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 <linux/dma-debug.h>
  11 #include <linux/gfp.h>
  12 #include <linux/memblock.h>
  13 #include <asm/bug.h>
  14 #include <asm/abs_addr.h>
  15
  16 /*
  17  * Generic direct DMA implementation
  18  *
  19  * This implementation supports a per-device offset that can be applied if
  20  * the address at which memory is visible to devices is not 0. Platform code
  21  * can set archdata.dma_data to an unsigned long holding the offset. By
  22  * default the offset is PCI_DRAM_OFFSET.
  23  */
  24
  25
  26 void *dma_direct_alloc_coherent(struct device *dev, size_t size,
  27                                 dma_addr_t *dma_handle, gfp_t flag)
  28 {
  29         void *ret;
  30 #ifdef CONFIG_NOT_COHERENT_CACHE
  31         ret = __dma_alloc_coherent(dev, size, dma_handle, flag);
  32         if (ret == NULL)
  33                 return NULL;
  34         *dma_handle += get_dma_offset(dev);
  35         return ret;
  36 #else
  37         struct page *page;
  38         int node = dev_to_node(dev);
  39
  40         /* ignore region specifiers */
  41         flag  &= ~(__GFP_HIGHMEM);
  42
  43         page = alloc_pages_node(node, flag, get_order(size));
  44         if (page == NULL)
  45                 return NULL;
  46         ret = page_address(page);
  47         memset(ret, 0, size);
  48         *dma_handle = virt_to_abs(ret) + get_dma_offset(dev);
  49
  50         return ret;
  51 #endif
  52 }
  53
  54 void dma_direct_free_coherent(struct device *dev, size_t size,
  55                               void *vaddr, dma_addr_t dma_handle)
  56 {
  57 #ifdef CONFIG_NOT_COHERENT_CACHE
  58         __dma_free_coherent(size, vaddr);
  59 #else
  60         free_pages((unsigned long)vaddr, get_order(size));
  61 #endif
  62 }
  63
  64 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
  65                              int nents, enum dma_data_direction direction,
  66                              struct dma_attrs *attrs)
  67 {
  68         struct scatterlist *sg;
  69         int i;
  70
  71         for_each_sg(sgl, sg, nents, i) {
  72                 sg->dma_address = sg_phys(sg) + get_dma_offset(dev);
  73                 sg->dma_length = sg->length;
  74                 __dma_sync_page(sg_page(sg), sg->offset, sg->length, direction);
  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 #ifdef CONFIG_PPC64
  89         /* Could be improved so platforms can set the limit in case
  90          * they have limited DMA windows
  91          */
  92         return mask >= (memblock_end_of_DRAM() - 1);
  93 #else
  94         return 1;
  95 #endif
  96 }
  97
  98 static inline dma_addr_t dma_direct_map_page(struct device *dev,
  99                                              struct page *page,
 100                                              unsigned long offset,
 101                                              size_t size,
 102                                              enum dma_data_direction dir,
 103                                              struct dma_attrs *attrs)
 104 {
 105         BUG_ON(dir == DMA_NONE);
 106         __dma_sync_page(page, offset, size, dir);
 107         return page_to_phys(page) + offset + get_dma_offset(dev);
 108 }
 109
 110 static inline void dma_direct_unmap_page(struct device *dev,
 111                                          dma_addr_t dma_address,
 112                                          size_t size,
 113                                          enum dma_data_direction direction,
 114                                          struct dma_attrs *attrs)
 115 {
 116 }
 117
 118 #ifdef CONFIG_NOT_COHERENT_CACHE
 119 static inline void dma_direct_sync_sg(struct device *dev,
 120                 struct scatterlist *sgl, int nents,
 121                 enum dma_data_direction direction)
 122 {
 123         struct scatterlist *sg;
 124         int i;
 125
 126         for_each_sg(sgl, sg, nents, i)
 127                 __dma_sync_page(sg_page(sg), sg->offset, sg->length, direction);
 128 }
 129
 130 static inline void dma_direct_sync_single(struct device *dev,
 131                                           dma_addr_t dma_handle, size_t size,
 132                                           enum dma_data_direction direction)
 133 {
 134         __dma_sync(bus_to_virt(dma_handle), size, direction);
 135 }
 136 #endif
 137
 138 struct dma_map_ops dma_direct_ops = {
 139         .alloc_coherent = dma_direct_alloc_coherent,
 140         .free_coherent  = dma_direct_free_coherent,
 141         .map_sg         = dma_direct_map_sg,
 142         .unmap_sg       = dma_direct_unmap_sg,
 143         .dma_supported  = dma_direct_dma_supported,
 144         .map_page       = dma_direct_map_page,
 145         .unmap_page     = dma_direct_unmap_page,
 146 #ifdef CONFIG_NOT_COHERENT_CACHE
 147         .sync_single_for_cpu            = dma_direct_sync_single,
 148         .sync_single_for_device         = dma_direct_sync_single,
 149         .sync_sg_for_cpu                = dma_direct_sync_sg,
 150         .sync_sg_for_device             = dma_direct_sync_sg,
 151 #endif
 152 };
 153 EXPORT_SYMBOL(dma_direct_ops);
 154
 155 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
 156
 157 static int __init dma_init(void)
 158 {
 159        dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 160
 161        return 0;
 162 }
 163 fs_initcall(dma_init);