Reorg of 32-bit dma code

[Kumar Gala]

On Feb 6, 2008, at 7:26 PM, Benjamin Herrenschmidt wrote:

>
> On Wed, 2008-02-06 at 18:32 -0600, Becky Bruce wrote:
>>
>> I've been looking at converting 32-bit powerpc's DMA code over to the
>> 64-bit method, where there is a dma_ops structure inside archdata
>> that tells us which operations a device should use for DMA.  I'll be
>> needing this shortly because I need to implement swiotlb to deal with
>> PCI and large amounts of RAM on 32-bit systems that support 36-bit
>> physical addressing. (Yes, I know.  Fun for me.  Woohoo.)
>>
>> Anyway, I have an initial booting first pass, and wanted to get some
>> feedback.  What I've done at this point is to make dma_64 common to  
>> both
>> architectures (will rename it when I send a real patch...).  The
>> dma_direct_* functions have been changed to work on both 32/64, and  
>> the
>> old dma_* functionality in dma-mapping.h has been removed.   For  
>> now, to
>> avoid whacking on every 32-bit platform, the get_dma_ops() function  
>> has
>> been changed to return &dma_direct_ops if the device pointer exists  
>> but
>> the dma_ops field is NULL.   I'm not sure if this needs to be  
>> ifdef'd for
>> 64-bit?
>
> I'd prefer so yes.

Can you explain why?  Got no issue with doing this, but its good to  
know hy.

>> I've copied a bit of code over from pci_64.c into pci_common.c -  
>> some of
>> it isn't in use yet but will be once I start doing actual setup in  
>> the
>> platform code. pcibios_setup_new_device() becomes common as well.
>
> Cool !
>
>>  I've
>> also temporarily hacked the 32-bit code to set archdata.dma_data to
>> PCI_DRAM_OFFSET, so we can eliminate the use of virt_to_bus() and  
>> instead
>> use the 64-bit method, which gets rid of some ugly ifdefs in the  
>> dma code.
>
> Ok.
>
>> That's really about it - the preliminary patch is below - clearly  
>> it will
>> need some cleanup, but I wanted to post early and often.  Any  
>> feedback or
>> suggestions on cleaning this up are greatly appreciated.
>
> I'll have a look asap, thanks for doing this !

Also, any ideas on how to handle setting dev->archdata for non-PCI  
devices would be welcome.

- k