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

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Message-Id: <20210128145837.2250561-6-hch@lst.de>
Date:   Thu, 28 Jan 2021 15:58:36 +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>,
        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>
---
 drivers/iommu/dma-iommu.c | 47 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 65af875ba8495c..938a2856b4a455 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -756,6 +756,49 @@ 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, dma_addr_t *dma_handle,
+		enum dma_data_direction dir, gfp_t gfp)
+{
+	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+	struct dma_sgt_handle *sh;
+
+	sh = kmalloc(sizeof(*sh), gfp);
+	if (!sh)
+		return NULL;
+
+	sh->pages = __iommu_dma_alloc_noncontiguous(dev, size, &sh->sgt,
+						    dma_handle, gfp,
+						    PAGE_KERNEL, 0);
+	if (!sh->pages)
+		goto out_free_sh;
+
+	if (sg_alloc_table_from_pages(&sh->sgt, sh->pages, count, 0, size,
+				      GFP_KERNEL))
+		goto out_free_pages;
+
+	return &sh->sgt;
+
+out_free_pages:
+	__iommu_dma_free_pages(sh->pages, count);
+out_free_sh:
+	kfree(sh);
+	return NULL;
+}
+
+static void iommu_dma_free_noncontiguous(struct device *dev, size_t size,
+		struct sg_table *sgt, dma_addr_t dma_handle,
+		enum dma_data_direction dir)
+{
+	struct dma_sgt_handle *sh = sgt_handle(sgt);
+
+	__iommu_dma_unmap(dev, dma_handle, 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)
 {
@@ -1271,6 +1314,10 @@ 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