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

[Allen Martin <amartin@nvidia.com>]

On Thu, Feb 14, 2013 at 12:21:34PM -0800, Stephen Warren wrote:
> 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.
> 

I don't think it will be that easy.  The different drivers would have
to coordinate on bus numbering, or there would have to be a new
"adapter number" addressing to differentiate the drivers, which would
be hard to do without impacting all the other non-fdt drivers as well.


> >> 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.

I haven't seen any, but I haven't been looking out for those patches
either, I'll look through the list archives and see if anyting turns
up. 

-Allen
-- 
nvpublic