--- zzzz-none-000/linux-4.9.279/arch/arm/mm/dma-mapping.c	2021-08-08 06:38:54.000000000 +0000
+++ puma7-arm-6591-750/linux-4.9.279/arch/arm/mm/dma-mapping.c	2023-02-08 10:58:12.000000000 +0000
@@ -9,6 +9,10 @@
  *
  *  DMA uncached mapping support.
  */
+/*
+Includes Intel Corporation's changes/modifications dated: 2014.
+Changed/modified portions - Copyright © 2014, Intel Corporation.
+*/
 #include <linux/bootmem.h>
 #include <linux/module.h>
 #include <linux/mm.h>
@@ -1187,6 +1191,30 @@
 }
 core_initcall(dma_debug_do_init);
 
+/*
+ * Make an area consistent for devices.
+ */
+void consistent_sync(void *vaddr, size_t size, int direction)
+{
+	unsigned long start = (unsigned long)vaddr;
+	unsigned long end   = start + size;
+
+	switch (direction) {
+	case DMA_FROM_DEVICE:		/* invalidate only */
+		dmac_inv_range((void*)start, (void*)end);
+		break;
+	case DMA_TO_DEVICE:		/* writeback only */
+		dmac_clean_range((void*)start, (void*)end);
+		break;
+	case DMA_BIDIRECTIONAL:		/* writeback and invalidate */
+		dmac_flush_range((void*)start, (void*)end);
+		break;
+	default:
+		BUG();
+	}
+}
+EXPORT_SYMBOL(consistent_sync);
+
 #ifdef CONFIG_ARM_DMA_USE_IOMMU
 
 /* IOMMU */