arm64: dma-mapping: implement dma_get_sgtable()

The default dma_common_get_sgtable() implementation relies on the CPU
address of the buffer being a regular lowmem address. This is not always
the case on arm64, since allocations from the various DMA pools may have
remapped vmalloc addresses, rendering the use of virt_to_page() invalid.

Fix this by providing our own implementation based on the fact that we
can safely derive a physical address from the DMA address in both cases.

CC: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
[will: made static]
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 63b2a117a03cad58390c8925bc0f5a363d69ef2d..e5d74cdfdb711db90a88b6249c69f72e18800fd1 100644 (file)
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -331,10 +331,24 @@ static int __swiotlb_mmap(struct device *dev,
        return ret;
 }
 
+static int __swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
+                                void *cpu_addr, dma_addr_t handle, size_t size,
+                                struct dma_attrs *attrs)
+{
+       int ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
+
+       if (!ret)
+               sg_set_page(sgt->sgl, phys_to_page(dma_to_phys(dev, handle)),
+                           PAGE_ALIGN(size), 0);
+
+       return ret;
+}
+
 static struct dma_map_ops swiotlb_dma_ops = {
        .alloc = __dma_alloc,
        .free = __dma_free,
        .mmap = __swiotlb_mmap,
+       .get_sgtable = __swiotlb_get_sgtable,
        .map_page = __swiotlb_map_page,
        .unmap_page = __swiotlb_unmap_page,
        .map_sg = __swiotlb_map_sg_attrs,