ACPI/IORT: Check ATS capability in root complex nodes

Root complex node in IORT has a bit telling whether it supports ATS or
not. Store this bit in the IOMMU fwspec when setting up a device, so it
can be accessed later by an IOMMU driver. In the future we'll probably
want to store this bit at the host bridge or SMMU rather than in each
endpoint.

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index e48894e002ba..4000902e57f0 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -1028,6 +1028,14 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
         dev_dbg(dev, "dma_pfn_offset(%#08llx)\n", offset);
 }
 
+static bool iort_pci_rc_supports_ats(struct acpi_iort_node *node)
+{
+        struct acpi_iort_root_complex *pci_rc;
+
+        pci_rc = (struct acpi_iort_root_complex *)node->node_data;
+        return pci_rc->ats_attribute & ACPI_IORT_ATS_SUPPORTED;
+}
+
 /**
  * iort_iommu_configure - Set-up IOMMU configuration for a device.
  *
@@ -1063,6 +1071,9 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
                 info.node = node;
                 err = pci_for_each_dma_alias(to_pci_dev(dev),
                                              iort_pci_iommu_init, &info);
+
+                if (!err && iort_pci_rc_supports_ats(node))
+                        dev->iommu_fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
         } else {
                 int i = 0;
 
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ffbbc7e39cee..6c1b4c900191 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -392,10 +392,14 @@ struct iommu_fwspec {
         const struct iommu_ops  *ops;
         struct fwnode_handle    *iommu_fwnode;
         void                    *iommu_priv;
+        u32                     flags;
         unsigned int            num_ids;
         u32                     ids[1];
 };
 
+/* ATS is supported */
+#define IOMMU_FWSPEC_PCI_RC_ATS                 (1 << 0)
+
 int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
                       const struct iommu_ops *ops);
 void iommu_fwspec_free(struct device *dev);