linux/kernel/dma/coherent.c
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   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
  13struct 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
  23static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
  24
  25static 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
  32static 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
  40static 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
  80out:
  81        kfree(dma_mem);
  82        if (mem_base)
  83                memunmap(mem_base);
  84        return ret;
  85}
  86
  87static 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
  97static 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 */
 127int 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
 143static 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;
 170err:
 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 */
 189int 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
 201void *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
 211static 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 */
 239int 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
 246int 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
 255static 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 */
 292int 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
 300int 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
 318static struct reserved_mem *dma_reserved_default_memory __initdata;
 319
 320static 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
 340static void rmem_dma_device_release(struct reserved_mem *rmem,
 341                                    struct device *dev)
 342{
 343        if (dev)
 344                dev->dma_mem = NULL;
 345}
 346
 347static const struct reserved_mem_ops rmem_dma_ops = {
 348        .device_init    = rmem_dma_device_init,
 349        .device_release = rmem_dma_device_release,
 350};
 351
 352static 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
 378static 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
 402core_initcall(dma_init_reserved_memory);
 403
 404RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
 405#endif
 406