[RFC/PATCH 1/3] powerpc: add ioremap_bat() function for setting up BAT translated IO regions.

[Kumar Gala]

On Aug 7, 2008, at 11:45 AM, Scott Wood wrote:

> On Wed, Aug 06, 2008 at 05:11:08PM -0600, Grant Likely wrote:
>> I do this particular test to make absolute sure that the caller
>> absolutely understands the limitations of the block mapping.  If they
>> call this with something that isn't 128k aligned, then I make it fail
>> immediately so the coder is forced to go and understand what they are
>> allowed to do.  Basically, I'm reinforcing the fact that this is not
>> the same as ioremap().
>>
>> I haven't decided yet if I should test size in the same way.   
>> Thoughts?
>
> I'd prefer it round up the size as needed to cover the requested  
> mapping
> and needed alignment.
>
> The minimum size is going to be different on Book E, for example,  
> and I
> can think of at least one user that will be shared between Book E and
> classic (CPM2 early console).

Which is how ioremap works today.  We ask for a size of 3 bytes and it  
rounds up to a 4k page.  The same should be true of the new interface  
(and round up to whatever the smallest size the HW we are using can  
handle).

- k