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/lmb.h>
  11 #include <asm/bug.h>
  12 #include <asm/abs_addr.h>
  13
  14 /*
  15  * Generic direct DMA implementation
  16  *
  17  * This implementation supports a per-device offset that can be applied if
  18  * the address at which memory is visible to devices is not 0. Platform code
  19  * can set archdata.dma_data to an unsigned long holding the offset. By
  20  * default the offset is PCI_DRAM_OFFSET.
  21  */
  22
  23 unsigned long get_dma_direct_offset(struct device *dev)
  24 {
  25         if (dev)
  26                 return (unsigned long)dev->archdata.dma_data;
  27
  28         return PCI_DRAM_OFFSET;
  29 }
  30
  31 void *dma_direct_alloc_coherent(struct device *dev, size_t size,
  32                                 dma_addr_t *dma_handle, gfp_t flag)
  33 {
  34         void *ret;
  35 #ifdef CONFIG_NOT_COHERENT_CACHE
  36         ret = __dma_alloc_coherent(dev, size, dma_handle, flag);
  37         if (ret == NULL)
  38                 return NULL;
  39         *dma_handle += get_dma_direct_offset(dev);
  40         return ret;
  41 #else
  42         struct page *page;
  43         int node = dev_to_node(dev);
  44
  45         /* ignore region specifiers */
  46         flag  &= ~(__GFP_HIGHMEM);
  47
  48         page = alloc_pages_node(node, flag, get_order(size));
  49         if (page == NULL)
  50                 return NULL;
  51         ret = page_address(page);
  52         memset(ret, 0, size);
  53         *dma_handle = virt_to_abs(ret) + get_dma_direct_offset(dev);
  54
  55         return ret;
  56 #endif
  57 }
  58
  59 void dma_direct_free_coherent(struct device *dev, size_t size,
  60                               void *vaddr, dma_addr_t dma_handle)
  61 {
  62 #ifdef CONFIG_NOT_COHERENT_CACHE
  63         __dma_free_coherent(size, vaddr);
  64 #else
  65         free_pages((unsigned long)vaddr, get_order(size));
  66 #endif
  67 }
  68
  69 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
  70                              int nents, enum dma_data_direction direction,
  71                              struct dma_attrs *attrs)
  72 {
  73         struct scatterlist *sg;
  74         int i;
  75
  76         for_each_sg(sgl, sg, nents, i) {
  77                 sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev);
  78                 sg->dma_length = sg->length;
  79                 __dma_sync_page(sg_page(sg), sg->offset, sg->length, direction);
  80         }
  81
  82         return nents;
  83 }
  84
  85 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg,
  86                                 int nents, enum dma_data_direction direction,
  87                                 struct dma_attrs *attrs)
  88 {
  89 }
  90
  91 static int dma_direct_dma_supported(struct device *dev, u64 mask)
  92 {
  93 #ifdef CONFIG_PPC64
  94         /* Could be improved so platforms can set the limit in case
  95          * they have limited DMA windows
  96          */
  97         return mask >= (lmb_end_of_DRAM() - 1);
  98 #else
  99         return 1;
 100 #endif
 101 }
 102
 103 static inline dma_addr_t dma_direct_map_page(struct device *dev,
 104                                              struct page *page,
 105                                              unsigned long offset,
 106                                              size_t size,
 107                                              enum dma_data_direction dir,
 108                                              struct dma_attrs *attrs)
 109 {
 110         BUG_ON(dir == DMA_NONE);
 111         __dma_sync_page(page, offset, size, dir);
 112         return page_to_phys(page) + offset + get_dma_direct_offset(dev);
 113 }
 114
 115 static inline void dma_direct_unmap_page(struct device *dev,
 116                                          dma_addr_t dma_address,
 117                                          size_t size,
 118                                          enum dma_data_direction direction,
 119                                          struct dma_attrs *attrs)
 120 {
 121 }
 122
 123 #ifdef CONFIG_NOT_COHERENT_CACHE
 124 static inline void dma_direct_sync_sg(struct device *dev,
 125                 struct scatterlist *sgl, int nents,
 126                 enum dma_data_direction direction)
 127 {
 128         struct scatterlist *sg;
 129         int i;
 130
 131         for_each_sg(sgl, sg, nents, i)
 132                 __dma_sync_page(sg_page(sg), sg->offset, sg->length, direction);
 133 }
 134
 135 static inline void dma_direct_sync_single_range(struct device *dev,
 136                 dma_addr_t dma_handle, unsigned long offset, size_t size,
 137                 enum dma_data_direction direction)
 138 {
 139         __dma_sync(bus_to_virt(dma_handle+offset), size, direction);
 140 }
 141 #endif
 142
 143 struct dma_mapping_ops dma_direct_ops = {
 144         .alloc_coherent = dma_direct_alloc_coherent,
 145         .free_coherent  = dma_direct_free_coherent,
 146         .map_sg         = dma_direct_map_sg,
 147         .unmap_sg       = dma_direct_unmap_sg,
 148         .dma_supported  = dma_direct_dma_supported,
 149         .map_page       = dma_direct_map_page,
 150         .unmap_page     = dma_direct_unmap_page,
 151 #ifdef CONFIG_NOT_COHERENT_CACHE
 152         .sync_single_range_for_cpu      = dma_direct_sync_single_range,
 153         .sync_single_range_for_device   = dma_direct_sync_single_range,
 154         .sync_sg_for_cpu                = dma_direct_sync_sg,
 155         .sync_sg_for_device             = dma_direct_sync_sg,
 156 #endif
 157 };
 158 EXPORT_SYMBOL(dma_direct_ops);