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 PCI_DRAM_OFFSET.
  20  */
  21
  22 static unsigned long get_dma_direct_offset(struct device *dev)
  23 {
  24         if (dev)
  25                 return (unsigned long)dev->archdata.dma_data;
  26
  27         return PCI_DRAM_OFFSET;
  28 }
  29
  30 void *dma_direct_alloc_coherent(struct device *dev, size_t size,
  31                                 dma_addr_t *dma_handle, gfp_t flag)
  32 {
  33         void *ret;
  34 #ifdef CONFIG_NOT_COHERENT_CACHE
  35         ret = __dma_alloc_coherent(size, dma_handle, flag);
  36         if (ret == NULL)
  37                 return NULL;
  38         *dma_handle += get_dma_direct_offset(dev);
  39         return ret;
  40 #else
  41         struct page *page;
  42         int node = dev_to_node(dev);
  43
  44         /* ignore region specifiers */
  45         flag  &= ~(__GFP_HIGHMEM);
  46
  47         page = alloc_pages_node(node, flag, get_order(size));
  48         if (page == NULL)
  49                 return NULL;
  50         ret = page_address(page);
  51         memset(ret, 0, size);
  52         *dma_handle = virt_to_abs(ret) + get_dma_direct_offset(dev);
  53
  54         return ret;
  55 #endif
  56 }
  57
  58 void dma_direct_free_coherent(struct device *dev, size_t size,
  59                               void *vaddr, dma_addr_t dma_handle)
  60 {
  61 #ifdef CONFIG_NOT_COHERENT_CACHE
  62         __dma_free_coherent(size, vaddr);
  63 #else
  64         free_pages((unsigned long)vaddr, get_order(size));
  65 #endif
  66 }
  67
  68 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
  69                              int nents, enum dma_data_direction direction,
  70                              struct dma_attrs *attrs)
  71 {
  72         struct scatterlist *sg;
  73         int i;
  74
  75         for_each_sg(sgl, sg, nents, i) {
  76                 sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev);
  77                 sg->dma_length = sg->length;
  78         }
  79
  80         return nents;
  81 }
  82
  83 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg,
  84                                 int nents, enum dma_data_direction direction,
  85                                 struct dma_attrs *attrs)
  86 {
  87 }
  88
  89 static int dma_direct_dma_supported(struct device *dev, u64 mask)
  90 {
  91 #ifdef CONFIG_PPC64
  92         /* Could be improved to check for memory though it better be
  93          * done via some global so platforms can set the limit in case
  94          * they have limited DMA windows
  95          */
  96         return mask >= DMA_32BIT_MASK;
  97 #else
  98         return 1;
  99 #endif
 100 }
 101
 102 static inline dma_addr_t dma_direct_map_page(struct device *dev,
 103                                              struct page *page,
 104                                              unsigned long offset,
 105                                              size_t size,
 106                                              enum dma_data_direction dir,
 107                                              struct dma_attrs *attrs)
 108 {
 109         BUG_ON(dir == DMA_NONE);
 110         __dma_sync_page(page, offset, size, dir);
 111         return page_to_phys(page) + offset + get_dma_direct_offset(dev);
 112 }
 113
 114 static inline void dma_direct_unmap_page(struct device *dev,
 115                                          dma_addr_t dma_address,
 116                                          size_t size,
 117                                          enum dma_data_direction direction,
 118                                          struct dma_attrs *attrs)
 119 {
 120 }
 121
 122 struct dma_mapping_ops dma_direct_ops = {
 123         .alloc_coherent = dma_direct_alloc_coherent,
 124         .free_coherent  = dma_direct_free_coherent,
 125         .map_sg         = dma_direct_map_sg,
 126         .unmap_sg       = dma_direct_unmap_sg,
 127         .dma_supported  = dma_direct_dma_supported,
 128         .map_page       = dma_direct_map_page,
 129         .unmap_page     = dma_direct_unmap_page,
 130 };
 131 EXPORT_SYMBOL(dma_direct_ops);