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 <linux/pci.h>
  16 #include <asm/io.h>
  17
  18 struct dma_coherent_mem {
  19         void            *virt_base;
  20         u32             device_base;
  21         int             size;
  22         int             flags;
  23         unsigned long   *bitmap;
  24 };
  25
  26 void *dma_alloc_coherent(struct device *dev, size_t size,
  27                            dma_addr_t *dma_handle, gfp_t gfp)
  28 {
  29         void *ret;
  30         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  31         int order = get_order(size);
  32         /* ignore region specifiers */
  33         gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
  34
  35         if (mem) {
  36                 int page = bitmap_find_free_region(mem->bitmap, mem->size,
  37                                                      order);
  38                 if (page >= 0) {
  39                         *dma_handle = mem->device_base + (page << PAGE_SHIFT);
  40                         ret = mem->virt_base + (page << PAGE_SHIFT);
  41                         memset(ret, 0, size);
  42                         return ret;
  43                 }
  44                 if (mem->flags & DMA_MEMORY_EXCLUSIVE)
  45                         return NULL;
  46         }
  47
  48         if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
  49                 gfp |= GFP_DMA;
  50
  51         ret = (void *)__get_free_pages(gfp, order);
  52
  53         if (ret != NULL) {
  54                 memset(ret, 0, size);
  55                 *dma_handle = virt_to_phys(ret);
  56         }
  57         return ret;
  58 }
  59 EXPORT_SYMBOL(dma_alloc_coherent);
  60
  61 void dma_free_coherent(struct device *dev, size_t size,
  62                          void *vaddr, dma_addr_t dma_handle)
  63 {
  64         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  65         int order = get_order(size);
  66
  67         if (mem && vaddr >= mem->virt_base && vaddr < (mem->virt_base + (mem->size << PAGE_SHIFT))) {
  68                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
  69
  70                 bitmap_release_region(mem->bitmap, page, order);
  71         } else
  72                 free_pages((unsigned long)vaddr, order);
  73 }
  74 EXPORT_SYMBOL(dma_free_coherent);
  75
  76 int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
  77                                 dma_addr_t device_addr, size_t size, int flags)
  78 {
  79         void __iomem *mem_base = NULL;
  80         int pages = size >> PAGE_SHIFT;
  81         int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
  82
  83         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  84                 goto out;
  85         if (!size)
  86                 goto out;
  87         if (dev->dma_mem)
  88                 goto out;
  89
  90         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
  91
  92         mem_base = ioremap(bus_addr, size);
  93         if (!mem_base)
  94                 goto out;
  95
  96         dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  97         if (!dev->dma_mem)
  98                 goto out;
  99         dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
 100         if (!dev->dma_mem->bitmap)
 101                 goto free1_out;
 102
 103         dev->dma_mem->virt_base = mem_base;
 104         dev->dma_mem->device_base = device_addr;
 105         dev->dma_mem->size = pages;
 106         dev->dma_mem->flags = flags;
 107
 108         if (flags & DMA_MEMORY_MAP)
 109                 return DMA_MEMORY_MAP;
 110
 111         return DMA_MEMORY_IO;
 112
 113  free1_out:
 114         kfree(dev->dma_mem);
 115  out:
 116         if (mem_base)
 117                 iounmap(mem_base);
 118         return 0;
 119 }
 120 EXPORT_SYMBOL(dma_declare_coherent_memory);
 121
 122 void dma_release_declared_memory(struct device *dev)
 123 {
 124         struct dma_coherent_mem *mem = dev->dma_mem;
 125
 126         if(!mem)
 127                 return;
 128         dev->dma_mem = NULL;
 129         iounmap(mem->virt_base);
 130         kfree(mem->bitmap);
 131         kfree(mem);
 132 }
 133 EXPORT_SYMBOL(dma_release_declared_memory);
 134
 135 void *dma_mark_declared_memory_occupied(struct device *dev,
 136                                         dma_addr_t device_addr, size_t size)
 137 {
 138         struct dma_coherent_mem *mem = dev->dma_mem;
 139         int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 140         int pos, err;
 141
 142         if (!mem)
 143                 return ERR_PTR(-EINVAL);
 144
 145         pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
 146         err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
 147         if (err != 0)
 148                 return ERR_PTR(err);
 149         return mem->virt_base + (pos << PAGE_SHIFT);
 150 }
 151 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 152
 153 #ifdef CONFIG_PCI
 154 /* Many VIA bridges seem to corrupt data for DAC. Disable it here */
 155
 156 int forbid_dac;
 157 EXPORT_SYMBOL(forbid_dac);
 158
 159 static __devinit void via_no_dac(struct pci_dev *dev)
 160 {
 161         if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) {
 162                 printk(KERN_INFO "PCI: VIA PCI bridge detected. Disabling DAC.\n");
 163                 forbid_dac = 1;
 164         }
 165 }
 166 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
 167
 168 static int check_iommu(char *s)
 169 {
 170         if (!strcmp(s, "usedac")) {
 171                 forbid_dac = -1;
 172                 return 1;
 173         }
 174         return 0;
 175 }
 176 __setup("iommu=", check_iommu);
 177 #endif