pci-dma.c

microwindows移植到S3C44B0的源码

/*
 * Copyright (C) 2000   Ani Joshi <[e-mail]>
 *
 *
 * Dynamic DMA mapping support.
 *
 * swiped from i386, and cloned for MIPS by Geert.
 *
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <asm/io.h>

void *pci_alloc_consistent(struct pci_dev *hwdev, size_t size,
			   dma_addr_t *dma_handle)
{
	void *ret;
	int gfp = GFP_ATOMIC;

	if (hwdev == NULL || hwdev->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_bus(ret);


                // REVISIT  this needs reviewal as mentioned in bug report
                // currently we bump kseg0 allocates to kseg1 uncacheable space

                if ((((unsigned int) ret) & 0xe0000000) == 0x80000000) {
	           //flush the cache to eliminate coherency problems
	           // and assure dirty lines won't later get written over any dma, etc.
                   flush_cache_all();
		   ret = (void*)((unsigned int)ret | 0x20000000); 
                }

                
	}
	return ret;
}


void pci_free_consistent(struct pci_dev *hwdev, size_t size,
			 void *vaddr, dma_addr_t dma_handle)
{
	free_pages((unsigned long)vaddr, get_order(size));
}