Re: GPMC in device tree

On Wed, 2015-08-05 at 00:22 +0300, Ran Shalit wrote:

On Tue, Aug 4, 2015 at 11:31 PM, Scott Wood [off-list ref] wrote:

quoted

On Tue, 2015-08-04 at 23:26 +0300, Ran Shalit wrote:

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On Tue, Aug 4, 2015 at 9:54 PM, Scott Wood [off-list ref] 
wrote:

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On Tue, 2015-08-04 at 18:29 +0300, Ran Shalit wrote:

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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

On more thing, if I may.
The localbus is also connected to nvram & cpld.
I've noticed that read/write works well, even though I didn't define
anything in device tree.
Is there any reasom to add these devices into device tree, or can we
use the cpld and nvram without the definition in device tree ?

I don't know what you're doing in your kernel to access devices that aren't 
in the device tree.  You should add the devices to the device tree, and have 
the kernel use it rather than hardcoded info.

-Scott