arch/microblaze/kernel/dma.c

   1 /*
   2  * Copyright (C) 2009-2010 PetaLogix
   3  * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
   4  *
   5  * Provide default implementations of the DMA mapping callbacks for
   6  * directly mapped busses.
   7  */
   8
   9 #include <linux/device.h>
  10 #include <linux/dma-mapping.h>
  11 #include <linux/gfp.h>
  12 #include <linux/dma-debug.h>
  13 #include <linux/export.h>
  14 #include <asm/bug.h>
  15 #include <asm/cacheflush.h>
  16
  17 /*
  18  * Generic direct DMA implementation
  19  *
  20  * This implementation supports a per-device offset that can be applied if
  21  * the address at which memory is visible to devices is not 0. Platform code
  22  * can set archdata.dma_data to an unsigned long holding the offset. By
  23  * default the offset is PCI_DRAM_OFFSET.
  24  */
  25 static inline void __dma_sync_page(unsigned long paddr, unsigned long offset,
  26                                 size_t size, enum dma_data_direction direction)
  27 {
  28         switch (direction) {
  29         case DMA_TO_DEVICE:
  30         case DMA_BIDIRECTIONAL:
  31                 flush_dcache_range(paddr + offset, paddr + offset + size);
  32                 break;
  33         case DMA_FROM_DEVICE:
  34                 invalidate_dcache_range(paddr + offset, paddr + offset + size);
  35                 break;
  36         default:
  37                 BUG();
  38         }
  39 }
  40
  41 static unsigned long get_dma_direct_offset(struct device *dev)
  42 {
  43         if (likely(dev))
  44                 return (unsigned long)dev->archdata.dma_data;
  45
  46         return PCI_DRAM_OFFSET; /* FIXME Not sure if is correct */
  47 }
  48
  49 #define NOT_COHERENT_CACHE
  50
  51 static void *dma_direct_alloc_coherent(struct device *dev, size_t size,
  52                                 dma_addr_t *dma_handle, gfp_t flag)
  53 {
  54 #ifdef NOT_COHERENT_CACHE
  55         return consistent_alloc(flag, size, dma_handle);
  56 #else
  57         void *ret;
  58         struct page *page;
  59         int node = dev_to_node(dev);
  60
  61         /* ignore region specifiers */
  62         flag  &= ~(__GFP_HIGHMEM);
  63
  64         page = alloc_pages_node(node, flag, get_order(size));
  65         if (page == NULL)
  66                 return NULL;
  67         ret = page_address(page);
  68         memset(ret, 0, size);
  69         *dma_handle = virt_to_phys(ret) + get_dma_direct_offset(dev);
  70
  71         return ret;
  72 #endif
  73 }
  74
  75 static void dma_direct_free_coherent(struct device *dev, size_t size,
  76                               void *vaddr, dma_addr_t dma_handle)
  77 {
  78 #ifdef NOT_COHERENT_CACHE
  79         consistent_free(size, vaddr);
  80 #else
  81         free_pages((unsigned long)vaddr, get_order(size));
  82 #endif
  83 }
  84
  85 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
  86                              int nents, enum dma_data_direction direction,
  87                              struct dma_attrs *attrs)
  88 {
  89         struct scatterlist *sg;
  90         int i;
  91
  92         /* FIXME this part of code is untested */
  93         for_each_sg(sgl, sg, nents, i) {
  94                 sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev);
  95                 __dma_sync_page(page_to_phys(sg_page(sg)), sg->offset,
  96                                                         sg->length, direction);
  97         }
  98
  99         return nents;
 100 }
 101
 102 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg,
 103                                 int nents, enum dma_data_direction direction,
 104                                 struct dma_attrs *attrs)
 105 {
 106 }
 107
 108 static int dma_direct_dma_supported(struct device *dev, u64 mask)
 109 {
 110         return 1;
 111 }
 112
 113 static inline dma_addr_t dma_direct_map_page(struct device *dev,
 114                                              struct page *page,
 115                                              unsigned long offset,
 116                                              size_t size,
 117                                              enum dma_data_direction direction,
 118                                              struct dma_attrs *attrs)
 119 {
 120         __dma_sync_page(page_to_phys(page), offset, size, direction);
 121         return page_to_phys(page) + offset + get_dma_direct_offset(dev);
 122 }
 123
 124 static inline void dma_direct_unmap_page(struct device *dev,
 125                                          dma_addr_t dma_address,
 126                                          size_t size,
 127                                          enum dma_data_direction direction,
 128                                          struct dma_attrs *attrs)
 129 {
 130 /* There is not necessary to do cache cleanup
 131  *
 132  * phys_to_virt is here because in __dma_sync_page is __virt_to_phys and
 133  * dma_address is physical address
 134  */
 135         __dma_sync_page(dma_address, 0 , size, direction);
 136 }
 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 };
 147 EXPORT_SYMBOL(dma_direct_ops);
 148
 149 /* Number of entries preallocated for DMA-API debugging */
 150 #define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
 151
 152 static int __init dma_init(void)
 153 {
 154        dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
 155
 156        return 0;
 157 }
 158 fs_initcall(dma_init);