arch/i386/kernel/pci-dma.c

   1 /*
   2  * Dynamic DMA mapping support.
   3  *
   4  * On i386 there is no hardware dynamic DMA address translation,
   5  * so consistent alloc/free are merely page allocation/freeing.
   6  * The rest of the dynamic DMA mapping interface is implemented
   7  * in asm/pci.h.
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/mm.h>
  12 #include <linux/string.h>
  13 #include <linux/pci.h>
  14 #include <linux/module.h>
  15 #include <asm/io.h>
  16
  17 struct dma_coherent_mem {
  18         void            *virt_base;
  19         u32             device_base;
  20         int             size;
  21         int             flags;
  22         unsigned long   *bitmap;
  23 };
  24
  25 void *dma_alloc_coherent(struct device *dev, size_t size,
  26                            dma_addr_t *dma_handle, gfp_t gfp)
  27 {
  28         void *ret;
  29         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  30         int order = get_order(size);
  31         /* ignore region specifiers */
  32         gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
  33
  34         if (mem) {
  35                 int page = bitmap_find_free_region(mem->bitmap, mem->size,
  36                                                      order);
  37                 if (page >= 0) {
  38                         *dma_handle = mem->device_base + (page << PAGE_SHIFT);
  39                         ret = mem->virt_base + (page << PAGE_SHIFT);
  40                         memset(ret, 0, size);
  41                         return ret;
  42                 }
  43                 if (mem->flags & DMA_MEMORY_EXCLUSIVE)
  44                         return NULL;
  45         }
  46
  47         if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
  48                 gfp |= GFP_DMA;
  49
  50         ret = (void *)__get_free_pages(gfp, order);
  51
  52         if (ret != NULL) {
  53                 memset(ret, 0, size);
  54                 *dma_handle = virt_to_phys(ret);
  55         }
  56         return ret;
  57 }
  58 EXPORT_SYMBOL(dma_alloc_coherent);
  59
  60 void dma_free_coherent(struct device *dev, size_t size,
  61                          void *vaddr, dma_addr_t dma_handle)
  62 {
  63         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  64         int order = get_order(size);
  65
  66         if (mem && vaddr >= mem->virt_base && vaddr < (mem->virt_base + (mem->size << PAGE_SHIFT))) {
  67                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
  68
  69                 bitmap_release_region(mem->bitmap, page, order);
  70         } else
  71                 free_pages((unsigned long)vaddr, order);
  72 }
  73 EXPORT_SYMBOL(dma_free_coherent);
  74
  75 int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
  76                                 dma_addr_t device_addr, size_t size, int flags)
  77 {
  78         void __iomem *mem_base = NULL;
  79         int pages = size >> PAGE_SHIFT;
  80         int bitmap_size = (pages + 31)/32;
  81
  82         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  83                 goto out;
  84         if (!size)
  85                 goto out;
  86         if (dev->dma_mem)
  87                 goto out;
  88
  89         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
  90
  91         mem_base = ioremap(bus_addr, size);
  92         if (!mem_base)
  93                 goto out;
  94
  95         dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  96         if (!dev->dma_mem)
  97                 goto out;
  98         dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  99         if (!dev->dma_mem->bitmap)
 100                 goto free1_out;
 101
 102         dev->dma_mem->virt_base = mem_base;
 103         dev->dma_mem->device_base = device_addr;
 104         dev->dma_mem->size = pages;
 105         dev->dma_mem->flags = flags;
 106
 107         if (flags & DMA_MEMORY_MAP)
 108                 return DMA_MEMORY_MAP;
 109
 110         return DMA_MEMORY_IO;
 111
 112  free1_out:
 113         kfree(dev->dma_mem->bitmap);
 114  out:
 115         if (mem_base)
 116                 iounmap(mem_base);
 117         return 0;
 118 }
 119 EXPORT_SYMBOL(dma_declare_coherent_memory);
 120
 121 void dma_release_declared_memory(struct device *dev)
 122 {
 123         struct dma_coherent_mem *mem = dev->dma_mem;
 124
 125         if(!mem)
 126                 return;
 127         dev->dma_mem = NULL;
 128         iounmap(mem->virt_base);
 129         kfree(mem->bitmap);
 130         kfree(mem);
 131 }
 132 EXPORT_SYMBOL(dma_release_declared_memory);
 133
 134 void *dma_mark_declared_memory_occupied(struct device *dev,
 135                                         dma_addr_t device_addr, size_t size)
 136 {
 137         struct dma_coherent_mem *mem = dev->dma_mem;
 138         int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 139         int pos, err;
 140
 141         if (!mem)
 142                 return ERR_PTR(-EINVAL);
 143
 144         pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
 145         err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
 146         if (err != 0)
 147                 return ERR_PTR(err);
 148         return mem->virt_base + (pos << PAGE_SHIFT);
 149 }
 150 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);