arch/x86/kernel/pci-dma_32.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 /* For i386, we make it point to the NULL address */
  18 dma_addr_t bad_dma_address __read_mostly = 0x0;
  19 EXPORT_SYMBOL(bad_dma_address);
  20
  21 struct dma_coherent_mem {
  22         void            *virt_base;
  23         u32             device_base;
  24         int             size;
  25         int             flags;
  26         unsigned long   *bitmap;
  27 };
  28
  29 void *dma_alloc_coherent(struct device *dev, size_t size,
  30                            dma_addr_t *dma_handle, gfp_t gfp)
  31 {
  32         void *ret;
  33         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  34         int order = get_order(size);
  35         /* ignore region specifiers */
  36         gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
  37
  38         if (mem) {
  39                 int page = bitmap_find_free_region(mem->bitmap, mem->size,
  40                                                      order);
  41                 if (page >= 0) {
  42                         *dma_handle = mem->device_base + (page << PAGE_SHIFT);
  43                         ret = mem->virt_base + (page << PAGE_SHIFT);
  44                         memset(ret, 0, size);
  45                         return ret;
  46                 }
  47                 if (mem->flags & DMA_MEMORY_EXCLUSIVE)
  48                         return NULL;
  49         }
  50
  51         if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
  52                 gfp |= GFP_DMA;
  53
  54         ret = (void *)__get_free_pages(gfp, order);
  55
  56         if (ret != NULL) {
  57                 memset(ret, 0, size);
  58                 *dma_handle = virt_to_phys(ret);
  59         }
  60         return ret;
  61 }
  62 EXPORT_SYMBOL(dma_alloc_coherent);
  63
  64 void dma_free_coherent(struct device *dev, size_t size,
  65                          void *vaddr, dma_addr_t dma_handle)
  66 {
  67         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  68         int order = get_order(size);
  69
  70         WARN_ON(irqs_disabled());       /* for portability */
  71         if (mem && vaddr >= mem->virt_base && vaddr < (mem->virt_base + (mem->size << PAGE_SHIFT))) {
  72                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
  73
  74                 bitmap_release_region(mem->bitmap, page, order);
  75         } else
  76                 free_pages((unsigned long)vaddr, order);
  77 }
  78 EXPORT_SYMBOL(dma_free_coherent);
  79
  80 int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
  81                                 dma_addr_t device_addr, size_t size, int flags)
  82 {
  83         void __iomem *mem_base = NULL;
  84         int pages = size >> PAGE_SHIFT;
  85         int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
  86
  87         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  88                 goto out;
  89         if (!size)
  90                 goto out;
  91         if (dev->dma_mem)
  92                 goto out;
  93
  94         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
  95
  96         mem_base = ioremap(bus_addr, size);
  97         if (!mem_base)
  98                 goto out;
  99
 100         dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
 101         if (!dev->dma_mem)
 102                 goto out;
 103         dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
 104         if (!dev->dma_mem->bitmap)
 105                 goto free1_out;
 106
 107         dev->dma_mem->virt_base = mem_base;
 108         dev->dma_mem->device_base = device_addr;
 109         dev->dma_mem->size = pages;
 110         dev->dma_mem->flags = flags;
 111
 112         if (flags & DMA_MEMORY_MAP)
 113                 return DMA_MEMORY_MAP;
 114
 115         return DMA_MEMORY_IO;
 116
 117  free1_out:
 118         kfree(dev->dma_mem);
 119  out:
 120         if (mem_base)
 121                 iounmap(mem_base);
 122         return 0;
 123 }
 124 EXPORT_SYMBOL(dma_declare_coherent_memory);
 125
 126 void dma_release_declared_memory(struct device *dev)
 127 {
 128         struct dma_coherent_mem *mem = dev->dma_mem;
 129
 130         if(!mem)
 131                 return;
 132         dev->dma_mem = NULL;
 133         iounmap(mem->virt_base);
 134         kfree(mem->bitmap);
 135         kfree(mem);
 136 }
 137 EXPORT_SYMBOL(dma_release_declared_memory);
 138
 139 void *dma_mark_declared_memory_occupied(struct device *dev,
 140                                         dma_addr_t device_addr, size_t size)
 141 {
 142         struct dma_coherent_mem *mem = dev->dma_mem;
 143         int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 144         int pos, err;
 145
 146         if (!mem)
 147                 return ERR_PTR(-EINVAL);
 148
 149         pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
 150         err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
 151         if (err != 0)
 152                 return ERR_PTR(err);
 153         return mem->virt_base + (pos << PAGE_SHIFT);
 154 }
 155 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);