drivers/base/dma-coherent.c

   1 /*
   2  * Coherent per-device memory handling.
   3  * Borrowed from i386
   4  */
   5 #include <linux/io.h>
   6 #include <linux/slab.h>
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/dma-mapping.h>
  10
  11 struct dma_coherent_mem {
  12         void            *virt_base;
  13         dma_addr_t      device_base;
  14         unsigned long   pfn_base;
  15         int             size;
  16         int             flags;
  17         unsigned long   *bitmap;
  18         spinlock_t      spinlock;
  19         bool            use_dev_dma_pfn_offset;
  20 };
  21
  22 static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
  23
  24 static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
  25 {
  26         if (dev && dev->dma_mem)
  27                 return dev->dma_mem;
  28         return dma_coherent_default_memory;
  29 }
  30
  31 static inline dma_addr_t dma_get_device_base(struct device *dev,
  32                                              struct dma_coherent_mem * mem)
  33 {
  34         if (mem->use_dev_dma_pfn_offset)
  35                 return (mem->pfn_base - dev->dma_pfn_offset) << PAGE_SHIFT;
  36         else
  37                 return mem->device_base;
  38 }
  39
  40 static bool dma_init_coherent_memory(
  41         phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags,
  42         struct dma_coherent_mem **mem)
  43 {
  44         struct dma_coherent_mem *dma_mem = NULL;
  45         void __iomem *mem_base = NULL;
  46         int pages = size >> PAGE_SHIFT;
  47         int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
  48
  49         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  50                 goto out;
  51         if (!size)
  52                 goto out;
  53
  54         if (flags & DMA_MEMORY_MAP)
  55                 mem_base = memremap(phys_addr, size, MEMREMAP_WC);
  56         else
  57                 mem_base = ioremap(phys_addr, size);
  58         if (!mem_base)
  59                 goto out;
  60
  61         dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  62         if (!dma_mem)
  63                 goto out;
  64         dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  65         if (!dma_mem->bitmap)
  66                 goto out;
  67
  68         dma_mem->virt_base = mem_base;
  69         dma_mem->device_base = device_addr;
  70         dma_mem->pfn_base = PFN_DOWN(phys_addr);
  71         dma_mem->size = pages;
  72         dma_mem->flags = flags;
  73         spin_lock_init(&dma_mem->spinlock);
  74
  75         *mem = dma_mem;
  76         return true;
  77
  78 out:
  79         kfree(dma_mem);
  80         if (mem_base) {
  81                 if (flags & DMA_MEMORY_MAP)
  82                         memunmap(mem_base);
  83                 else
  84                         iounmap(mem_base);
  85         }
  86         return false;
  87 }
  88
  89 static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
  90 {
  91         if (!mem)
  92                 return;
  93
  94         if (mem->flags & DMA_MEMORY_MAP)
  95                 memunmap(mem->virt_base);
  96         else
  97                 iounmap(mem->virt_base);
  98         kfree(mem->bitmap);
  99         kfree(mem);
 100 }
 101
 102 static int dma_assign_coherent_memory(struct device *dev,
 103                                       struct dma_coherent_mem *mem)
 104 {
 105         if (!dev)
 106                 return -ENODEV;
 107
 108         if (dev->dma_mem)
 109                 return -EBUSY;
 110
 111         dev->dma_mem = mem;
 112         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
 113
 114         return 0;
 115 }
 116
 117 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 118                                 dma_addr_t device_addr, size_t size, int flags)
 119 {
 120         struct dma_coherent_mem *mem;
 121
 122         if (!dma_init_coherent_memory(phys_addr, device_addr, size, flags,
 123                                       &mem))
 124                 return 0;
 125
 126         if (dma_assign_coherent_memory(dev, mem) == 0)
 127                 return flags & DMA_MEMORY_MAP ? DMA_MEMORY_MAP : DMA_MEMORY_IO;
 128
 129         dma_release_coherent_memory(mem);
 130         return 0;
 131 }
 132 EXPORT_SYMBOL(dma_declare_coherent_memory);
 133
 134 void dma_release_declared_memory(struct device *dev)
 135 {
 136         struct dma_coherent_mem *mem = dev->dma_mem;
 137
 138         if (!mem)
 139                 return;
 140         dma_release_coherent_memory(mem);
 141         dev->dma_mem = NULL;
 142 }
 143 EXPORT_SYMBOL(dma_release_declared_memory);
 144
 145 void *dma_mark_declared_memory_occupied(struct device *dev,
 146                                         dma_addr_t device_addr, size_t size)
 147 {
 148         struct dma_coherent_mem *mem = dev->dma_mem;
 149         unsigned long flags;
 150         int pos, err;
 151
 152         size += device_addr & ~PAGE_MASK;
 153
 154         if (!mem)
 155                 return ERR_PTR(-EINVAL);
 156
 157         spin_lock_irqsave(&mem->spinlock, flags);
 158         pos = PFN_DOWN(device_addr - dma_get_device_base(dev, mem));
 159         err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
 160         spin_unlock_irqrestore(&mem->spinlock, flags);
 161
 162         if (err != 0)
 163                 return ERR_PTR(err);
 164         return mem->virt_base + (pos << PAGE_SHIFT);
 165 }
 166 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 167
 168 /**
 169  * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
 170  *
 171  * @dev:        device from which we allocate memory
 172  * @size:       size of requested memory area
 173  * @dma_handle: This will be filled with the correct dma handle
 174  * @ret:        This pointer will be filled with the virtual address
 175  *              to allocated area.
 176  *
 177  * This function should be only called from per-arch dma_alloc_coherent()
 178  * to support allocation from per-device coherent memory pools.
 179  *
 180  * Returns 0 if dma_alloc_coherent should continue with allocating from
 181  * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 182  */
 183 int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 184                                        dma_addr_t *dma_handle, void **ret)
 185 {
 186         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 187         int order = get_order(size);
 188         unsigned long flags;
 189         int pageno;
 190         int dma_memory_map;
 191
 192         if (!mem)
 193                 return 0;
 194
 195         *ret = NULL;
 196         spin_lock_irqsave(&mem->spinlock, flags);
 197
 198         if (unlikely(size > (mem->size << PAGE_SHIFT)))
 199                 goto err;
 200
 201         pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
 202         if (unlikely(pageno < 0))
 203                 goto err;
 204
 205         /*
 206          * Memory was found in the per-device area.
 207          */
 208         *dma_handle = dma_get_device_base(dev, mem) + (pageno << PAGE_SHIFT);
 209         *ret = mem->virt_base + (pageno << PAGE_SHIFT);
 210         dma_memory_map = (mem->flags & DMA_MEMORY_MAP);
 211         spin_unlock_irqrestore(&mem->spinlock, flags);
 212         if (dma_memory_map)
 213                 memset(*ret, 0, size);
 214         else
 215                 memset_io(*ret, 0, size);
 216
 217         return 1;
 218
 219 err:
 220         spin_unlock_irqrestore(&mem->spinlock, flags);
 221         /*
 222          * In the case where the allocation can not be satisfied from the
 223          * per-device area, try to fall back to generic memory if the
 224          * constraints allow it.
 225          */
 226         return mem->flags & DMA_MEMORY_EXCLUSIVE;
 227 }
 228 EXPORT_SYMBOL(dma_alloc_from_coherent);
 229
 230 /**
 231  * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
 232  * @dev:        device from which the memory was allocated
 233  * @order:      the order of pages allocated
 234  * @vaddr:      virtual address of allocated pages
 235  *
 236  * This checks whether the memory was allocated from the per-device
 237  * coherent memory pool and if so, releases that memory.
 238  *
 239  * Returns 1 if we correctly released the memory, or 0 if
 240  * dma_release_coherent() should proceed with releasing memory from
 241  * generic pools.
 242  */
 243 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 244 {
 245         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 246
 247         if (mem && vaddr >= mem->virt_base && vaddr <
 248                    (mem->virt_base + (mem->size << PAGE_SHIFT))) {
 249                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 250                 unsigned long flags;
 251
 252                 spin_lock_irqsave(&mem->spinlock, flags);
 253                 bitmap_release_region(mem->bitmap, page, order);
 254                 spin_unlock_irqrestore(&mem->spinlock, flags);
 255                 return 1;
 256         }
 257         return 0;
 258 }
 259 EXPORT_SYMBOL(dma_release_from_coherent);
 260
 261 /**
 262  * dma_mmap_from_coherent() - try to mmap the memory allocated from
 263  * per-device coherent memory pool to userspace
 264  * @dev:        device from which the memory was allocated
 265  * @vma:        vm_area for the userspace memory
 266  * @vaddr:      cpu address returned by dma_alloc_from_coherent
 267  * @size:       size of the memory buffer allocated by dma_alloc_from_coherent
 268  * @ret:        result from remap_pfn_range()
 269  *
 270  * This checks whether the memory was allocated from the per-device
 271  * coherent memory pool and if so, maps that memory to the provided vma.
 272  *
 273  * Returns 1 if we correctly mapped the memory, or 0 if the caller should
 274  * proceed with mapping memory from generic pools.
 275  */
 276 int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
 277                            void *vaddr, size_t size, int *ret)
 278 {
 279         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 280
 281         if (mem && vaddr >= mem->virt_base && vaddr + size <=
 282                    (mem->virt_base + (mem->size << PAGE_SHIFT))) {
 283                 unsigned long off = vma->vm_pgoff;
 284                 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 285                 int user_count = vma_pages(vma);
 286                 int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 287
 288                 *ret = -ENXIO;
 289                 if (off < count && user_count <= count - off) {
 290                         unsigned long pfn = mem->pfn_base + start + off;
 291                         *ret = remap_pfn_range(vma, vma->vm_start, pfn,
 292                                                user_count << PAGE_SHIFT,
 293                                                vma->vm_page_prot);
 294                 }
 295                 return 1;
 296         }
 297         return 0;
 298 }
 299 EXPORT_SYMBOL(dma_mmap_from_coherent);
 300
 301 /*
 302  * Support for reserved memory regions defined in device tree
 303  */
 304 #ifdef CONFIG_OF_RESERVED_MEM
 305 #include <linux/of.h>
 306 #include <linux/of_fdt.h>
 307 #include <linux/of_reserved_mem.h>
 308
 309 static struct reserved_mem *dma_reserved_default_memory __initdata;
 310
 311 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 312 {
 313         struct dma_coherent_mem *mem = rmem->priv;
 314
 315         if (!mem &&
 316             !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
 317                                       DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
 318                                       &mem)) {
 319                 pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
 320                         &rmem->base, (unsigned long)rmem->size / SZ_1M);
 321                 return -ENODEV;
 322         }
 323         mem->use_dev_dma_pfn_offset = true;
 324         rmem->priv = mem;
 325         dma_assign_coherent_memory(dev, mem);
 326         return 0;
 327 }
 328
 329 static void rmem_dma_device_release(struct reserved_mem *rmem,
 330                                     struct device *dev)
 331 {
 332         if (dev)
 333                 dev->dma_mem = NULL;
 334 }
 335
 336 static const struct reserved_mem_ops rmem_dma_ops = {
 337         .device_init    = rmem_dma_device_init,
 338         .device_release = rmem_dma_device_release,
 339 };
 340
 341 static int __init rmem_dma_setup(struct reserved_mem *rmem)
 342 {
 343         unsigned long node = rmem->fdt_node;
 344
 345         if (of_get_flat_dt_prop(node, "reusable", NULL))
 346                 return -EINVAL;
 347
 348 #ifdef CONFIG_ARM
 349         if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
 350                 pr_err("Reserved memory: regions without no-map are not yet supported\n");
 351                 return -EINVAL;
 352         }
 353
 354         if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
 355                 WARN(dma_reserved_default_memory,
 356                      "Reserved memory: region for default DMA coherent area is redefined\n");
 357                 dma_reserved_default_memory = rmem;
 358         }
 359 #endif
 360
 361         rmem->ops = &rmem_dma_ops;
 362         pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
 363                 &rmem->base, (unsigned long)rmem->size / SZ_1M);
 364         return 0;
 365 }
 366
 367 static int __init dma_init_reserved_memory(void)
 368 {
 369         const struct reserved_mem_ops *ops;
 370         int ret;
 371
 372         if (!dma_reserved_default_memory)
 373                 return -ENOMEM;
 374
 375         ops = dma_reserved_default_memory->ops;
 376
 377         /*
 378          * We rely on rmem_dma_device_init() does not propagate error of
 379          * dma_assign_coherent_memory() for "NULL" device.
 380          */
 381         ret = ops->device_init(dma_reserved_default_memory, NULL);
 382
 383         if (!ret) {
 384                 dma_coherent_default_memory = dma_reserved_default_memory->priv;
 385                 pr_info("DMA: default coherent area is set\n");
 386         }
 387
 388         return ret;
 389 }
 390
 391 core_initcall(dma_init_reserved_memory);
 392
 393 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
 394 #endif