To allow use of large memory (> 4Gb) with 32bit devices we need to use
IOMMU based DMA mappings for such 32bit devices. The IOMMU dt-bindings
allows us do this by specifying 'iommus' attribute in 32bit device DT
node. Unfortunately, specifying 'iommus' attribute does not work with
current SMMUv1/SMMUv2 driver because it requires of_xlate() operation
to be implemented by the driver.
This patch adds a stub implementation of of_xlate() in SMMUv1/SMMUv2
driver to allow usage of 'iommus' attribute in DT for 32bit devices.
Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxxxx>
Reviewed-by: Ray Jui <rjui@xxxxxxxxxxxx>
Reviewed-by: Scott Branden <sbranden@xxxxxxxxxxxx>
---
drivers/iommu/arm-smmu.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 02cd67d..8e090d8 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1398,6 +1398,16 @@ static int arm_smmu_init_platform_device(struct device *dev,
return 0;
}
+int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args *args)
+{
+ /*
+ * Nothing to do here because SMMU is already aware of all
+ * MMU masters and their stream IDs using mmu-master attibute
+ * SMMU DT node.
+ */
+ return 0;
+}
+
static int arm_smmu_add_device(struct device *dev)
{
struct iommu_group *group;
@@ -1495,6 +1505,7 @@ static struct iommu_ops arm_smmu_ops = {
.unmap = arm_smmu_unmap,
.map_sg = default_iommu_map_sg,
.iova_to_phys = arm_smmu_iova_to_phys,
+ .of_xlate = arm_smmu_of_xlate,
.add_device = arm_smmu_add_device,
.remove_device = arm_smmu_remove_device,
.device_group = arm_smmu_device_group,
--
1.9.1
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