Re: [RESEND,PATCH 03/13] iommu/mediatek: Add mtk_iommu_pgtable structure

[chao hao]

On Mon, 2019-12-16 at 20:13 +0800, Yong Wu wrote:
> On Mon, 2019-11-04 at 19:52 +0800, Chao Hao wrote:
> > Start with this patch, we will change the SW architecture
> > to support multiple domains. SW architecture will has a big change,
> > so we need to modify a little bit by more than one patch.
> > The new SW overall architecture is as below:
> > 
> > 				iommu0   iommu1
> > 				  |	    |
> > 				  -----------
> > 					|
> > 				mtk_iommu_pgtable
> > 					|
> > 			------------------------------------------
> > 			|		     |			 |
> > 		mtk_iommu_domain1   mtk_iommu_domain2  mtk_iommu_domain3
> > 			|                    |                   |
> > 		iommu_group1         iommu_group2           iommu_group3
> > 			|                    |                   |
> > 		iommu_domain1       iommu_domain2	    iommu_domain3
> > 			|                    |                   |
> > 		iova region1(normal)  iova region2(CCU)    iova region3(VPU)
> > 
> > For current structure, no matter how many iommus there are,
> > they use the same page table to simplify the usage of module.
> > In order to make the software architecture more explicit, this
> > patch will create a global mtk_iommu_pgtable structure to describe
> > page table and all the iommus use it.
> 
> Thanks for the hard work of this file. Actually this patch and the later
> ones confuse me. Why do you make this flow change? 
> for making the code "more explicit" or for adding multi-domain support
> in 13/13.
> 
> IMHO, the change is unnecessary.
> a) For me, this change has no improvement. currently we use a global
> mtk_iommu_get_m4u_data to get the M4U data. I will be very glad if you
> could get rid of it. But in this patchset, You use a another global
> mtk_iommu_pgtable to instead. For me. It has no improvement.

Thanks for you advice!

For current SW arch, all the IOMMU HW use the same page table, we can
use a global mtk_iommu_pgtable to discribe the information of page table
and all the IOMMU attach it, I think that it is more clear and
unambiguous. For beginners, it maybe more easily explicable? 

> 
> b) This patchset break the original flow. device_group give you a
> software chance for initializing, then you move pagetable allocating
> code into it. But it isn't device_group job.
> 

As is shown above diagram, mtk_iommu_pgtable includes iommu_group and
iommu_domain,so we need to allocate mtk_iommu_pgtable and initialize it
in device_group firstly,and then execute the original flow, it only
changes place for creating mtk_iommu_pgtable and don't break original
device_group flow.




> I can not decide if your flow is right. But if you only want to add
> support multi-domain, I guess you could extend the current "m4u_group"
> to a array "m4u_group[N]". It may be more simple. To make mt6779
> progress easily, I suggest you can use this way to support multi-domain
> firstly. Then you could send this new mtk_iommu_pgtable patchset for the
> code "more explicit" if you insist.
> 
> > The diagram is as below:
> > 
> > 	mtk_iommu_data1(MM)       mtk_iommu_data2(APU)
> > 		|			   |
> > 		|			   |
> > 		------mtk_iommu_pgtable-----
> > 
> > We need to create global mtk_iommu_pgtable to include all the iova
> > regions firstly and special iova regions by divided based on it,
> > so the information of pgtable needs to be created in device_group.
> > 
> > Signed-off-by: Chao Hao <chao.hao@xxxxxxxxxxxx>
> > ---
> >  drivers/iommu/mtk_iommu.c | 84 +++++++++++++++++++++++++++++++++++++++
> >  drivers/iommu/mtk_iommu.h |  1 +
> >  2 files changed, 85 insertions(+)
> > 
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index f2847e661137..fcbde6b0f58d 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -123,6 +123,12 @@ struct mtk_iommu_domain {
> >  	struct iommu_domain		domain;
> >  };
> >  
> > +struct mtk_iommu_pgtable {
> > +	struct io_pgtable_cfg	cfg;
> > +	struct io_pgtable_ops	*iop;
> > +};
> > +
> > +static struct mtk_iommu_pgtable *share_pgtable;
> >  static const struct iommu_ops mtk_iommu_ops;
> >  
> >  /*
> > @@ -170,6 +176,11 @@ static struct mtk_iommu_data *mtk_iommu_get_m4u_data(void)
> >  	return NULL;
> >  }
> >  
> > +static struct mtk_iommu_pgtable *mtk_iommu_get_pgtable(void)
> > +{
> > +	return share_pgtable;
> > +}
> > +
> >  static struct mtk_iommu_domain *to_mtk_domain(struct iommu_domain *dom)
> >  {
> >  	return container_of(dom, struct mtk_iommu_domain, domain);
> > @@ -322,6 +333,13 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom)
> >  {
> >  	struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
> >  
> > +	if (data->pgtable) {
> > +		dom->cfg = data->pgtable->cfg;
> > +		dom->iop = data->pgtable->iop;
> > +		dom->domain.pgsize_bitmap = data->pgtable->cfg.pgsize_bitmap;
> > +		return 0;
> > +	}
> > +
> >  	dom->cfg = (struct io_pgtable_cfg) {
> >  		.quirks = IO_PGTABLE_QUIRK_ARM_NS |
> >  			IO_PGTABLE_QUIRK_NO_PERMS |
> > @@ -345,6 +363,61 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom)
> >  	return 0;
> >  }
> >  
> > +static struct mtk_iommu_pgtable *create_pgtable(struct mtk_iommu_data *data)
> > +{
> > +	struct mtk_iommu_pgtable *pgtable;
> > +
> > +	pgtable = kzalloc(sizeof(*pgtable), GFP_KERNEL);
> > +	if (!pgtable)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	pgtable->cfg = (struct io_pgtable_cfg) {
> > +		.quirks = IO_PGTABLE_QUIRK_ARM_NS |
> > +			IO_PGTABLE_QUIRK_NO_PERMS |
> > +			IO_PGTABLE_QUIRK_TLBI_ON_MAP |
> > +			IO_PGTABLE_QUIRK_ARM_MTK_EXT,
> > +		.pgsize_bitmap = mtk_iommu_ops.pgsize_bitmap,
> > +		.ias = 32,
> > +		.oas = 34,
> > +		.tlb = &mtk_iommu_flush_ops,
> > +		.iommu_dev = data->dev,
> > +	};
> > +
> > +	pgtable->iop = alloc_io_pgtable_ops(ARM_V7S, &pgtable->cfg, data);
> > +	if (!pgtable->iop) {
> > +		dev_err(data->dev, "Failed to alloc io pgtable\n");
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	dev_info(data->dev, "%s create pgtable done\n", __func__);
> > +
> > +	return pgtable;
> > +}
> > +
> > +static int mtk_iommu_attach_pgtable(struct mtk_iommu_data *data,
> > +				    struct device *dev)
> > +{
> > +	struct mtk_iommu_pgtable *pgtable = mtk_iommu_get_pgtable();
> > +
> > +	/* create share pgtable */
> > +	if (!pgtable) {
> > +		pgtable = create_pgtable(data);
> > +		if (IS_ERR(pgtable)) {
> > +			dev_err(data->dev, "Failed to create pgtable\n");
> > +			return -ENOMEM;
> > +		}
> > +
> > +		share_pgtable = pgtable;
> > +	}
> > +
> > +	/* binding to pgtable */
> > +	data->pgtable = pgtable;
> > +
> > +	dev_info(data->dev, "m4u%d attach_pgtable done!\n", data->m4u_id);
> > +
> > +	return 0;
> > +}
> > +
> >  static struct iommu_domain *mtk_iommu_domain_alloc(unsigned type)
> >  {
> >  	struct mtk_iommu_domain *dom;
> > @@ -508,10 +581,21 @@ static void mtk_iommu_remove_device(struct device *dev)
> >  static struct iommu_group *mtk_iommu_device_group(struct device *dev)
> >  {
> >  	struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
> > +	struct mtk_iommu_pgtable *pgtable;
> > +	int ret = 0;
> >  
> >  	if (!data)
> >  		return ERR_PTR(-ENODEV);
> >  
> > +	pgtable = data->pgtable;
> > +	if (!pgtable) {
> > +		ret = mtk_iommu_attach_pgtable(data, dev);
> > +		if (ret) {
> > +			dev_err(data->dev, "Failed to device_group\n");
> > +			return NULL;
> > +		}
> > +	}
> > +
> >  	/* All the client devices are in the same m4u iommu-group */
> >  	if (!data->m4u_group) {
> >  		data->m4u_group = iommu_group_alloc();
> > diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> > index 132dc765a40b..dd5f19f78b62 100644
> > --- a/drivers/iommu/mtk_iommu.h
> > +++ b/drivers/iommu/mtk_iommu.h
> > @@ -61,6 +61,7 @@ struct mtk_iommu_data {
> >  	struct clk			*bclk;
> >  	phys_addr_t			protect_base; /* protect memory base */
> >  	struct mtk_iommu_suspend_reg	reg;
> > +	struct mtk_iommu_pgtable	*pgtable;
> >  	struct mtk_iommu_domain		*m4u_dom;
> >  	struct iommu_group		*m4u_group;
> >  	bool                            enable_4GB;
> 
>