dmaengine: mcf-edma: add ColdFire mcf5441x eDMA support

[Vinod Koul <vkoul@kernel.org>]

On 22-05-18, 23:28, Angelo Dureghello wrote:
> Hi Vinod,
> 
> On Mon, May 07, 2018 at 07:45:35PM +0530, Vinod Koul wrote:
> > On Fri, May 04, 2018 at 09:18:19PM +0200, Angelo Dureghello wrote:
> > > Hi Vinod,
> > > 
> > > thanks for the review,
> > > 
> > > On Thu, May 03, 2018 at 10:18:30PM +0530, Vinod Koul wrote:
> > > > On Wed, Apr 25, 2018 at 10:08:17PM +0200, Angelo Dureghello wrote:
> > > > > This patch adds dma support for NXP mcf5441x (ColdFire) family.
> > > > > 
> > > > > ColdFire mcf5441x implements an edma hw module similar to the
> > > > 
> > > > Is it similar to to edma ?
> > > > 
> > > 
> > > It is similar to Freescale "edma" but with a different number of
> > > channels, a bit different register set, different interrupt
> > > structure, no channel multiplexer.
> > 
> > ok
> > 
> > > > > one implemented in Vybrid VFxxx controllers, but with a slightly
> > > > > different register set, more dma channels (64 instead of 32),
> > > > > a different interrupt mechanism and some other minor differences.
> > > > > 
> > > > > For the above reasons, modfying fsl-edma.c was too complex and
> > > > > likely too ugly. From here, the decision to create a different
> > > > > driver, but starting from fsl-edma.
> > > > 
> > > > can the common stuff be made into a lib and shared between then two rather
> > > > than having a same driver or different drivers?
> > > 
> > > It should be possible to collect some common code in a kind of
> > > mcf_edma_core.c common module, but in this case i cannot then test
> > > the Vybrid edma after the changes since i miss that hardware.
> > 
> > Sure you should send the patches and folks who care about fsl driver
> > would look it up and test
> > 
> > > Would be maybe possible for you to diff fsl-edma and this mcf-edma,
> > > just to confirm if i can still stay this way, or if moving to a
> > > library becomes mandatory ?
> > 
> > well since you know the IP you would make a better guess on that, best is
> > to check register sets in drivers
> > 
> I fixed all the discussed points.
> 
> Actaully mcf-edma (ColdFire) has a slightly different register set (due to 64
> channels in place of 16 of fsl-edma) and, for the same reason, a different
> DMA interrupt structure.
> Also, i simplified some parts of the driver considering ColdFire (mcf) 
> big endian architecture.
> 
> So i would send a rev 2 patch with all the fixes, than eventually in a second
> phase i may try to create some common code, but at least we have the ColdFire
> DMA. What do you think ?

wouldn't it be easier to just make common parts and then add edma specific code.
If I was doing this it would be my apprach and that way code edma specific will
be lesser and faster review