?Hi,
I am working on a PXA270 based custom board which has a serial port and a USB
port as its interfaces. And, I would like to use u-boot as my boot loader.
Due to PCB space limitation, we only wired the USB client support only on it.
Thus, I do not have a way to use the USB host functions. But, we know its USB
client port worked as a HID device in our previous PCB design iteration.
I have successfully modified the colibri_pxa270 configuration of u-boot to boot
up my board serially. And, I am having trouble getting the USB client port
function to work on it. I have followed the u-boot Readme instructions to
#define CONFIG_USB_DEVICE, CONFIG_USB_TTY, and CONFIG_SYS_CONSOLE_IS_IN_ENV on
my modified colibri_pxa270.h file. And, I have also #undef CONFIG_CMD_USB
since I do not have USB Host support on this board whatsoever.
To my best knowledge on this that if those three defines are #defined in my
configuration file and "setenv stdin=usbtty; setenv stdout usbtty", the USBTTY
functions will bring to live on the board. But in reality, it shows up as a
"Unknown Device" on my PC even though I have set my board up as
"usbtty=cdc_acm" and got the correct VBus pull up GPIO pin setup.
So, does u-boot supports USB client or not? From the documents on my u-boot
source code, u-boot-v2010.09, it should support both functions.
If u-boot does support USB client mode, what are the steps I have to take for
it to work on my PXA270 based board? All I want is a USB to work like a
serial port like a serial console!. Do I have to enable interrupts on my
boards to in order to do it? Or, I can do polling?
How dose the USBTTY stuff getting called after all anyway? Base on my best
code tracing abilities, I can see it is stdio_register() all the usbtty
handlers. But what comes next is not really clear to me. Can someone answer
this for me? How does those usbtty_xxx() get utilized?
Thanks.
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