--- linux-4.9.37/arch/arm/mm/dma-mapping.c	2017-07-12 16:42:41.000000000 +0300
+++ linux-4.9.y/arch/arm/mm/dma-mapping.c	2021-06-07 13:01:32.000000000 +0300
@@ -275,7 +275,7 @@
 	return mask;
 }
 
-static void __dma_clear_buffer(struct page *page, size_t size, int coherent_flag)
+void __dma_clear_buffer(struct page *page, size_t size, int coherent_flag)
 {
 	/*
 	 * Ensure that the allocated pages are zeroed, and that any data
@@ -304,6 +304,7 @@
 		}
 	}
 }
+EXPORT_SYMBOL(__dma_clear_buffer);
 
 /*
  * Allocate a DMA buffer for 'dev' of size 'size' using the
@@ -528,6 +529,12 @@
 	flush_tlb_kernel_range(start, end);
 }
 
+void bsp_flush_tlb_kernel_range(unsigned long start, unsigned long end)
+{
+	flush_tlb_kernel_range(start, end);
+}
+EXPORT_SYMBOL(bsp_flush_tlb_kernel_range);
+
 static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
 				 pgprot_t prot, struct page **ret_page,
 				 const void *caller, bool want_vaddr)
@@ -2397,3 +2404,10 @@
 {
 	arm_teardown_iommu_dma_ops(dev);
 }
+
+void bsp_dmac_map_area(const void *kaddr, size_t size,
+			enum dma_data_direction dir)
+{
+	dmac_map_area(kaddr, size, dir);
+}
+EXPORT_SYMBOL(bsp_dmac_map_area);