[U-Boot] [PATCH 05/14] spi: add common fdt SPI driver interface

[Stephen Warren <swarren@wwwdotorg.org>]

On 02/14/2013 01:07 PM, Allen Martin wrote:
> On Wed, Feb 13, 2013 at 02:40:29PM -0800, Stephen Warren wrote:
>> On 02/12/2013 08:23 PM, Allen Martin wrote:
>>> Add a common interface to fdt based SPI drivers.  Each driver is
>>> represented by a table entry in fdt_spi_drivers[].  If there are
>>> multiple SPI drivers in the table, the first driver to return success
>>> from spi_init() will be registered as the SPI driver.
>>
>> I don't think there should be a global concept of "the" SPI driver;
>> instances of both SPI blocks exist on Tegra20, so they should be able to
>> co-exist, using the SFLASH driver for 1 SPI port, and the SLINK driver
>> for the other 4 ports.
> 
> I agree, but that's probably beyond the scope of this series, as
> that's a more global problem.  Other drivers call directly into the
> SPI driver by use of well known function names, so that would need to
> be abstracted to fix.

It should be simple to fix; you already have a table of all known
(DT-based) SPI drivers; simply iterate over all entries in the table
always, rather than stopping when you hit the first one. Also, don't
store /a/ pointer to the driver, but store a pointer per instance. I
think the modifications to your patch series to solve this shouldn't be
large at all.

>> How does this patch interact with any SPI-related device manager work?
> 
> I'm not sure what device manager is in the context of u-boot.  Is that
> the same as the unified driver model that's being documented in
> doc/driver-model?

Yes.

> If so I think this fits in really well with that.
> The "struct ops" described there is almost identical to the callbacks
> I added in "struct fdt_spi_driver" 

The code certainly looks like a move in the right direction. I was
thinking more along the lines of: Is anyone actively working on this
right now, so your patches will conflict.