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/*
* 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/export.h>
#include <linux/mutex.h>
#include <linux/poison.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/wait.h>
#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
#define DMAPOOL_DEBUG 1
#endif
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];
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;
};
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;
spin_lock_irq(&pool->lock);
list_for_each_entry(page, &pool->page_list, page_list) {
pages++;
blocks += page->in_use;
}
spin_unlock_irq(&pool->lock);
/* 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_LIST_HEAD(&retval->pools);
mutex_lock(&pools_lock);
if (list_empty(&dev->dma_pools) &&
device_create_file(dev, &dev_attr_pools)) {
kfree(retval);
retval = NULL;
} else
list_add(&retval->pools, &dev->dma_pools);
mutex_unlock(&pools_lock);
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 DMAPOOL_DEBUG
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
#endif
pool_initialise_page(pool, page);
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 DMAPOOL_DEBUG
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
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