Re: [Qemu-devel] spidev with omap3 running on qemu

[Peter Crosthwaite]

On Sat, Oct 27, 2012 at 7:24 PM, johan marx <address@hidden> wrote:
> Hi Peter,
>
> Thanks for the quick reply. I'm building with qemu-linaro

Hi Johan,

Sorry about the delay.

Ive had a quick browse of this tree. The OMAP spi work there is ahead
of whats in mainline, but is still divergent from the the ssi based in
mainline that I have been working on. Should be a fairly mechanical
conversion to bring what PMM has done there over to SSI so there is
only one SPI bus implementation that can all the devices. That
something of a long term goal though.

and launching qemu
> with "qemu-system-arm -M overo -m 512M -sd sd-image.img -clock unix -display
> none -serial stdio".
> For the spi device, I thought of using the omap_spi. I have been playing
> around last night with the spi_create_device function and I was able to have
> data going through. I used the tsc2005 device as the omap_spi device
> reported "Property '.channel' not found".

Thats sounds like a bug in QEMU, probably in the Linaro tree SPI framework.

> My final aim being to use qemu in a simulator, I would have to send the spi
> data to the PC linux side where the emulated hardware will be. I'm therefore
> not yet sure if it is not easier for me to develop my own spi device

My guess is fixing the bugs you have encountered in the OMAP spi
controller is the path of least resistance.

> directly instead of putting another layer on top of the omap_spi.

Shouldn't be a layer onto of OMAP spi, rather a SPI device definition.
You should be able to do it in a self contained way without having to
worry about what spi controller (OMAP or otherwise) is driving your
device.

Regards,
Peter

> Regards,
> Johan
>
>> Date: Sat, 27 Oct 2012 11:06:07 +1000
>> Subject: Re: [Qemu-devel] spidev with omap3 running on qemu
>> From: address@hidden
>> To: address@hidden
>> CC: address@hidden; address@hidden
>
>>
>> Hi Johan,
>>
>> On Sat, Oct 27, 2012 at 5:03 AM, johan marx <address@hidden> wrote:
>> > Hi,
>> > I have been trying to get the spi working on an emulated omap3 with qemu
>> > but
>> > so far I wasn't able to complete the cycle. I decided to use spidev in
>> > order
>> > to ease things. Here is what I currently did:
>> >
>>
>> What tree are you building QEMU from and what's your command line
>> invocation?
>>
>> > I changed the kernel so everything is working on the real overo board.
>> > So it
>> > is definitely a qemu problem.
>> > I put logging messages into the qemu code to see where I was stucked at:
>> > it
>> > is transmitting the spi messages but it gets stuck in the spi.c at the
>> > line
>> > if ((dev = bus->device[channel])).
>> >
>> > From that I think the bit I'm missing is the initialisation of the
>> > spidev
>> > device on the qemu side. I don't know if that has to be defined when
>> > launching qemu or if that has to be created in qemu source code (then
>> > where
>> > and how?).
>>
>> I know there is some OMAP SPI stuff in qemu but its not QOMified (the
>> frawework that lets you command line create devices) so you will have
>> to change source code if this is the case (assuming it is a device
>> creation problem). I recently did some work apadting hw/ssi.c for spi
>> and that is QOMified so may be worthwhile bringing you SPI devices
>> into that framework so you can command line create attached SPI
>> devices. If you can point me at a tree and the device models that are
>> your spi controller and devices (im guessing hw/omap_spi,c), then Ill
>> be able to give an idea of the effort involved.
>>
>> I may be able to help you contribute here, the biggest obstacle for me
>> however is testing. If you can provide tests that exercise the omap
>> SPI then I may be able to help with a OMAP SPI QOMification effort
>> (and you bug will hopefully come out in the wash).
>>
>> Regards,
>> Peter
>>
>> I haven't been able to find anything on that subject so I hope
>> > someone here can give me a hint.
>> >
>> > Thank you for your help,
>> > Johan