[U-Boot] [PATCH V3 3/4] rockchip:usb: add a simple readme for rockusb

[Eddie Cai <eddie.cai.linux@gmail.com>]

add a simple readme to introduce rockusb and tell people how to use it

Signed-off-by: Eddie Cai <eddie.cai.linux@gmail.com>

Changes in v3:
-fix checkpatch error
---
 doc/README.rockusb | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 doc/README.rockusb

diff --git a/doc/README.rockusb b/doc/README.rockusb
new file mode 100644
index 0000000..262596e
--- /dev/null
+++ b/doc/README.rockusb
@@ -0,0 +1,37 @@
+Rockusb (Rockchip USB protocol)
+=====================================================
+
+Overview
+--------
+
+Rockusb protocol is widely used with Rockchip devices.
+It can read/write info, image to/from devices. This
+document briefly describes how to use Rockusb for upgrading
+firmware (e.g. kernel, u-boot, rootfs, etc.).
+
+Tools
+--------
+There are many tools can support Rockusb protocol. rkdeveloptool
+(https://github.com/rockchip-linux/rkdeveloptool) is open source,
+It is maintained by Rockchip. People don't want to build from source
+can download from here
+(https://github.com/rockchip-linux/rkbin/blob/master/tools/rkdeveloptool)
+
+Usage
+--------
+The Usage of Rockusb command is
+rockusb <USB_controller> <devtype> <dev[:part]>
+e.g. rockusb 0 mmc 0
+On your U-Boot console, type this command to enter rockusb mode.
+On your host PC. use lsusb command. you should see a usb device
+using 0x2207 as its USB verdor id. Then use rkdeveloptool
+sudo rkdeveloptool wl  <BeginSec> <File>
+to flash U-Boot image use command
+sudo rkdeveloptool wl  64 <U-Boot binary>
+There are plenty of Rockusb command. but wl(write lba) and
+rd(reboot) command. These two command can let people flash
+image to device.
+
+To do
+-----
+* Fully support Rockusb protocol
-- 
1.9.1