spi-omap2: AM335x SPI interface 3WIRE mode

spi-omap2: AM335x SPI interface 3WIRE mode

[Daniele Nicolodi]

Hello,

I would like to interface a SoC system based on an AM335x processor (in
the specific a BeagleBone Black) to some peripherals speaking SPI in
3-wire mode.

Looking at the spi-omap2 driver code (kernel version 3.11.4), the 3WIRE
mode is not supported, but a comment in the code suggests that this may
be supported by the hardware. The TRM indeed reports that the the McSPI
in the AM335x processors supports 3-wire SPI.

Does anyone have the code to add 3-wire SPI mode support to the driver?

No?! I guess that would have been too much luck.  In that case, can
someone point me to what needs to be done to add this support to the
driver?  I may figure it out by myself, but a little guidance would
probably help to make it happen before I loose interest :-)

Thank you!  Best,
Daniele
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Re: spi-omap2: AM335x SPI interface 3WIRE mode

[Daniele Nicolodi]

On 6/7/17 5:01 PM, Daniele Nicolodi wrote:
> Hello,
> 
> I would like to interface a SoC system based on an AM335x processor (in
> the specific a BeagleBone Black) to some peripherals speaking SPI in
> 3-wire mode.
> 
> Looking at the spi-omap2 driver code (kernel version 3.11.4), the 3WIRE
> mode is not supported, but a comment in the code suggests that this may
> be supported by the hardware. The TRM indeed reports that the the McSPI
> in the AM335x processors supports 3-wire SPI.
> 
> Does anyone have the code to add 3-wire SPI mode support to the driver?
> 
> No?! I guess that would have been too much luck.  In that case, can
> someone point me to what needs to be done to add this support to the
> driver?  I may figure it out by myself, but a little guidance would
> probably help to make it happen before I loose interest :-)
> 
> Thank you!  Best,
> Daniele
> 

PS: The emails to the authors of the spi-omap2 driver have bounced. This
is not too surprisingly given the domain is nokia.com.

I'm adding Mark to the recipients of this email as suggested by
get_maintainers.pl.  Who else may be interested on this driver or be
able to comment on my issue?

Thanks! Cheers,
Daniele

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Re: spi-omap2: AM335x SPI interface 3WIRE mode

[Mark Brown]

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On Wed, Jun 07, 2017 at 05:14:22PM -0600, Daniele Nicolodi wrote:

> PS: The emails to the authors of the spi-omap2 driver have bounced. This
> is not too surprisingly given the domain is nokia.com.

> I'm adding Mark to the recipients of this email as suggested by
> get_maintainers.pl.  Who else may be interested on this driver or be
> able to comment on my issue?

I don't know that anyone is particularly interested in the driver,
there's a couple of people from TI (Franklin and Peter) who I've added
to the CCs who sent patches relatively recently but I'm not sure they're
doing more than fixing up systems they're working on.

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