iommu: Introduce iommu_capable API function

This function will replace the current iommu_domain_has_cap
function and clean up the interface while at it.

Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -817,6 +817,15 @@ bool iommu_present(struct bus_type *bus)
 }
 EXPORT_SYMBOL_GPL(iommu_present);
 
+bool iommu_capable(struct bus_type *bus, enum iommu_cap cap)
+{
+	if (!bus->iommu_ops || !bus->iommu_ops->capable)
+		return false;
+
+	return bus->iommu_ops->capable(cap);
+}
+EXPORT_SYMBOL_GPL(iommu_capable);
+
 /**
  * iommu_set_fault_handler() - set a fault handler for an iommu domain
  * @domain: iommu domain
@@ -950,10 +959,13 @@ EXPORT_SYMBOL_GPL(iommu_iova_to_phys);
 int iommu_domain_has_cap(struct iommu_domain *domain,
 			 enum iommu_cap cap)
 {
-	if (unlikely(domain->ops->domain_has_cap == NULL))
-		return 0;
+	if (domain->ops->domain_has_cap != NULL)
+		return domain->ops->domain_has_cap(domain, cap);
 
-	return domain->ops->domain_has_cap(domain, cap);
+	if (domain->ops->capable != NULL)
+		return domain->ops->capable(cap);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(iommu_domain_has_cap);
 

include/linux/iommu.h

@@ -105,6 +105,7 @@ enum iommu_attr {
  * @pgsize_bitmap: bitmap of supported page sizes
  */
 struct iommu_ops {
+	bool (*capable)(enum iommu_cap);
 	int (*domain_init)(struct iommu_domain *domain);
 	void (*domain_destroy)(struct iommu_domain *domain);
 	int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
@@ -145,6 +146,7 @@ struct iommu_ops {
 
 extern int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops);
 extern bool iommu_present(struct bus_type *bus);
+extern bool iommu_capable(struct bus_type *bus, enum iommu_cap cap);
 extern struct iommu_domain *iommu_domain_alloc(struct bus_type *bus);
 extern struct iommu_group *iommu_group_get_by_id(int id);
 extern void iommu_domain_free(struct iommu_domain *domain);
@@ -253,6 +255,11 @@ static inline bool iommu_present(struct bus_type *bus)
 	return false;
 }
 
+static inline bool iommu_capable(struct bus_type *bus, enum iommu_cap cap)
+{
+	return false;
+}
+
 static inline struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
 {
 	return NULL;