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-direct.h>
  11 #include <linux/dma-map-ops.h>
  12
  13 struct dma_coherent_mem {
  14         void            *virt_base;
  15         dma_addr_t      device_base;
  16         unsigned long   pfn_base;
  17         int             size;
  18         unsigned long   *bitmap;
  19         spinlock_t      spinlock;
  20         bool            use_dev_dma_pfn_offset;
  21 };
  22
  23 static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
  24
  25 static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
  26 {
  27         if (dev && dev->dma_mem)
  28                 return dev->dma_mem;
  29         return NULL;
  30 }
  31
  32 static inline dma_addr_t dma_get_device_base(struct device *dev,
  33                                              struct dma_coherent_mem * mem)
  34 {
  35         if (mem->use_dev_dma_pfn_offset)
  36                 return phys_to_dma(dev, PFN_PHYS(mem->pfn_base));
  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 /*
 111  * Declare a region of memory to be handed out by dma_alloc_coherent() when it
 112  * is asked for coherent memory for this device.  This shall only be used
 113  * from platform code, usually based on the device tree description.
 114  *
 115  * phys_addr is the CPU physical address to which the memory is currently
 116  * assigned (this will be ioremapped so the CPU can access the region).
 117  *
 118  * device_addr is the DMA address the device needs to be programmed with to
 119  * actually address this memory (this will be handed out as the dma_addr_t in
 120  * dma_alloc_coherent()).
 121  *
 122  * size is the size of the area (must be a multiple of PAGE_SIZE).
 123  *
 124  * As a simplification for the platforms, only *one* such region of memory may
 125  * be declared per device.
 126  */
 127 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 128                                 dma_addr_t device_addr, size_t size)
 129 {
 130         struct dma_coherent_mem *mem;
 131         int ret;
 132
 133         ret = dma_init_coherent_memory(phys_addr, device_addr, size, &mem);
 134         if (ret)
 135                 return ret;
 136
 137         ret = dma_assign_coherent_memory(dev, mem);
 138         if (ret)
 139                 dma_release_coherent_memory(mem);
 140         return ret;
 141 }
 142
 143 static void *__dma_alloc_from_coherent(struct device *dev,
 144                                        struct dma_coherent_mem *mem,
 145                                        ssize_t size, dma_addr_t *dma_handle)
 146 {
 147         int order = get_order(size);
 148         unsigned long flags;
 149         int pageno;
 150         void *ret;
 151
 152         spin_lock_irqsave(&mem->spinlock, flags);
 153
 154         if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT)))
 155                 goto err;
 156
 157         pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
 158         if (unlikely(pageno < 0))
 159                 goto err;
 160
 161         /*
 162          * Memory was found in the coherent area.
 163          */
 164         *dma_handle = dma_get_device_base(dev, mem) +
 165                         ((dma_addr_t)pageno << PAGE_SHIFT);
 166         ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT);
 167         spin_unlock_irqrestore(&mem->spinlock, flags);
 168         memset(ret, 0, size);
 169         return ret;
 170 err:
 171         spin_unlock_irqrestore(&mem->spinlock, flags);
 172         return NULL;
 173 }
 174
 175 /**
 176  * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
 177  * @dev:        device from which we allocate memory
 178  * @size:       size of requested memory area
 179  * @dma_handle: This will be filled with the correct dma handle
 180  * @ret:        This pointer will be filled with the virtual address
 181  *              to allocated area.
 182  *
 183  * This function should be only called from per-arch dma_alloc_coherent()
 184  * to support allocation from per-device coherent memory pools.
 185  *
 186  * Returns 0 if dma_alloc_coherent should continue with allocating from
 187  * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 188  */
 189 int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
 190                 dma_addr_t *dma_handle, void **ret)
 191 {
 192         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 193
 194         if (!mem)
 195                 return 0;
 196
 197         *ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle);
 198         return 1;
 199 }
 200
 201 void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
 202                                      dma_addr_t *dma_handle)
 203 {
 204         if (!dma_coherent_default_memory)
 205                 return NULL;
 206
 207         return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
 208                                          dma_handle);
 209 }
 210
 211 static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
 212                                        int order, void *vaddr)
 213 {
 214         if (mem && vaddr >= mem->virt_base && vaddr <
 215                    (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
 216                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 217                 unsigned long flags;
 218
 219                 spin_lock_irqsave(&mem->spinlock, flags);
 220                 bitmap_release_region(mem->bitmap, page, order);
 221                 spin_unlock_irqrestore(&mem->spinlock, flags);
 222                 return 1;
 223         }
 224         return 0;
 225 }
 226
 227 /**
 228  * dma_release_from_dev_coherent() - free memory to device coherent memory pool
 229  * @dev:        device from which the memory was allocated
 230  * @order:      the order of pages allocated
 231  * @vaddr:      virtual address of allocated pages
 232  *
 233  * This checks whether the memory was allocated from the per-device
 234  * coherent memory pool and if so, releases that memory.
 235  *
 236  * Returns 1 if we correctly released the memory, or 0 if the caller should
 237  * proceed with releasing memory from generic pools.
 238  */
 239 int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
 240 {
 241         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 242
 243         return __dma_release_from_coherent(mem, order, vaddr);
 244 }
 245
 246 int dma_release_from_global_coherent(int order, void *vaddr)
 247 {
 248         if (!dma_coherent_default_memory)
 249                 return 0;
 250
 251         return __dma_release_from_coherent(dma_coherent_default_memory, order,
 252                         vaddr);
 253 }
 254
 255 static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
 256                 struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
 257 {
 258         if (mem && vaddr >= mem->virt_base && vaddr + size <=
 259                    (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
 260                 unsigned long off = vma->vm_pgoff;
 261                 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 262                 unsigned long user_count = vma_pages(vma);
 263                 int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 264
 265                 *ret = -ENXIO;
 266                 if (off < count && user_count <= count - off) {
 267                         unsigned long pfn = mem->pfn_base + start + off;
 268                         *ret = remap_pfn_range(vma, vma->vm_start, pfn,
 269                                                user_count << PAGE_SHIFT,
 270                                                vma->vm_page_prot);
 271                 }
 272                 return 1;
 273         }
 274         return 0;
 275 }
 276
 277 /**
 278  * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
 279  * @dev:        device from which the memory was allocated
 280  * @vma:        vm_area for the userspace memory
 281  * @vaddr:      cpu address returned by dma_alloc_from_dev_coherent
 282  * @size:       size of the memory buffer allocated
 283  * @ret:        result from remap_pfn_range()
 284  *
 285  * This checks whether the memory was allocated from the per-device
 286  * coherent memory pool and if so, maps that memory to the provided vma.
 287  *
 288  * Returns 1 if @vaddr belongs to the device coherent pool and the caller
 289  * should return @ret, or 0 if they should proceed with mapping memory from
 290  * generic areas.
 291  */
 292 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
 293                            void *vaddr, size_t size, int *ret)
 294 {
 295         struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
 296
 297         return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
 298 }
 299
 300 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
 301                                    size_t size, int *ret)
 302 {
 303         if (!dma_coherent_default_memory)
 304                 return 0;
 305
 306         return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
 307                                         vaddr, size, ret);
 308 }
 309
 310 /*
 311  * Support for reserved memory regions defined in device tree
 312  */
 313 #ifdef CONFIG_OF_RESERVED_MEM
 314 #include <linux/of.h>
 315 #include <linux/of_fdt.h>
 316 #include <linux/of_reserved_mem.h>
 317
 318 static struct reserved_mem *dma_reserved_default_memory __initdata;
 319
 320 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
 321 {
 322         struct dma_coherent_mem *mem = rmem->priv;
 323         int ret;
 324
 325         if (!mem) {
 326                 ret = dma_init_coherent_memory(rmem->base, rmem->base,
 327                                                rmem->size, &mem);
 328                 if (ret) {
 329                         pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
 330                                 &rmem->base, (unsigned long)rmem->size / SZ_1M);
 331                         return ret;
 332                 }
 333         }
 334         mem->use_dev_dma_pfn_offset = true;
 335         rmem->priv = mem;
 336         dma_assign_coherent_memory(dev, mem);
 337         return 0;
 338 }
 339
 340 static void rmem_dma_device_release(struct reserved_mem *rmem,
 341                                     struct device *dev)
 342 {
 343         if (dev)
 344                 dev->dma_mem = NULL;
 345 }
 346
 347 static const struct reserved_mem_ops rmem_dma_ops = {
 348         .device_init    = rmem_dma_device_init,
 349         .device_release = rmem_dma_device_release,
 350 };
 351
 352 static int __init rmem_dma_setup(struct reserved_mem *rmem)
 353 {
 354         unsigned long node = rmem->fdt_node;
 355
 356         if (of_get_flat_dt_prop(node, "reusable", NULL))
 357                 return -EINVAL;
 358
 359 #ifdef CONFIG_ARM
 360         if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
 361                 pr_err("Reserved memory: regions without no-map are not yet supported\n");
 362                 return -EINVAL;
 363         }
 364
 365         if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
 366                 WARN(dma_reserved_default_memory,
 367                      "Reserved memory: region for default DMA coherent area is redefined\n");
 368                 dma_reserved_default_memory = rmem;
 369         }
 370 #endif
 371
 372         rmem->ops = &rmem_dma_ops;
 373         pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
 374                 &rmem->base, (unsigned long)rmem->size / SZ_1M);
 375         return 0;
 376 }
 377
 378 static int __init dma_init_reserved_memory(void)
 379 {
 380         const struct reserved_mem_ops *ops;
 381         int ret;
 382
 383         if (!dma_reserved_default_memory)
 384                 return -ENOMEM;
 385
 386         ops = dma_reserved_default_memory->ops;
 387
 388         /*
 389          * We rely on rmem_dma_device_init() does not propagate error of
 390          * dma_assign_coherent_memory() for "NULL" device.
 391          */
 392         ret = ops->device_init(dma_reserved_default_memory, NULL);
 393
 394         if (!ret) {
 395                 dma_coherent_default_memory = dma_reserved_default_memory->priv;
 396                 pr_info("DMA: default coherent area is set\n");
 397         }
 398
 399         return ret;
 400 }
 401
 402 core_initcall(dma_init_reserved_memory);
 403
 404 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
 405 #endif