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        wait_queue_head_t waitq;
  54        struct list_head pools;
  55};
  56
  57struct dma_page {               /* cacheable header for 'allocation' bytes */
  58        struct list_head page_list;
  59        void *vaddr;
  60        dma_addr_t dma;
  61        unsigned int in_use;
  62        unsigned int offset;
  63};
  64
  65#define POOL_TIMEOUT_JIFFIES    ((100 /* msec */ * HZ) / 1000)
  66
  67static DEFINE_MUTEX(pools_lock);
  68
  69static ssize_t
  70show_pools(struct device *dev, struct device_attribute *attr, char *buf)
  71{
  72        unsigned temp;
  73        unsigned size;
  74        char *next;
  75        struct dma_page *page;
  76        struct dma_pool *pool;
  77
  78        next = buf;
  79        size = PAGE_SIZE;
  80
  81        temp = scnprintf(next, size, "poolinfo - 0.1\n");
  82        size -= temp;
  83        next += temp;
  84
  85        mutex_lock(&pools_lock);
  86        list_for_each_entry(pool, &dev->dma_pools, pools) {
  87                unsigned pages = 0;
  88                unsigned blocks = 0;
  89
  90                spin_lock_irq(&pool->lock);
  91                list_for_each_entry(page, &pool->page_list, page_list) {
  92                        pages++;
  93                        blocks += page->in_use;
  94                }
  95                spin_unlock_irq(&pool->lock);
  96
  97                /* per-pool info, no real statistics yet */
  98                temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
  99                                 pool->name, blocks,
 100                                 pages * (pool->allocation / pool->size),
 101                                 pool->size, pages);
 102                size -= temp;
 103                next += temp;
 104        }
 105        mutex_unlock(&pools_lock);
 106
 107        return PAGE_SIZE - size;
 108}
 109
 110static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
 111
 112/**
 113 * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 114 * @name: name of pool, for diagnostics
 115 * @dev: device that will be doing the DMA
 116 * @size: size of the blocks in this pool.
 117 * @align: alignment requirement for blocks; must be a power of two
 118 * @boundary: returned blocks won't cross this power of two boundary
 119 * Context: !in_interrupt()
 120 *
 121 * Returns a dma allocation pool with the requested characteristics, or
 122 * null if one can't be created.  Given one of these pools, dma_pool_alloc()
 123 * may be used to allocate memory.  Such memory will all have "consistent"
 124 * DMA mappings, accessible by the device and its driver without using
 125 * cache flushing primitives.  The actual size of blocks allocated may be
 126 * larger than requested because of alignment.
 127 *
 128 * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
 129 * cross that size boundary.  This is useful for devices which have
 130 * addressing restrictions on individual DMA transfers, such as not crossing
 131 * boundaries of 4KBytes.
 132 */
 133struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 134                                 size_t size, size_t align, size_t boundary)
 135{
 136        struct dma_pool *retval;
 137        size_t allocation;
 138
 139        if (align == 0) {
 140                align = 1;
 141        } else if (align & (align - 1)) {
 142                return NULL;
 143        }
 144
 145        if (size == 0) {
 146                return NULL;
 147        } else if (size < 4) {
 148                size = 4;
 149        }
 150
 151        if ((size % align) != 0)
 152                size = ALIGN(size, align);
 153
 154        allocation = max_t(size_t, size, PAGE_SIZE);
 155
 156        if (!boundary) {
 157                boundary = allocation;
 158        } else if ((boundary < size) || (boundary & (boundary - 1))) {
 159                return NULL;
 160        }
 161
 162        retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
 163        if (!retval)
 164                return retval;
 165
 166        strlcpy(retval->name, name, sizeof(retval->name));
 167
 168        retval->dev = dev;
 169
 170        INIT_LIST_HEAD(&retval->page_list);
 171        spin_lock_init(&retval->lock);
 172        retval->size = size;
 173        retval->boundary = boundary;
 174        retval->allocation = allocation;
 175        init_waitqueue_head(&retval->waitq);
 176
 177        if (dev) {
 178                int ret;
 179
 180                mutex_lock(&pools_lock);
 181                if (list_empty(&dev->dma_pools))
 182                        ret = device_create_file(dev, &dev_attr_pools);
 183                else
 184                        ret = 0;
 185                /* note:  not currently insisting "name" be unique */
 186                if (!ret)
 187                        list_add(&retval->pools, &dev->dma_pools);
 188                else {
 189                        kfree(retval);
 190                        retval = NULL;
 191                }
 192                mutex_unlock(&pools_lock);
 193        } else
 194                INIT_LIST_HEAD(&retval->pools);
 195
 196        return retval;
 197}
 198EXPORT_SYMBOL(dma_pool_create);
 199
 200static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 201{
 202        unsigned int offset = 0;
 203        unsigned int next_boundary = pool->boundary;
 204
 205        do {
 206                unsigned int next = offset + pool->size;
 207                if (unlikely((next + pool->size) >= next_boundary)) {
 208                        next = next_boundary;
 209                        next_boundary += pool->boundary;
 210                }
 211                *(int *)(page->vaddr + offset) = next;
 212                offset = next;
 213        } while (offset < pool->allocation);
 214}
 215
 216static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 217{
 218        struct dma_page *page;
 219
 220        page = kmalloc(sizeof(*page), mem_flags);
 221        if (!page)
 222                return NULL;
 223        page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 224                                         &page->dma, mem_flags);
 225        if (page->vaddr) {
 226#ifdef  DMAPOOL_DEBUG
 227                memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 228#endif
 229                pool_initialise_page(pool, page);
 230                list_add(&page->page_list, &pool->page_list);
 231                page->in_use = 0;
 232                page->offset = 0;
 233        } else {
 234                kfree(page);
 235                page = NULL;
 236        }
 237        return page;
 238}
 239
 240static inline int is_page_busy(struct dma_page *page)
 241{
 242        return page->in_use != 0;
 243}
 244
 245static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 246{
 247        dma_addr_t dma = page->dma;
 248
 249#ifdef  DMAPOOL_DEBUG
 250        memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 251#endif
 252        dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 253        list_del(&page->page_list);
 254        kfree(page);
 255}
 256
 257/**
 258 * dma_pool_destroy - destroys a pool of dma memory blocks.
 259 * @pool: dma pool that will be destroyed
 260 * Context: !in_interrupt()
 261 *
 262 * Caller guarantees that no more memory from the pool is in use,
 263 * and that nothing will try to use the pool after this call.
 264 */
 265void dma_pool_destroy(struct dma_pool *pool)
 266{
 267        mutex_lock(&pools_lock);
 268        list_del(&pool->pools);
 269        if (pool->dev && list_empty(&pool->dev->dma_pools))
 270                device_remove_file(pool->dev, &dev_attr_pools);
 271        mutex_unlock(&pools_lock);
 272
 273        while (!list_empty(&pool->page_list)) {
 274                struct dma_page *page;
 275                page = list_entry(pool->page_list.next,
 276                                  struct dma_page, page_list);
 277                if (is_page_busy(page)) {
 278                        if (pool->dev)
 279                                dev_err(pool->dev,
 280                                        "dma_pool_destroy %s, %p busy\n",
 281                                        pool->name, page->vaddr);
 282                        else
 283                                printk(KERN_ERR
 284                                       "dma_pool_destroy %s, %p busy\n",
 285                                       pool->name, page->vaddr);
 286                        /* leak the still-in-use consistent memory */
 287                        list_del(&page->page_list);
 288                        kfree(page);
 289                } else
 290                        pool_free_page(pool, page);
 291        }
 292
 293        kfree(pool);
 294}
 295EXPORT_SYMBOL(dma_pool_destroy);
 296
 297/**
 298 * dma_pool_alloc - get a block of consistent memory
 299 * @pool: dma pool that will produce the block
 300 * @mem_flags: GFP_* bitmask
 301 * @handle: pointer to dma address of block
 302 *
 303 * This returns the kernel virtual address of a currently unused block,
 304 * and reports its dma address through the handle.
 305 * If such a memory block can't be allocated, %NULL is returned.
 306 */
 307void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 308                     dma_addr_t *handle)
 309{
 310        unsigned long flags;
 311        struct dma_page *page;
 312        size_t offset;
 313        void *retval;
 314
 315        might_sleep_if(mem_flags & __GFP_WAIT);
 316
 317        spin_lock_irqsave(&pool->lock, flags);
 318 restart:
 319        list_for_each_entry(page, &pool->page_list, page_list) {
 320                if (page->offset < pool->allocation)
 321                        goto ready;
 322        }
 323        page = pool_alloc_page(pool, GFP_ATOMIC);
 324        if (!page) {
 325                if (mem_flags & __GFP_WAIT) {
 326                        DECLARE_WAITQUEUE(wait, current);
 327
 328                        __set_current_state(TASK_UNINTERRUPTIBLE);
 329                        __add_wait_queue(&pool->waitq, &wait);
 330                        spin_unlock_irqrestore(&pool->lock, flags);
 331
 332                        schedule_timeout(POOL_TIMEOUT_JIFFIES);
 333
 334                        spin_lock_irqsave(&pool->lock, flags);
 335                        __remove_wait_queue(&pool->waitq, &wait);
 336                        goto restart;
 337                }
 338                retval = NULL;
 339                goto done;
 340        }
 341
 342 ready:
 343        page->in_use++;
 344        offset = page->offset;
 345        page->offset = *(int *)(page->vaddr + offset);
 346        retval = offset + page->vaddr;
 347        *handle = offset + page->dma;
 348#ifdef  DMAPOOL_DEBUG
 349        memset(retval, POOL_POISON_ALLOCATED, pool->size);
 350#endif
 351 done:
 352        spin_unlock_irqrestore(&pool->lock, flags);
 353        return retval;
 354}
 355EXPORT_SYMBOL(dma_pool_alloc);
 356
 357static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 358{
 359        struct dma_page *page;
 360
 361        list_for_each_entry(page, &pool->page_list, page_list) {
 362                if (dma < page->dma)
 363                        continue;
 364                if (dma < (page->dma + pool->allocation))
 365                        return page;
 366        }
 367        return NULL;
 368}
 369
 370/**
 371 * dma_pool_free - put block back into dma pool
 372 * @pool: the dma pool holding the block
 373 * @vaddr: virtual address of block
 374 * @dma: dma address of block
 375 *
 376 * Caller promises neither device nor driver will again touch this block
 377 * unless it is first re-allocated.
 378 */
 379void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 380{
 381        struct dma_page *page;
 382        unsigned long flags;
 383        unsigned int offset;
 384
 385        spin_lock_irqsave(&pool->lock, flags);
 386        page = pool_find_page(pool, dma);
 387        if (!page) {
 388                spin_unlock_irqrestore(&pool->lock, flags);
 389                if (pool->dev)
 390                        dev_err(pool->dev,
 391                                "dma_pool_free %s, %p/%lx (bad dma)\n",
 392                                pool->name, vaddr, (unsigned long)dma);
 393                else
 394                        printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 395                               pool->name, vaddr, (unsigned long)dma);
 396                return;
 397        }
 398
 399        offset = vaddr - page->vaddr;
 400#ifdef  DMAPOOL_DEBUG
 401        if ((dma - page->dma) != offset) {
 402                spin_unlock_irqrestore(&pool->lock, flags);
 403                if (pool->dev)
 404                        dev_err(pool->dev,
 405                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 406                                pool->name, vaddr, (unsigned long long)dma);
 407                else
 408                        printk(KERN_ERR
 409                               "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 410                               pool->name, vaddr, (unsigned long long)dma);
 411                return;
 412        }
 413        {
 414                unsigned int chain = page->offset;
 415                while (chain < pool->allocation) {
 416                        if (chain != offset) {
 417                                chain = *(int *)(page->vaddr + chain);
 418                                continue;
 419                        }
 420                        spin_unlock_irqrestore(&pool->lock, flags);
 421                        if (pool->dev)
 422                                dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
 423                                        "already free\n", pool->name,
 424                                        (unsigned long long)dma);
 425                        else
 426                                printk(KERN_ERR "dma_pool_free %s, dma %Lx "
 427                                        "already free\n", pool->name,
 428                                        (unsigned long long)dma);
 429                        return;
 430                }
 431        }
 432        memset(vaddr, POOL_POISON_FREED, pool->size);
 433#endif
 434
 435        page->in_use--;
 436        *(int *)vaddr = page->offset;
 437        page->offset = offset;
 438        if (waitqueue_active(&pool->waitq))
 439                wake_up_locked(&pool->waitq);
 440        /*
 441         * Resist a temptation to do
 442         *    if (!is_page_busy(page)) pool_free_page(pool, page);
 443         * Better have a few empty pages hang around.
 444         */
 445        spin_unlock_irqrestore(&pool->lock, flags);
 446}
 447EXPORT_SYMBOL(dma_pool_free);
 448
 449/*
 450 * Managed DMA pool
 451 */
 452static void dmam_pool_release(struct device *dev, void *res)
 453{
 454        struct dma_pool *pool = *(struct dma_pool **)res;
 455
 456        dma_pool_destroy(pool);
 457}
 458
 459static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 460{
 461        return *(struct dma_pool **)res == match_data;
 462}
 463
 464/**
 465 * dmam_pool_create - Managed dma_pool_create()
 466 * @name: name of pool, for diagnostics
 467 * @dev: device that will be doing the DMA
 468 * @size: size of the blocks in this pool.
 469 * @align: alignment requirement for blocks; must be a power of two
 470 * @allocation: returned blocks won't cross this boundary (or zero)
 471 *
 472 * Managed dma_pool_create().  DMA pool created with this function is
 473 * automatically destroyed on driver detach.
 474 */
 475struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 476                                  size_t size, size_t align, size_t allocation)
 477{
 478        struct dma_pool **ptr, *pool;
 479
 480        ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 481        if (!ptr)
 482                return NULL;
 483
 484        pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 485        if (pool)
 486                devres_add(dev, ptr);
 487        else
 488                devres_free(ptr);
 489
 490        return pool;
 491}
 492EXPORT_SYMBOL(dmam_pool_create);
 493
 494/**
 495 * dmam_pool_destroy - Managed dma_pool_destroy()
 496 * @pool: dma pool that will be destroyed
 497 *
 498 * Managed dma_pool_destroy().
 499 */
 500void dmam_pool_destroy(struct dma_pool *pool)
 501{
 502        struct device *dev = pool->dev;
 503
 504        WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
 505        dma_pool_destroy(pool);
 506}
 507EXPORT_SYMBOL(dmam_pool_destroy);
 508
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