[Bug 1000819] Add support for Atmel AT91SAM9263

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--- Comment #29 from Mark Mumford <markthetyke@4dv.net> 2011-05-18 22:15:19 BST ---
Hi,

I'm new here but I'm not averse to expressing my opinion and nobody else has
weighed in yet, I have also done a couple of ports to an ARM7 and an ARM9
platform so I have spent time exploring the directory structure. In my opinion
I would forget the tag AT91 this doesn't represent a variant in the ECOS sense
as it includes 3 different processor architectures the ARM7, ARM9 and ARM
Cortex-M. These are different architectures because first they have different
instruction sets, second they have different pipeline, cache and bus configs.
So the AT91SAM9 series use the variant ARM922EJ-S cpu. There are already a
number of platforms under the hal/arm/arm9 directory. As such the AT91SAM9
series should be implemented as 4 separate platforms under this structure,
although they probably be using common peripheral devices which may also be
shared with the rest of the AT91 family. The AT91SAM7 series should be
implemented under the hal/arm structure and the AT91SAM3 series under the
hal/cortexm structure. Should the arm9 have been a separate architecture
instead of a sub-architecture, who cares it's too late to change it now. The
question I see is do we need to introduce a new set of devices for the AT91SAM9
series, only if there are significant enhancements or interoperability issues
would be my humble opinion. The problem I see with supporting the SAM3 from the
same IO package is that the peripheral bus structure usually implemented on
cortex devices is not the same as the earlier models. Perhaps the IO package
should be divided by peripheral bus structure AHB,AMBA etc. Okay that's enough
from me.

Mark M

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