iommu/arm-smmu: Support DMA-API domains

With DMA mapping ops provided by the iommu-dma code, only a minimal
contribution from the IOMMU driver is needed to create a suitable
DMA-API domain for them to use. Implement this for the ARM SMMUs.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 1f9093d76d93..e8e7bcc4540c 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>
@@ -966,7 +967,7 @@ 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.
@@ -977,6 +978,12 @@ 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);
 
@@ -991,6 +998,7 @@ 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);
 }