Hi Marek,

On Wed, 29 Feb 2012 16:04:22 +0100
Marek Szyprowski [off-list ref] wrote:

This patch add a complete implementation of DMA-mapping API for
devices that have IOMMU support. All DMA-mapping calls are supported.

This patch contains some of the code kindly provided by Krishna Reddy
[off-list ref] and Andrzej Pietrasiewicz [off-list ref]

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Konrad Rzeszutek Wilk <redacted>
---
 arch/arm/Kconfig                 |    8 +
 arch/arm/include/asm/device.h    |    3 +
 arch/arm/include/asm/dma-iommu.h |   34 ++
 arch/arm/mm/dma-mapping.c        |  726 +++++++++++++++++++++++++++++++++++++-
 arch/arm/mm/vmregion.h           |    2 +-
 5 files changed, 758 insertions(+), 15 deletions(-)
 create mode 100644 arch/arm/include/asm/dma-iommu.h

<snip>

+/*
+ * Map a part of the scatter-gather list into contiguous io address space
+ */
+static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
+                         size_t size, dma_addr_t *handle,
+                         enum dma_data_direction dir)
+{
+       struct dma_iommu_mapping *mapping = dev->archdata.mapping;
+       dma_addr_t iova, iova_base;
+       int ret = 0;
+       unsigned int count;
+       struct scatterlist *s;
+
+       size = PAGE_ALIGN(size);
+       *handle = ARM_DMA_ERROR;
+
+       iova_base = iova = __alloc_iova(mapping, size);
+       if (iova == ARM_DMA_ERROR)
+               return -ENOMEM;
+
+       for (count = 0, s = sg; count < (size >> PAGE_SHIFT); s = sg_next(s))
+       {
+               phys_addr_t phys = page_to_phys(sg_page(s));
+               unsigned int len = PAGE_ALIGN(s->offset + s->length);
+
+               if (!arch_is_coherent())
+                       __dma_page_cpu_to_dev(sg_page(s), s->offset, s->length, dir);
+
+               ret = iommu_map(mapping->domain, iova, phys, len, 0);
+               if (ret < 0)
+                       goto fail;
+               count += len >> PAGE_SHIFT;
+               iova += len;
+       }
+       *handle = iova_base;
+
+       return 0;
+fail:
+       iommu_unmap(mapping->domain, iova_base, count * PAGE_SIZE);
+       __free_iova(mapping, iova_base, size);
+       return ret;
+}

Do we need to set dma_address as below?

From e8bcc3cdac5375b5d7f5ac5b3f716a11c1008f38 Mon Sep 17 00:00:00 2001

From: Hiroshi DOYU <redacted>
Date: Thu, 29 Mar 2012 09:59:04 +0300
Subject: [PATCH 1/1] ARM: dma-mapping: Fix dma_address in sglist

s->dma_address wasn't set at mapping.

Signed-off-by: Hiroshi DOYU <redacted>
---
 arch/arm/mm/dma-mapping.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 3347c37..11a9d65 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c

@@ -1111,6 +1111,8 @@ static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
 		ret = iommu_map(mapping->domain, iova, phys, len, 0);
 		if (ret < 0)
 			goto fail;
+		s->dma_address = iova;
+
 		count += len >> PAGE_SHIFT;
 		iova += len;
 	}

-- 
1.7.5.4