On Fri, Dec 12, 2008 at 09:22:02AM -0500, Steven A. Falco wrote:
> This patch adds a dummy GPIO driver, which is useful for SPI devices
> that do not have a physical chip select.
>
> Signed-off-by: Steven A. Falco <sfa...@harris.com>
> ---
> The SPI subsystem requires a chip-select for each connected slave
> device. I have a custom board with an Atmel "co-processor". This part
> is reprogrammed via SPI, so it needs a chip select to satisfy the SPI
> subsystem, but my hardware does not have a physical CS connected.
>
> I could waste a "no-connect" GPIO pin, but I'd rather not. So, I've
> written a dummy GPIO driver, which behaves exactly like a real GPIO
> device, but with no underlying hardware. This could also be useful
> as a template for real GPIO drivers.
>
> I use the following dts entry:
>
> GPIO3: du...@ef500000 {
> compatible = "linux,dummy-gpio";
> reg = <ef500000 1>;
> gpio-controller;
> #gpio-cells = <2>;
> };
This is not sane. I can see reasons it might be useful to have a
dummy gpio driver within the kernel, but since this doesn't represent
any real hardware, it should not appear in the device tree.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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