Q: MTD RAM in OF Device Tree

Q: MTD RAM in OF Device Tree

[Albrecht Dreß]

Hi all,

is there a standard way to define a ram chip (in my case a battery-buffered=
 nv ram, attached to the 5200's Local Bus) in the OF tree, and are there an=
y drivers (on 2.6.29.1) which pick up the chip/partition specification for =
mtd?  Does such a driver exist, or do I have to write one (probably based o=
n plat-ram.c?)?  I think of something like

localbus {
=09[...]
=09ranges =3D < 0 0 0xfe000000 0x02000000
=09=09   1 0 0xfc000000 0x00080000>;

        flash@0,0 {
=09=09[flash definition & partitions]
=09};

=09nvram@1,0 {
=09=09compatible =3D "mtd-ram";
=09=09reg =3D <1 0x0 0x00080000>;
=09=09bank-width =3D <2>;
=09=09device-width =3D <2>;
=09=09#size-cells =3D <1>;
=09=09#address-cells =3D <1>;
=09=09part@0 {
=09=09=09label =3D "pdata";
=09=09=09reg =3D <0x00000000 0x00080000>;
=09=09};
=09};
};

Thanks,
Albrecht.

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Re: Q: MTD RAM in OF Device Tree

[Wolfram Sang]

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Hello Albrecht,

(adding linux-mtd)

On Tue, May 19, 2009 at 01:59:00PM +0200, Albrecht Dreß wrote:
> 
> is there a standard way to define a ram chip (in my case a battery-buffered
> nv ram, attached to the 5200's Local Bus) in the OF tree, and are there any
> drivers (on 2.6.29.1) which pick up the chip/partition specification for mtd?
> Does such a driver exist, or do I have to write one (probably based on
> plat-ram.c?)?  I think of something like

I wrote such a driver (yet without partitioning support) and I am trying to get
it mainline, just didn't get any comments so far:

http://patchwork.ozlabs.org/patch/23557/
http://patchwork.ozlabs.org/patch/23556/

I'd be happy if you could give it a try and donate some
{Acked|Tested|Reviewed}-by tags. Maybe this will help for my next try to get
it mainline.

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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Re: Q: MTD RAM in OF Device Tree

[Grant Likely]

On Tue, May 19, 2009 at 6:27 AM, Wolfram Sang <w.sang@pengutronix.de> wrote=
:
> Hello Albrecht,
>
> (adding linux-mtd)
>
> On Tue, May 19, 2009 at 01:59:00PM +0200, Albrecht Dre=DF wrote:
>>
>> is there a standard way to define a ram chip (in my case a battery-buffe=
red
>> nv ram, attached to the 5200's Local Bus) in the OF tree, and are there =
any
>> drivers (on 2.6.29.1) which pick up the chip/partition specification for=
 mtd?
>> Does such a driver exist, or do I have to write one (probably based on
>> plat-ram.c?)? =A0I think of something like
>
> I wrote such a driver (yet without partitioning support) and I am trying =
to get
> it mainline, just didn't get any comments so far:
>
> http://patchwork.ozlabs.org/patch/23557/
> http://patchwork.ozlabs.org/patch/23556/
>
> I'd be happy if you could give it a try and donate some
> {Acked|Tested|Reviewed}-by tags. Maybe this will help for my next try to =
get
> it mainline.

I missed them when you posted them.  I'll go look now.
--=20
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

Re: Q: MTD RAM in OF Device Tree

[Albrecht Dreß]

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Hi Wolfram!

Am 19.05.09 14:27 schrieb(en) Wolfram Sang:
> I wrote such a driver (yet without partitioning support) and I am  
> trying to get it mainline, just didn't get any comments so far:
> 
> http://patchwork.ozlabs.org/patch/23557/
> http://patchwork.ozlabs.org/patch/23556/

Thanks a lot, this is *exactly* what I was looking for!  Actually,  
partition support is not important as I want to use the whole chip -  
512k isn't *that* much...

> I'd be happy if you could give it a try and donate some  
> {Acked|Tested|Reviewed}-by tags. Maybe this will help for my next try  
> to get it mainline.

Will do that once I get it running completely.  The first test  
triggered some strange problems when I wrote to /dev/mtdn and read back  
the data (which is supposed to give "raw" direct access, right?) - the  
last dword in each 512 byte block is partly broken.  Probably something  
in the localbus layout or timing...

Thanks again,
Albrecht.

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