/*
* 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 <ddk.h>
#include <linux/mutex.h>
#include <syscall.h>
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;
};
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);
/**
* 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);
allocation = (allocation+0x7FFF) & ~0x7FFF;
if (!boundary) {
boundary = allocation;
} else if ((boundary < size) || (boundary & (boundary - 1))) {
return NULL;
}
retval = kmalloc(sizeof(*retval), GFP_KERNEL);
if (!retval)
return retval;
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);
return retval;
}
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)
{
struct dma_page *page;
if (!page)
return NULL;
page->vaddr = (void*)KernelAlloc(pool->allocation);
dbgprintf("%s 0x%0x ",__FUNCTION__, page->vaddr);
if (page->vaddr)
{
page->dma = GetPgAddr(page->vaddr);
dbgprintf("dma 0x%0x\n", page->dma);
pool_initialise_page(pool, page);
list_add(&page->page_list, &pool->page_list);
page->in_use = 0;
page->offset = 0;
} else {
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;
KernelFree(page->vaddr);
list_del(&page->page_list);
}
/**
* 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);
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);
}
kfree(pool);
}
/**
* 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;
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;
}
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;
}
static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
{
struct dma_page *page;
u32_t efl;
efl = safe_cli();
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);
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;
u32_t efl;
page = pool_find_page(pool, dma);
if (!page) {
printk(KERN_ERR "dma_pool_free %p/%lx (bad dma)\n",
vaddr, (unsigned long)dma);
return;
}
offset = vaddr - page->vaddr;
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);
}