[coreboot] [RFC] flashrom: sector-based flashing

[ron minnich]

On Fri, Oct 10, 2008 at 8:38 PM, Carl-Daniel Hailfinger
<c-d.hailfinger.devel.2006 at gmx.net> wrote:
> Hi,
>
> flashrom hasn't seen any major design changes in the last few months and
> most chips still perform whole-chip erase instead of sector-based erase.
>
> I'd like to introduce a function which takes a range and rounds the
> start and the end of the range to the nearest block boundary.
> void roundup(struct flashchip *flash, int *startpos, int *endpos);
>
> Take an example 256 kByte flash chip with the following sector layout:
> 0x00000-0x0ffff 64kB block
> 0x10000-0x1ffff 64kB block
> 0x20000-0x2ffff 64kB block
> 0x30000-0x37fff 32kB block
> 0x38000-0x3bfff 16kB block
> 0x3c000-0x3dfff 8kB block
> 0x3e000-0x3efff 4kB block
> 0x3f000-0x3ffff 4kB block
>
> startpos=0x38123;
> endpos=0x3e005;
> roundup(flash, &startpos, &endpos);
> //results follow:
> //startpos=0x38000;
> //endpos=0x3efff;
>
> That way, it is easily possible to check whether a given range can be
> handled by sector-based erase and write.
> You can use that result to tell the user that a range outside the
> intended range will get flashed. It is also possible to refuse flashing
> in that case.
>
> Since the function will be generic and take a struct flashchip, there's
> no need to store a pointer to it with each chip and you can call the
> generic one from anywhere.
>
> What do you think?
>

This is a good idea. Once cheap trick we could also do (or do we?):
before sector erase, see if the sector is already erased, and skip
that one.

ron