Commit 545d2927 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-mapping: move dma_common_{mmap,get_sgtable} out of mapping.c 



Add a new file that contains helpers for misc DMA ops, which is only
built when CONFIG_DMA_OPS is set.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
parent 5ceda740

kernel/dma/Makefile

+1 −0
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0



obj-$(CONFIG_HAS_DMA)			+= mapping.o direct.o

obj-$(CONFIG_DMA_OPS)			+= ops_helpers.o

obj-$(CONFIG_DMA_OPS)			+= dummy.o

obj-$(CONFIG_DMA_CMA)			+= contiguous.o

obj-$(CONFIG_DMA_DECLARE_COHERENT)	+= coherent.o

kernel/dma/mapping.c

+1 −46
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
#include <linux/memblock.h> /* for max_pfn */

#include <linux/acpi.h>

#include <linux/dma-direct.h>

#include <linux/dma-noncoherent.h>

#include <linux/dma-mapping.h>

#include <linux/export.h>

#include <linux/gfp.h>

#include <linux/of_device.h>
@@ -295,22 +295,6 @@ void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, 
}

EXPORT_SYMBOL(dma_sync_sg_for_device);



/*

 * Create scatter-list for the already allocated DMA buffer.

 */

int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,

		 void *cpu_addr, dma_addr_t dma_addr, size_t size,

		 unsigned long attrs)

{

	struct page *page = virt_to_page(cpu_addr);

	int ret;



	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);

	if (!ret)

		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);

	return ret;

}



/*

 * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems

 * that the intention is to allow exporting memory allocated via the
@@ -358,35 +342,6 @@ pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs) 
}

#endif /* CONFIG_MMU */



/*

 * Create userspace mapping for the DMA-coherent memory.

 */

int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,

		void *cpu_addr, dma_addr_t dma_addr, size_t size,

		unsigned long attrs)

{

#ifdef CONFIG_MMU

	unsigned long user_count = vma_pages(vma);

	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;

	unsigned long off = vma->vm_pgoff;

	int ret = -ENXIO;



	vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);



	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))

		return ret;



	if (off >= count || user_count > count - off)

		return -ENXIO;



	return remap_pfn_range(vma, vma->vm_start,

			page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,

			user_count << PAGE_SHIFT, vma->vm_page_prot);

#else

	return -ENXIO;

#endif /* CONFIG_MMU */

}



/**

 * dma_can_mmap - check if a given device supports dma_mmap_*

 * @dev: device to check

kernel/dma/ops_helpers.c

0 → 100644
+51 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Helpers for DMA ops implementations.  These generally rely on the fact that

 * the allocated memory contains normal pages in the direct kernel mapping.

 */

#include <linux/dma-noncoherent.h>



/*

 * Create scatter-list for the already allocated DMA buffer.

 */

int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,

		 void *cpu_addr, dma_addr_t dma_addr, size_t size,

		 unsigned long attrs)

{

	struct page *page = virt_to_page(cpu_addr);

	int ret;



	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);

	if (!ret)

		sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);

	return ret;

}



/*

 * Create userspace mapping for the DMA-coherent memory.

 */

int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,

		void *cpu_addr, dma_addr_t dma_addr, size_t size,

		unsigned long attrs)

{

#ifdef CONFIG_MMU

	unsigned long user_count = vma_pages(vma);

	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;

	unsigned long off = vma->vm_pgoff;

	int ret = -ENXIO;



	vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);



	if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))

		return ret;



	if (off >= count || user_count > count - off)

		return -ENXIO;



	return remap_pfn_range(vma, vma->vm_start,

			page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,

			user_count << PAGE_SHIFT, vma->vm_page_prot);

#else

	return -ENXIO;

#endif /* CONFIG_MMU */

}