[ECOS] Flash driver system updated

[Jonathan Larmour <jifl at eCosCentric dot com>]

As readers of ecos-patches will have noticed from earlier this week, the
eCos flash driver system has undergone a major revision in the trunk of
CVS, based on work that took place on the "flash v2" CVS branch. This work
was primarily developed by Andrew Lunn at Ascom and Bart on behalf of
eCosCentric, with further additions/fixes/improvements from Nick G and
myself also of eCosCentric, and an Atmel dataflash driver from Savin Zlobec
of Elatec.

As well as copious cleanup, the main focus of this work was to allow
multiple flash drivers and chips simultaneously. The changes to do this
have been extensive, and we very much would like people to test and report
back in advance of eCos 3.0. Of course since this affects flash drivers,
some caution is advised to be sure you don't brick your hardware!

The flash driver API has been updated, both for users of the flash API, and
for the interface between the generic flash layer and underlying drivers.
Existing flash drivers (informally "flash v1" drivers) are still supported
in a legacy mode. While they will continue to be supported in the upcoming
eCos 3.0 release, the intention is naturally to transfer as many ports as
possible to use flash v2 drivers.

As well as updating this initial work with many fixes, especially to
RedBoot, eCosCentric has added an improved Intel Strataflash flash driver
supporting the updated flash interface. And just like the AMD AM29xxxxx
driver previously contributed by eCoscentric, it supports CFI to ease flash
configuration.

Andrew and Bart have also provided an updated synthetic target flash
driver, and SST 39VFxxx driver; as well as there being Savin's
aforementioned Atmel dataflash driver.

For those wishing to update their targets, there is plenty of documentation
in the generic package, and also within the AM29xxxxx and Strataflash
driver packages if using those parts. You will also find concrete usage
examples around the place for each driver. e.g. For AM29xxxxx there is the
PPC Adder HAL and for Strataflash, the IXDP425 HAL. If you want to update
your favourite targets before the eCos 3.0 release, I recommend looking at
that immediately (especially if an FSF copyright assignment is likely to be
required).

There may still be further changes prior to eCos 3.0, but I think the only
thing that is likely to happen may be a minor change to cyg_flash_init().

Jifl
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