iommu/arm-smmu-v3: Parse PASID devicetree property of platform devices

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, which will also be used for PCI
PASID.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 4a9442f..2717c2b 100644 (file)
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -289,6 +289,12 @@
 
 #define CTXDESC_CD_1_TTB0_MASK         GENMASK_ULL(51, 4)
 
+/*
+ * When the SMMU only supports linear context descriptor tables, pick a
+ * reasonable size limit (64kB).
+ */
+#define CTXDESC_LINEAR_CDMAX           ilog2(SZ_64K / (CTXDESC_CD_DWORDS << 3))
+
 /* Command queue */
 #define CMDQ_ENT_SZ_SHIFT              4
 #define CMDQ_ENT_DWORDS                        ((1 << CMDQ_ENT_SZ_SHIFT) >> 3)
@@ -627,6 +633,7 @@ struct arm_smmu_master {
        u32                             *sids;
        unsigned int                    num_sids;
        bool                            ats_enabled;
+       unsigned int                    ssid_bits;
 };
 
 /* SMMU private data for an IOMMU domain */
@@ -2559,6 +2566,12 @@ static int arm_smmu_add_device(struct device *dev)
                }
        }
 
+       master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);
+
+       if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB))
+               master->ssid_bits = min_t(u8, master->ssid_bits,
+                                         CTXDESC_LINEAR_CDMAX);
+
        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 e7bc8b7..20738aa 100644 (file)
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -203,8 +203,12 @@ 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 90007c9..c1ad152 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -579,6 +579,7 @@ struct iommu_group *fsl_mc_device_group(struct device *dev);
  * @ops: ops for this device's IOMMU
  * @iommu_fwnode: firmware handle for this device's IOMMU
  * @iommu_priv: IOMMU driver private data for this device
+ * @num_pasid_bits: number of PASID bits supported by this device
  * @num_ids: number of associated device IDs
  * @ids: IDs which this device may present to the IOMMU
  */
@@ -587,6 +588,7 @@ struct iommu_fwspec {
        struct fwnode_handle    *iommu_fwnode;
        void                    *iommu_priv;
        u32                     flags;
+       u32                     num_pasid_bits;
        unsigned int            num_ids;
        u32                     ids[1];
 };