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Subject: Re: GPMC in device tree
From: Scott Wood <scottwood@freescale.com>
To: Ran Shalit <ranshalit@gmail.com>
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Date: Tue, 4 Aug 2015 15:31:08 -0500
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On Tue, 2015-08-04 at 23:26 +0300, Ran Shalit wrote:
> On Tue, Aug 4, 2015 at 9:54 PM, Scott Wood <scottwood@freescale.com> wrote:
> > On Tue, 2015-08-04 at 18:29 +0300, Ran Shalit wrote:
> > > Hello,
> > > 
> > > I would please like to ask if describing flash nor used with GPMC,
> > > whould be done as described in:
> > > https://www.kernel.org/doc/Documentation/devicetree/bindings/mtd/gpmc-nor.txt
> > > It is described in the above link as "TI's GPMC", so I'm not sure if
> > > it is relevent for powerpc too.
> > 
> > That binding is for TI GPMC.
> > 
> > Are you saying you have some PPC chip that has a flash controller called 
> > GPMC?
> > 
> > -Scott
> > 
> 
> Hi Scott,
> 
> Thanks, I've worked with TI's chips, so I now understand that I made
> here some confusion...
> It is GPCM , not GPMC, my mistake.
> We already configured it in u-boot, but on doing read/write from
> kernel it doesn not work.
> It seems that for the linux to use the correct driver, we need to
> define the nor in the device tree.
> Is there any example how to define nor GPCM in device tree ? Is it
> possible not to override the existing GPCM configuration ?

Pretty much all of the mpc8xxx/qoriq device trees have GPCM NOR defined.  See 
Documentation/devicetree/bindings/powerpc/fsl/lbc.txt and examples such as 
arch/powerpc/boot/dts/p4080ds.dts (part of the lbc node is in 
arch/powerpc/boot/dts/fsl/p4080si-post.dtsi).

Linux will not change the GPCM configuration.

-Scott