Re: Support for ARM940T core Samsung S3C2510A MCU under Linux

[Madhavi Manchala <madhavi.linux@gmail.com>]

Hi Greg,

Thank you very much for your valuable information and suggestions.

On Mon, Mar 21, 2011 at 4:57 PM, Greg Ungerer <gerg@snapgear.com> wrote:
>
> Hi Madhavi,
>
> On 19/03/11 01:54, Madhavi Manchala wrote:
>>
>> I have one basic question about the architecture files in Linux
>> kernels. We have a board with Samsung S3C2510A MCU (ARM940T core)
>> which is a no-mmu based CPU. I heard that "there was not a lot of ARM
>> no-mmu support at the moment" from Ben Dooks.
>
> The core is there, but there is very little specific machine support.
> The one I use for testing is non-MMU ARM is the Atmel/AT91X40 (that is
> CONFIG_ARCH_AT91X40). I don't run it on real hardware, but on the
> SkyEye emulator.

I saw the mach-at91/at91x40.c and mach-at91/at91x40_time.c file
sources. There is a few lines of code is available in these two files.
I guess, some of the common files are there for all Atmel boards and
that is also included as a part of at91x40 board. Am I correct?

I found only at91_aic_init() function only called from at91x40.c file.
What about other initialization like serial etc.?  Is this included
from common files for Atmel boards?

>
>> So, I started developing the architecture files for my Samsung
>> S3C2510A MCU (ARM940T core) by looking at the existing S3C2410A
>> (ARM920 core) architecture files. Is this my porting (developing the
>> architecture files) correct?
>
> Would make sense to start on something similar, yes.

I downloaded the latest uClinux sources from
http://sourceforge.net/projects/uclinux/files/uClinux%20Stable/ and
the name of the file is uClinux-dist-20101026.tar.bz2. In this
distribution, I found mach-s3c24a0, mach-s3c3410, s3c44b0x and
mach-s5c7375 sources in linux-2.6.x/arch/arm/ directory. (Arnd asked
me to see these sources as a reference, only). So, I am looking at
these sources and especially s3c3410 sources as remaining are
different like s3c24a0 is a MMU based etc.

>
>> How can I port the Linux on to my board which has a Samsung S3C2510A
>> MCU (ARM940T core) which is a NO-MMU based CPU?
>>
>> Thanks for your suggestions / hints / comments.
>
> You can look at what I did with the AT91X40 for an example.
> Or look at the patches that Ithamar Adema sent to the ARM linux
> mailing list in the last few days for supporting the NXP LPC2K
> family as another example (they are also non-MMU parts).

As I said above, there are only two files which are related to at91x40
board. However, I found some sources for the Ithamar Adema patches at
the following link.
http://www.spinics.net/lists/arm-kernel/msg118932.html

These sources (patches) are similar to samsung sources which are
available in uClinux-dist. So, I will look into the Ithamar Adema
patches and uClinux-dist samsung machine directory sources. Please
suggest me.

My final question, All these samsung machines (s3c24a0, s3c3410,
s3c44b0x and s5c7375) are ARM7TDMI core based MCUs. My MCU (Samsung
s3c2510A) is a ARM9TDMI core based. So, is this porting will help?

I am extreamly sorry, If I asked silly questions here.

Once again, thanks for your suggestions and valuable inforamtion.

Thanks and Regards,
Madhavi. M

> Regards
> Greg
>
>
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