[PATCH] iommu/arm-smmu: Add global SMR masking property
From: mark.rutland@arm.com (Mark Rutland)
Date: 2017-03-07 18:35:55
Also in:
linux-devicetree, linux-iommu
On Tue, Mar 07, 2017 at 06:26:28PM +0000, Robin Murphy wrote:
quoted hunk
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. Tested-by: Nipun Gupta <redacted> Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- Time to rekindle the discussion about whether an architecture-level concept with a rather specific name needs a vendor prefix ;) Robin. Documentation/devicetree/bindings/iommu/arm,smmu.txt | 10 ++++++++++ drivers/iommu/arm-smmu.c | 4 +++- 2 files changed, 13 insertions(+), 1 deletion(-)diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt index 6cdf32d037fc..d66f355e174f 100644 --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt@@ -60,6 +60,16 @@ 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). This property is + not valid for SMMUs using stream indexing, and may be + ignored if stream matching is not supported. +
Generally, this sounds fine. However, there is an ambiguity here (inherited from the existing #iommu-cells = <2> case), in that it's not clear what is meant by "to combine".
From the example at the end of the file, this appears to be a mask of
bits to not consider for matching purposes? Would you mind clarifying that in both cases? This could also do with an example. Thanks, Mark.
quoted hunk
** 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 abf6496843a6..e394d55146a6 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c@@ -1590,13 +1590,15 @@ 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); }-- 2.11.0.dirty