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Commit fb05a379 authored by Becky Bruce's avatar Becky Bruce Committed by Ingo Molnar
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swiotlb: add support for systems with highmem 



Impact: extend code for highmem - existing users unaffected

On highmem systems, the original dma buffer might not
have a virtual mapping - we need to kmap it in to perform
the bounce.  Extract the code that does the actual
copy into a function that does the kmap if highmem
is enabled, and default to the normal swiotlb memcpy
if not.

[ ported by Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> ]

Signed-off-by: default avatarBecky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent bc40ac66

lib/swiotlb.c

+51 −17
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
 * 04/07/.. ak		Better overflow handling. Assorted fixes.

 * 05/09/10 linville	Add support for syncing ranges, support syncing for

 *			DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.

 * 08/12/11 beckyb	Add highmem support

 */



#include <linux/cache.h>
@@ -24,6 +25,7 @@ 
#include <linux/swiotlb.h>

#include <linux/string.h>

#include <linux/swiotlb.h>

#include <linux/pfn.h>

#include <linux/types.h>

#include <linux/ctype.h>

#include <linux/highmem.h>
@@ -149,11 +151,6 @@ int __weak swiotlb_arch_range_needs_mapping(void *ptr, size_t size) 
	return 0;

}



static dma_addr_t swiotlb_sg_to_bus(struct device *hwdev, struct scatterlist *sg)

{

	return swiotlb_phys_to_bus(hwdev, page_to_phys(sg_page(sg)) + sg->offset);

}



static void swiotlb_print_info(unsigned long bytes)

{

	phys_addr_t pstart, pend;
@@ -329,6 +326,47 @@ static int is_swiotlb_buffer(char *addr) 
	return addr >= io_tlb_start && addr < io_tlb_end;

}



/*

 * Bounce: copy the swiotlb buffer back to the original dma location

 */

static void swiotlb_bounce(phys_addr_t phys, char *dma_addr, size_t size,

			   enum dma_data_direction dir)

{

	unsigned long pfn = PFN_DOWN(phys);



	if (PageHighMem(pfn_to_page(pfn))) {

		/* The buffer does not have a mapping.  Map it in and copy */

		unsigned int offset = phys & ~PAGE_MASK;

		char *buffer;

		unsigned int sz = 0;

		unsigned long flags;



		while (size) {

			sz = min(PAGE_SIZE - offset, size);



			local_irq_save(flags);

			buffer = kmap_atomic(pfn_to_page(pfn),

					     KM_BOUNCE_READ);

			if (dir == DMA_TO_DEVICE)

				memcpy(dma_addr, buffer + offset, sz);

			else

				memcpy(buffer + offset, dma_addr, sz);

			kunmap_atomic(buffer, KM_BOUNCE_READ);

			local_irq_restore(flags);



			size -= sz;

			pfn++;

			dma_addr += sz;

			offset = 0;

		}

	} else {

		if (dir == DMA_TO_DEVICE)

			memcpy(dma_addr, phys_to_virt(phys), size);

		else

			memcpy(phys_to_virt(phys), dma_addr, size);

	}

}



/*

 * Allocates bounce buffer and returns its kernel virtual address.

 */
@@ -430,7 +468,7 @@ map_single(struct device *hwdev, phys_addr_t phys, size_t size, int dir) 
	for (i = 0; i < nslots; i++)

		io_tlb_orig_addr[index+i] = phys + (i << IO_TLB_SHIFT);

	if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)

		memcpy(dma_addr, phys_to_virt(phys), size);

		swiotlb_bounce(phys, dma_addr, size, DMA_TO_DEVICE);



	return dma_addr;

}
@@ -450,11 +488,7 @@ unmap_single(struct device *hwdev, char *dma_addr, size_t size, int dir) 
	 * First, sync the memory before unmapping the entry

	 */

	if (phys && ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))

		/*

		 * bounce... copy the data back into the original buffer * and

		 * delete the bounce buffer.

		 */

		memcpy(phys_to_virt(phys), dma_addr, size);

		swiotlb_bounce(phys, dma_addr, size, DMA_FROM_DEVICE);



	/*

	 * Return the buffer to the free list by setting the corresponding
@@ -494,13 +528,13 @@ sync_single(struct device *hwdev, char *dma_addr, size_t size, 
	switch (target) {

	case SYNC_FOR_CPU:

		if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))

			memcpy(phys_to_virt(phys), dma_addr, size);

			swiotlb_bounce(phys, dma_addr, size, DMA_FROM_DEVICE);

		else

			BUG_ON(dir != DMA_TO_DEVICE);

		break;

	case SYNC_FOR_DEVICE:

		if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))

			memcpy(dma_addr, phys_to_virt(phys), size);

			swiotlb_bounce(phys, dma_addr, size, DMA_TO_DEVICE);

		else

			BUG_ON(dir != DMA_FROM_DEVICE);

		break;
@@ -817,11 +851,11 @@ swiotlb_unmap_sg_attrs(struct device *hwdev, struct scatterlist *sgl, 
	BUG_ON(dir == DMA_NONE);



	for_each_sg(sgl, sg, nelems, i) {

		if (sg->dma_address != swiotlb_sg_to_bus(hwdev, sg))

		if (sg->dma_address != swiotlb_virt_to_bus(hwdev, sg_virt(sg)))

			unmap_single(hwdev, swiotlb_bus_to_virt(sg->dma_address),

				     sg->dma_length, dir);

		else if (dir == DMA_FROM_DEVICE)

			dma_mark_clean(swiotlb_bus_to_virt(sg->dma_address), sg->dma_length);

			dma_mark_clean(sg_virt(sg), sg->dma_length);

	}

}

EXPORT_SYMBOL(swiotlb_unmap_sg_attrs);
@@ -850,11 +884,11 @@ swiotlb_sync_sg(struct device *hwdev, struct scatterlist *sgl, 
	BUG_ON(dir == DMA_NONE);



	for_each_sg(sgl, sg, nelems, i) {

		if (sg->dma_address != swiotlb_sg_to_bus(hwdev, sg))

		if (sg->dma_address != swiotlb_virt_to_bus(hwdev, sg_virt(sg)))

			sync_single(hwdev, swiotlb_bus_to_virt(sg->dma_address),

				    sg->dma_length, dir, target);

		else if (dir == DMA_FROM_DEVICE)

			dma_mark_clean(swiotlb_bus_to_virt(sg->dma_address), sg->dma_length);

			dma_mark_clean(sg_virt(sg), sg->dma_length);

	}

}