Re: Linux SPI slave support

[Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>]

Dear Shubhrajyoti Datta,

> On Mon, Jul 16, 2012 at 5:56 AM, Marek Vasut <marex-ynQEQJNshbs@public.gmane.org> wrote:
> > Dear Shubhrajyoti Datta,
> > 
> >> Hello,
> >> 
> >> On Sat, Jun 30, 2012 at 8:45 AM, Marek Vasut <marex-ynQEQJNshbs@public.gmane.org> wrote:
> >> > Hello,
> >> > 
> >> > is there currently any ongoing effort to support SPI slave mode in
> >> > Linux?
> >> > 
> >> > If there is none, could you please share any hints that might help me
> >> > better choose and go in the direction of implementing the SPI slave
> >> > support?
> >> 
> >> May be you may want to check the archives.
> >> You may want to see below before designing.
> >> 
> >> http://permalink.gmane.org/gmane.linux.kernel.spi.devel/7495
> > 
> > [...]
> > 
> > So, idea V2:
> > 
> > 1) Separate out common parts from struct spi_master
> > 2) Create struct spi_slave
> > 2a) Implement spi_slave_send_message for spi_slave
> > 2b) Implement <?> netlink interface to push and pull messages to/from
> > userland ?
> > 
> > The protocol won't be done in kernel, but completely in userland.
> > 
> > Is this good approach to take? Or maybe 2b can be replaced by blocking
> > read on character device? I think netlink interface might actually be
> > suited quite well for this task.
> 
> The other option is to have something like a gpio  for synchronization.

Synchronisation of what exactly? With my hardware (that doesn't exist yet I 
guess), the idea is to simply cross-connect the MISO/MOSI pins and connect the 
CLK signal. Is that possible btw?

Thanks!

> > Best regards,
> > Marek Vasut

Best regards,
Marek Vasut

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