[U-Boot] [PATCH] spi/cadence: Adding Cadence SPI driver support for SOCFPGA

[Gerhard Sittig]

On Thu, Dec 19, 2013 at 08:46 -0600, Chin Liang See wrote:
> 
> Hi Gerhard,
> 
> On Thu, 2013-12-19 at 14:50 +0100, Gerhard Sittig wrote:
> > On Wed, Dec 18, 2013 at 14:05 -0600, Chin Liang See wrote:
> > > 
> > > To add the Cadence SPI driver support for Altera SOCFPGA. It
> > > required information such as clocks and timing from platform's
> > > configuration header file within include/configs folder
> > > 
> > > [ ... ]
> > 
> > Can you please add the information which header file is required?
> > And do I get it right that this header file does not come with
> > the source but is provided "externally" to the U-Boot project?
> > 
> 
> Oh actually its part of the header file within include/configs. For our
> case, it would be include/configs/socfpga_cyclone5.h. Its not external
> or generated file.

Ah, thank you for the explanation.  So the board's configuration
file is referenced as usual.  That's OK.

> But it would need macro in order to get some customization to the
> driver. Wonder would it be good we need to document the required macros?
> Or just the standard way where people normally just grep macro used in
> others platform header file (which I normally did).

Well, grepping sources may not always be as obvious as code
authors may think. :)  Some textual description with the complete
set of possible options, their type and units would be nice.
It's hard to guess for e.g. clocks whether a number is cycles or
nanoseconds or a frequency or bit times or any other arbitrary
thing that may need to get written to hardware with or without
any further conversion.

In current master's socfpga_cyclone5.h I can't see any SPI
related defines, and your patch set does not update this file.
So I'm still afraid that simply enabling the controller in the
config won't result in successful build output.  And waiting for
compile errors is the only way to learn when settings are
missing.  And still you won't notice when settings are wrong
(like booleans).  This would be unsatisfying an experience.
Users should not have to read and reverse engineer code just to
find out how to enable and use it.

To cut it short, please provide example entries in the cyclone5
board configuration, and a either a text document or a comment in
the driver source listing all options and their meaning.


virtually yours
Gerhard Sittig
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