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Date: Mon, 26 Apr 2010 12:05:56 +0100
Subject: Obtaining start/end address of an MTD partition
From: "Matthew Lear" <matt@bubblegen.co.uk>
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Hello all,

Is it possible to obtain an MTD partition's starting address through usage
of the MTD ioctls? I've had a very quick look and from what I can tell,
this doesn't seem to be possible.

To be clear, I'd like to obtain the addresses below (displayed by Linux
when it detects the MTD partitions on boot).

Creating 6 MTD partitions on "physmap-flash.0":
0x00000000-0x00120000 : "RedBoot"
0x00120000-0x01000000 : "foo"
0x01000000-0x01400000 : "bar"

I can obviously use the MEMGETINFO ioctl on a particular MTD device to
return info in struct mtd_info_user, but this doesn't give me all the
information I need for that particular partition (ie start and end offsets
in terms of 'physical' addresses).

Basically, I'm trying to cater for using another flash driver instead of 
the MTD sub-system on some custom hw in order to access the flash device.
I'd like to be able to get the MTD partition start and end addresses so I
know where to operate on this other device. A bit clunky, I know (if it
were my decision MTD would be used).

RedBoot creates the FIS entries above and Linux parses this just fine at
boot. If I were using MTD to access the flash device I could open
/dev/mtd<x> or /dev/mtdblock<x> accordingly. However, there is a
requirement to access the flash through another device (/dev/flash). For
example, if I wanted to write to the area covered by /dev/mtd1, I need to
be able to:

i)  get the start address of /dev/mtd1
ii) open /dev/flash and seek to the offset provided by (i) above.
iii) perform the operation(s).

...so I need the partition start addresses (and end too if possible). Can
these offsets be obtained through the MTD user space ioctls?

Many thanks,
--  Matt