linux-kernel - [PATCH 3/3] ARM/dma-mapping: Merge IOMMU ops

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Message-Id: <394482083c51c7596587a87edf012010f846feb0.1650539846.git.robin.murphy@arm.com>
Date:   Thu, 21 Apr 2022 12:36:59 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     hch@....de, linux@...linux.org.uk
Cc:     linux-arm-kernel@...ts.infradead.org, m.szyprowski@...sung.com,
        arnd@...nel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] ARM/dma-mapping: Merge IOMMU ops

The dma_sync_* operations are now the only difference between the
coherent and non-coherent IOMMU ops. Some minor tweaks to make those
safe for coherent devices with minimal overhead, and we can condense
down to a single set of DMA ops.

Signed-off-by: Robin Murphy <robin.murphy@....com>
---
 arch/arm/mm/dma-mapping.c | 37 +++++++++++++------------------------
 1 file changed, 13 insertions(+), 24 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 10e5e5800d78..dd46cce61579 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1341,6 +1341,9 @@ static void arm_iommu_sync_sg_for_cpu(struct device *dev,
 	struct scatterlist *s;
 	int i;
 
+	if (dev->dma_coherent)
+		return;
+
 	for_each_sg(sg, s, nents, i)
 		__dma_page_dev_to_cpu(sg_page(s), s->offset, s->length, dir);
 
@@ -1360,6 +1363,9 @@ static void arm_iommu_sync_sg_for_device(struct device *dev,
 	struct scatterlist *s;
 	int i;
 
+	if (dev->dma_coherent)
+		return;
+
 	for_each_sg(sg, s, nents, i)
 		__dma_page_cpu_to_dev(sg_page(s), s->offset, s->length, dir);
 }
@@ -1493,12 +1499,13 @@ static void arm_iommu_sync_single_for_cpu(struct device *dev,
 {
 	struct dma_iommu_mapping *mapping = to_dma_iommu_mapping(dev);
 	dma_addr_t iova = handle & PAGE_MASK;
-	struct page *page = phys_to_page(iommu_iova_to_phys(mapping->domain, iova));
+	struct page *page;
 	unsigned int offset = handle & ~PAGE_MASK;
 
-	if (!iova)
+	if (dev->dma_coherent || !iova)
 		return;
 
+	page = phys_to_page(iommu_iova_to_phys(mapping->domain, iova));
 	__dma_page_dev_to_cpu(page, offset, size, dir);
 }
 
@@ -1507,12 +1514,13 @@ static void arm_iommu_sync_single_for_device(struct device *dev,
 {
 	struct dma_iommu_mapping *mapping = to_dma_iommu_mapping(dev);
 	dma_addr_t iova = handle & PAGE_MASK;
-	struct page *page = phys_to_page(iommu_iova_to_phys(mapping->domain, iova));
+	struct page *page;
 	unsigned int offset = handle & ~PAGE_MASK;
 
-	if (!iova)
+	if (dev->dma_coherent || !iova)
 		return;
 
+	page = phys_to_page(iommu_iova_to_phys(mapping->domain, iova));
 	__dma_page_cpu_to_dev(page, offset, size, dir);
 }
 
@@ -1536,22 +1544,6 @@ static const struct dma_map_ops iommu_ops = {
 	.unmap_resource		= arm_iommu_unmap_resource,
 };
 
-static const struct dma_map_ops iommu_coherent_ops = {
-	.alloc		= arm_iommu_alloc_attrs,
-	.free		= arm_iommu_free_attrs,
-	.mmap		= arm_iommu_mmap_attrs,
-	.get_sgtable	= arm_iommu_get_sgtable,
-
-	.map_page	= arm_iommu_map_page,
-	.unmap_page	= arm_iommu_unmap_page,
-
-	.map_sg		= arm_iommu_map_sg,
-	.unmap_sg	= arm_iommu_unmap_sg,
-
-	.map_resource	= arm_iommu_map_resource,
-	.unmap_resource	= arm_iommu_unmap_resource,
-};
-
 /**
  * arm_iommu_create_mapping
  * @bus: pointer to the bus holding the client device (for IOMMU calls)
@@ -1750,10 +1742,7 @@ static void arm_setup_iommu_dma_ops(struct device *dev, u64 dma_base, u64 size,
 		return;
 	}
 
-	if (coherent)
-		set_dma_ops(dev, &iommu_coherent_ops);
-	else
-		set_dma_ops(dev, &iommu_ops);
+	set_dma_ops(dev, &iommu_ops);
 }
 
 static void arm_teardown_iommu_dma_ops(struct device *dev)
-- 
2.35.3.dirty