySAC0,115200"
		$save
		# "192.168.0.231" is your host ip; "192.168.0.232" is your board's ip;
		# "192.168.0.201" is gateway; "255.255.255.0" is mask.