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Linux/lib/dma-noop.c

  1 /*
  2  *      lib/dma-noop.c
  3  *
  4  * Simple DMA noop-ops that map 1:1 with memory
  5  */
  6 #include <linux/export.h>
  7 #include <linux/mm.h>
  8 #include <linux/dma-mapping.h>
  9 #include <linux/scatterlist.h>
 10 
 11 static void *dma_noop_alloc(struct device *dev, size_t size,
 12                             dma_addr_t *dma_handle, gfp_t gfp,
 13                             unsigned long attrs)
 14 {
 15         void *ret;
 16 
 17         ret = (void *)__get_free_pages(gfp, get_order(size));
 18         if (ret)
 19                 *dma_handle = virt_to_phys(ret);
 20         return ret;
 21 }
 22 
 23 static void dma_noop_free(struct device *dev, size_t size,
 24                           void *cpu_addr, dma_addr_t dma_addr,
 25                           unsigned long attrs)
 26 {
 27         free_pages((unsigned long)cpu_addr, get_order(size));
 28 }
 29 
 30 static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
 31                                       unsigned long offset, size_t size,
 32                                       enum dma_data_direction dir,
 33                                       unsigned long attrs)
 34 {
 35         return page_to_phys(page) + offset;
 36 }
 37 
 38 static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
 39                              enum dma_data_direction dir,
 40                              unsigned long attrs)
 41 {
 42         int i;
 43         struct scatterlist *sg;
 44 
 45         for_each_sg(sgl, sg, nents, i) {
 46                 void *va;
 47 
 48                 BUG_ON(!sg_page(sg));
 49                 va = sg_virt(sg);
 50                 sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
 51                 sg_dma_len(sg) = sg->length;
 52         }
 53 
 54         return nents;
 55 }
 56 
 57 static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr)
 58 {
 59         return 0;
 60 }
 61 
 62 static int dma_noop_supported(struct device *dev, u64 mask)
 63 {
 64         return 1;
 65 }
 66 
 67 struct dma_map_ops dma_noop_ops = {
 68         .alloc                  = dma_noop_alloc,
 69         .free                   = dma_noop_free,
 70         .map_page               = dma_noop_map_page,
 71         .map_sg                 = dma_noop_map_sg,
 72         .mapping_error          = dma_noop_mapping_error,
 73         .dma_supported          = dma_noop_supported,
 74 };
 75 
 76 EXPORT_SYMBOL(dma_noop_ops);
 77 

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