DT based systems have a generic kernel API to configure IOMMUs
for devices (ie of_iommu_configure()).

On ARM based ACPI systems, the of_iommu_configure() equivalent can
be implemented atop ACPI IORT kernel API, with the corresponding
functions to map device identifiers to IOMMUs and retrieve the
corresponding IOMMU operations necessary for DMA operations set-up.

By relying on the iommu_fwspec generic kernel infrastructure,
implement the IORT based IOMMU configuration for ARM ACPI systems
and hook it up in the ACPI kernel layer that implements DMA
configuration for a device.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
Cc: Hanjun Guo <hanjun....@linaro.org>
Cc: Tomasz Nowicki <t...@semihalf.com>
Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
---
 drivers/acpi/arm64/iort.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/acpi/scan.c       |  7 +++-
 include/linux/acpi_iort.h |  6 +++
 3 files changed, 111 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index db7b153..5741bfd 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -28,6 +28,8 @@
 
 #define IORT_TYPE_MASK(type)   (1 << (type))
 #define IORT_MSI_TYPE          (1 << ACPI_IORT_NODE_ITS_GROUP)
+#define IORT_IOMMU_TYPE                ((1 << ACPI_IORT_NODE_SMMU) |   \
+                               (1 << ACPI_IORT_NODE_SMMU_V3))
 
 struct iort_its_msi_chip {
        struct list_head        list;
@@ -501,6 +503,103 @@ struct irq_domain *iort_get_device_domain(struct device 
*dev, u32 req_id)
        return irq_find_matching_fwnode(handle, DOMAIN_BUS_PCI_MSI);
 }
 
+static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
+{
+       u32 *rid = data;
+
+       *rid = alias;
+       return 0;
+}
+
+static int arm_smmu_iort_xlate(struct device *dev, u32 streamid,
+                              struct fwnode_handle *fwnode,
+                              const struct iommu_ops *ops)
+{
+       int ret = iommu_fwspec_init(dev, fwnode, ops);
+
+       if (!ret)
+               ret = iommu_fwspec_add_ids(dev, &streamid, 1);
+
+       return ret;
+}
+
+static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
+                                       struct acpi_iort_node *node,
+                                       u32 streamid)
+{
+       struct fwnode_handle *iort_fwnode = NULL;
+       const struct iommu_ops *ops = NULL;
+       int ret = -ENODEV;
+
+       if (node) {
+               iort_fwnode = iort_get_fwnode(node);
+               if (!iort_fwnode)
+                       return NULL;
+
+               ops = fwnode_iommu_get_ops(iort_fwnode);
+               if (!ops)
+                       return NULL;
+
+               ret = arm_smmu_iort_xlate(dev, streamid,
+                                         iort_fwnode, ops);
+       }
+
+       return ret ? NULL : ops;
+}
+
+/**
+ * iort_iommu_configure - Set-up IOMMU configuration for a device.
+ *
+ * @dev: device to configure
+ *
+ * Returns: iommu_ops pointer on configuration success
+ *          NULL on configuration failure
+ */
+const struct iommu_ops *iort_iommu_configure(struct device *dev)
+{
+       struct acpi_iort_node *node, *parent;
+       const struct iommu_ops *ops = NULL;
+       u32 streamid = 0;
+
+       if (dev_is_pci(dev)) {
+               struct pci_bus *bus = to_pci_dev(dev)->bus;
+               u32 rid;
+
+               pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid,
+                                      &rid);
+
+               node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
+                                     iort_match_node_callback, &bus->dev);
+               if (!node)
+                       return NULL;
+
+               parent = iort_node_map_rid(node, rid, &streamid,
+                                          IORT_IOMMU_TYPE);
+
+               ops = iort_iommu_xlate(dev, parent, streamid);
+
+       } else {
+               int i = 0;
+
+               node = iort_scan_node(ACPI_IORT_NODE_NAMED_COMPONENT,
+                                     iort_match_node_callback, dev);
+               if (!node)
+                       return NULL;
+
+               parent = iort_node_get_id(node, &streamid,
+                                         IORT_IOMMU_TYPE, i++);
+
+               while (parent) {
+                       ops = iort_iommu_xlate(dev, parent, streamid);
+
+                       parent = iort_node_get_id(node, &streamid,
+                                                 IORT_IOMMU_TYPE, i++);
+               }
+       }
+
+       return ops;
+}
+
 static void __init acpi_iort_register_irq(int hwirq, const char *name,
                                          int trigger,
                                          struct resource *res)
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 694e0b6..e5f7004 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -7,6 +7,7 @@
 #include <linux/slab.h>
 #include <linux/kernel.h>
 #include <linux/acpi.h>
+#include <linux/acpi_iort.h>
 #include <linux/signal.h>
 #include <linux/kthread.h>
 #include <linux/dmi.h>
@@ -1377,6 +1378,8 @@ enum dev_dma_attr acpi_get_dma_attr(struct acpi_device 
*adev)
  */
 void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr)
 {
+       const struct iommu_ops *iommu;
+
        /*
         * Set default coherent_dma_mask to 32 bit.  Drivers are expected to
         * setup the correct supported mask.
@@ -1391,11 +1394,13 @@ void acpi_dma_configure(struct device *dev, enum 
dev_dma_attr attr)
        if (!dev->dma_mask)
                dev->dma_mask = &dev->coherent_dma_mask;
 
+       iommu = iort_iommu_configure(dev);
+
        /*
         * Assume dma valid range starts at 0 and covers the whole
         * coherent_dma_mask.
         */
-       arch_setup_dma_ops(dev, 0, dev->coherent_dma_mask + 1, NULL,
+       arch_setup_dma_ops(dev, 0, dev->coherent_dma_mask + 1, iommu,
                           attr == DEV_DMA_COHERENT);
 }
 EXPORT_SYMBOL_GPL(acpi_dma_configure);
diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
index 79ba1bb..dcb2b60 100644
--- a/include/linux/acpi_iort.h
+++ b/include/linux/acpi_iort.h
@@ -34,6 +34,8 @@ void acpi_iort_init(void);
 bool iort_node_match(u8 type);
 u32 iort_msi_map_rid(struct device *dev, u32 req_id);
 struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id);
+/* IOMMU interface */
+const struct iommu_ops *iort_iommu_configure(struct device *dev);
 #else
 static inline void acpi_iort_init(void) { }
 static inline bool iort_node_match(u8 type) { return false; }
@@ -42,6 +44,10 @@ static inline u32 iort_msi_map_rid(struct device *dev, u32 
req_id)
 static inline struct irq_domain *iort_get_device_domain(struct device *dev,
                                                        u32 req_id)
 { return NULL; }
+/* IOMMU interface */
+static inline
+const struct iommu_ops *iort_iommu_configure(struct device *dev)
+{ return NULL; }
 #endif
 
 #define IORT_ACPI_DECLARE(name, table_id, fn)          \
-- 
2.10.0

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