dma-direct: rename dma_noop to dma_direct

The trivial direct mapping implementation already does a virtual to
physical translation which isn't strictly a noop, and will soon learn
to do non-direct but linear physical to dma translations through the
device offset and a few small tricks.  Rename it to a better fitting
name.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>

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);