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 <nipun.gupta@xxxxxxx>
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
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.
+
** 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
--
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