iommu: Remove ops->set_platform_dma_ops()

All drivers are now using IDENTITY or PLATFORM domains for what this did,
we can remove it now. It is no longer possible to attach to a NULL domain.

Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Tested-by: Steven Price <steven.price@arm.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/15-v8-81230027b2fa+9d-iommu_all_defdom_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -2351,21 +2351,8 @@ static int __iommu_group_set_domain_internal(struct iommu_group *group,
 	if (group->domain == new_domain)
 		return 0;
 
-	/*
-	 * New drivers should support default domains, so set_platform_dma()
-	 * op will never be called. Otherwise the NULL domain represents some
-	 * platform specific behavior.
-	 */
-	if (!new_domain) {
-		for_each_group_device(group, gdev) {
-			const struct iommu_ops *ops = dev_iommu_ops(gdev->dev);
-
-			if (!WARN_ON(!ops->set_platform_dma_ops))
-				ops->set_platform_dma_ops(gdev->dev);
-		}
-		group->domain = NULL;
-		return 0;
-	}
+	if (WARN_ON(!new_domain))
+		return -EINVAL;
 
 	/*
 	 * Changing the domain is done by calling attach_dev() on the new
@@ -2401,19 +2388,15 @@ static int __iommu_group_set_domain_internal(struct iommu_group *group,
 	 */
 	last_gdev = gdev;
 	for_each_group_device(group, gdev) {
-		const struct iommu_ops *ops = dev_iommu_ops(gdev->dev);
-
 		/*
-		 * If set_platform_dma_ops is not present a NULL domain can
-		 * happen only for first probe, in which case we leave
-		 * group->domain as NULL and let release clean everything up.
+		 * A NULL domain can happen only for first probe, in which case
+		 * we leave group->domain as NULL and let release clean
+		 * everything up.
 		 */
 		if (group->domain)
 			WARN_ON(__iommu_device_set_domain(
 				group, gdev->dev, group->domain,
 				IOMMU_SET_DOMAIN_MUST_SUCCEED));
-		else if (ops->set_platform_dma_ops)
-			ops->set_platform_dma_ops(gdev->dev);
 		if (gdev == last_gdev)
 			break;
 	}
@@ -3036,9 +3019,6 @@ static int iommu_setup_default_domain(struct iommu_group *group,
 	/*
 	 * There are still some drivers which don't support default domains, so
 	 * we ignore the failure and leave group->default_domain NULL.
-	 *
-	 * We assume that the iommu driver starts up the device in
-	 * 'set_platform_dma_ops' mode if it does not support default domains.
 	 */
 	dom = iommu_group_alloc_default_domain(group, req_type);
 	if (!dom) {

include/linux/iommu.h

@@ -243,9 +243,6 @@ struct iommu_iotlb_gather {
  * @release_device: Remove device from iommu driver handling
  * @probe_finalize: Do final setup work after the device is added to an IOMMU
  *                  group and attached to the groups domain
- * @set_platform_dma_ops: Returning control back to the platform DMA ops. This op
- *                        is to support old IOMMU drivers, new drivers should use
- *                        default domains, and the common IOMMU DMA ops.
  * @device_group: find iommu group for a particular device
  * @get_resv_regions: Request list of reserved regions for a device
  * @of_xlate: add OF master IDs to iommu grouping
@@ -280,7 +277,6 @@ struct iommu_ops {
 	struct iommu_device *(*probe_device)(struct device *dev);
 	void (*release_device)(struct device *dev);
 	void (*probe_finalize)(struct device *dev);
-	void (*set_platform_dma_ops)(struct device *dev);
 	struct iommu_group *(*device_group)(struct device *dev);
 
 	/* Request/Free a list of reserved regions for a device */