Question on UDC driver for the Alchemy Au1550

Question on UDC driver for the Alchemy Au1550

[elmar gerdes]

Hi folks,


to make this short:

   Is anybody working on a UDC driver for the Alchemy Au1550
   (MIPS-based)?

If you are interested in details, please read on:




I'm working with an Au1550-based board and would like to run it as a USB
device.  There have been a few drivers around for Au1xxx-based boards,
but none of them seems to be adequate for this processor (or else I
missed something...):

  a) in the kernel tree: arch/mips/au1000/common/usbdev.c

     This one was for Au1000, Au1100, and Au1500 IIRC.  But it didn't
     even compile for quite some kernel versions and now it has been
     removed from the tree.

  b1) drivers/usb/gadget/au1200udc.c

     This driver hasn't made it (yet) into the kernel tree.  I grabbed it
     from some postings to linux-usb-devel, but it's for the Au1200 (and
     Geode LX companion chip).

  b2) drivers/usb/gadget/amd5536udc.c

     from RMI.  This looks very similar to the au1200udc.c driver.  I
     would consider it a predecessor.


The first driver (usbdev.c) cannot work this way, but the access to
registers and endpoints is like that for the Au1500 which should be
correct for the Au1500, too.  But the Au1550's DMA differs.

The second driver (au1200udc.c / amd5536udc.c) has the same DMA, but the
registers and endpoint stuff are different, and it supports USB 2.0
whereas the Au1550 only supports USB 1.1.

It looks like the Au1550 needs a driver merged from the 2 (or 3) above
drivers.

Is anybody working on that?  Can anybody point me to some projects,
people or other source code that could help me?

Regards,

 	Elmar

Re: Question on UDC driver for the Alchemy Au1550

[Sergei Shtylyov]

Hello.

elmar gerdes wrote:
> to make this short:

>   Is anybody working on a UDC driver for the Alchemy Au1550
>   (MIPS-based)?

> If you are interested in details, please read on:

> I'm working with an Au1550-based board and would like to run it as a USB
> device.  There have been a few drivers around for Au1xxx-based boards,
> but none of them seems to be adequate for this processor (or else I
> missed something...):

>  a) in the kernel tree: arch/mips/au1000/common/usbdev.c
> 
>     This one was for Au1000, Au1100, and Au1500 IIRC.  But it didn't
>     even compile for quite some kernel versions and now it has been
>     removed from the tree.

> The first driver (usbdev.c) cannot work this way, but the access to

    It was written by MontaVista in the ancient times when there was no USB
gadget stack I think. It was never completeed because of the known USB device
  interrupt latency issues in the early revisions of Au1xx0 chips.

> registers and endpoints is like that for the Au1500 which should be
> correct for the Au1500, too.  But the Au1550's DMA differs.

> The second driver (au1200udc.c / amd5536udc.c) has the same DMA, but the
> registers and endpoint stuff are different, and it supports USB 2.0
> whereas the Au1550 only supports USB 1.1.

    Au1200 has OTG controller, hasn't it?

> It looks like the Au1550 needs a driver merged from the 2 (or 3) above
> drivers.

    Probably.

> Is anybody working on that?  Can anybody point me to some projects,
> people or other source code that could help me?

    I think Rodolfo Giometti was working on Au1100 (and hence Au1000/1500) USB
device support.
    The topic of Alchemy USB device has been touched several times on 
linux-mips, I'd suggest to look thru the list archives. Getting the Au1550 
spec. update would be a good idea too... although you're probably lucky with 
Au1550 -- I'm not seeing any USB device errata listed for there.

> Regards,

>     Elmar

WBR, Sergei