iommu: iommu_alloc_resv_region

Introduce a new helper serving the purpose to allocate a reserved
region. This will be used in iommu driver implementing reserved
region callbacks.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
Tested-by: Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
Tested-by: Bharat Bhushan <bharat.bhushan@nxp.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/iommu/iommu.c

@@ -1575,6 +1575,24 @@ void iommu_put_resv_regions(struct device *dev, struct list_head *list)
 		ops->put_resv_regions(dev, list);
 }
 
+struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
+						  size_t length,
+						  int prot, int type)
+{
+	struct iommu_resv_region *region;
+
+	region = kzalloc(sizeof(*region), GFP_KERNEL);
+	if (!region)
+		return NULL;
+
+	INIT_LIST_HEAD(&region->list);
+	region->start = start;
+	region->length = length;
+	region->prot = prot;
+	region->type = type;
+	return region;
+}
+
 /* Request that a device is direct mapped by the IOMMU */
 int iommu_request_dm_for_dev(struct device *dev)
 {

include/linux/iommu.h

@@ -244,6 +244,8 @@ extern void iommu_set_fault_handler(struct iommu_domain *domain,
 extern void iommu_get_resv_regions(struct device *dev, struct list_head *list);
 extern void iommu_put_resv_regions(struct device *dev, struct list_head *list);
 extern int iommu_request_dm_for_dev(struct device *dev);
+extern struct iommu_resv_region *
+iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot, int type);
 
 extern int iommu_attach_group(struct iommu_domain *domain,
 			      struct iommu_group *group);