v4.19.13 snapshot.
diff --git a/kernel/dma/noncoherent.c b/kernel/dma/noncoherent.c
new file mode 100644
index 0000000..031fe23
--- /dev/null
+++ b/kernel/dma/noncoherent.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Christoph Hellwig.
+ *
+ * DMA operations that map physical memory directly without providing cache
+ * coherence.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-direct.h>
+#include <linux/dma-noncoherent.h>
+#include <linux/scatterlist.h>
+
+static void dma_noncoherent_sync_single_for_device(struct device *dev,
+ dma_addr_t addr, size_t size, enum dma_data_direction dir)
+{
+ arch_sync_dma_for_device(dev, dma_to_phys(dev, addr), size, dir);
+}
+
+static void dma_noncoherent_sync_sg_for_device(struct device *dev,
+ struct scatterlist *sgl, int nents, enum dma_data_direction dir)
+{
+ struct scatterlist *sg;
+ int i;
+
+ for_each_sg(sgl, sg, nents, i)
+ arch_sync_dma_for_device(dev, sg_phys(sg), sg->length, dir);
+}
+
+static dma_addr_t dma_noncoherent_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size, enum dma_data_direction dir,
+ unsigned long attrs)
+{
+ dma_addr_t addr;
+
+ addr = dma_direct_map_page(dev, page, offset, size, dir, attrs);
+ if (!dma_mapping_error(dev, addr) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ arch_sync_dma_for_device(dev, page_to_phys(page) + offset,
+ size, dir);
+ return addr;
+}
+
+static int dma_noncoherent_map_sg(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+ nents = dma_direct_map_sg(dev, sgl, nents, dir, attrs);
+ if (nents > 0 && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ dma_noncoherent_sync_sg_for_device(dev, sgl, nents, dir);
+ return nents;
+}
+
+#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
+ defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
+static void dma_noncoherent_sync_single_for_cpu(struct device *dev,
+ dma_addr_t addr, size_t size, enum dma_data_direction dir)
+{
+ arch_sync_dma_for_cpu(dev, dma_to_phys(dev, addr), size, dir);
+ arch_sync_dma_for_cpu_all(dev);
+}
+
+static void dma_noncoherent_sync_sg_for_cpu(struct device *dev,
+ struct scatterlist *sgl, int nents, enum dma_data_direction dir)
+{
+ struct scatterlist *sg;
+ int i;
+
+ for_each_sg(sgl, sg, nents, i)
+ arch_sync_dma_for_cpu(dev, sg_phys(sg), sg->length, dir);
+ arch_sync_dma_for_cpu_all(dev);
+}
+
+static void dma_noncoherent_unmap_page(struct device *dev, dma_addr_t addr,
+ size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ dma_noncoherent_sync_single_for_cpu(dev, addr, size, dir);
+}
+
+static void dma_noncoherent_unmap_sg(struct device *dev, struct scatterlist *sgl,
+ int nents, enum dma_data_direction dir, unsigned long attrs)
+{
+ if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+ dma_noncoherent_sync_sg_for_cpu(dev, sgl, nents, dir);
+}
+#endif
+
+const struct dma_map_ops dma_noncoherent_ops = {
+ .alloc = arch_dma_alloc,
+ .free = arch_dma_free,
+ .mmap = arch_dma_mmap,
+ .sync_single_for_device = dma_noncoherent_sync_single_for_device,
+ .sync_sg_for_device = dma_noncoherent_sync_sg_for_device,
+ .map_page = dma_noncoherent_map_page,
+ .map_sg = dma_noncoherent_map_sg,
+#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
+ defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
+ .sync_single_for_cpu = dma_noncoherent_sync_single_for_cpu,
+ .sync_sg_for_cpu = dma_noncoherent_sync_sg_for_cpu,
+ .unmap_page = dma_noncoherent_unmap_page,
+ .unmap_sg = dma_noncoherent_unmap_sg,
+#endif
+ .dma_supported = dma_direct_supported,
+ .mapping_error = dma_direct_mapping_error,
+ .cache_sync = arch_dma_cache_sync,
+};
+EXPORT_SYMBOL(dma_noncoherent_ops);