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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. |
*/ |
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#include <ddk.h> |
#include <linux/mutex.h> |
#include <syscall.h> |
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struct dma_pool { /* the pool */ |
struct list_head page_list; |
struct mutex lock; |
size_t size; |
size_t allocation; |
size_t boundary; |
struct list_head pools; |
}; |
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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; |
}; |
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static DEFINE_MUTEX(pools_lock); |
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/** |
* 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; |
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if (align == 0) { |
align = 1; |
} else if (align & (align - 1)) { |
return NULL; |
} |
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if (size == 0) { |
return NULL; |
} else if (size < 4) { |
size = 4; |
} |
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if ((size % align) != 0) |
size = ALIGN(size, align); |
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allocation = max_t(size_t, size, PAGE_SIZE); |
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allocation = (allocation+0x7FFF) & ~0x7FFF; |
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if (!boundary) { |
boundary = allocation; |
} else if ((boundary < size) || (boundary & (boundary - 1))) { |
return NULL; |
} |
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retval = kmalloc(sizeof(*retval), GFP_KERNEL); |
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if (!retval) |
return retval; |
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INIT_LIST_HEAD(&retval->page_list); |
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// spin_lock_init(&retval->lock); |
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retval->size = size; |
retval->boundary = boundary; |
retval->allocation = allocation; |
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INIT_LIST_HEAD(&retval->pools); |
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return retval; |
} |
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static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) |
{ |
unsigned int offset = 0; |
unsigned int next_boundary = pool->boundary; |
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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); |
} |
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static struct dma_page *pool_alloc_page(struct dma_pool *pool) |
{ |
struct dma_page *page; |
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page = malloc(sizeof(*page)); |
if (!page) |
return NULL; |
page->vaddr = (void*)KernelAlloc(pool->allocation); |
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dbgprintf("%s 0x%0x ",__FUNCTION__, page->vaddr); |
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if (page->vaddr) |
{ |
page->dma = GetPgAddr(page->vaddr); |
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dbgprintf("dma 0x%0x\n", page->dma); |
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pool_initialise_page(pool, page); |
list_add(&page->page_list, &pool->page_list); |
page->in_use = 0; |
page->offset = 0; |
} else { |
free(page); |
page = NULL; |
} |
return page; |
} |
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static inline int is_page_busy(struct dma_page *page) |
{ |
return page->in_use != 0; |
} |
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static void pool_free_page(struct dma_pool *pool, struct dma_page *page) |
{ |
dma_addr_t dma = page->dma; |
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KernelFree(page->vaddr); |
list_del(&page->page_list); |
free(page); |
} |
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/** |
* 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); |
mutex_unlock(&pools_lock); |
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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)) |
{ |
printk(KERN_ERR "dma_pool_destroy %p busy\n", |
page->vaddr); |
/* leak the still-in-use consistent memory */ |
list_del(&page->page_list); |
kfree(page); |
} else |
pool_free_page(pool, page); |
} |
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kfree(pool); |
} |
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/** |
* 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) |
{ |
u32_t efl; |
struct dma_page *page; |
size_t offset; |
void *retval; |
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efl = safe_cli(); |
restart: |
list_for_each_entry(page, &pool->page_list, page_list) { |
if (page->offset < pool->allocation) |
goto ready; |
} |
page = pool_alloc_page(pool); |
if (!page) |
{ |
retval = NULL; |
goto done; |
} |
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ready: |
page->in_use++; |
offset = page->offset; |
page->offset = *(int *)(page->vaddr + offset); |
retval = offset + page->vaddr; |
*handle = offset + page->dma; |
done: |
safe_sti(efl); |
return retval; |
} |
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static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma) |
{ |
struct dma_page *page; |
u32_t efl; |
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efl = safe_cli(); |
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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: |
safe_sti(efl); |
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return page; |
} |
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/** |
* 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; |
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u32_t efl; |
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page = pool_find_page(pool, dma); |
if (!page) { |
printk(KERN_ERR "dma_pool_free %p/%lx (bad dma)\n", |
vaddr, (unsigned long)dma); |
return; |
} |
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offset = vaddr - page->vaddr; |
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efl = safe_cli(); |
{ |
page->in_use--; |
*(int *)vaddr = page->offset; |
page->offset = offset; |
/* |
* Resist a temptation to do |
* if (!is_page_busy(page)) pool_free_page(pool, page); |
* Better have a few empty pages hang around. |
*/ |
}safe_sti(efl); |
} |
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