[PATCH] [RFC] arm: add documentation describing Marvell families of SoC

[arnd@arndb.de (Arnd Bergmann)]

On Tuesday 17 July 2012, Thomas Petazzoni wrote:
> As stated in the introduction of the document, the families of ARM
> SoCs at Marvell are very complicated, and it is difficult for
> newcomers to understand the organization of this SoC family and how it
> relates to the Linux kernel support for those hardware platforms.
> 
> This document is only at RFC stage for now, it requires reviews and
> comments from the Marvell maintainers, the PXA maintainers and the MMP
> maintainers. For correctness of course, but also to add any other
> information that would be useful. For example, one of the thing that
> wasn't clear how to detail in the documentation is how the SoCs relate
> to each other in terms of hardware IP blocks. For example, most of the
> Kirkwood/Dove/Armada 370-XP/etc. hardware IPs (I2C, SPI, USB, SATA,
> etc.) are identical, while the PXA and MMP families are completely
> separate.

This is wonderful! Even if there are some pieces missing or incorrect,
it looks extremely valuable. I remember countless times of browsing
through the marvell web site and the source code trying to make sense
of how things fit together.

Thanks a lot for compiling the list!

> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Cc: Andrew Lunn <andrew@lunn.ch>
> Cc: Jason Cooper <jason@lakedaemon.net>
> Cc: Gregory Clement <gregory.clement@free-electrons.com>
> Cc: Eric Miao <eric.y.miao@gmail.com>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
> Cc: Nicolas Pitre <nico@fluxnic.net>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Olof Johansson <olof@lixom.net>

Acked-by: Arnd Bergmann <arnd@arndb.de>


> +Orion family
> +------------
> +
> +  Flavors:
> +        88F5082
> +        88F5181
> +        88F5181L
> +        88F5182
> +        88F5281
> +        88F6183
> +  Core: ARMv5 compatible
> +  Linux kernel directory: arch/arm/mach-orion5x
> +  No public datasheets available.

I would also mention that the core in this is "Feroceon", not just that it's ARMv5.
Same for mv78xx0 and kirkwood.

> +        PXA930, PXA935, PXA955
> +             Core: ARMv5 compatible Sheeva core

This looks wrong. According to the Kconfig file, PXA93x actually uses the
same core as PXA3xx, while PXA955 uses an ARMv7 PJ4 core.

> +MMP/MMP2 family (communication processor)
> +-----------------------------------------
> +             Core: ARMv5 compatible Marvell PJ1 (Mohawk)
> +        MMP2, a.k.a Armada 610
> +             Product Brief        : http://www.marvell.com/application-processors/armada-600/assets/armada610_pb.pdf
> +             Core: ARMv7 compatible Sheeva PJ4 core
> +   Linux kernel directory: arch/arm/mach-mmp

I'd also like to bring up the question of merging the pxa and mmp
directories again. It would simplify the task of building a multiplatform
kernel significantly as they have shared device drivers with some duplicate
header files (e.g. dma, gpio, ...).

	Arnd