Toolchain
default toolchain is arm-eabi-4.6 which is also the default toolchain android use now. put uboot in the root directory of android. it can recognise toolchain by itself.if you want to use another toolchain. you can modify CROSS_COMPILE in arch/arm/config.mk.

Build
make rk30xx                            use this command to build uboot,it will generate all the image and bin below
make distclean                         use this command to clean uboot
charge.img                             image which cantain charge animation
uboot.img                              uboot image can only act as second level loader and it should be flashed to specific partition which define in parameter
RKxxxxLoader_miniall.bin               rkloader with nand driver in it. it can only act as first level bootloader
RKxxxxLoader_miniall_debug.bin         RKxxxxLoader_miniall loader with debug message
RKxxxxLoader_mini.bin                  rkloader with emmc driver only in it. it can only act as first level bootloader
RK3188Loader_mini_debug.bin            RKxxxxLoader_mini loader with debug message
RKxxxxLoader_uboot.bin                 uboot image can act as first level bootloader or second level bootloader. 

Chipset
support RK3066,RK3188,RK3168,RK3026

Storage
support emmc and nand flash. 

Boot stage
there are 3 boot mode.
1. RKxxxxLoader_miniall.bin used as first level boot loader.uboot.img used as second level boot loader. it support nand flash storage.
2. RKxxxxLoader_mini.bin used as first level boot loader.uboot.img used as second level boot loader. it support emmc storage.
3. RKxxxxLoader_uboot.bin used as first level boot loader. do not have second level boot loader. it support emmc storage.
CONFIG_SECOND_LEVEL_BOOTLOADER in include/configs/rk30xx.h should be defined for boot mode 1 and 2.

Logo
support display logo in uboot. 
CONFIG_RK_FB and CONFIG_CMD_BMP should be defined in include/configs/rk30xx.h. 
rk_backlight_ctrl and rk_fb_init should be modified to fit the board.
replace tools/logos/denx.bmp by your own logo. 

Rockusb
support all the function for rockusb.
plug in usb cable with volume + pressed can enter rockusb mode. you can use pc tool to flash image. 
please modify RockusbKeyInit in board/rockchip/rk30xx/rk30xx.c if you want to use another key for entering rockusb. 
you can modify pid and vid of rockusb in ModifyUsbVidPid of board/rockchip/common/platform/rk30/chipDepend.c

Charge animation
support display charge animation in uboot.
CONFIG_RK_FB, CONFIG_CMD_BMP and CONFIG_CMD_CHARGE_ANIM should be defined in include/configs/rk30xx.h. 
rk_backlight_ctrl and rk_fb_init should be modified to fit the board. 
it need battery driver for battery voltage detction.there are 3 battery define in include/configs/rk30xx.h. shows as below 
//#define CONFIG_BATTERY_BQ27541
//#define CONFIG_BATTERY_RICOH619
#define CONFIG_BATTERY_RK_SAMPLE  //battery driver
CONFIG_BATTERY_RK_SAMPLE is a fake one. if you want to write one by yourself, you can use this as sample
put your charge animation bitmap in tools/logos/charge/images/

Recovery
there is 2 way to enter android recovery
1. long press volume + and power key without usb cable pluged. 
2. use adb command "adb reboot recovery"
please modify RockusbKeyInit in board/rockchip/rk30xx/rk30xx.c if you want to use another key for entering android recovery.

Fastboot
there is 2 way to enter android recovery
1. plug in usb cable with volume - pressed. 
2. use adb command "adb reboot fastboot"
we use the same pid and vid as rockchip adb because the window usb driver for fastboot is the same as adb.
you can modify CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID in include/configs/rk30xx.h if you want to use another pid, vid.
fastboot support below command
fastboot getvar version
fastboot getvar version-bootloader
fastboot getvar unlocked
fastboot getvar secure
fastboot getvar product
fastboot getvar serialno
fastboot getvar partition-type:<partition_name>
fastboot getvar partition-size:<partition_name>
fastboot oem recovery
fastboot oem recovery:wipe_data
fastboot oem unlock
fastboot oem unlock_accept
fastboot oem lock
fastboot flash <partition_name> [ <filename> ]
fastboot reboot
fastboot reboot-bootloader
fastboot continue
fastboot boot <kernel> [ <ramdisk> ]
fastboot update <filename> (this file should use make updatepackage in android root directory to generate it)
fastboot flashall

tool
please use git clone ssh://git@git.rockchip.com.cn:2222/repo/tools  to get tool repository. flash tool is in AndroidTool directory. parameter is in parameter directory.this parameter has uboot partition defined. uboot.img should be flash to uboot partition.