[U-Boot] usbtty Support on AT91SAM9XXX chipsets

[Daniel Sherwood]

Hi

 

I am interested in getting usbtty support running on an AT91SAM9G20
board.  I have picked up the latest code on the CDC head on the
u-boot-usb GIT tree and am currently attempting to get the CDC-Ether
support up and running (merging various changes from the 9261 board to
the 9260).  

 

However in order to support our factory processes (which are currently
set up to use serial ports) we need to use the usbtty framework.  I have
had a quick go at replacing CONFIG_USG_ETHER with CONFIG_USB_TTY in the
config file but it doesn't work.  Digging around a bit I think this is
due to the following points:

 

1.	usbtty.c uses a global function call based UDC framework
(udc_init, udc_endpoint_read|write etc)
2.	This framework is implemented on the older UDC devices
(omap1510_udc.c, pxa27x_udh.c & mpc8xx_udc.c) but is not implemented on
at91_udc.c.
3.	drivers/usb/gadget/ether.c uses a new (Linux derived?) USB
gadget framework based on registering function tables and accessing via
helper functions in gadget.h.
4.	at91_udc.c is implemented to this framework.

 

Hence omap1510, pxa27x & mpc8xx support USB TTY operation and at91
supports ethernet operation but other combinations are not currently
possible.

 

Please could someone advise on the best way forward, initially I can
think of a couple of options as follows:

 

1.	create a wrapper that implements the old framework functions
(udc_init, udc_endpoint_read|write etc) and simply maps them on to the
new framework.
2.	import the appropriate TTY gadget implementation from Linux (as
for ether.c) and get it working and registered as a proper device.

 

I suspect 2 is the better option and the way that the project was
moving, but I thought I'd check if this was the way to go and whether
anyone else had made any progress in this area.  Also, if this is the
way to go, could someone confirm which version of the Linux Gadget
framework ether.c and friends are based on.  It appears to be completely
different to the latest version.

 

Cheers

 

Daniel Sherwood
Software Engineer
 
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