iMX31 MBX registers Porting problem

Russell King - ARM Linux linux at
Mon Jan 31 10:45:23 EST 2011

On Sun, Jan 30, 2011 at 10:08:02PM -0700, Chris wrote:
> Ok, I did that and it inserts and removes an entry I am not sure about
> what would be wrong.
> 0x7f000000-0x7f002000    8192 module_alloc_update_bounds+0x18/0x68
> pages=1 vmalloc
> ...
> 0x848a0000-0x848a5000   20480 reg_probe+0x94/0x12c [reg] ioremap
> 0x7f006000-0x7f008000    8192 module_alloc_update_bounds+0x18/0x68
> pages=1 vmalloc
> ...
> 0x848a8000-0x848ad000   20480 reg_probe+0x94/0x12c [reg] ioremap
> here are two insertions, also showing the module bounds update, not
> sure what to make of this information.

The 'module_alloc_update_bounds+0x18/0x68' entry is the space used for
your module.  As it is free'd lazily, each time you insert it you'll
get different virtual addresses.

> when I cat /proc/iomem I can see my entry:
>    c0000000-c0003fff : mx3_mbx_regs.0
> how can I know that the mapping is pointing me to my location?

ioremap() always gives you a cookie for use with readl() or NULL.
If it's successful, the mapping will have been created and pointing at
the requested bus address.

I can't see anything wrong with your code, so I suspect you're missing
something with the hardware - maybe a clock which isn't running or an
enable bit somewhere?

I've no idea how MBX works on the MX platforms, so I can't really suggest
anything further.

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