iommu: Add domain_has_cap iommu_ops

This iommu_op can tell if domain have a specific capability, like snooping
control for Intel IOMMU, which can be used by other components of kernel to
adjust the behaviour.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 8a7bfb1b6ca0..0cf3a4e43f23 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -28,6 +28,8 @@ struct iommu_domain {
         void *priv;
 };
 
+#define IOMMU_CAP_CACHE_COHERENCY       0x1
+
 struct iommu_ops {
         int (*domain_init)(struct iommu_domain *domain);
         void (*domain_destroy)(struct iommu_domain *domain);
@@ -39,6 +41,8 @@ struct iommu_ops {
                       size_t size);
         phys_addr_t (*iova_to_phys)(struct iommu_domain *domain,
                                     unsigned long iova);
+        int (*domain_has_cap)(struct iommu_domain *domain,
+                              unsigned long cap);
 };
 
 #ifdef CONFIG_IOMMU_API
@@ -57,6 +61,8 @@ extern void iommu_unmap_range(struct iommu_domain *domain, unsigned long iova,
                               size_t size);
 extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
                                       unsigned long iova);
+extern int iommu_domain_has_cap(struct iommu_domain *domain,
+                                unsigned long cap);
 
 #else /* CONFIG_IOMMU_API */
 
@@ -107,6 +113,12 @@ static inline phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
         return 0;
 }
 
+static inline int domain_has_cap(struct iommu_domain *domain,
+                                 unsigned long cap)
+{
+        return 0;
+}
+
 #endif /* CONFIG_IOMMU_API */
 
 #endif /* __LINUX_IOMMU_H */