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-rw-r--r--lib/dma-direct.c63
1 files changed, 63 insertions, 0 deletions
diff --git a/lib/dma-direct.c b/lib/dma-direct.c
new file mode 100644
index 000000000000..0ec3262a3148
--- /dev/null
+++ b/lib/dma-direct.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * lib/dma-noop.c
+ *
+ * DMA operations that map to physical addresses without flushing memory.
+ */
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+#include <linux/pfn.h>
+
+static void *dma_direct_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 = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
+
+ return ret;
+}
+
+static void dma_direct_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_direct_map_page(struct device *dev, struct page *page,
+ unsigned long offset, size_t size, enum dma_data_direction dir,
+ unsigned long attrs)
+{
+ return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
+}
+
+static int dma_direct_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) {
+ dma_addr_t offset = PFN_PHYS(dev->dma_pfn_offset);
+ void *va;
+
+ BUG_ON(!sg_page(sg));
+ va = sg_virt(sg);
+ sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va) - offset;
+ sg_dma_len(sg) = sg->length;
+ }
+
+ return nents;
+}
+
+const struct dma_map_ops dma_direct_ops = {
+ .alloc = dma_direct_alloc,
+ .free = dma_direct_free,
+ .map_page = dma_direct_map_page,
+ .map_sg = dma_direct_map_sg,
+};
+EXPORT_SYMBOL(dma_direct_ops);