mmap support for m25p80 device

[Simon Falsig]

Hi,

I'm currently working on a new custom board (with a TI AM3356 ARM-Cortex
A8
CPU), with a 32 kB Everspin MR25H256 MRAM chip, attached over SPI. It
works
fine using the m25p80 driver, but I was wondering how complex it would be
to
add the possibility of memory-mapping the device in userspace? - mainly to
make the interface consistent with the board that it is replacing, which
uses
a different, mmap-able, RAM chip.

I'm not very experienced in the deeper aspects of the kernel, but I've
been
poking around a bit in the mtd subsystem, and it seems as if the main
thing
that is missing, is a valid get_unmapped_area() function for the m25p80
driver, and then to change the mtdchar_mmap() function (in mtdchar.c) to
actually allow mmap'ing on MMU systems.

But - does it even make sense to create such a function for m25p80? - and
how would I start?

Any pointers and/or comments are appreciated!
Thanks and best regards,
Simon Falsig
simon at newtec.dk