1 files changed, 59 insertions, 0 deletions
diff --git a/kernel/dma/virt.c b/kernel/dma/virt.c
new file mode 100644
index 000000000..631ddec4b
--- /dev/null
+++ b/kernel/dma/virt.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DMA operations that map to virtual addresses without flushing memory.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+
+static void *dma_virt_alloc(struct device *dev, size_t size,
+			    dma_addr_t *dma_handle, gfp_t gfp,
+			    unsigned long attrs)
+{
+	void *ret;
+
+	ret = (void *)__get_free_pages(gfp, get_order(size));
+	if (ret)
+		*dma_handle = (uintptr_t)ret;
+	return ret;
+}
+
+static void dma_virt_free(struct device *dev, size_t size,
+			  void *cpu_addr, dma_addr_t dma_addr,
+			  unsigned long attrs)
+{
+	free_pages((unsigned long)cpu_addr, get_order(size));
+}
+
+static dma_addr_t dma_virt_map_page(struct device *dev, struct page *page,
+				    unsigned long offset, size_t size,
+				    enum dma_data_direction dir,
+				    unsigned long attrs)
+{
+	return (uintptr_t)(page_address(page) + offset);
+}
+
+static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
+			   int nents, enum dma_data_direction dir,
+			   unsigned long attrs)
+{
+	int i;
+	struct scatterlist *sg;
+
+	for_each_sg(sgl, sg, nents, i) {
+		BUG_ON(!sg_page(sg));
+		sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
+		sg_dma_len(sg) = sg->length;
+	}
+
+	return nents;
+}
+
+const struct dma_map_ops dma_virt_ops = {
+	.alloc			= dma_virt_alloc,
+	.free			= dma_virt_free,
+	.map_page		= dma_virt_map_page,
+	.map_sg			= dma_virt_map_sg,
+};
+EXPORT_SYMBOL(dma_virt_ops);