blob: acc4190e2731ec1bf65def9b8dcb250eac8fcaf7 [file] [log] [blame]
* 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_noop_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_noop_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_noop_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_noop_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;
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_noop_ops = {
.alloc = dma_noop_alloc,
.free = dma_noop_free,
.map_page = dma_noop_map_page,
.map_sg = dma_noop_map_sg,