kernel/dma/coherent.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Coherent per-device memory handling.
   4  * Borrowed from i386
   5  */
   6 #include <linux/io.h>
   7 #include <linux/slab.h>
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/dma-mapping.h>
  11
  12 struct dma_coherent_mem {
  13         void            *virt_base;
  14         dma_addr_t      device_base;
  15         unsigned long   pfn_base;
  16         int             size;
  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 NULL;
  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 int dma_init_coherent_memory(phys_addr_t phys_addr,
  41                 dma_addr_t device_addr, size_t size,
  42                 struct dma_coherent_mem **mem)
  43 {
  44         struct dma_coherent_mem *dma_mem = NULL;
  45         void *mem_base = NULL;
  46         int pages = size >> PAGE_SHIFT;
  47         int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
  48         int ret;
  49
  50         if (!size) {
  51                 ret = -EINVAL;
  52                 goto out;
  53         }
  54
  55         mem_base = memremap(phys_addr, size, MEMREMAP_WC);
  56         if (!mem_base) {
  57                 ret = -EINVAL;
  58                 goto out;
  59         }
  60         dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  61         if (!dma_mem) {
  62                 ret = -ENOMEM;
  63                 goto out;
  64         }
  65         dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  66         if (!dma_mem->bitmap) {
  67                 ret = -ENOMEM;
  68                 goto out;
  69         }
  70
  71         dma_mem->virt_base = mem_base;
  72         dma_mem->device_base = device_addr;
  73         dma_mem->pfn_base = PFN_DOWN(phys_addr);
  74         dma_mem->size = pages;
  75         spin_lock_init(&dma_mem->spinlock);
  76
  77         *mem = dma_mem;
  78         return 0;
  79
  80 out:
  81         kfree(dma_mem);
  82         if (mem_base)
  83                 memunmap(mem_base);
  84         return ret;
  85 }
  86
  87 static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
  88 {
  89         if (!mem)
  90                 return;
  91
  92         memunmap(mem->virt_base);
  93         kfree(mem->bitmap);
  94         kfree(mem);
  95 }
  96
  97 static int dma_assign_coherent_memory(struct device *dev,
  98                                       struct dma_coherent_mem *mem)
  99 {
 100         if (!dev)
 101                 return -ENODEV;
 102
 103         if (dev->dma_mem)
 104                 return -EBUSY;
 105
 106         dev->dma_mem = mem;
 107         return 0;
 108 }
 109
 110 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 111                                 dma_addr_t device_addr, size_t size)
 112 {
 113         struct dma_coherent_mem *mem;
 114         int ret;
 115
 116         ret = dma_init_coherent_memory(phys_addr, device_addr, size, &mem);
 117         if (ret)
 118                 return ret;
 119
 120         ret = dma_assign_coherent_memory(dev, mem);
 121         if (ret)
 122                 dma_release_coherent_memory(mem);
 123         return ret;
 124 }
 125
 126 static void *__dma_alloc_from_coherent(struct device *dev,
 127                                        struct dma_coherent_mem *mem,
 128                                        ssize_t size, dma_addr_t *dma_handle)
 129 {
 130         int order = get_order(size);
 131         unsigned long flags;
 132         int pageno;
 133         void *ret;
 134
 135         spin_lock_irqsave(&mem->spinlock, flags);
 136
 137         if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT)))
 138                 goto err;
 139
 140         pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
 141         if (unlikely(pageno < 0))
 142                 goto err;
 143
 144         /*
 145          * Memory was found in the coherent area.
 146          */
 147         *dma_handle = dma_get_device_base(dev, mem) +
 148                         ((dma_addr_t)pageno << PAGE_SHIFT);
 149         ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT);
 150         spin_unlock_irqrestore(&mem->spinlock, flags);
 151         memset(ret, 0, size);
 152         return ret;
 153 err:
 154         spin_unlock_irqrestore(&mem->spinlock, flags);
 155         return NULL;
 156 }
 157
 158 /**
 159  * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
 160  * @dev:        device from which we allocate memory
 161  * @size:       size of requested memory area
 162  * @dma_handle: This will be filled with the correct dma handle
 163  * @ret:        This pointer will be filled with the virtual address
 164  *              to allocated area.
 165  *
 166  * This function should be only called from per-arch dma_alloc_coherent()
 167  * to support allocation from per-device coherent memory pools.
 168  *
 169  * Returns 0 if dma_alloc_coherent should continue with allocating from
 170  * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 171  */
 172 int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
 173                 dma_addr_t *dma_handle, void **ret)
 174 {
 175         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 176
 177         if (!mem)
 178                 return 0;
 179
 180         *ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle);
 181         return 1;
 182 }
 183
 184 void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
 185                                      dma_addr_t *dma_handle)
 186 {
 187         if (!dma_coherent_default_memory)
 188                 return NULL;
 189
 190         return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
 191                                          dma_handle);
 192 }
 193
 194 static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
 195                                        int order, void *vaddr)
 196 {
 197         if (mem && vaddr >= mem->virt_base && vaddr <
 198                    (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
 199                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 200                 unsigned long flags;
 201
 202                 spin_lock_irqsave(&mem->spinlock, flags);
 203                 bitmap_release_region(mem->bitmap, page, order);
 204                 spin_unlock_irqrestore(&mem->spinlock, flags);
 205                 return 1;
 206         }
 207         return 0;
 208 }
 209
 210 /**
 211  * dma_release_from_dev_coherent() - free memory to device coherent memory pool
 212  * @dev:        device from which the memory was allocated
 213  * @order:      the order of pages allocated
 214  * @vaddr:      virtual address of allocated pages
 215  *
 216  * This checks whether the memory was allocated from the per-device
 217  * coherent memory pool and if so, releases that memory.
 218  *
 219  * Returns 1 if we correctly released the memory, or 0 if the caller should
 220  * proceed with releasing memory from generic pools.
 221  */
 222 int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
 223 {
 224         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 225
 226         return __dma_release_from_coherent(mem, order, vaddr);
 227 }
 228
 229 int dma_release_from_global_coherent(int order, void *vaddr)
 230 {
 231         if (!dma_coherent_default_memory)
 232                 return 0;
 233
 234         return __dma_release_from_coherent(dma_coherent_default_memory, order,
 235                         vaddr);
 236 }
 237
 238 static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
 239                 struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
 240 {
 241         if (mem && vaddr >= mem->virt_base && vaddr + size <=
 242                    (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
 243                 unsigned long off = vma->vm_pgoff;
 244                 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 245                 unsigned long user_count = vma_pages(vma);
 246                 int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 247
 248                 *ret = -ENXIO;
 249                 if (off < count && user_count <= count - off) {
 250                         unsigned long pfn = mem->pfn_base + start + off;
 251                         *ret = remap_pfn_range(vma, vma->vm_start, pfn,
 252                                                user_count << PAGE_SHIFT,
 253                                                vma->vm_page_prot);
 254                 }
 255                 return 1;
 256         }
 257         return 0;
 258 }
 259
 260 /**
 261  * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
 262  * @dev:        device from which the memory was allocated
 263  * @vma:        vm_area for the userspace memory
 264  * @vaddr:      cpu address returned by dma_alloc_from_dev_coherent
 265  * @size:       size of the memory buffer allocated
 266  * @ret:        result from remap_pfn_range()
 267  *
 268  * This checks whether the memory was allocated from the per-device
 269  * coherent memory pool and if so, maps that memory to the provided vma.
 270  *
 271  * Returns 1 if @vaddr belongs to the device coherent pool and the caller
 272  * should return @ret, or 0 if they should proceed with mapping memory from
 273  * generic areas.
 274  */
 275 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
 276                            void *vaddr, size_t size, int *ret)
 277 {
 278         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 279
 280         return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
 281 }
 282
 283 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
 284                                    size_t size, int *ret)
 285 {
 286         if (!dma_coherent_default_memory)
 287                 return 0;
 288
 289         return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
 290                                         vaddr, size, ret);
 291 }
 292
 293 /*
 294  * Support for reserved memory regions defined in device tree
 295  */
 296 #ifdef CONFIG_OF_RESERVED_MEM
 297 #include <linux/of.h>
 298 #include <linux/of_fdt.h>
 299 #include <linux/of_reserved_mem.h>
 300
 301 static struct reserved_mem *dma_reserved_default_memory __initdata;
 302
 303 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 304 {
 305         struct dma_coherent_mem *mem = rmem->priv;
 306         int ret;
 307
 308         if (!mem) {
 309                 ret = dma_init_coherent_memory(rmem->base, rmem->base,
 310                                                rmem->size, &mem);
 311                 if (ret) {
 312                         pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
 313                                 &rmem->base, (unsigned long)rmem->size / SZ_1M);
 314                         return ret;
 315                 }
 316         }
 317         mem->use_dev_dma_pfn_offset = true;
 318         rmem->priv = mem;
 319         dma_assign_coherent_memory(dev, mem);
 320         return 0;
 321 }
 322
 323 static void rmem_dma_device_release(struct reserved_mem *rmem,
 324                                     struct device *dev)
 325 {
 326         if (dev)
 327                 dev->dma_mem = NULL;
 328 }
 329
 330 static const struct reserved_mem_ops rmem_dma_ops = {
 331         .device_init    = rmem_dma_device_init,
 332         .device_release = rmem_dma_device_release,
 333 };
 334
 335 static int __init rmem_dma_setup(struct reserved_mem *rmem)
 336 {
 337         unsigned long node = rmem->fdt_node;
 338
 339         if (of_get_flat_dt_prop(node, "reusable", NULL))
 340                 return -EINVAL;
 341
 342 #ifdef CONFIG_ARM
 343         if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
 344                 pr_err("Reserved memory: regions without no-map are not yet supported\n");
 345                 return -EINVAL;
 346         }
 347
 348         if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
 349                 WARN(dma_reserved_default_memory,
 350                      "Reserved memory: region for default DMA coherent area is redefined\n");
 351                 dma_reserved_default_memory = rmem;
 352         }
 353 #endif
 354
 355         rmem->ops = &rmem_dma_ops;
 356         pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
 357                 &rmem->base, (unsigned long)rmem->size / SZ_1M);
 358         return 0;
 359 }
 360
 361 static int __init dma_init_reserved_memory(void)
 362 {
 363         const struct reserved_mem_ops *ops;
 364         int ret;
 365
 366         if (!dma_reserved_default_memory)
 367                 return -ENOMEM;
 368
 369         ops = dma_reserved_default_memory->ops;
 370
 371         /*
 372          * We rely on rmem_dma_device_init() does not propagate error of
 373          * dma_assign_coherent_memory() for "NULL" device.
 374          */
 375         ret = ops->device_init(dma_reserved_default_memory, NULL);
 376
 377         if (!ret) {
 378                 dma_coherent_default_memory = dma_reserved_default_memory->priv;
 379                 pr_info("DMA: default coherent area is set\n");
 380         }
 381
 382         return ret;
 383 }
 384
 385 core_initcall(dma_init_reserved_memory);
 386
 387 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
 388 #endif