IORT named components provide firmware configuration describing
how many address bits a given device is capable of generating
to address memory.

Add code to the kernel to retrieve memory address limits
configuration for IORT named components and configure DMA masks
accordingly.

Signed-off-by: Lorenzo Pieralisi <redacted>
Cc: Will Deacon <redacted>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Nate Watterson <redacted>
---
  drivers/acpi/arm64/iort.c | 40 ++++++++++++++++++++++++++++++----------
  1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 67b85ae..b85d19f 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c

@@ -680,6 +680,24 @@ static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
  	return ret ? NULL : ops;
  }
  
+static int nc_dma_get_range(struct device *dev, u64 *size)
+{
+	struct acpi_iort_node *node;
+	struct acpi_iort_named_component *ncomp;
+
+	node = iort_scan_node(ACPI_IORT_NODE_NAMED_COMPONENT,
+			      iort_match_node_callback, dev);
+	if (!node)
+		return -ENODEV;
+
+	ncomp = (struct acpi_iort_named_component *)node->node_data;
+
+	*size = ncomp->memory_address_limit >= 64 ? ~0ULL :
+			1ULL<<ncomp->memory_address_limit;