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/*
* Dynamic DMA mapping support
*
* Copyright 2005-2009 Analog Devices Inc.
*
* Licensed under the GPL-2 or later
*/
#include <linux/types.h>
#include <linux/gfp.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/dma-mapping.h>
#include <linux/scatterlist.h>
static spinlock_t dma_page_lock;
static unsigned long *dma_page;
static unsigned int dma_pages;
static unsigned long dma_base;
static unsigned long dma_size;
static unsigned int dma_initialized;
static void dma_alloc_init(unsigned long start, unsigned long end)
{
spin_lock_init(&dma_page_lock);
dma_initialized = 0;
dma_page = (unsigned long *)__get_free_page(GFP_KERNEL);
memset(dma_page, 0, PAGE_SIZE);
dma_base = PAGE_ALIGN(start);
dma_size = PAGE_ALIGN(end) - PAGE_ALIGN(start);
dma_pages = dma_size >> PAGE_SHIFT;
memset((void *)dma_base, 0, DMA_UNCACHED_REGION);
dma_initialized = 1;
printk(KERN_INFO "%s: dma_page @ 0x%p - %d pages at 0x%08lx\n", __func__,
dma_page, dma_pages, dma_base);
}
static inline unsigned int get_pages(size_t size)
{
return ((size - 1) >> PAGE_SHIFT) + 1;
}
static unsigned long __alloc_dma_pages(unsigned int pages)
{
unsigned long ret = 0, flags;
int i, count = 0;
if (dma_initialized == 0)
dma_alloc_init(_ramend - DMA_UNCACHED_REGION, _ramend);
spin_lock_irqsave(&dma_page_lock, flags);
for (i = 0; i < dma_pages;) {
if (test_bit(i++, dma_page) == 0) {
if (++count == pages) {
while (count--)
__set_bit(--i, dma_page);
ret = dma_base + (i << PAGE_SHIFT);
break;
}
} else
count = 0;
}
spin_unlock_irqrestore(&dma_page_lock, flags);
return ret;
}
static void __free_dma_pages(unsigned long addr, unsigned int pages)
{
unsigned long page = (addr - dma_base) >> PAGE_SHIFT;
unsigned long flags;
int i;
if ((page + pages) > dma_pages) {
printk(KERN_ERR "%s: freeing outside range.\n", __func__);
BUG();
}
spin_lock_irqsave(&dma_page_lock, flags);
for (i = page; i < page + pages; i++)
__clear_bit(i, dma_page);
spin_unlock_irqrestore(&dma_page_lock, flags);
}
void *dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp)
{
void *ret;
ret = (void *)__alloc_dma_pages(get_pages(size));
if (ret) {
memset(ret, 0, size);
*dma_handle = virt_to_phys(ret);
}
return ret;
}
EXPORT_SYMBOL(dma_alloc_coherent);
void
dma_free_coherent(struct device *dev, size_t size, void *vaddr,
dma_addr_t dma_handle)
{
__free_dma_pages((unsigned long)vaddr, get_pages(size));
}
EXPORT_SYMBOL(dma_free_coherent);
/*
* Streaming DMA mappings
*/
void __dma_sync(dma_addr_t addr, size_t size,
enum dma_data_direction dir)
{
_dma_sync(addr, size, dir);
}
EXPORT_SYMBOL(__dma_sync);
int
dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
enum dma_data_direction direction)
{
int i;
for (i = 0; i < nents; i++, sg++) {
sg->dma_address = (dma_addr_t) sg_virt(sg);
__dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction);
}
return nents;
}
EXPORT_SYMBOL(dma_map_sg);
void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
int nelems, enum dma_data_direction direction)
{
int i;
for (i = 0; i < nelems; i++, sg++) {
sg->dma_address = (dma_addr_t) sg_virt(sg);
__dma_sync(sg_dma_address(sg), sg_dma_len(sg), direction);
}
}
EXPORT_SYMBOL(dma_sync_sg_for_device);
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