Re: [PATCH 0/3] spi: SPI bus multiplexer

[Mark Brown]

On Fri, Apr 12, 2019 at 05:02:10PM +1200, Chris Packham wrote:

> Unfortunately recent changes have stopped my hacks from working. I've
> tried adapting cs-gpios to work with my particular hardware but I came
> to the realisation that the current cs-gpios support assumes a 1:1
> mapping of gpio to SPI device whereas my hardware used the state of the
> gpio selecting the device i.e. a 1:2 mapping.

> This is my attempt to implement a driver to deal with this. One nice
> property is that it is pretty much self contained. The only change to
> the core SPI infrastructure is exposing a function I needed to lookup
> the spi_controller instance.

Why not implement the device that demuxes the GPIOs you're using for
chip select as a GPIO controller?  Presumably it might get used for
things other than chip selects.

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