[RFC PATCH 4/6] iommu/arm-smmu: Add support for IOMMU_DOMAIN_DMA in SMMUv1/SMMUv2 driver

[Anup Patel]

To allow use of large memory (> 4Gb) with 32bit devices we need to use
some kind of iommu for such 32bit devices.

This patch extends SMMUv1/SMMUv2 driver to support DMA domains which
in-turn will allows us to use iommu based DMA mappings 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 | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 9bdf6b2..43424fe 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -29,6 +29,7 @@
 #define pr_fmt(fmt) "arm-smmu: " fmt
 
 #include <linux/delay.h>
+#include <linux/dma-iommu.h>
 #include <linux/dma-mapping.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
@@ -967,7 +968,7 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
 {
 	struct arm_smmu_domain *smmu_domain;
 
-	if (type != IOMMU_DOMAIN_UNMANAGED)
+	if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
 		return NULL;
 	/*
 	 * Allocate the domain and initialise some of its data structures.
@@ -978,6 +979,12 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
 	if (!smmu_domain)
 		return NULL;
 
+	if (type == IOMMU_DOMAIN_DMA &&
+	    iommu_get_dma_cookie(&smmu_domain->domain)) {
+		kfree(smmu_domain);
+		return NULL;
+	}
+
 	mutex_init(&smmu_domain->init_mutex);
 	spin_lock_init(&smmu_domain->pgtbl_lock);
 
@@ -992,6 +999,7 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
 	 * Free the domain resources. We assume that all devices have
 	 * already been detached.
 	 */
+	iommu_put_dma_cookie(domain);
 	arm_smmu_destroy_domain_context(domain);
 	kfree(smmu_domain);
 }
@@ -1361,6 +1369,16 @@ 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;
@@ -1458,6 +1476,7 @@ 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