LXR linux/lib/dma-virt.c

   1/*
   2 *      lib/dma-virt.c
   3 *
   4 * DMA operations that map to virtual addresses without flushing 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_virt_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 = (uintptr_t)ret;
  20        return ret;
  21}
  22
  23static void dma_virt_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
  30static dma_addr_t dma_virt_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 (uintptr_t)(page_address(page) + offset);
  36}
  37
  38static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
  39                           int nents, 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                BUG_ON(!sg_page(sg));
  47                sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
  48                sg_dma_len(sg) = sg->length;
  49        }
  50
  51        return nents;
  52}
  53
  54const struct dma_map_ops dma_virt_ops = {
  55        .alloc                  = dma_virt_alloc,
  56        .free                   = dma_virt_free,
  57        .map_page               = dma_virt_map_page,
  58        .map_sg                 = dma_virt_map_sg,
  59};
  60EXPORT_SYMBOL(dma_virt_ops);
  61