dma: Take into account dma_pfn_offset

Even though dma-noop-ops assumes 1:1 memory mapping DMA memory range
can be different to RAM. For example, ARM STM32F4 MCU offers the
possibility to remap SDRAM from 0xc000_0000 to 0x0 to get CPU
performance boost, but DMA continue to see SDRAM at 0xc000_0000. This
difference in mapping is handled via device-tree "dma-range" property
which leads to dev->dma_pfn_offset is set nonzero. To handle such
cases take dma_pfn_offset into account.

Cc: Joerg Roedel <jroedel@suse.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Reported-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Andras Szemzo <sza@esh.hu>
Tested-by: Alexandre TORGUE <alexandre.torgue@st.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/lib/dma-noop.c b/lib/dma-noop.c
index 643a074f139d9c2346d0b65b69ed036fe0b5d633..acc4190e2731ec1bf65def9b8dcb250eac8fcaf7 100644 (file)
--- a/lib/dma-noop.c
+++ b/lib/dma-noop.c
@@ -7,6 +7,7 @@
 #include <linux/mm.h>
 #include <linux/dma-mapping.h>
 #include <linux/scatterlist.h>
+#include <linux/pfn.h>
 
 static void *dma_noop_alloc(struct device *dev, size_t size,
                            dma_addr_t *dma_handle, gfp_t gfp,
@@ -16,7 +17,8 @@ static void *dma_noop_alloc(struct device *dev, size_t size,
 
        ret = (void *)__get_free_pages(gfp, get_order(size));
        if (ret)
-               *dma_handle = virt_to_phys(ret);
+               *dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
+
        return ret;
 }
 
@@ -32,7 +34,7 @@ static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
                                      enum dma_data_direction dir,
                                      unsigned long attrs)
 {
-       return page_to_phys(page) + offset;
+       return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
 }
 
 static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
@@ -43,11 +45,12 @@ static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nent
        struct scatterlist *sg;
 
        for_each_sg(sgl, sg, nents, i) {
+               dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset);
                void *va;
 
                BUG_ON(!sg_page(sg));
                va = sg_virt(sg);
-               sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
+               sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va) - offset;
                sg_dma_len(sg) = sg->length;
        }