[PATCH 04/21] dt-binding: mediatek: Add binding for mt8192 IOMMU and SMI

[Yong Wu]

On Mon, 2020-07-20 at 17:16 -0600, Rob Herring wrote:
> On Sat, Jul 11, 2020 at 02:48:29PM +0800, Yong Wu wrote:
> > This patch adds decriptions for mt8192 IOMMU and SMI.
> > 
> > mt8192 also is MTK IOMMU gen2 which uses ARM Short-Descriptor translation
> > table format. The M4U-SMI HW diagram is as below:
> > 
> >                           EMI
> >                            |
> >                           M4U
> >                            |
> >                       ------------
> >                        SMI Common
> >                       ------------
> >                            |
> >   +-------+------+------+----------------------+-------+
> >   |       |      |      |       ......         |       |
> >   |       |      |      |                      |       |
> > larb0   larb1  larb2  larb4     ......      larb19   larb20
> > disp0   disp1   mdp    vdec                   IPE      IPE
> > 
> > All the connections are HW fixed, SW can NOT adjust it.
> > 
> > mt8192 M4U support 0~16GB iova range. we preassign different engines
> > into different iova ranges:
> > 
> > domain-id  module     iova-range                  larbs
> >    0       disp        0 ~ 4G                      larb0/1
> >    1       vcodec      4G ~ 8G                     larb4/5/7
> >    2       cam/mdp     8G ~ 12G             larb2/9/11/13/14/16/17/18/19/20
> >    3       CCU0    0x4000_0000 ~ 0x43ff_ffff     larb13: port 9/10
> >    4       CCU1    0x4400_0000 ~ 0x47ff_ffff     larb14: port 4/5
> 
> You probably want to use dma-ranges for defining these 
> address restrictions. 

Yes. Please see the commit message of [18/21] in this patchset.

> 
> How is the domain-id used or needed?

Here we assign different larb/ports in different iova ranges.
In the iommu driver, we will list the iova ranges as above and use the
domain-id to get the detailed iova range, then create a iommu domain for
each a iova range.

For the iommu masters, it only need use its special port in its dtsi
node, then the iova got from dma_alloc_attrs for that device will locate
in the special iova ranges.

> 
> Rob 
> 
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