[RFC PATCH] iommu/arm-smmu: Add global SMR masking property

[Nipun Gupta]

Hi Robin/Will,

This patch is currently not applied on the tree.
I had verified the patch and it seems good.
Is ack required on the patch or do I need to send a non RFC patch (with Robin's signoff)?
This is very much required to support SMMU on NXP platform.

Thanks,
Nipun


> -----Original Message-----
> From: Nipun Gupta
> Sent: Sunday, December 18, 2016 2:37
> To: Robin Murphy <robin.murphy at arm.com>; iommu at lists.linux-
> foundation.org; devicetree at vger.kernel.org; linux-arm-
> kernel at lists.infradead.org
> Cc: mark.rutland at arm.com; will.deacon at arm.com; Stuart Yoder
> <stuart.yoder at nxp.com>
> Subject: RE: [RFC PATCH] iommu/arm-smmu: Add global SMR masking property
> 
> 
> 
> > -----Original Message-----
> > From: iommu-bounces at lists.linux-foundation.org [mailto:iommu-
> > bounces at lists.linux-foundation.org] On Behalf Of Robin Murphy
> > Sent: Friday, December 16, 2016 18:49
> > To: iommu at lists.linux-foundation.org; devicetree at vger.kernel.org; linux-
> arm-
> > kernel at lists.infradead.org
> > Cc: mark.rutland at arm.com; will.deacon at arm.com; Stuart Yoder
> > <stuart.yoder at nxp.com>
> > Subject: [RFC PATCH] iommu/arm-smmu: Add global SMR masking property
> >
> > The current SMR masking support using a 2-cell iommu-specifier is
> > primarily intended to handle individual masters with large and/or
> > complex Stream ID assignments; it quickly gets a bit clunky in other SMR
> > use-cases where we just want to consistently mask out the same part of
> > every Stream ID (e.g. for MMU-500 configurations where the appended TBU
> > number gets in the way unnecessarily). Let's add a new property to allow
> > a single global mask value to better fit the latter situation.
> >
> > CC: Stuart Yoder <stuart.yoder at nxp.com>
> 
> Tested-by: Nipun Gupta <nipun.gupta at nxp.com>
> 
> > Signed-off-by: Robin Murphy <robin.murphy at arm.com>
> > ---
> >
> > Compile-tested only...
> >
> >  Documentation/devicetree/bindings/iommu/arm,smmu.txt | 8 ++++++++
> >  drivers/iommu/arm-smmu.c                             | 4 +++-
> >  2 files changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> > b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> > index e862d1485205..98f5cbe5fdb4 100644
> > --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> > +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> > @@ -60,6 +60,14 @@ conditions.
> >                    aliases of secure registers have to be used during
> >                    SMMU configuration.
> >
> > +- stream-match-mask : Specifies a fixed SMR mask value to combine with
> > +                  the Stream ID value from every iommu-specifier. This
> > +                  may be used instead of an "#iommu-cells" value of 2
> > +                  when there is no need for per-master SMR masks, but
> > +                  it is still desired to mask some portion of every
> > +                  Stream ID (e.g. for certain MMU-500 configurations
> > +                  given globally unique external IDs).
> > +
> >  ** Deprecated properties:
> >
> >  - mmu-masters (deprecated in favour of the generic "iommus" binding) :
> > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> > index 8f7281444551..f1abcb7dde36 100644
> > --- a/drivers/iommu/arm-smmu.c
> > +++ b/drivers/iommu/arm-smmu.c
> > @@ -1534,13 +1534,15 @@ static int arm_smmu_domain_set_attr(struct
> > iommu_domain *domain,
> >
> >  static int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args
> *args)
> >  {
> > -	u32 fwid = 0;
> > +	u32 mask, fwid = 0;
> >
> >  	if (args->args_count > 0)
> >  		fwid |= (u16)args->args[0];
> >
> >  	if (args->args_count > 1)
> >  		fwid |= (u16)args->args[1] << SMR_MASK_SHIFT;
> > +	else if (!of_property_read_u32(args->np, "stream-match-mask",
> > &mask))
> > +		fwid |= (u16)mask << SMR_MASK_SHIFT;
> >
> >  	return iommu_fwspec_add_ids(dev, &fwid, 1);
> >  }
> > --
> > 2.10.2.dirty
> >
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