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 <asm/io.h>
  15
  16 struct dma_coherent_mem {
  17         void            *virt_base;
  18         u32             device_base;
  19         int             size;
  20         int             flags;
  21         unsigned long   *bitmap;
  22 };
  23
  24 void *dma_alloc_coherent(struct device *dev, size_t size,
  25                            dma_addr_t *dma_handle, unsigned int __nocast gfp)
  26 {
  27         void *ret;
  28         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  29         int order = get_order(size);
  30         /* ignore region specifiers */
  31         gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
  32
  33         if (mem) {
  34                 int page = bitmap_find_free_region(mem->bitmap, mem->size,
  35                                                      order);
  36                 if (page >= 0) {
  37                         *dma_handle = mem->device_base + (page << PAGE_SHIFT);
  38                         ret = mem->virt_base + (page << PAGE_SHIFT);
  39                         memset(ret, 0, size);
  40                         return ret;
  41                 }
  42                 if (mem->flags & DMA_MEMORY_EXCLUSIVE)
  43                         return NULL;
  44         }
  45
  46         if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
  47                 gfp |= GFP_DMA;
  48
  49         ret = (void *)__get_free_pages(gfp, order);
  50
  51         if (ret != NULL) {
  52                 memset(ret, 0, size);
  53                 *dma_handle = virt_to_phys(ret);
  54         }
  55         return ret;
  56 }
  57
  58 void dma_free_coherent(struct device *dev, size_t size,
  59                          void *vaddr, dma_addr_t dma_handle)
  60 {
  61         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  62         int order = get_order(size);
  63
  64         if (mem && vaddr >= mem->virt_base && vaddr < (mem->virt_base + (mem->size << PAGE_SHIFT))) {
  65                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
  66
  67                 bitmap_release_region(mem->bitmap, page, order);
  68         } else
  69                 free_pages((unsigned long)vaddr, order);
  70 }
  71
  72 int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
  73                                 dma_addr_t device_addr, size_t size, int flags)
  74 {
  75         void __iomem *mem_base;
  76         int pages = size >> PAGE_SHIFT;
  77         int bitmap_size = (pages + 31)/32;
  78
  79         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  80                 goto out;
  81         if (!size)
  82                 goto out;
  83         if (dev->dma_mem)
  84                 goto out;
  85
  86         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
  87
  88         mem_base = ioremap(bus_addr, size);
  89         if (!mem_base)
  90                 goto out;
  91
  92         dev->dma_mem = kmalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  93         if (!dev->dma_mem)
  94                 goto out;
  95         memset(dev->dma_mem, 0, sizeof(struct dma_coherent_mem));
  96         dev->dma_mem->bitmap = kmalloc(bitmap_size, GFP_KERNEL);
  97         if (!dev->dma_mem->bitmap)
  98                 goto free1_out;
  99         memset(dev->dma_mem->bitmap, 0, bitmap_size);
 100
 101         dev->dma_mem->virt_base = mem_base;
 102         dev->dma_mem->device_base = device_addr;
 103         dev->dma_mem->size = pages;
 104         dev->dma_mem->flags = flags;
 105
 106         if (flags & DMA_MEMORY_MAP)
 107                 return DMA_MEMORY_MAP;
 108
 109         return DMA_MEMORY_IO;
 110
 111  free1_out:
 112         kfree(dev->dma_mem->bitmap);
 113  out:
 114         return 0;
 115 }
 116 EXPORT_SYMBOL(dma_declare_coherent_memory);
 117
 118 void dma_release_declared_memory(struct device *dev)
 119 {
 120         struct dma_coherent_mem *mem = dev->dma_mem;
 121
 122         if(!mem)
 123                 return;
 124         dev->dma_mem = NULL;
 125         iounmap(mem->virt_base);
 126         kfree(mem->bitmap);
 127         kfree(mem);
 128 }
 129 EXPORT_SYMBOL(dma_release_declared_memory);
 130
 131 void *dma_mark_declared_memory_occupied(struct device *dev,
 132                                         dma_addr_t device_addr, size_t size)
 133 {
 134         struct dma_coherent_mem *mem = dev->dma_mem;
 135         int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 136         int pos, err;
 137
 138         if (!mem)
 139                 return ERR_PTR(-EINVAL);
 140
 141         pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
 142         err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
 143         if (err != 0)
 144                 return ERR_PTR(err);
 145         return mem->virt_base + (pos << PAGE_SHIFT);
 146 }
 147 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);