ARM: dma-mapping: add support for DMA_ATTR_FORCE_CONTIGUOUS attribute

This patch adds support for DMA_ATTR_FORCE_CONTIGUOUS attribute for
dma_alloc_attrs() in IOMMU-aware implementation. For allocating physically
contiguous buffers Contiguous Memory Allocator is used.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

1 files changed, 33 insertions, 8 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 58bc3e4d3bd0..f076f209c7a4 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1036,7 +1036,8 @@ static inline void __free_iova(struct dma_iommu_mapping *mapping,
         spin_unlock_irqrestore(&mapping->lock, flags);
 }
 
-static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
+static struct page **__iommu_alloc_buffer(struct device *dev, size_t size,
+                                          gfp_t gfp, struct dma_attrs *attrs)
 {
         struct page **pages;
         int count = size >> PAGE_SHIFT;
@@ -1050,6 +1051,23 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, gfp_t
         if (!pages)
                 return NULL;
 
+        if (dma_get_attr(DMA_ATTR_FORCE_CONTIGUOUS, attrs))
+        {
+                unsigned long order = get_order(size);
+                struct page *page;
+
+                page = dma_alloc_from_contiguous(dev, count, order);
+                if (!page)
+                        goto error;
+
+                __dma_clear_buffer(page, size);
+
+                for (i = 0; i < count; i++)
+                        pages[i] = page + i;
+
+                return pages;
+        }
+
         while (count) {
                 int j, order = __fls(count);
 
@@ -1083,14 +1101,21 @@ error:
         return NULL;
 }
 
-static int __iommu_free_buffer(struct device *dev, struct page **pages, size_t size)
+static int __iommu_free_buffer(struct device *dev, struct page **pages,
+                               size_t size, struct dma_attrs *attrs)
 {
         int count = size >> PAGE_SHIFT;
         int array_size = count * sizeof(struct page *);
         int i;
-        for (i = 0; i < count; i++)
-                if (pages[i])
-                        __free_pages(pages[i], 0);
+
+        if (dma_get_attr(DMA_ATTR_FORCE_CONTIGUOUS, attrs)) {
+                dma_release_from_contiguous(dev, pages[0], count);
+        } else {
+                for (i = 0; i < count; i++)
+                        if (pages[i])
+                                __free_pages(pages[i], 0);
+        }
+
         if (array_size <= PAGE_SIZE)
                 kfree(pages);
         else
@@ -1252,7 +1277,7 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
         if (gfp & GFP_ATOMIC)
                 return __iommu_alloc_atomic(dev, size, handle);
 
-        pages = __iommu_alloc_buffer(dev, size, gfp);
+        pages = __iommu_alloc_buffer(dev, size, gfp, attrs);
         if (!pages)
                 return NULL;
 
@@ -1273,7 +1298,7 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
 err_mapping:
         __iommu_remove_mapping(dev, *handle, size);
 err_buffer:
-        __iommu_free_buffer(dev, pages, size);
+        __iommu_free_buffer(dev, pages, size, attrs);
         return NULL;
 }
 
@@ -1329,7 +1354,7 @@ void arm_iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
         }
 
         __iommu_remove_mapping(dev, handle, size);
-        __iommu_free_buffer(dev, pages, size);
+        __iommu_free_buffer(dev, pages, size, attrs);
 }
 
 static int arm_iommu_get_sgtable(struct device *dev, struct sg_table *sgt,