iommu/exynos: Implement an IDENTITY domain

What exynos calls exynos_iommu_detach_device is actually putting the iommu
into identity mode.

Move to the new core support for ARM_DMA_USE_IOMMU by defining
ops->identity_domain.
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/10-v8-81230027b2fa+9d-iommu_all_defdom_jgg@nvidia.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/exynos-iommu.c

@@ -24,6 +24,7 @@
 
 typedef u32 sysmmu_iova_t;
 typedef u32 sysmmu_pte_t;
+static struct iommu_domain exynos_identity_domain;
 
 /* We do not consider super section mapping (16MB) */
 #define SECT_ORDER 20
@@ -829,7 +830,7 @@ static int __maybe_unused exynos_sysmmu_suspend(struct device *dev)
 		struct exynos_iommu_owner *owner = dev_iommu_priv_get(master);
 
 		mutex_lock(&owner->rpm_lock);
-		if (data->domain) {
+		if (&data->domain->domain != &exynos_identity_domain) {
 			dev_dbg(data->sysmmu, "saving state\n");
 			__sysmmu_disable(data);
 		}
@@ -847,7 +848,7 @@ static int __maybe_unused exynos_sysmmu_resume(struct device *dev)
 		struct exynos_iommu_owner *owner = dev_iommu_priv_get(master);
 
 		mutex_lock(&owner->rpm_lock);
-		if (data->domain) {
+		if (&data->domain->domain != &exynos_identity_domain) {
 			dev_dbg(data->sysmmu, "restoring state\n");
 			__sysmmu_enable(data);
 		}
@@ -980,17 +981,20 @@ static void exynos_iommu_domain_free(struct iommu_domain *iommu_domain)
 	kfree(domain);
 }
 
-static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
-				    struct device *dev)
+static int exynos_iommu_identity_attach(struct iommu_domain *identity_domain,
+					struct device *dev)
 {
-	struct exynos_iommu_domain *domain = to_exynos_domain(iommu_domain);
 	struct exynos_iommu_owner *owner = dev_iommu_priv_get(dev);
-	phys_addr_t pagetable = virt_to_phys(domain->pgtable);
+	struct exynos_iommu_domain *domain;
+	phys_addr_t pagetable;
 	struct sysmmu_drvdata *data, *next;
 	unsigned long flags;
 
-	if (!has_sysmmu(dev) || owner->domain != iommu_domain)
-		return;
+	if (owner->domain == identity_domain)
+		return 0;
+
+	domain = to_exynos_domain(owner->domain);
+	pagetable = virt_to_phys(domain->pgtable);
 
 	mutex_lock(&owner->rpm_lock);
 
@@ -1009,15 +1013,25 @@ static void exynos_iommu_detach_device(struct iommu_domain *iommu_domain,
 		list_del_init(&data->domain_node);
 		spin_unlock(&data->lock);
 	}
-	owner->domain = NULL;
+	owner->domain = identity_domain;
 	spin_unlock_irqrestore(&domain->lock, flags);
 
 	mutex_unlock(&owner->rpm_lock);
 
-	dev_dbg(dev, "%s: Detached IOMMU with pgtable %pa\n", __func__,
-		&pagetable);
+	dev_dbg(dev, "%s: Restored IOMMU to IDENTITY from pgtable %pa\n",
+		__func__, &pagetable);
+	return 0;
 }
 
+static struct iommu_domain_ops exynos_identity_ops = {
+	.attach_dev = exynos_iommu_identity_attach,
+};
+
+static struct iommu_domain exynos_identity_domain = {
+	.type = IOMMU_DOMAIN_IDENTITY,
+	.ops = &exynos_identity_ops,
+};
+
 static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
 				   struct device *dev)
 {
@@ -1026,12 +1040,11 @@ static int exynos_iommu_attach_device(struct iommu_domain *iommu_domain,
 	struct sysmmu_drvdata *data;
 	phys_addr_t pagetable = virt_to_phys(domain->pgtable);
 	unsigned long flags;
+	int err;
 
-	if (!has_sysmmu(dev))
-		return -ENODEV;
-
-	if (owner->domain)
-		exynos_iommu_detach_device(owner->domain, dev);
+	err = exynos_iommu_identity_attach(&exynos_identity_domain, dev);
+	if (err)
+		return err;
 
 	mutex_lock(&owner->rpm_lock);
 
@@ -1407,26 +1420,12 @@ static struct iommu_device *exynos_iommu_probe_device(struct device *dev)
 	return &data->iommu;
 }
 
-static void exynos_iommu_set_platform_dma(struct device *dev)
-{
-	struct exynos_iommu_owner *owner = dev_iommu_priv_get(dev);
-
-	if (owner->domain) {
-		struct iommu_group *group = iommu_group_get(dev);
-
-		if (group) {
-			exynos_iommu_detach_device(owner->domain, dev);
-			iommu_group_put(group);
-		}
-	}
-}
-
 static void exynos_iommu_release_device(struct device *dev)
 {
 	struct exynos_iommu_owner *owner = dev_iommu_priv_get(dev);
 	struct sysmmu_drvdata *data;
 
-	exynos_iommu_set_platform_dma(dev);
+	WARN_ON(exynos_iommu_identity_attach(&exynos_identity_domain, dev));
 
 	list_for_each_entry(data, &owner->controllers, owner_node)
 		device_link_del(data->link);
@@ -1457,6 +1456,7 @@ static int exynos_iommu_of_xlate(struct device *dev,
 
 		INIT_LIST_HEAD(&owner->controllers);
 		mutex_init(&owner->rpm_lock);
+		owner->domain = &exynos_identity_domain;
 		dev_iommu_priv_set(dev, owner);
 	}
 
@@ -1471,11 +1471,9 @@ static int exynos_iommu_of_xlate(struct device *dev,
 }
 
 static const struct iommu_ops exynos_iommu_ops = {
+	.identity_domain = &exynos_identity_domain,
 	.domain_alloc = exynos_iommu_domain_alloc,
 	.device_group = generic_device_group,
-#ifdef CONFIG_ARM
-	.set_platform_dma_ops = exynos_iommu_set_platform_dma,
-#endif
 	.probe_device = exynos_iommu_probe_device,
 	.release_device = exynos_iommu_release_device,
 	.pgsize_bitmap = SECT_SIZE | LPAGE_SIZE | SPAGE_SIZE,