[ARM] introduce dma_cache_maint_page()

This is a helper to be used by the DMA mapping API to handle cache
maintenance for memory identified by a page structure instead of a
virtual address.  Those pages may or may not be highmem pages, and
when they're highmem pages, they may or may not be virtually mapped.
When they're not mapped then there is no L1 cache to worry about. But
even in that case the L2 cache must be processed since unmapped highmem
pages can still be L2 cached.

Signed-off-by: Nicolas Pitre <nico@marvell.com>

2 files changed, 6 insertions, 1 deletions

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index 22cb14ec3438..59fa762e9c66 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -57,6 +57,8 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
  * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
  */
 extern void dma_cache_maint(const void *kaddr, size_t size, int rw);
+extern void dma_cache_maint_page(struct page *page, unsigned long offset,
+                                 size_t size, int rw);
 
 /*
  * Return whether the given device DMA address mask can be supported
@@ -316,7 +318,7 @@ static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
         BUG_ON(!valid_dma_direction(dir));
 
         if (!arch_is_coherent())
-                dma_cache_maint(page_address(page) + offset, size, dir);
+                dma_cache_maint_page(page, offset, size, dir);
 
         return page_to_dma(dev, page) + offset;
 }
diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
index 023d5b374544..7f36d00600b4 100644
--- a/arch/arm/include/asm/highmem.h
+++ b/arch/arm/include/asm/highmem.h
@@ -15,7 +15,10 @@
 
 extern pte_t *pkmap_page_table;
 
+#define ARCH_NEEDS_KMAP_HIGH_GET
+
 extern void *kmap_high(struct page *page);
+extern void *kmap_high_get(struct page *page);
 extern void kunmap_high(struct page *page);
 
 extern void *kmap(struct page *page);