Re: [PATCH] mcspi: Add support for GPIO chip select lines

[Ben Gamari <bgamari.foss@gmail.com>]

On Thu, 23 Dec 2010 14:38:57 -0700, Grant Likely <grant.likely@secretlab.ca> wrote:
> On Tue, Dec 21, 2010 at 10:56 AM, Ben Gamari <bgamari.foss@gmail.com> wrote:
> > This mechanism is in large part stolen from the s3c64xx-spi module. To
> > use this functionality, one simply must define a set_level function to
> > set the CS state and a omap2_mcspi_csinfo struct for each chip select in
> > the board file.
> >
> > Each spi_board_info.controller_data should then be set
> > to point to the appropriate csinfo struct. This will cause the driver to
> > call the csinfo->set_level function instead of toggling the McSPI chip
> > select lines.
> >
> > Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>
> 
> I'd rather see the spi driver modified to use the gpio api directly.
> The drivers are already tending in that direction and it doesn't
> require machine specific set_level functions to be defined.
> 
The reason I left this up to the board is it's easy to foresee cases
where you want a non-trivial mapping between logical CS numbers and CS
pin states. In my case, I using a 2-to-4 multiplexer as the source of
chip select.

- Ben