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 #ifdef CONFIG_NOT_COHERENT_CACHE
  34         return __dma_alloc_coherent(size, dma_handle, flag);
  35 #else
  36         struct page *page;
  37         void *ret;
  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_direct_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_direct_offset(dev);
  73                 sg->dma_length = sg->length;
  74         }
  75
  76         return nents;
  77 }
  78
  79 static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg,
  80                                 int nents, enum dma_data_direction direction,
  81                                 struct dma_attrs *attrs)
  82 {
  83 }
  84
  85 static int dma_direct_dma_supported(struct device *dev, u64 mask)
  86 {
  87 #ifdef CONFIG_PPC64
  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 #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_direct_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 struct dma_mapping_ops dma_direct_ops = {
 119         .alloc_coherent = dma_direct_alloc_coherent,
 120         .free_coherent  = dma_direct_free_coherent,
 121         .map_sg         = dma_direct_map_sg,
 122         .unmap_sg       = dma_direct_unmap_sg,
 123         .dma_supported  = dma_direct_dma_supported,
 124         .map_page       = dma_direct_map_page,
 125         .unmap_page     = dma_direct_unmap_page,
 126 };
 127 EXPORT_SYMBOL(dma_direct_ops);