[U-Boot-Users] "stacked" memory mapped flash assisted with GPIOs

Haavard Skinnemoen
2008-01-21T22:20:44Z

On Mon, 21 Jan 2008 08:01:48 -0500 Mike Frysinger <vapier@gentoo.org> wrote:
> that would allow board porters to select an arbitrary address and say "if you
> wish to erase/write the flash in a contiguous manner, you need to use the
> base address 0x........ rather than the real base address 0x........".

Hmm...yeah. Fake physical addresses...perhaps not exactly pretty, but
it will do the trick as long as nothing is actually accessible from the
"fake" addresses.

On the other hand, the extra GPIO-controlled lines really _do_ form a
part of the physical address, at least as far as the flash is
concerned.

> however, from what i can see, this would only account for erase/writes.
> reads are done directly by u-boot using physical addresses, so those have no
> provision for catching accesses.

True. Maybe the code reading the flash really _should_ use the
map_physmem() interface, though...doing cached reads from the flash
might very well cause trouble later, when writing commands to it...

Haavard