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Commit a8463d4b authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Michael S. Tsirkin
Browse files

dma: Provide simple noop dma ops 



We are going to require dma_ops for several common drivers, even for
systems that do have an identity mapping. Lets provide some minimal
no-op dma_ops that can be used for that purpose.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent e1f33be9

include/linux/dma-mapping.h

+2 −0
Original line number Diff line number Diff line
@@ -70,6 +70,8 @@ struct dma_map_ops { 
	int is_phys;

};



extern struct dma_map_ops dma_noop_ops;



#define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))



#define DMA_MASK_NONE	0x0ULL

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \ 
obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o

lib-$(CONFIG_MMU) += ioremap.o

lib-$(CONFIG_SMP) += cpumask.o

lib-$(CONFIG_HAS_DMA) += dma-noop.o



lib-y	+= kobject.o klist.o

obj-y	+= lockref.o

lib/dma-noop.c

0 → 100644
+75 −0
Original line number Diff line number Diff line 
/*

 *	lib/dma-noop.c

 *

 * Simple DMA noop-ops that map 1:1 with memory

 */

#include <linux/export.h>

#include <linux/mm.h>

#include <linux/dma-mapping.h>

#include <linux/scatterlist.h>



static void *dma_noop_alloc(struct device *dev, size_t size,

			    dma_addr_t *dma_handle, gfp_t gfp,

			    struct dma_attrs *attrs)

{

	void *ret;



	ret = (void *)__get_free_pages(gfp, get_order(size));

	if (ret)

		*dma_handle = virt_to_phys(ret);

	return ret;

}



static void dma_noop_free(struct device *dev, size_t size,

			  void *cpu_addr, dma_addr_t dma_addr,

			  struct dma_attrs *attrs)

{

	free_pages((unsigned long)cpu_addr, get_order(size));

}



static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,

				      unsigned long offset, size_t size,

				      enum dma_data_direction dir,

				      struct dma_attrs *attrs)

{

	return page_to_phys(page) + offset;

}



static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,

			     enum dma_data_direction dir, struct dma_attrs *attrs)

{

	int i;

	struct scatterlist *sg;



	for_each_sg(sgl, sg, nents, i) {

		void *va;



		BUG_ON(!sg_page(sg));

		va = sg_virt(sg);

		sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);

		sg_dma_len(sg) = sg->length;

	}



	return nents;

}



static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr)

{

	return 0;

}



static int dma_noop_supported(struct device *dev, u64 mask)

{

	return 1;

}



struct dma_map_ops dma_noop_ops = {

	.alloc			= dma_noop_alloc,

	.free			= dma_noop_free,

	.map_page		= dma_noop_map_page,

	.map_sg			= dma_noop_map_sg,

	.mapping_error		= dma_noop_mapping_error,

	.dma_supported		= dma_noop_supported,

};



EXPORT_SYMBOL(dma_noop_ops);