LXR 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
  11static void *dma_noop_alloc(struct device *dev, size_t size,
  12                            dma_addr_t *dma_handle, gfp_t gfp,
  13                            struct dma_attrs *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
  23static void dma_noop_free(struct device *dev, size_t size,
  24                          void *cpu_addr, dma_addr_t dma_addr,
  25                          struct dma_attrs *attrs)
  26{
  27        free_pages((unsigned long)cpu_addr, get_order(size));
  28}
  29
  30static 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                                      struct dma_attrs *attrs)
  34{
  35        return page_to_phys(page) + offset;
  36}
  37
  38static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
  39                             enum dma_data_direction dir, struct dma_attrs *attrs)
  40{
  41        int i;
  42        struct scatterlist *sg;
  43
  44        for_each_sg(sgl, sg, nents, i) {
  45                void *va;
  46
  47                BUG_ON(!sg_page(sg));
  48                va = sg_virt(sg);
  49                sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
  50                sg_dma_len(sg) = sg->length;
  51        }
  52
  53        return nents;
  54}
  55
  56static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr)
  57{
  58        return 0;
  59}
  60
  61static int dma_noop_supported(struct device *dev, u64 mask)
  62{
  63        return 1;
  64}
  65
  66struct dma_map_ops dma_noop_ops = {
  67        .alloc                  = dma_noop_alloc,
  68        .free                   = dma_noop_free,
  69        .map_page               = dma_noop_map_page,
  70        .map_sg                 = dma_noop_map_sg,
  71        .mapping_error          = dma_noop_mapping_error,
  72        .dma_supported          = dma_noop_supported,
  73};
  74
  75EXPORT_SYMBOL(dma_noop_ops);
  76