Dear Richard Retanubun,
In message 4D515D06.7020209@RuggedCom.com you wrote:
If by "how NOR flash in handled" you mean cmd_flash.c::flash_sect_roundb() then yes, I do want to do this but I need to know what number to round it to, no?
The code needs to know that, you don't ;-)
In the context of cmd_flash, it has access to flash_info_t which contains the sector_size information. Also cfi_flash.c also provides a function called flash_sector_size() that is called by other components that needs to know. If I have misunderstood what you mean, sorry, please clarify.
You are right.
To have SPI flash do this, for example; stmicro.c::stmicro_erase() function will auto round up to the nearest sector_size. Which is indeed the simpler way. Right now, most drivers/mtd/spi/*.c just does this check:
<quoted_code> sector_size = stm->params->page_size * stm->params->pages_per_sector;
if (offset % sector_size || len % sector_size) { debug("SF: Erase offset/length not multiple of sector size\n"); return -1; }
</quoted_code>
This is ok if an explicit size is given - you will se ethe same behaviour on NOR flash when trying something like
erase 40000000 40002345
I am worried about unintentionally erasing more than what the caller requested. Would it be better to round up manually and then calls the erase?
No. If the caller uses the "+<size>" notation he explictly requests to round up. He is supposed to know what he is doing.
Being able to use "+${filesize}" allows for many powerful solutions to standard tasks that without this would result in cumbersome manipulation of the size - which would then probably break if you issue a new revision of your hardware with different flash chips fit.
Best regards,
Wolfgang Denk