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

[Robin Murphy]

On 02/03/17 04:18, Nipun Gupta wrote:
> 
> 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.

It's still sat in my "patches to do something with" queue - I don't
think we ever reached a concrete decision on the property name for a DT
maintainer ack, but I've tweaked the description per Will's comment;
thanks for the reminder. I'll send an rc1-based version out next week to
reboot the discussion.

Robin.

> 
> 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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>>> iommu at lists.linux-foundation.org
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