[RFC] OpenFirmware bindings for the MMC-over-SPI driver

Grant Likely grant.likely at secretlab.ca
Sun May 25 14:47:08 EST 2008

On Sat, May 24, 2008 at 1:56 PM, David Brownell <david-b at pacbell.net> wrote:
> On Friday 23 May 2008, Anton Vorontsov wrote:
>> This is second attempt to write the OpenFirmware bindings for the
>> MMC-over-SPI (and SPI bindings in general).
> Summary:  an OF-specific wrapper around the mmc_spi platform code.
> I think a wrapper to encapsulate all the OF-specific knowledge makes
> much sense here.
> The only thing that looks odd to me about this is that the wrapper
> is a spi_device rather than an of_device.  To me it makes more sense
> to just have an of_device setting up the right spi_device.  (Though
> maybe I missed some discussion about why that can't work.)

It's not so much that I can't work; more like it's not necessary.
of_platform bus is by no means the prescribed way to work with the
device tree.  In fact, there is talk about moving away from
of_platform bus entirely and using
platform_device/spi_device/i2c_device/etc directly instead since the
of_platform bus is mostly a clone of the platform bus with different
device binding semantics.

As Anton's patch shows, it is straight forward to add a binding that
can extract the platform data out of the device tree without the
overhead of adding an additional of_platform bus device & driver pair.


Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

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