[PATCH 3/8] iommu/arm-smmu-v3: Support platform SSID

Jean-Philippe Brucker
2019-06-10T18:51:57Z

For platform devices that support SubstreamID (SSID), firmware provides
the number of supported SSID bits. Restrict it to what the SMMU supports
and cache it into master->ssid_bits.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
---
drivers/iommu/arm-smmu-v3.c | 11 +++++++++++
drivers/iommu/of_iommu.c | 6 +++++-
include/linux/iommu.h | 1 +
3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 4d5a694f02c2..3254f473e681 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -604,6 +604,7 @@ struct arm_smmu_master {
struct list_head domain_head;
u32 *sids;
unsigned int num_sids;
+ unsigned int ssid_bits;
bool ats_enabled :1;
};

@@ -2097,6 +2098,16 @@ static int arm_smmu_add_device(struct device *dev)
}
}

+ master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);
+
+ /*
+ * If the SMMU doesn't support 2-stage CD, limit the linear
+ * tables to a reasonable number of contexts, let's say
+ * 64kB / sizeof(ctx_desc) = 1024 = 2^10
+ */
+ if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB))
+ master->ssid_bits = min(master->ssid_bits, 10U);
+
group = iommu_group_get_for_dev(dev);
if (!IS_ERR(group)) {
iommu_group_put(group);
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index f04a6df65eb8..04f4f6b95d82 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -206,8 +206,12 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
if (err)
break;
}
- }

+ fwspec = dev_iommu_fwspec_get(dev);
+ if (!err && fwspec)
+ of_property_read_u32(master_np, "pasid-num-bits",
+ &fwspec->num_pasid_bits);
+ }

/*
* Two success conditions can be represented by non-negative err here:
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 519e40fb23ce..b91df613385f 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -536,6 +536,7 @@ struct iommu_fwspec {
struct fwnode_handle *iommu_fwnode;
void *iommu_priv;
u32 flags;
+ u32 num_pasid_bits;
unsigned int num_ids;
u32 ids[1];
};
--
2.21.0