[PATCH V3 8/8] arm64: dma-mapping: Remove the notifier trick to handle early setting of dma_ops

-----Original Message-----
From: linux-arm-kernel [mailto:linux-arm-kernel-bounces at lists.infradead.org] On Behalf Of Sricharan R
Sent: Tuesday, October 04, 2016 10:34 PM
To: will.deacon at arm.com; robin.murphy at arm.com; joro at 8bytes.org; iommu at lists.linux-foundation.org; linux-arm-
kernel at lists.infradead.org; linux-arm-msm at vger.kernel.org; laurent.pinchart at ideasonboard.com; m.szyprowski at samsung.com;
tfiga at chromium.org; srinivas.kandagatla at linaro.org
Cc: sricharan at codeaurora.org
Subject: [PATCH V3 8/8] 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.

Signed-off-by: Sricharan R <redacted>
---
arch/arm64/mm/dma-mapping.c | 100 ++------------------------------------------
1 file changed, 3 insertions(+), 97 deletions(-)

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index faf4b92..eb593af 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c

@@ -799,24 +799,6 @@ static 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 bool do_iommu_attach(struct device *dev, const struct iommu_ops *ops,
			   u64 dma_base, u64 size)
{

@@ -837,79 +819,9 @@ static bool do_iommu_attach(struct device *dev, const struct iommu_ops *ops,

	return true;
}

-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;
+	return iommu_dma_init();
}
arch_initcall(__iommu_dma_init);

@@ -920,18 +832,12 @@ static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,

	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);
	}
}