diff options
Diffstat (limited to 'mm/dmapool.c')
| -rw-r--r-- | mm/dmapool.c | 500 |
1 files changed, 500 insertions, 0 deletions
diff --git a/mm/dmapool.c b/mm/dmapool.c new file mode 100644 index 00000000000..34aaac451a9 --- /dev/null +++ b/mm/dmapool.c @@ -0,0 +1,500 @@ +/* + * DMA Pool allocator + * + * Copyright 2001 David Brownell + * Copyright 2007 Intel Corporation + * Author: Matthew Wilcox <willy@linux.intel.com> + * + * This software may be redistributed and/or modified under the terms of + * the GNU General Public License ("GPL") version 2 as published by the + * Free Software Foundation. + * + * This allocator returns small blocks of a given size which are DMA-able by + * the given device. It uses the dma_alloc_coherent page allocator to get + * new pages, then splits them up into blocks of the required size. + * Many older drivers still have their own code to do this. + * + * The current design of this allocator is fairly simple. The pool is + * represented by the 'struct dma_pool' which keeps a doubly-linked list of + * allocated pages. Each page in the page_list is split into blocks of at + * least 'size' bytes. Free blocks are tracked in an unsorted singly-linked + * list of free blocks within the page. Used blocks aren't tracked, but we + * keep a count of how many are currently allocated from each page. + */ + +#include <linux/device.h> +#include <linux/dma-mapping.h> +#include <linux/dmapool.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/poison.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/wait.h> + +struct dma_pool { /* the pool */ + struct list_head page_list; + spinlock_t lock; + size_t size; + struct device *dev; + size_t allocation; + size_t boundary; + char name[32]; + wait_queue_head_t waitq; + struct list_head pools; +}; + +struct dma_page { /* cacheable header for 'allocation' bytes */ + struct list_head page_list; + void *vaddr; + dma_addr_t dma; + unsigned int in_use; + unsigned int offset; +}; + +#define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000) + +static DEFINE_MUTEX(pools_lock); + +static ssize_t +show_pools(struct device *dev, struct device_attribute *attr, char *buf) +{ + unsigned temp; + unsigned size; + char *next; + struct dma_page *page; + struct dma_pool *pool; + + next = buf; + size = PAGE_SIZE; + + temp = scnprintf(next, size, "poolinfo - 0.1\n"); + size -= temp; + next += temp; + + mutex_lock(&pools_lock); + list_for_each_entry(pool, &dev->dma_pools, pools) { + unsigned pages = 0; + unsigned blocks = 0; + + list_for_each_entry(page, &pool->page_list, page_list) { + pages++; + blocks += page->in_use; + } + + /* per-pool info, no real statistics yet */ + temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n", + pool->name, blocks, + pages * (pool->allocation / pool->size), + pool->size, pages); + size -= temp; + next += temp; + } + mutex_unlock(&pools_lock); + + return PAGE_SIZE - size; +} + +static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL); + +/** + * dma_pool_create - Creates a pool of consistent memory blocks, for dma. + * @name: name of pool, for diagnostics + * @dev: device that will be doing the DMA + * @size: size of the blocks in this pool. + * @align: alignment requirement for blocks; must be a power of two + * @boundary: returned blocks won't cross this power of two boundary + * Context: !in_interrupt() + * + * Returns a dma allocation pool with the requested characteristics, or + * null if one can't be created. Given one of these pools, dma_pool_alloc() + * may be used to allocate memory. Such memory will all have "consistent" + * DMA mappings, accessible by the device and its driver without using + * cache flushing primitives. The actual size of blocks allocated may be + * larger than requested because of alignment. + * + * If @boundary is nonzero, objects returned from dma_pool_alloc() won't + * cross that size boundary. This is useful for devices which have + * addressing restrictions on individual DMA transfers, such as not crossing + * boundaries of 4KBytes. + */ +struct dma_pool *dma_pool_create(const char *name, struct device *dev, + size_t size, size_t align, size_t boundary) +{ + struct dma_pool *retval; + size_t allocation; + + if (align == 0) { + align = 1; + } else if (align & (align - 1)) { + return NULL; + } + + if (size == 0) { + return NULL; + } else if (size < 4) { + size = 4; + } + + if ((size % align) != 0) + size = ALIGN(size, align); + + allocation = max_t(size_t, size, PAGE_SIZE); + + if (!boundary) { + boundary = allocation; + } else if ((boundary < size) || (boundary & (boundary - 1))) { + return NULL; + } + + retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev)); + if (!retval) + return retval; + + strlcpy(retval->name, name, sizeof(retval->name)); + + retval->dev = dev; + + INIT_LIST_HEAD(&retval->page_list); + spin_lock_init(&retval->lock); + retval->size = size; + retval->boundary = boundary; + retval->allocation = allocation; + init_waitqueue_head(&retval->waitq); + + if (dev) { + int ret; + + mutex_lock(&pools_lock); + if (list_empty(&dev->dma_pools)) + ret = device_create_file(dev, &dev_attr_pools); + else + ret = 0; + /* note: not currently insisting "name" be unique */ + if (!ret) + list_add(&retval->pools, &dev->dma_pools); + else { + kfree(retval); + retval = NULL; + } + mutex_unlock(&pools_lock); + } else + INIT_LIST_HEAD(&retval->pools); + + return retval; +} +EXPORT_SYMBOL(dma_pool_create); + +static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) +{ + unsigned int offset = 0; + unsigned int next_boundary = pool->boundary; + + do { + unsigned int next = offset + pool->size; + if (unlikely((next + pool->size) >= next_boundary)) { + next = next_boundary; + next_boundary += pool->boundary; + } + *(int *)(page->vaddr + offset) = next; + offset = next; + } while (offset < pool->allocation); +} + +static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags) +{ + struct dma_page *page; + + page = kmalloc(sizeof(*page), mem_flags); + if (!page) + return NULL; + page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation, + &page->dma, mem_flags); + if (page->vaddr) { +#ifdef CONFIG_DEBUG_SLAB + memset(page->vaddr, POOL_POISON_FREED, pool->allocation); +#endif + pool_initialise_page(pool, page); + list_add(&page->page_list, &pool->page_list); + page->in_use = 0; + page->offset = 0; + } else { + kfree(page); + page = NULL; + } + return page; +} + +static inline int is_page_busy(struct dma_page *page) +{ + return page->in_use != 0; +} + +static void pool_free_page(struct dma_pool *pool, struct dma_page *page) +{ + dma_addr_t dma = page->dma; + +#ifdef CONFIG_DEBUG_SLAB + memset(page->vaddr, POOL_POISON_FREED, pool->allocation); +#endif + dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma); + list_del(&page->page_list); + kfree(page); +} + +/** + * dma_pool_destroy - destroys a pool of dma memory blocks. + * @pool: dma pool that will be destroyed + * Context: !in_interrupt() + * + * Caller guarantees that no more memory from the pool is in use, + * and that nothing will try to use the pool after this call. + */ +void dma_pool_destroy(struct dma_pool *pool) +{ + mutex_lock(&pools_lock); + list_del(&pool->pools); + if (pool->dev && list_empty(&pool->dev->dma_pools)) + device_remove_file(pool->dev, &dev_attr_pools); + mutex_unlock(&pools_lock); + + while (!list_empty(&pool->page_list)) { + struct dma_page *page; + page = list_entry(pool->page_list.next, + struct dma_page, page_list); + if (is_page_busy(page)) { + if (pool->dev) + dev_err(pool->dev, + "dma_pool_destroy %s, %p busy\n", + pool->name, page->vaddr); + else + printk(KERN_ERR + "dma_pool_destroy %s, %p busy\n", + pool->name, page->vaddr); + /* leak the still-in-use consistent memory */ + list_del(&page->page_list); + kfree(page); + } else + pool_free_page(pool, page); + } + + kfree(pool); +} +EXPORT_SYMBOL(dma_pool_destroy); + +/** + * dma_pool_alloc - get a block of consistent memory + * @pool: dma pool that will produce the block + * @mem_flags: GFP_* bitmask + * @handle: pointer to dma address of block + * + * This returns the kernel virtual address of a currently unused block, + * and reports its dma address through the handle. + * If such a memory block can't be allocated, %NULL is returned. + */ +void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags, + dma_addr_t *handle) +{ + unsigned long flags; + struct dma_page *page; + size_t offset; + void *retval; + + spin_lock_irqsave(&pool->lock, flags); + restart: + list_for_each_entry(page, &pool->page_list, page_list) { + if (page->offset < pool->allocation) + goto ready; + } + page = pool_alloc_page(pool, GFP_ATOMIC); + if (!page) { + if (mem_flags & __GFP_WAIT) { + DECLARE_WAITQUEUE(wait, current); + + __set_current_state(TASK_INTERRUPTIBLE); + __add_wait_queue(&pool->waitq, &wait); + spin_unlock_irqrestore(&pool->lock, flags); + + schedule_timeout(POOL_TIMEOUT_JIFFIES); + + spin_lock_irqsave(&pool->lock, flags); + __remove_wait_queue(&pool->waitq, &wait); + goto restart; + } + retval = NULL; + goto done; + } + + ready: + page->in_use++; + offset = page->offset; + page->offset = *(int *)(page->vaddr + offset); + retval = offset + page->vaddr; + *handle = offset + page->dma; +#ifdef CONFIG_DEBUG_SLAB + memset(retval, POOL_POISON_ALLOCATED, pool->size); +#endif + done: + spin_unlock_irqrestore(&pool->lock, flags); + return retval; +} +EXPORT_SYMBOL(dma_pool_alloc); + +static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) +{ + unsigned long flags; + struct dma_page *page; + + spin_lock_irqsave(&pool->lock, flags); + list_for_each_entry(page, &pool->page_list, page_list) { + if (dma < page->dma) + continue; + if (dma < (page->dma + pool->allocation)) + goto done; + } + page = NULL; + done: + spin_unlock_irqrestore(&pool->lock, flags); + return page; +} + +/** + * dma_pool_free - put block back into dma pool + * @pool: the dma pool holding the block + * @vaddr: virtual address of block + * @dma: dma address of block + * + * Caller promises neither device nor driver will again touch this block + * unless it is first re-allocated. + */ +void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) +{ + struct dma_page *page; + unsigned long flags; + unsigned int offset; + + page = pool_find_page(pool, dma); + if (!page) { + if (pool->dev) + dev_err(pool->dev, + "dma_pool_free %s, %p/%lx (bad dma)\n", + pool->name, vaddr, (unsigned long)dma); + else + printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n", + pool->name, vaddr, (unsigned long)dma); + return; + } + + offset = vaddr - page->vaddr; +#ifdef CONFIG_DEBUG_SLAB + if ((dma - page->dma) != offset) { + if (pool->dev) + dev_err(pool->dev, + "dma_pool_free %s, %p (bad vaddr)/%Lx\n", + pool->name, vaddr, (unsigned long long)dma); + else + printk(KERN_ERR + "dma_pool_free %s, %p (bad vaddr)/%Lx\n", + pool->name, vaddr, (unsigned long long)dma); + return; + } + { + unsigned int chain = page->offset; + while (chain < pool->allocation) { + if (chain != offset) { + chain = *(int *)(page->vaddr + chain); + continue; + } + if (pool->dev) + dev_err(pool->dev, "dma_pool_free %s, dma %Lx " + "already free\n", pool->name, + (unsigned long long)dma); + else + printk(KERN_ERR "dma_pool_free %s, dma %Lx " + "already free\n", pool->name, + (unsigned long long)dma); + return; + } + } + memset(vaddr, POOL_POISON_FREED, pool->size); +#endif + + spin_lock_irqsave(&pool->lock, flags); + page->in_use--; + *(int *)vaddr = page->offset; + page->offset = offset; + if (waitqueue_active(&pool->waitq)) + wake_up_locked(&pool->waitq); + /* + * Resist a temptation to do + * if (!is_page_busy(page)) pool_free_page(pool, page); + * Better have a few empty pages hang around. + */ + spin_unlock_irqrestore(&pool->lock, flags); +} +EXPORT_SYMBOL(dma_pool_free); + +/* + * Managed DMA pool + */ +static void dmam_pool_release(struct device *dev, void *res) +{ + struct dma_pool *pool = *(struct dma_pool **)res; + + dma_pool_destroy(pool); +} + +static int dmam_pool_match(struct device *dev, void *res, void *match_data) +{ + return *(struct dma_pool **)res == match_data; +} + +/** + * dmam_pool_create - Managed dma_pool_create() + * @name: name of pool, for diagnostics + * @dev: device that will be doing the DMA + * @size: size of the blocks in this pool. + * @align: alignment requirement for blocks; must be a power of two + * @allocation: returned blocks won't cross this boundary (or zero) + * + * Managed dma_pool_create(). DMA pool created with this function is + * automatically destroyed on driver detach. + */ +struct dma_pool *dmam_pool_create(const char *name, struct device *dev, + size_t size, size_t align, size_t allocation) +{ + struct dma_pool **ptr, *pool; + + ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL); + if (!ptr) + return NULL; + + pool = *ptr = dma_pool_create(name, dev, size, align, allocation); + if (pool) + devres_add(dev, ptr); + else + devres_free(ptr); + + return pool; +} +EXPORT_SYMBOL(dmam_pool_create); + +/** + * dmam_pool_destroy - Managed dma_pool_destroy() + * @pool: dma pool that will be destroyed + * + * Managed dma_pool_destroy(). + */ +void dmam_pool_destroy(struct dma_pool *pool) +{ + struct device *dev = pool->dev; + + dma_pool_destroy(pool); + WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool)); +} +EXPORT_SYMBOL(dmam_pool_destroy); |