arm64: dma-mapping: Remove the notifier trick to handle early setting of dma_ops

With arch_setup_dma_ops now being called late during device's probe after
the device's iommu is probed, the notifier trick required to handle the
early setup of dma_ops before the iommu group gets created is not
required. So removing the notifier's here.
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
[rm: clean up even more]
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

arch/arm64/mm/dma-mapping.c

@@ -813,34 +813,26 @@ static const struct dma_map_ops iommu_dma_ops = {
 	.mapping_error = iommu_dma_mapping_error,
 };
 
-/*
- * TODO: Right now __iommu_setup_dma_ops() gets called too early to do
- * everything it needs to - the device is only partially created and the
- * IOMMU driver hasn't seen it yet, so it can't have a group. Thus we
- * need this delayed attachment dance. Once IOMMU probe ordering is sorted
- * to move the arch_setup_dma_ops() call later, all the notifier bits below
- * become unnecessary, and will go away.
- */
-struct iommu_dma_notifier_data {
-	struct list_head list;
-	struct device *dev;
-	const struct iommu_ops *ops;
-	u64 dma_base;
-	u64 size;
-};
-static LIST_HEAD(iommu_dma_masters);
-static DEFINE_MUTEX(iommu_dma_notifier_lock);
+static int __init __iommu_dma_init(void)
+{
+	return iommu_dma_init();
+}
+arch_initcall(__iommu_dma_init);
 
-static bool do_iommu_attach(struct device *dev, const struct iommu_ops *ops,
-			   u64 dma_base, u64 size)
+static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+				  const struct iommu_ops *ops)
 {
-	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+	struct iommu_domain *domain;
+
+	if (!ops)
+		return;
 
 	/*
-	 * If the IOMMU driver has the DMA domain support that we require,
-	 * then the IOMMU core will have already configured a group for this
-	 * device, and allocated the default domain for that group.
+	 * The IOMMU core code allocates the default DMA domain, which the
+	 * underlying IOMMU driver needs to support via the dma-iommu layer.
 	 */
+	domain = iommu_get_domain_for_dev(dev);
+
 	if (!domain)
 		goto out_err;
 
@@ -851,109 +843,11 @@ static bool do_iommu_attach(struct device *dev, const struct iommu_ops *ops,
 		dev->dma_ops = &iommu_dma_ops;
 	}
 
-	return true;
+	return;
+
 out_err:
-	pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
+	 pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",
 		 dev_name(dev));
-	return false;
-}
-
-static void queue_iommu_attach(struct device *dev, const struct iommu_ops *ops,
-			      u64 dma_base, u64 size)
-{
-	struct iommu_dma_notifier_data *iommudata;
-
-	iommudata = kzalloc(sizeof(*iommudata), GFP_KERNEL);
-	if (!iommudata)
-		return;
-
-	iommudata->dev = dev;
-	iommudata->ops = ops;
-	iommudata->dma_base = dma_base;
-	iommudata->size = size;
-
-	mutex_lock(&iommu_dma_notifier_lock);
-	list_add(&iommudata->list, &iommu_dma_masters);
-	mutex_unlock(&iommu_dma_notifier_lock);
-}
-
-static int __iommu_attach_notifier(struct notifier_block *nb,
-				   unsigned long action, void *data)
-{
-	struct iommu_dma_notifier_data *master, *tmp;
-
-	if (action != BUS_NOTIFY_BIND_DRIVER)
-		return 0;
-
-	mutex_lock(&iommu_dma_notifier_lock);
-	list_for_each_entry_safe(master, tmp, &iommu_dma_masters, list) {
-		if (data == master->dev && do_iommu_attach(master->dev,
-				master->ops, master->dma_base, master->size)) {
-			list_del(&master->list);
-			kfree(master);
-			break;
-		}
-	}
-	mutex_unlock(&iommu_dma_notifier_lock);
-	return 0;
-}
-
-static int __init register_iommu_dma_ops_notifier(struct bus_type *bus)
-{
-	struct notifier_block *nb = kzalloc(sizeof(*nb), GFP_KERNEL);
-	int ret;
-
-	if (!nb)
-		return -ENOMEM;
-
-	nb->notifier_call = __iommu_attach_notifier;
-
-	ret = bus_register_notifier(bus, nb);
-	if (ret) {
-		pr_warn("Failed to register DMA domain notifier; IOMMU DMA ops unavailable on bus '%s'\n",
-			bus->name);
-		kfree(nb);
-	}
-	return ret;
-}
-
-static int __init __iommu_dma_init(void)
-{
-	int ret;
-
-	ret = iommu_dma_init();
-	if (!ret)
-		ret = register_iommu_dma_ops_notifier(&platform_bus_type);
-	if (!ret)
-		ret = register_iommu_dma_ops_notifier(&amba_bustype);
-#ifdef CONFIG_PCI
-	if (!ret)
-		ret = register_iommu_dma_ops_notifier(&pci_bus_type);
-#endif
-	return ret;
-}
-arch_initcall(__iommu_dma_init);
-
-static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
-				  const struct iommu_ops *ops)
-{
-	struct iommu_group *group;
-
-	if (!ops)
-		return;
-	/*
-	 * TODO: As a concession to the future, we're ready to handle being
-	 * called both early and late (i.e. after bus_add_device). Once all
-	 * the platform bus code is reworked to call us late and the notifier
-	 * junk above goes away, move the body of do_iommu_attach here.
-	 */
-	group = iommu_group_get(dev);
-	if (group) {
-		do_iommu_attach(dev, ops, dma_base, size);
-		iommu_group_put(group);
-	} else {
-		queue_iommu_attach(dev, ops, dma_base, size);
-	}
 }
 
 void arch_teardown_dma_ops(struct device *dev)