ACPI/IORT: Introduce iort_iommu_configure

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.pieralisi@arm.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [ACPI core]
Reviewed-by: Tomasz Nowicki <tn@semihalf.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Tested-by: Tomasz Nowicki <tn@semihalf.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Tomasz Nowicki <tn@semihalf.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 45b5710..80698d3 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);