Commit e36863a5 authored by Dezhong Diao's avatar Dezhong Diao Committed by Ralf Baechle
Browse files

MIPS: HIGHMEM DMA on noncoherent MIPS32 processors 

[v4: Patch applies to linux-queue.git with kmap_atomic patches:
 https://patchwork.kernel.org/patch/189932/
 https://patchwork.kernel.org/patch/194552/
 https://patchwork.kernel.org/patch/189912/

 ]

The MIPS DMA coherency functions do not work properly (i.e. kernel oops)
when HIGHMEM pages are passed in as arguments.  Use kmap_atomic() to
temporarily map high pages for cache maintenance operations.

Tested on a 2.6.36-rc7 1GB HIGHMEM SMP no-alias system.

Signed-off-by: default avatarDezhong Diao <dediao@cisco.com>
Signed-off-by: default avatarKevin Cernekee <cernekee@gmail.com>
Cc: Dezhong Diao <dediao@cisco.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: David VomLehn <dvomlehn@cisco.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/1695/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent d0be89f6

arch/mips/mm/dma-default.c

+68 −46
Original line number Diff line number Diff line
@@ -15,18 +15,18 @@ 
#include <linux/scatterlist.h>

#include <linux/string.h>

#include <linux/gfp.h>

#include <linux/highmem.h>



#include <asm/cache.h>

#include <asm/io.h>



#include <dma-coherence.h>



static inline unsigned long dma_addr_to_virt(struct device *dev,

static inline struct page *dma_addr_to_page(struct device *dev,

	dma_addr_t dma_addr)

{

	unsigned long addr = plat_dma_addr_to_phys(dev, dma_addr);



	return (unsigned long)phys_to_virt(addr);

	return pfn_to_page(

		plat_dma_addr_to_phys(dev, dma_addr) >> PAGE_SHIFT);

}



/*
@@ -148,20 +148,20 @@ static void mips_dma_free_coherent(struct device *dev, size_t size, void *vaddr, 
	free_pages(addr, get_order(size));

}



static inline void __dma_sync(unsigned long addr, size_t size,

static inline void __dma_sync_virtual(void *addr, size_t size,

	enum dma_data_direction direction)

{

	switch (direction) {

	case DMA_TO_DEVICE:

		dma_cache_wback(addr, size);

		dma_cache_wback((unsigned long)addr, size);

		break;



	case DMA_FROM_DEVICE:

		dma_cache_inv(addr, size);

		dma_cache_inv((unsigned long)addr, size);

		break;



	case DMA_BIDIRECTIONAL:

		dma_cache_wback_inv(addr, size);

		dma_cache_wback_inv((unsigned long)addr, size);

		break;



	default:
@@ -169,12 +169,49 @@ static inline void __dma_sync(unsigned long addr, size_t size, 
	}

}



/*

 * A single sg entry may refer to multiple physically contiguous

 * pages. But we still need to process highmem pages individually.

 * If highmem is not configured then the bulk of this loop gets

 * optimized out.

 */

static inline void __dma_sync(struct page *page,

	unsigned long offset, size_t size, enum dma_data_direction direction)

{

	size_t left = size;



	do {

		size_t len = left;



		if (PageHighMem(page)) {

			void *addr;



			if (offset + len > PAGE_SIZE) {

				if (offset >= PAGE_SIZE) {

					page += offset >> PAGE_SHIFT;

					offset &= ~PAGE_MASK;

				}

				len = PAGE_SIZE - offset;

			}



			addr = kmap_atomic(page);

			__dma_sync_virtual(addr + offset, len, direction);

			kunmap_atomic(addr);

		} else

			__dma_sync_virtual(page_address(page) + offset,

					   size, direction);

		offset = 0;

		page++;

		left -= len;

	} while (left);

}



static void mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr,

	size_t size, enum dma_data_direction direction, struct dma_attrs *attrs)

{

	if (cpu_is_noncoherent_r10000(dev))

		__dma_sync(dma_addr_to_virt(dev, dma_addr), size,

		           direction);

		__dma_sync(dma_addr_to_page(dev, dma_addr),

			   dma_addr & ~PAGE_MASK, size, direction);



	plat_unmap_dma_mem(dev, dma_addr, size, direction);

}
@@ -185,13 +222,11 @@ static int mips_dma_map_sg(struct device *dev, struct scatterlist *sg, 
	int i;



	for (i = 0; i < nents; i++, sg++) {

		unsigned long addr;



		addr = (unsigned long) sg_virt(sg);

		if (!plat_device_is_coherent(dev) && addr)

			__dma_sync(addr, sg->length, direction);

		sg->dma_address = plat_map_dma_mem(dev,

				                   (void *)addr, sg->length);

		if (!plat_device_is_coherent(dev))

			__dma_sync(sg_page(sg), sg->offset, sg->length,

				   direction);

		sg->dma_address = plat_map_dma_mem_page(dev, sg_page(sg)) +

				  sg->offset;

	}



	return nents;
@@ -201,30 +236,23 @@ static dma_addr_t mips_dma_map_page(struct device *dev, struct page *page, 
	unsigned long offset, size_t size, enum dma_data_direction direction,

	struct dma_attrs *attrs)

{

	unsigned long addr;



	addr = (unsigned long) page_address(page) + offset;



	if (!plat_device_is_coherent(dev))

		__dma_sync(addr, size, direction);

		__dma_sync(page, offset, size, direction);



	return plat_map_dma_mem(dev, (void *)addr, size);

	return plat_map_dma_mem_page(dev, page) + offset;

}



static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sg,

	int nhwentries, enum dma_data_direction direction,

	struct dma_attrs *attrs)

{

	unsigned long addr;

	int i;



	for (i = 0; i < nhwentries; i++, sg++) {

		if (!plat_device_is_coherent(dev) &&

		    direction != DMA_TO_DEVICE) {

			addr = (unsigned long) sg_virt(sg);

			if (addr)

				__dma_sync(addr, sg->length, direction);

		}

		    direction != DMA_TO_DEVICE)

			__dma_sync(sg_page(sg), sg->offset, sg->length,

				   direction);

		plat_unmap_dma_mem(dev, sg->dma_address, sg->length, direction);

	}

}
@@ -232,24 +260,18 @@ static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sg, 
static void mips_dma_sync_single_for_cpu(struct device *dev,

	dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)

{

	if (cpu_is_noncoherent_r10000(dev)) {

		unsigned long addr;



		addr = dma_addr_to_virt(dev, dma_handle);

		__dma_sync(addr, size, direction);

	}

	if (cpu_is_noncoherent_r10000(dev))

		__dma_sync(dma_addr_to_page(dev, dma_handle),

			   dma_handle & ~PAGE_MASK, size, direction);

}



static void mips_dma_sync_single_for_device(struct device *dev,

	dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)

{

	plat_extra_sync_for_device(dev);

	if (!plat_device_is_coherent(dev)) {

		unsigned long addr;



		addr = dma_addr_to_virt(dev, dma_handle);

		__dma_sync(addr, size, direction);

	}

	if (!plat_device_is_coherent(dev))

		__dma_sync(dma_addr_to_page(dev, dma_handle),

			   dma_handle & ~PAGE_MASK, size, direction);

}



static void mips_dma_sync_sg_for_cpu(struct device *dev,
@@ -260,8 +282,8 @@ static void mips_dma_sync_sg_for_cpu(struct device *dev, 
	/* Make sure that gcc doesn't leave the empty loop body.  */

	for (i = 0; i < nelems; i++, sg++) {

		if (cpu_is_noncoherent_r10000(dev))

			__dma_sync((unsigned long)page_address(sg_page(sg)),

			           sg->length, direction);

			__dma_sync(sg_page(sg), sg->offset, sg->length,

				   direction);

	}

}
@@ -273,8 +295,8 @@ static void mips_dma_sync_sg_for_device(struct device *dev, 
	/* Make sure that gcc doesn't leave the empty loop body.  */

	for (i = 0; i < nelems; i++, sg++) {

		if (!plat_device_is_coherent(dev))

			__dma_sync((unsigned long)page_address(sg_page(sg)),

			           sg->length, direction);

			__dma_sync(sg_page(sg), sg->offset, sg->length,

				   direction);

	}

}
@@ -295,7 +317,7 @@ void dma_cache_sync(struct device *dev, void *vaddr, size_t size, 


	plat_extra_sync_for_device(dev);

	if (!plat_device_is_coherent(dev))

		__dma_sync((unsigned long)vaddr, size, direction);

		__dma_sync_virtual(vaddr, size, direction);

}



EXPORT_SYMBOL(dma_cache_sync);

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