linux-kernel - [PATCH 5/6] dma-iommu: implement ->alloc

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Date:   Mon,  1 Mar 2021 09:52:35 +0100
From:   Christoph Hellwig <hch@....de>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Ricardo Ribalda <ribalda@...omium.org>,
        Sergey Senozhatsky <senozhatsky@...gle.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        iommu@...ts.linux-foundation.org
Cc:     Robin Murphy <robin.murphy@....com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: [PATCH 5/6] dma-iommu: implement ->alloc_noncontiguous

Implement support for allocating a non-contiguous DMA region.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Tomasz Figa <tfiga@...omium.org>
Tested-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/iommu/dma-iommu.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index b4d7bfffb3a0d2..714fa930d7b576 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -707,6 +707,7 @@ static struct page **__iommu_dma_alloc_noncontiguous(struct device *dev,
 		goto out_free_sg;
 
 	sgt->sgl->dma_address = iova;
+	sgt->sgl->dma_length = size;
 	return pages;
 
 out_free_sg:
@@ -744,6 +745,37 @@ static void *iommu_dma_alloc_remap(struct device *dev, size_t size,
 	return NULL;
 }
 
+#ifdef CONFIG_DMA_REMAP
+static struct sg_table *iommu_dma_alloc_noncontiguous(struct device *dev,
+		size_t size, enum dma_data_direction dir, gfp_t gfp,
+		unsigned long attrs)
+{
+	struct dma_sgt_handle *sh;
+
+	sh = kmalloc(sizeof(*sh), gfp);
+	if (!sh)
+		return NULL;
+
+	sh->pages = __iommu_dma_alloc_noncontiguous(dev, size, &sh->sgt, gfp,
+						    PAGE_KERNEL, attrs);
+	if (!sh->pages) {
+		kfree(sh);
+		return NULL;
+	}
+	return &sh->sgt;
+}
+
+static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
+		struct sg_table *sgt, enum dma_data_direction dir)
+{
+	struct dma_sgt_handle *sh = sgt_handle(sgt);
+
+	__iommu_dma_unmap(dev, sgt->sgl->dma_address, size);
+	__iommu_dma_free_pages(sh->pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
+	sg_free_table(&sh->sgt);
+}
+#endif /* CONFIG_DMA_REMAP */
+
 static void iommu_dma_sync_single_for_cpu(struct device *dev,
 		dma_addr_t dma_handle, size_t size, enum dma_data_direction dir)
 {
@@ -1260,6 +1292,10 @@ static const struct dma_map_ops iommu_dma_ops = {
 	.free			= iommu_dma_free,
 	.alloc_pages		= dma_common_alloc_pages,
 	.free_pages		= dma_common_free_pages,
+#ifdef CONFIG_DMA_REMAP
+	.alloc_noncontiguous	= iommu_dma_alloc_noncontiguous,
+	.free_noncontiguous	= iommu_dma_free_noncontiguous,
+#endif
 	.mmap			= iommu_dma_mmap,
 	.get_sgtable		= iommu_dma_get_sgtable,
 	.map_page		= iommu_dma_map_page,
-- 
2.29.2