[ECOS] Non linearly-mapped flash devices

[Ian Campbell <icampbell at arcom dot co dot uk>]

Hello,

I am trying to get eCOs to support the flash parts on a board which only
supports flash access via a paged window in memory. 

It seems from looking at the (current CVS) code that only linearly
mapped flash devices are supported, for example there is no 'flash_read'
function/define but rather RedBoot seems to use memcpy to read flash
(from my reading of redboot's flash.c at least).

Now, at first I thought it would simply be a matter of replacing those
memcpy's with a #define which degenerated to a memcpy in the linear case
or to a function which handles paging etc to do the copy. However, upon
closer investigation it seems as if the whole flash interface
(ecos/packages/io/flash/current/include/flash.h) uses the linear address
in memory inorder to refer to parts of flash, rather than an offset into
the flash itself, this is problematic in the paged case since a linear
address isn't a very useful concept. Obviously re-vamping the flash
interface is a lot of work...

So, what I was wondering was if there is any support for paged flash in
the pipeline, for example as a part of the upcoming jffs2 support in
eCos 2.0 (I don't think this is the case though), or if anyone has any
ideas how to easily implement this.

What I am trying to achieve is to have RedBoot as a boot monitor
(booting linux) on our board and be able to use RedBoot to update the
kernel/filesystem images in flash.

Cheers, 
Ian.

-- 
Ian Campbell
Design Engineer

Arcom Control Systems Ltd,
Clifton Road,
Cambridge CB1 7EA
United Kingdom

Tel: +44 (0)1223 403465
E-Mail: icampbell@arcom.co.uk
Web: http://www.arcomcontrols.com


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