1 files changed, 71 insertions, 1 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f1ef5613ccd4..510c179b0ac8 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -19,6 +19,7 @@
 #include <linux/dma-mapping.h>
 
 #include <asm/memory.h>
+#include <asm/highmem.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/sizes.h>
@@ -517,6 +518,74 @@ void dma_cache_maint(const void *start, size_t size, int direction)
 }
 EXPORT_SYMBOL(dma_cache_maint);
 
+static void dma_cache_maint_contiguous(struct page *page, unsigned long offset,
+                                       size_t size, int direction)
+{
+        void *vaddr;
+        unsigned long paddr;
+        void (*inner_op)(const void *, const void *);
+        void (*outer_op)(unsigned long, unsigned long);
+
+        switch (direction) {
+        case DMA_FROM_DEVICE:           /* invalidate only */
+                inner_op = dmac_inv_range;
+                outer_op = outer_inv_range;
+                break;
+        case DMA_TO_DEVICE:             /* writeback only */
+                inner_op = dmac_clean_range;
+                outer_op = outer_clean_range;
+                break;
+        case DMA_BIDIRECTIONAL:         /* writeback and invalidate */
+                inner_op = dmac_flush_range;
+                outer_op = outer_flush_range;
+                break;
+        default:
+                BUG();
+        }
+
+        if (!PageHighMem(page)) {
+                vaddr = page_address(page) + offset;
+                inner_op(vaddr, vaddr + size);
+        } else {
+                vaddr = kmap_high_get(page);
+                if (vaddr) {
+                        vaddr += offset;
+                        inner_op(vaddr, vaddr + size);
+                        kunmap_high(page);
+                }
+        }
+
+        paddr = page_to_phys(page) + offset;
+        outer_op(paddr, paddr + size);
+}
+
+void dma_cache_maint_page(struct page *page, unsigned long offset,
+                          size_t size, int dir)
+{
+        /*
+         * A single sg entry may refer to multiple physically contiguous
+         * pages.  But we still need to process highmem pages individually.
+         * If highmem is not configured then the bulk of this loop gets
+         * optimized out.
+         */
+        size_t left = size;
+        do {
+                size_t len = left;
+                if (PageHighMem(page) && len + offset > PAGE_SIZE) {
+                        if (offset >= PAGE_SIZE) {
+                                page += offset / PAGE_SIZE;
+                                offset %= PAGE_SIZE;
+                        }
+                        len = PAGE_SIZE - offset;
+                }
+                dma_cache_maint_contiguous(page, offset, len, dir);
+                offset = 0;
+                page++;
+                left -= len;
+        } while (left);
+}
+EXPORT_SYMBOL(dma_cache_maint_page);
+
 /**
  * dma_map_sg - map a set of SG buffers for streaming mode DMA
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
@@ -614,7 +683,8 @@ void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
                         continue;
 
                 if (!arch_is_coherent())
-                        dma_cache_maint(sg_virt(s), s->length, dir);
+                        dma_cache_maint_page(sg_page(s), s->offset,
+                                             s->length, dir);
         }
 }
 EXPORT_SYMBOL(dma_sync_sg_for_device);