dma_no.c

/*
 * Dynamic DMA mapping support.
 *
 * We never have any address translations to worry about, so this
 * is just alloc/free.
 */

#include <linux/types.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <asm/cacheflush.h>

void *dma_alloc_coherent(struct device *dev, size_t size,
			   dma_addr_t *dma_handle, gfp_t gfp)
{
	void *ret;
	/* ignore region specifiers */
	gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);

	if (dev == NULL || (*dev->dma_mask < 0xffffffff))
		gfp |= GFP_DMA;
	ret = (void *)__get_free_pages(gfp, get_order(size));

	if (ret != NULL) {
		memset(ret, 0, size);
		*dma_handle = virt_to_phys(ret);
	}
	return ret;
}

void dma_free_coherent(struct device *dev, size_t size,
			 void *vaddr, dma_addr_t dma_handle)
{
	free_pages((unsigned long)vaddr, get_order(size));
}

void dma_sync_single_for_device(struct device *dev, dma_addr_t handle,
				size_t size, enum dma_data_direction dir)
{
	switch (dir) {
	case DMA_TO_DEVICE:
		flush_dcache_range(handle, size);
		break;
	case DMA_FROM_DEVICE:
		/* Should be clear already */
		break;
	default:
		if (printk_ratelimit())
			printk("dma_sync_single_for_device: unsupported dir %u\n", dir);
		break;
	}
}

EXPORT_SYMBOL(dma_sync_single_for_device);
dma_addr_t dma_map_single(struct device *dev, void *addr, size_t size,
			  enum dma_data_direction dir)
{
	dma_addr_t handle = virt_to_phys(addr);
	flush_dcache_range(handle, size);
	return handle;
}
EXPORT_SYMBOL(dma_map_single);

dma_addr_t dma_map_page(struct device *dev, struct page *page,
			unsigned long offset, size_t size,
			enum dma_data_direction dir)
{
	dma_addr_t handle = page_to_phys(page) + offset;
	dma_sync_single_for_device(dev, handle, size, dir);
	return handle;
}
EXPORT_SYMBOL(dma_map_page);