drivers/base/dma-coherent.c

   1 /*
   2  * Coherent per-device memory handling.
   3  * Borrowed from i386
   4  */
   5 #include <linux/slab.h>
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/dma-mapping.h>
   9
  10 struct dma_coherent_mem {
  11         void            *virt_base;
  12         dma_addr_t      device_base;
  13         unsigned long   pfn_base;
  14         int             size;
  15         int             flags;
  16         unsigned long   *bitmap;
  17         spinlock_t      spinlock;
  18 };
  19
  20 static int dma_init_coherent_memory(phys_addr_t phys_addr, dma_addr_t device_addr,
  21                              size_t size, int flags,
  22                              struct dma_coherent_mem **mem)
  23 {
  24         struct dma_coherent_mem *dma_mem = NULL;
  25         void __iomem *mem_base = NULL;
  26         int pages = size >> PAGE_SHIFT;
  27         int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
  28
  29         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  30                 goto out;
  31         if (!size)
  32                 goto out;
  33
  34         mem_base = ioremap(phys_addr, size);
  35         if (!mem_base)
  36                 goto out;
  37
  38         dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  39         if (!dma_mem)
  40                 goto out;
  41         dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  42         if (!dma_mem->bitmap)
  43                 goto out;
  44
  45         dma_mem->virt_base = mem_base;
  46         dma_mem->device_base = device_addr;
  47         dma_mem->pfn_base = PFN_DOWN(phys_addr);
  48         dma_mem->size = pages;
  49         dma_mem->flags = flags;
  50         spin_lock_init(&dma_mem->spinlock);
  51
  52         *mem = dma_mem;
  53
  54         if (flags & DMA_MEMORY_MAP)
  55                 return DMA_MEMORY_MAP;
  56
  57         return DMA_MEMORY_IO;
  58
  59 out:
  60         kfree(dma_mem);
  61         if (mem_base)
  62                 iounmap(mem_base);
  63         return 0;
  64 }
  65
  66 static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
  67 {
  68         if (!mem)
  69                 return;
  70         iounmap(mem->virt_base);
  71         kfree(mem->bitmap);
  72         kfree(mem);
  73 }
  74
  75 static int dma_assign_coherent_memory(struct device *dev,
  76                                       struct dma_coherent_mem *mem)
  77 {
  78         if (dev->dma_mem)
  79                 return -EBUSY;
  80
  81         dev->dma_mem = mem;
  82         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
  83
  84         return 0;
  85 }
  86
  87 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
  88                                 dma_addr_t device_addr, size_t size, int flags)
  89 {
  90         struct dma_coherent_mem *mem;
  91         int ret;
  92
  93         ret = dma_init_coherent_memory(phys_addr, device_addr, size, flags,
  94                                        &mem);
  95         if (ret == 0)
  96                 return 0;
  97
  98         if (dma_assign_coherent_memory(dev, mem) == 0)
  99                 return ret;
 100
 101         dma_release_coherent_memory(mem);
 102         return 0;
 103 }
 104 EXPORT_SYMBOL(dma_declare_coherent_memory);
 105
 106 void dma_release_declared_memory(struct device *dev)
 107 {
 108         struct dma_coherent_mem *mem = dev->dma_mem;
 109
 110         if (!mem)
 111                 return;
 112         dma_release_coherent_memory(mem);
 113         dev->dma_mem = NULL;
 114 }
 115 EXPORT_SYMBOL(dma_release_declared_memory);
 116
 117 void *dma_mark_declared_memory_occupied(struct device *dev,
 118                                         dma_addr_t device_addr, size_t size)
 119 {
 120         struct dma_coherent_mem *mem = dev->dma_mem;
 121         unsigned long flags;
 122         int pos, err;
 123
 124         size += device_addr & ~PAGE_MASK;
 125
 126         if (!mem)
 127                 return ERR_PTR(-EINVAL);
 128
 129         spin_lock_irqsave(&mem->spinlock, flags);
 130         pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
 131         err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
 132         spin_unlock_irqrestore(&mem->spinlock, flags);
 133
 134         if (err != 0)
 135                 return ERR_PTR(err);
 136         return mem->virt_base + (pos << PAGE_SHIFT);
 137 }
 138 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 139
 140 /**
 141  * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
 142  *
 143  * @dev:        device from which we allocate memory
 144  * @size:       size of requested memory area
 145  * @dma_handle: This will be filled with the correct dma handle
 146  * @ret:        This pointer will be filled with the virtual address
 147  *              to allocated area.
 148  *
 149  * This function should be only called from per-arch dma_alloc_coherent()
 150  * to support allocation from per-device coherent memory pools.
 151  *
 152  * Returns 0 if dma_alloc_coherent should continue with allocating from
 153  * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 154  */
 155 int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 156                                        dma_addr_t *dma_handle, void **ret)
 157 {
 158         struct dma_coherent_mem *mem;
 159         int order = get_order(size);
 160         unsigned long flags;
 161         int pageno;
 162
 163         if (!dev)
 164                 return 0;
 165         mem = dev->dma_mem;
 166         if (!mem)
 167                 return 0;
 168
 169         *ret = NULL;
 170         spin_lock_irqsave(&mem->spinlock, flags);
 171
 172         if (unlikely(size > (mem->size << PAGE_SHIFT)))
 173                 goto err;
 174
 175         pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
 176         if (unlikely(pageno < 0))
 177                 goto err;
 178
 179         /*
 180          * Memory was found in the per-device area.
 181          */
 182         *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
 183         *ret = mem->virt_base + (pageno << PAGE_SHIFT);
 184         memset(*ret, 0, size);
 185         spin_unlock_irqrestore(&mem->spinlock, flags);
 186
 187         return 1;
 188
 189 err:
 190         spin_unlock_irqrestore(&mem->spinlock, flags);
 191         /*
 192          * In the case where the allocation can not be satisfied from the
 193          * per-device area, try to fall back to generic memory if the
 194          * constraints allow it.
 195          */
 196         return mem->flags & DMA_MEMORY_EXCLUSIVE;
 197 }
 198 EXPORT_SYMBOL(dma_alloc_from_coherent);
 199
 200 /**
 201  * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
 202  * @dev:        device from which the memory was allocated
 203  * @order:      the order of pages allocated
 204  * @vaddr:      virtual address of allocated pages
 205  *
 206  * This checks whether the memory was allocated from the per-device
 207  * coherent memory pool and if so, releases that memory.
 208  *
 209  * Returns 1 if we correctly released the memory, or 0 if
 210  * dma_release_coherent() should proceed with releasing memory from
 211  * generic pools.
 212  */
 213 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 214 {
 215         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
 216
 217         if (mem && vaddr >= mem->virt_base && vaddr <
 218                    (mem->virt_base + (mem->size << PAGE_SHIFT))) {
 219                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 220                 unsigned long flags;
 221
 222                 spin_lock_irqsave(&mem->spinlock, flags);
 223                 bitmap_release_region(mem->bitmap, page, order);
 224                 spin_unlock_irqrestore(&mem->spinlock, flags);
 225                 return 1;
 226         }
 227         return 0;
 228 }
 229 EXPORT_SYMBOL(dma_release_from_coherent);
 230
 231 /**
 232  * dma_mmap_from_coherent() - try to mmap the memory allocated from
 233  * per-device coherent memory pool to userspace
 234  * @dev:        device from which the memory was allocated
 235  * @vma:        vm_area for the userspace memory
 236  * @vaddr:      cpu address returned by dma_alloc_from_coherent
 237  * @size:       size of the memory buffer allocated by dma_alloc_from_coherent
 238  * @ret:        result from remap_pfn_range()
 239  *
 240  * This checks whether the memory was allocated from the per-device
 241  * coherent memory pool and if so, maps that memory to the provided vma.
 242  *
 243  * Returns 1 if we correctly mapped the memory, or 0 if the caller should
 244  * proceed with mapping memory from generic pools.
 245  */
 246 int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
 247                            void *vaddr, size_t size, int *ret)
 248 {
 249         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
 250
 251         if (mem && vaddr >= mem->virt_base && vaddr + size <=
 252                    (mem->virt_base + (mem->size << PAGE_SHIFT))) {
 253                 unsigned long off = vma->vm_pgoff;
 254                 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 255                 int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 256                 int count = size >> PAGE_SHIFT;
 257
 258                 *ret = -ENXIO;
 259                 if (off < count && user_count <= count - off) {
 260                         unsigned long pfn = mem->pfn_base + start + off;
 261                         *ret = remap_pfn_range(vma, vma->vm_start, pfn,
 262                                                user_count << PAGE_SHIFT,
 263                                                vma->vm_page_prot);
 264                 }
 265                 return 1;
 266         }
 267         return 0;
 268 }
 269 EXPORT_SYMBOL(dma_mmap_from_coherent);
 270
 271 /*
 272  * Support for reserved memory regions defined in device tree
 273  */
 274 #ifdef CONFIG_OF_RESERVED_MEM
 275 #include <linux/of.h>
 276 #include <linux/of_fdt.h>
 277 #include <linux/of_reserved_mem.h>
 278
 279 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 280 {
 281         struct dma_coherent_mem *mem = rmem->priv;
 282
 283         if (!mem &&
 284             dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
 285                                      DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
 286                                      &mem) != DMA_MEMORY_MAP) {
 287                 pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
 288                         &rmem->base, (unsigned long)rmem->size / SZ_1M);
 289                 return -ENODEV;
 290         }
 291         rmem->priv = mem;
 292         dma_assign_coherent_memory(dev, mem);
 293         return 0;
 294 }
 295
 296 static void rmem_dma_device_release(struct reserved_mem *rmem,
 297                                     struct device *dev)
 298 {
 299         dev->dma_mem = NULL;
 300 }
 301
 302 static const struct reserved_mem_ops rmem_dma_ops = {
 303         .device_init    = rmem_dma_device_init,
 304         .device_release = rmem_dma_device_release,
 305 };
 306
 307 static int __init rmem_dma_setup(struct reserved_mem *rmem)
 308 {
 309         unsigned long node = rmem->fdt_node;
 310
 311         if (of_get_flat_dt_prop(node, "reusable", NULL))
 312                 return -EINVAL;
 313
 314 #ifdef CONFIG_ARM
 315         if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
 316                 pr_err("Reserved memory: regions without no-map are not yet supported\n");
 317                 return -EINVAL;
 318         }
 319 #endif
 320
 321         rmem->ops = &rmem_dma_ops;
 322         pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
 323                 &rmem->base, (unsigned long)rmem->size / SZ_1M);
 324         return 0;
 325 }
 326 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
 327 #endif