arch/powerpc/kernel/dma.c

   1 /*
   2  * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
   3  *
   4  * Provide default implementations of the DMA mapping callbacks for
   5  * directly mapped busses.
   6  */
   7
   8 #include <linux/device.h>
   9 #include <linux/dma-mapping.h>
  10 #include <asm/bug.h>
  11 #include <asm/abs_addr.h>
  12
  13 /*
  14  * Generic direct DMA implementation
  15  *
  16  * This implementation supports a per-device offset that can be applied if
  17  * the address at which memory is visible to devices is not 0. Platform code
  18  * can set archdata.dma_data to an unsigned long holding the offset. By
  19  * default the offset is zero.
  20  */
  21
  22 static unsigned long get_dma_direct_offset(struct device *dev)
  23 {
  24         return (unsigned long)dev->archdata.dma_data;
  25 }
  26
  27 static void *dma_direct_alloc_coherent(struct device *dev, size_t size,
  28                                        dma_addr_t *dma_handle, gfp_t flag)
  29 {
  30         struct page *page;
  31         void *ret;
  32         int node = dev->archdata.numa_node;
  33
  34         page = alloc_pages_node(node, flag, get_order(size));
  35         if (page == NULL)
  36                 return NULL;
  37         ret = page_address(page);
  38         memset(ret, 0, size);
  39         *dma_handle = virt_to_abs(ret) + get_dma_direct_offset(dev);
  40
  41         return ret;
  42 }
  43
  44 static void dma_direct_free_coherent(struct device *dev, size_t size,
  45                                      void *vaddr, dma_addr_t dma_handle)
  46 {
  47         free_pages((unsigned long)vaddr, get_order(size));
  48 }
  49
  50 static dma_addr_t dma_direct_map_single(struct device *dev, void *ptr,
  51                                         size_t size,
  52                                         enum dma_data_direction direction,
  53                                         struct dma_attrs *attrs)
  54 {
  55         return virt_to_abs(ptr) + get_dma_direct_offset(dev);
  56 }
  57
  58 static void dma_direct_unmap_single(struct device *dev, dma_addr_t dma_addr,
  59                                     size_t size,
  60                                     enum dma_data_direction direction,
  61                                     struct dma_attrs *attrs)
  62 {
  63 }
  64
  65 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
  66                              int nents, enum dma_data_direction direction,
  67                              struct dma_attrs *attrs)
  68 {
  69         struct scatterlist *sg;
  70         int i;
  71
  72         for_each_sg(sgl, sg, nents, i) {
  73                 sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev);
  74                 sg->dma_length = sg->length;
  75         }
  76
  77         return nents;
  78 }
  79
  80 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg,
  81                                 int nents, enum dma_data_direction direction,
  82                                 struct dma_attrs *attrs)
  83 {
  84 }
  85
  86 static int dma_direct_dma_supported(struct device *dev, u64 mask)
  87 {
  88         /* Could be improved to check for memory though it better be
  89          * done via some global so platforms can set the limit in case
  90          * they have limited DMA windows
  91          */
  92         return mask >= DMA_32BIT_MASK;
  93 }
  94
  95 struct dma_mapping_ops dma_direct_ops = {
  96         .alloc_coherent = dma_direct_alloc_coherent,
  97         .free_coherent  = dma_direct_free_coherent,
  98         .map_single     = dma_direct_map_single,
  99         .unmap_single   = dma_direct_unmap_single,
 100         .map_sg         = dma_direct_map_sg,
 101         .unmap_sg       = dma_direct_unmap_sg,
 102         .dma_supported  = dma_direct_dma_supported,
 103 };
 104 EXPORT_SYMBOL(dma_direct_ops);