linux/mm/dmapool.c
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   1/*
   2 * DMA Pool allocator
   3 *
   4 * Copyright 2001 David Brownell
   5 * Copyright 2007 Intel Corporation
   6 *   Author: Matthew Wilcox <willy@linux.intel.com>
   7 *
   8 * This software may be redistributed and/or modified under the terms of
   9 * the GNU General Public License ("GPL") version 2 as published by the
  10 * Free Software Foundation.
  11 *
  12 * This allocator returns small blocks of a given size which are DMA-able by
  13 * the given device.  It uses the dma_alloc_coherent page allocator to get
  14 * new pages, then splits them up into blocks of the required size.
  15 * Many older drivers still have their own code to do this.
  16 *
  17 * The current design of this allocator is fairly simple.  The pool is
  18 * represented by the 'struct dma_pool' which keeps a doubly-linked list of
  19 * allocated pages.  Each page in the page_list is split into blocks of at
  20 * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
  21 * list of free blocks within the page.  Used blocks aren't tracked, but we
  22 * keep a count of how many are currently allocated from each page.
  23 */
  24
  25#include <linux/device.h>
  26#include <linux/dma-mapping.h>
  27#include <linux/dmapool.h>
  28#include <linux/kernel.h>
  29#include <linux/list.h>
  30#include <linux/export.h>
  31#include <linux/mutex.h>
  32#include <linux/poison.h>
  33#include <linux/sched.h>
  34#include <linux/slab.h>
  35#include <linux/stat.h>
  36#include <linux/spinlock.h>
  37#include <linux/string.h>
  38#include <linux/types.h>
  39#include <linux/wait.h>
  40
  41#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
  42#define DMAPOOL_DEBUG 1
  43#endif
  44
  45struct dma_pool {               /* the pool */
  46        struct list_head page_list;
  47        spinlock_t lock;
  48        size_t size;
  49        struct device *dev;
  50        size_t allocation;
  51        size_t boundary;
  52        char name[32];
  53        struct list_head pools;
  54};
  55
  56struct dma_page {               /* cacheable header for 'allocation' bytes */
  57        struct list_head page_list;
  58        void *vaddr;
  59        dma_addr_t dma;
  60        unsigned int in_use;
  61        unsigned int offset;
  62};
  63
  64static DEFINE_MUTEX(pools_lock);
  65
  66static ssize_t
  67show_pools(struct device *dev, struct device_attribute *attr, char *buf)
  68{
  69        unsigned temp;
  70        unsigned size;
  71        char *next;
  72        struct dma_page *page;
  73        struct dma_pool *pool;
  74
  75        next = buf;
  76        size = PAGE_SIZE;
  77
  78        temp = scnprintf(next, size, "poolinfo - 0.1\n");
  79        size -= temp;
  80        next += temp;
  81
  82        mutex_lock(&pools_lock);
  83        list_for_each_entry(pool, &dev->dma_pools, pools) {
  84                unsigned pages = 0;
  85                unsigned blocks = 0;
  86
  87                spin_lock_irq(&pool->lock);
  88                list_for_each_entry(page, &pool->page_list, page_list) {
  89                        pages++;
  90                        blocks += page->in_use;
  91                }
  92                spin_unlock_irq(&pool->lock);
  93
  94                /* per-pool info, no real statistics yet */
  95                temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
  96                                 pool->name, blocks,
  97                                 pages * (pool->allocation / pool->size),
  98                                 pool->size, pages);
  99                size -= temp;
 100                next += temp;
 101        }
 102        mutex_unlock(&pools_lock);
 103
 104        return PAGE_SIZE - size;
 105}
 106
 107static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
 108
 109/**
 110 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 111 * @name: name of pool, for diagnostics
 112 * @dev: device that will be doing the DMA
 113 * @size: size of the blocks in this pool.
 114 * @align: alignment requirement for blocks; must be a power of two
 115 * @boundary: returned blocks won't cross this power of two boundary
 116 * Context: !in_interrupt()
 117 *
 118 * Returns a dma allocation pool with the requested characteristics, or
 119 * null if one can't be created.  Given one of these pools, dma_pool_alloc()
 120 * may be used to allocate memory.  Such memory will all have "consistent"
 121 * DMA mappings, accessible by the device and its driver without using
 122 * cache flushing primitives.  The actual size of blocks allocated may be
 123 * larger than requested because of alignment.
 124 *
 125 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
 126 * cross that size boundary.  This is useful for devices which have
 127 * addressing restrictions on individual DMA transfers, such as not crossing
 128 * boundaries of 4KBytes.
 129 */
 130struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 131                                 size_t size, size_t align, size_t boundary)
 132{
 133        struct dma_pool *retval;
 134        size_t allocation;
 135
 136        if (align == 0) {
 137                align = 1;
 138        } else if (align & (align - 1)) {
 139                return NULL;
 140        }
 141
 142        if (size == 0) {
 143                return NULL;
 144        } else if (size < 4) {
 145                size = 4;
 146        }
 147
 148        if ((size % align) != 0)
 149                size = ALIGN(size, align);
 150
 151        allocation = max_t(size_t, size, PAGE_SIZE);
 152
 153        if (!boundary) {
 154                boundary = allocation;
 155        } else if ((boundary < size) || (boundary & (boundary - 1))) {
 156                return NULL;
 157        }
 158
 159        retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
 160        if (!retval)
 161                return retval;
 162
 163        strlcpy(retval->name, name, sizeof(retval->name));
 164
 165        retval->dev = dev;
 166
 167        INIT_LIST_HEAD(&retval->page_list);
 168        spin_lock_init(&retval->lock);
 169        retval->size = size;
 170        retval->boundary = boundary;
 171        retval->allocation = allocation;
 172
 173        if (dev) {
 174                int ret;
 175
 176                mutex_lock(&pools_lock);
 177                if (list_empty(&dev->dma_pools))
 178                        ret = device_create_file(dev, &dev_attr_pools);
 179                else
 180                        ret = 0;
 181                /* note:  not currently insisting "name" be unique */
 182                if (!ret)
 183                        list_add(&retval->pools, &dev->dma_pools);
 184                else {
 185                        kfree(retval);
 186                        retval = NULL;
 187                }
 188                mutex_unlock(&pools_lock);
 189        } else
 190                INIT_LIST_HEAD(&retval->pools);
 191
 192        return retval;
 193}
 194EXPORT_SYMBOL(dma_pool_create);
 195
 196static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 197{
 198        unsigned int offset = 0;
 199        unsigned int next_boundary = pool->boundary;
 200
 201        do {
 202                unsigned int next = offset + pool->size;
 203                if (unlikely((next + pool->size) >= next_boundary)) {
 204                        next = next_boundary;
 205                        next_boundary += pool->boundary;
 206                }
 207                *(int *)(page->vaddr + offset) = next;
 208                offset = next;
 209        } while (offset < pool->allocation);
 210}
 211
 212static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 213{
 214        struct dma_page *page;
 215
 216        page = kmalloc(sizeof(*page), mem_flags);
 217        if (!page)
 218                return NULL;
 219        page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 220                                         &page->dma, mem_flags);
 221        if (page->vaddr) {
 222#ifdef  DMAPOOL_DEBUG
 223                memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 224#endif
 225                pool_initialise_page(pool, page);
 226                page->in_use = 0;
 227                page->offset = 0;
 228        } else {
 229                kfree(page);
 230                page = NULL;
 231        }
 232        return page;
 233}
 234
 235static inline int is_page_busy(struct dma_page *page)
 236{
 237        return page->in_use != 0;
 238}
 239
 240static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 241{
 242        dma_addr_t dma = page->dma;
 243
 244#ifdef  DMAPOOL_DEBUG
 245        memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 246#endif
 247        dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 248        list_del(&page->page_list);
 249        kfree(page);
 250}
 251
 252/**
 253 * dma_pool_destroy - destroys a pool of dma memory blocks.
 254 * @pool: dma pool that will be destroyed
 255 * Context: !in_interrupt()
 256 *
 257 * Caller guarantees that no more memory from the pool is in use,
 258 * and that nothing will try to use the pool after this call.
 259 */
 260void dma_pool_destroy(struct dma_pool *pool)
 261{
 262        mutex_lock(&pools_lock);
 263        list_del(&pool->pools);
 264        if (pool->dev && list_empty(&pool->dev->dma_pools))
 265                device_remove_file(pool->dev, &dev_attr_pools);
 266        mutex_unlock(&pools_lock);
 267
 268        while (!list_empty(&pool->page_list)) {
 269                struct dma_page *page;
 270                page = list_entry(pool->page_list.next,
 271                                  struct dma_page, page_list);
 272                if (is_page_busy(page)) {
 273                        if (pool->dev)
 274                                dev_err(pool->dev,
 275                                        "dma_pool_destroy %s, %p busy\n",
 276                                        pool->name, page->vaddr);
 277                        else
 278                                printk(KERN_ERR
 279                                       "dma_pool_destroy %s, %p busy\n",
 280                                       pool->name, page->vaddr);
 281                        /* leak the still-in-use consistent memory */
 282                        list_del(&page->page_list);
 283                        kfree(page);
 284                } else
 285                        pool_free_page(pool, page);
 286        }
 287
 288        kfree(pool);
 289}
 290EXPORT_SYMBOL(dma_pool_destroy);
 291
 292/**
 293 * dma_pool_alloc - get a block of consistent memory
 294 * @pool: dma pool that will produce the block
 295 * @mem_flags: GFP_* bitmask
 296 * @handle: pointer to dma address of block
 297 *
 298 * This returns the kernel virtual address of a currently unused block,
 299 * and reports its dma address through the handle.
 300 * If such a memory block can't be allocated, %NULL is returned.
 301 */
 302void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 303                     dma_addr_t *handle)
 304{
 305        unsigned long flags;
 306        struct dma_page *page;
 307        size_t offset;
 308        void *retval;
 309
 310        might_sleep_if(mem_flags & __GFP_WAIT);
 311
 312        spin_lock_irqsave(&pool->lock, flags);
 313        list_for_each_entry(page, &pool->page_list, page_list) {
 314                if (page->offset < pool->allocation)
 315                        goto ready;
 316        }
 317
 318        /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
 319        spin_unlock_irqrestore(&pool->lock, flags);
 320
 321        page = pool_alloc_page(pool, mem_flags);
 322        if (!page)
 323                return NULL;
 324
 325        spin_lock_irqsave(&pool->lock, flags);
 326
 327        list_add(&page->page_list, &pool->page_list);
 328 ready:
 329        page->in_use++;
 330        offset = page->offset;
 331        page->offset = *(int *)(page->vaddr + offset);
 332        retval = offset + page->vaddr;
 333        *handle = offset + page->dma;
 334#ifdef  DMAPOOL_DEBUG
 335        memset(retval, POOL_POISON_ALLOCATED, pool->size);
 336#endif
 337        spin_unlock_irqrestore(&pool->lock, flags);
 338        return retval;
 339}
 340EXPORT_SYMBOL(dma_pool_alloc);
 341
 342static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 343{
 344        struct dma_page *page;
 345
 346        list_for_each_entry(page, &pool->page_list, page_list) {
 347                if (dma < page->dma)
 348                        continue;
 349                if (dma < (page->dma + pool->allocation))
 350                        return page;
 351        }
 352        return NULL;
 353}
 354
 355/**
 356 * dma_pool_free - put block back into dma pool
 357 * @pool: the dma pool holding the block
 358 * @vaddr: virtual address of block
 359 * @dma: dma address of block
 360 *
 361 * Caller promises neither device nor driver will again touch this block
 362 * unless it is first re-allocated.
 363 */
 364void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 365{
 366        struct dma_page *page;
 367        unsigned long flags;
 368        unsigned int offset;
 369
 370        spin_lock_irqsave(&pool->lock, flags);
 371        page = pool_find_page(pool, dma);
 372        if (!page) {
 373                spin_unlock_irqrestore(&pool->lock, flags);
 374                if (pool->dev)
 375                        dev_err(pool->dev,
 376                                "dma_pool_free %s, %p/%lx (bad dma)\n",
 377                                pool->name, vaddr, (unsigned long)dma);
 378                else
 379                        printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 380                               pool->name, vaddr, (unsigned long)dma);
 381                return;
 382        }
 383
 384        offset = vaddr - page->vaddr;
 385#ifdef  DMAPOOL_DEBUG
 386        if ((dma - page->dma) != offset) {
 387                spin_unlock_irqrestore(&pool->lock, flags);
 388                if (pool->dev)
 389                        dev_err(pool->dev,
 390                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 391                                pool->name, vaddr, (unsigned long long)dma);
 392                else
 393                        printk(KERN_ERR
 394                               "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 395                               pool->name, vaddr, (unsigned long long)dma);
 396                return;
 397        }
 398        {
 399                unsigned int chain = page->offset;
 400                while (chain < pool->allocation) {
 401                        if (chain != offset) {
 402                                chain = *(int *)(page->vaddr + chain);
 403                                continue;
 404                        }
 405                        spin_unlock_irqrestore(&pool->lock, flags);
 406                        if (pool->dev)
 407                                dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
 408                                        "already free\n", pool->name,
 409                                        (unsigned long long)dma);
 410                        else
 411                                printk(KERN_ERR "dma_pool_free %s, dma %Lx "
 412                                        "already free\n", pool->name,
 413                                        (unsigned long long)dma);
 414                        return;
 415                }
 416        }
 417        memset(vaddr, POOL_POISON_FREED, pool->size);
 418#endif
 419
 420        page->in_use--;
 421        *(int *)vaddr = page->offset;
 422        page->offset = offset;
 423        /*
 424         * Resist a temptation to do
 425         *    if (!is_page_busy(page)) pool_free_page(pool, page);
 426         * Better have a few empty pages hang around.
 427         */
 428        spin_unlock_irqrestore(&pool->lock, flags);
 429}
 430EXPORT_SYMBOL(dma_pool_free);
 431
 432/*
 433 * Managed DMA pool
 434 */
 435static void dmam_pool_release(struct device *dev, void *res)
 436{
 437        struct dma_pool *pool = *(struct dma_pool **)res;
 438
 439        dma_pool_destroy(pool);
 440}
 441
 442static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 443{
 444        return *(struct dma_pool **)res == match_data;
 445}
 446
 447/**
 448 * dmam_pool_create - Managed dma_pool_create()
 449 * @name: name of pool, for diagnostics
 450 * @dev: device that will be doing the DMA
 451 * @size: size of the blocks in this pool.
 452 * @align: alignment requirement for blocks; must be a power of two
 453 * @allocation: returned blocks won't cross this boundary (or zero)
 454 *
 455 * Managed dma_pool_create().  DMA pool created with this function is
 456 * automatically destroyed on driver detach.
 457 */
 458struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 459                                  size_t size, size_t align, size_t allocation)
 460{
 461        struct dma_pool **ptr, *pool;
 462
 463        ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 464        if (!ptr)
 465                return NULL;
 466
 467        pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 468        if (pool)
 469                devres_add(dev, ptr);
 470        else
 471                devres_free(ptr);
 472
 473        return pool;
 474}
 475EXPORT_SYMBOL(dmam_pool_create);
 476
 477/**
 478 * dmam_pool_destroy - Managed dma_pool_destroy()
 479 * @pool: dma pool that will be destroyed
 480 *
 481 * Managed dma_pool_destroy().
 482 */
 483void dmam_pool_destroy(struct dma_pool *pool)
 484{
 485        struct device *dev = pool->dev;
 486
 487        WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
 488        dma_pool_destroy(pool);
 489}
 490EXPORT_SYMBOL(dmam_pool_destroy);
 491
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