arch/arm/mm/dma-mapping.c - kernel/msm - Gitiles

 /*
  *  linux/arch/arm/mm/dma-mapping.c
  *
  *  Copyright (C) 2000-2004 Russell King
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  *  DMA uncached mapping support.
  */
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
 #include <linux/list.h>
 #include <linux/init.h>
 #include <linux/device.h>
 #include <linux/dma-mapping.h>

 #include <asm/memory.h>
 #include <asm/highmem.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/sizes.h>

 /* Sanity check size */
 #if (CONSISTENT_DMA_SIZE % SZ_2M)
 #error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
 #endif

 #define CONSISTENT_END	(0xffe00000)
 #define CONSISTENT_BASE	(CONSISTENT_END - CONSISTENT_DMA_SIZE)

 #define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
 #define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PGDIR_SHIFT)
 #define NUM_CONSISTENT_PTES (CONSISTENT_DMA_SIZE >> PGDIR_SHIFT)

 static u64 get_coherent_dma_mask(struct device *dev)
 {
 	u64 mask = ISA_DMA_THRESHOLD;

 	if (dev) {
 		mask = dev->coherent_dma_mask;

 		/*
 		 * Sanity check the DMA mask - it must be non-zero, and
 		 * must be able to be satisfied by a DMA allocation.
 		 */
 		if (mask == 0) {
 			dev_warn(dev, "coherent DMA mask is unset\n");
 			return 0;
 		}

 		if ((~mask) & ISA_DMA_THRESHOLD) {
 			dev_warn(dev, "coherent DMA mask %#llx is smaller "
 				 "than system GFP_DMA mask %#llx\n",
 				 mask, (unsigned long long)ISA_DMA_THRESHOLD);
 			return 0;
 		}
 	}

 	return mask;
 }

 /*
  * Allocate a DMA buffer for 'dev' of size 'size' using the
  * specified gfp mask.  Note that 'size' must be page aligned.
  */
 static struct page *__dma_alloc_buffer(struct device *dev, size_t size, gfp_t gfp)
 {
 	unsigned long order = get_order(size);
 	struct page *page, *p, *e;
 	void *ptr;
 	u64 mask = get_coherent_dma_mask(dev);

 #ifdef CONFIG_DMA_API_DEBUG
 	u64 limit = (mask + 1) & ~mask;
 	if (limit && size >= limit) {
 		dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n",
 			size, mask);
 		return NULL;
 	}
 #endif

 	if (!mask)
 		return NULL;

 	if (mask < 0xffffffffULL)
 		gfp |= GFP_DMA;

 	page = alloc_pages(gfp, order);
 	if (!page)
 		return NULL;

 	/*
 	 * Now split the huge page and free the excess pages
 	 */
 	split_page(page, order);
 	for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++)
 		__free_page(p);

 	/*
 	 * Ensure that the allocated pages are zeroed, and that any data
 	 * lurking in the kernel direct-mapped region is invalidated.
 	 */
 	ptr = page_address(page);
 	memset(ptr, 0, size);
 	dmac_flush_range(ptr, ptr + size);
 	outer_flush_range(__pa(ptr), __pa(ptr) + size);

 	return page;
 }

 /*
  * Free a DMA buffer.  'size' must be page aligned.
  */
 static void __dma_free_buffer(struct page *page, size_t size)
 {
 	struct page *e = page + (size >> PAGE_SHIFT);

 	while (page < e) {
 		__free_page(page);
 		page++;
 	}
 }

 #ifdef CONFIG_MMU
 /*
  * These are the page tables (2MB each) covering uncached, DMA consistent allocations
  */
 static pte_t *consistent_pte[NUM_CONSISTENT_PTES];

 #include "vmregion.h"

 static struct arm_vmregion_head consistent_head = {
 	.vm_lock	= __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
 	.vm_list	= LIST_HEAD_INIT(consistent_head.vm_list),
 	.vm_start	= CONSISTENT_BASE,
 	.vm_end		= CONSISTENT_END,
 };

 #ifdef CONFIG_HUGETLB_PAGE
 #error ARM Coherent DMA allocator does not (yet) support huge TLB
 #endif

 /*
  * Initialise the consistent memory allocation.
  */
 static int __init consistent_init(void)
 {
 	int ret = 0;
 	pgd_t *pgd;
 	pmd_t *pmd;
 	pte_t *pte;
 	int i = 0;
 	u32 base = CONSISTENT_BASE;

 	do {
 		pgd = pgd_offset(&init_mm, base);
 		pmd = pmd_alloc(&init_mm, pgd, base);
 		if (!pmd) {
 			printk(KERN_ERR "%s: no pmd tables\n", __func__);
 			ret = -ENOMEM;
 			break;
 		}
 		WARN_ON(!pmd_none(*pmd));

 		pte = pte_alloc_kernel(pmd, base);
 		if (!pte) {
 			printk(KERN_ERR "%s: no pte tables\n", __func__);
 			ret = -ENOMEM;
 			break;
 		}

 		consistent_pte[i++] = pte;
 		base += (1 << PGDIR_SHIFT);
 	} while (base < CONSISTENT_END);

 	return ret;
 }

 core_initcall(consistent_init);

 static void *
 __dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
 {
 	struct arm_vmregion *c;

 	if (!consistent_pte[0]) {
 		printk(KERN_ERR "%s: not initialised\n", __func__);
 		dump_stack();
 		return NULL;
 	}

 	/*
 	 * Allocate a virtual address in the consistent mapping region.
 	 */
 	c = arm_vmregion_alloc(&consistent_head, size,
 			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
 	if (c) {
 		pte_t *pte;
 		int idx = CONSISTENT_PTE_INDEX(c->vm_start);
 		u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);

 		pte = consistent_pte[idx] + off;
 		c->vm_pages = page;

 		do {
 			BUG_ON(!pte_none(*pte));

 			set_pte_ext(pte, mk_pte(page, prot), 0);
 			page++;
 			pte++;
 			off++;
 			if (off >= PTRS_PER_PTE) {
 				off = 0;
 				pte = consistent_pte[++idx];
 			}
 		} while (size -= PAGE_SIZE);

 		return (void *)c->vm_start;
 	}
 	return NULL;
 }

 static void __dma_free_remap(void *cpu_addr, size_t size)
 {
 	struct arm_vmregion *c;
 	unsigned long addr;
 	pte_t *ptep;
 	int idx;
 	u32 off;

 	c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
 	if (!c) {
 		printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
 		       __func__, cpu_addr);
 		dump_stack();
 		return;
 	}

 	if ((c->vm_end - c->vm_start) != size) {
 		printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
 		       __func__, c->vm_end - c->vm_start, size);
 		dump_stack();
 		size = c->vm_end - c->vm_start;
 	}

 	idx = CONSISTENT_PTE_INDEX(c->vm_start);
 	off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 	ptep = consistent_pte[idx] + off;
 	addr = c->vm_start;
 	do {
 		pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);

 		ptep++;
 		addr += PAGE_SIZE;
 		off++;
 		if (off >= PTRS_PER_PTE) {
 			off = 0;
 			ptep = consistent_pte[++idx];
 		}

 		if (pte_none(pte) || !pte_present(pte))
 			printk(KERN_CRIT "%s: bad page in kernel page table\n",
 			       __func__);
 	} while (size -= PAGE_SIZE);

 	flush_tlb_kernel_range(c->vm_start, c->vm_end);

 	arm_vmregion_free(&consistent_head, c);
 }

 #else	/* !CONFIG_MMU */

 #define __dma_alloc_remap(page, size, gfp, prot)	page_address(page)
 #define __dma_free_remap(addr, size)			do { } while (0)

 #endif	/* CONFIG_MMU */

 static void *
 __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
 	    pgprot_t prot)
 {
 	struct page *page;
 	void *addr;

 	*handle = ~0;
 	size = PAGE_ALIGN(size);

 	page = __dma_alloc_buffer(dev, size, gfp);
 	if (!page)
 		return NULL;

 	if (!arch_is_coherent())
 		addr = __dma_alloc_remap(page, size, gfp, prot);
 	else
 		addr = page_address(page);

 	if (addr)
 		*handle = page_to_dma(dev, page);

 	return addr;
 }

 /*
  * Allocate DMA-coherent memory space and return both the kernel remapped
  * virtual and bus address for that space.
  */
 void *
 dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 {
 	void *memory;

 	if (dma_alloc_from_coherent(dev, size, handle, &memory))
 		return memory;

 	return __dma_alloc(dev, size, handle, gfp,
 			   pgprot_dmacoherent(pgprot_kernel));
 }
 EXPORT_SYMBOL(dma_alloc_coherent);

 /*
  * Allocate a writecombining region, in much the same way as
  * dma_alloc_coherent above.
  */
 void *
 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 {
 	return __dma_alloc(dev, size, handle, gfp,
 			   pgprot_writecombine(pgprot_kernel));
 }
 EXPORT_SYMBOL(dma_alloc_writecombine);

 static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 		    void *cpu_addr, dma_addr_t dma_addr, size_t size)
 {
 	int ret = -ENXIO;
 #ifdef CONFIG_MMU
 	unsigned long user_size, kern_size;
 	struct arm_vmregion *c;

 	user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;

 	c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
 	if (c) {
 		unsigned long off = vma->vm_pgoff;

 		kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;

 		if (off < kern_size &&
 		    user_size <= (kern_size - off)) {
 			ret = remap_pfn_range(vma, vma->vm_start,
 					      page_to_pfn(c->vm_pages) + off,
 					      user_size << PAGE_SHIFT,
 					      vma->vm_page_prot);
 		}
 	}
 #endif	/* CONFIG_MMU */

 	return ret;
 }

 int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
 		      void *cpu_addr, dma_addr_t dma_addr, size_t size)
 {
 	vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
 	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 }
 EXPORT_SYMBOL(dma_mmap_coherent);

 int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
 			  void *cpu_addr, dma_addr_t dma_addr, size_t size)
 {
 	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 }
 EXPORT_SYMBOL(dma_mmap_writecombine);

 /*
  * free a page as defined by the above mapping.
  * Must not be called with IRQs disabled.
  */
 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 {
 	WARN_ON(irqs_disabled());

 	if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
 		return;

 	size = PAGE_ALIGN(size);

 	if (!arch_is_coherent())
 		__dma_free_remap(cpu_addr, size);

 	__dma_free_buffer(dma_to_page(dev, handle), size);
 }
 EXPORT_SYMBOL(dma_free_coherent);

 /*
  * Make an area consistent for devices.
  * Note: Drivers should NOT use this function directly, as it will break
  * platforms with CONFIG_DMABOUNCE.
  * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
  */
 void ___dma_single_cpu_to_dev(const void *kaddr, size_t size,
 	enum dma_data_direction dir)
 {
 	unsigned long paddr;

 	BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));

 	dmac_map_area(kaddr, size, dir);

 	paddr = __pa(kaddr);
 	if (dir == DMA_FROM_DEVICE) {
 		outer_inv_range(paddr, paddr + size);
 	} else {
 		outer_clean_range(paddr, paddr + size);
 	}
 	/* FIXME: non-speculating: flush on bidirectional mappings? */
 }
 EXPORT_SYMBOL(___dma_single_cpu_to_dev);

 void ___dma_single_dev_to_cpu(const void *kaddr, size_t size,
 	enum dma_data_direction dir)
 {
 	BUG_ON(!virt_addr_valid(kaddr) || !virt_addr_valid(kaddr + size - 1));

 	/* FIXME: non-speculating: not required */
 	/* don't bother invalidating if DMA to device */
 	if (dir != DMA_TO_DEVICE) {
 		unsigned long paddr = __pa(kaddr);
 		outer_inv_range(paddr, paddr + size);
 	}

 	dmac_unmap_area(kaddr, size, dir);
 }
 EXPORT_SYMBOL(___dma_single_dev_to_cpu);

 static void dma_cache_maint_page(struct page *page, unsigned long offset,
 	size_t size, enum dma_data_direction dir,
 	void (*op)(const void *, size_t, int))
 {
 	/*
 	 * 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.
 	 */
 	size_t left = size;
 	do {
 		size_t len = left;
 		void *vaddr;

 		if (PageHighMem(page)) {
 			if (len + offset > PAGE_SIZE) {
 				if (offset >= PAGE_SIZE) {
 					page += offset / PAGE_SIZE;
 					offset %= PAGE_SIZE;
 				}
 				len = PAGE_SIZE - offset;
 			}
 			vaddr = kmap_high_get(page);
 			if (vaddr) {
 				vaddr += offset;
 				op(vaddr, len, dir);
 				kunmap_high(page);
 			}
 		} else {
 			vaddr = page_address(page) + offset;
 			op(vaddr, len, dir);
 		}
 		offset = 0;
 		page++;
 		left -= len;
 	} while (left);
 }

 void ___dma_page_cpu_to_dev(struct page *page, unsigned long off,
 	size_t size, enum dma_data_direction dir)
 {
 	unsigned long paddr;

 	dma_cache_maint_page(page, off, size, dir, dmac_map_area);

 	paddr = page_to_phys(page) + off;
 	if (dir == DMA_FROM_DEVICE) {
 		outer_inv_range(paddr, paddr + size);
 	} else {
 		outer_clean_range(paddr, paddr + size);
 	}
 	/* FIXME: non-speculating: flush on bidirectional mappings? */
 }
 EXPORT_SYMBOL(___dma_page_cpu_to_dev);

 void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
 	size_t size, enum dma_data_direction dir)
 {
 	unsigned long paddr = page_to_phys(page) + off;

 	/* FIXME: non-speculating: not required */
 	/* don't bother invalidating if DMA to device */
 	if (dir != DMA_TO_DEVICE)
 		outer_inv_range(paddr, paddr + size);

 	dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
 }
 EXPORT_SYMBOL(___dma_page_dev_to_cpu);

 /**
  * dma_map_sg - map a set of SG buffers for streaming mode DMA
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
  * @sg: list of buffers
  * @nents: number of buffers to map
  * @dir: DMA transfer direction
  *
  * Map a set of buffers described by scatterlist in streaming mode for DMA.
  * This is the scatter-gather version of the dma_map_single interface.
  * Here the scatter gather list elements are each tagged with the
  * appropriate dma address and length.  They are obtained via
  * sg_dma_{address,length}.
  *
  * Device ownership issues as mentioned for dma_map_single are the same
  * here.
  */
 int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 		enum dma_data_direction dir)
 {
 	struct scatterlist *s;
 	int i, j;

 	for_each_sg(sg, s, nents, i) {
 		s->dma_address = dma_map_page(dev, sg_page(s), s->offset,
 						s->length, dir);
 		if (dma_mapping_error(dev, s->dma_address))
 			goto bad_mapping;
 	}
 	return nents;

  bad_mapping:
 	for_each_sg(sg, s, i, j)
 		dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 	return 0;
 }
 EXPORT_SYMBOL(dma_map_sg);

 /**
  * dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
  * @sg: list of buffers
  * @nents: number of buffers to unmap (returned from dma_map_sg)
  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
  *
  * Unmap a set of streaming mode DMA translations.  Again, CPU access
  * rules concerning calls here are the same as for dma_unmap_single().
  */
 void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
 		enum dma_data_direction dir)
 {
 	struct scatterlist *s;
 	int i;

 	for_each_sg(sg, s, nents, i)
 		dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
 }
 EXPORT_SYMBOL(dma_unmap_sg);

 /**
  * dma_sync_sg_for_cpu
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
  * @sg: list of buffers
  * @nents: number of buffers to map (returned from dma_map_sg)
  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
  */
 void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
 			int nents, enum dma_data_direction dir)
 {
 	struct scatterlist *s;
 	int i;

 	for_each_sg(sg, s, nents, i) {
 		if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
 					    sg_dma_len(s), dir))
 			continue;

 		__dma_page_dev_to_cpu(sg_page(s), s->offset,
 				      s->length, dir);
 	}
 }
 EXPORT_SYMBOL(dma_sync_sg_for_cpu);

 /**
  * dma_sync_sg_for_device
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
  * @sg: list of buffers
  * @nents: number of buffers to map (returned from dma_map_sg)
  * @dir: DMA transfer direction (same as was passed to dma_map_sg)
  */
 void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 			int nents, enum dma_data_direction dir)
 {
 	struct scatterlist *s;
 	int i;

 	for_each_sg(sg, s, nents, i) {
 		if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0,
 					sg_dma_len(s), dir))
 			continue;

 		__dma_page_cpu_to_dev(sg_page(s), s->offset,
 				      s->length, dir);
 	}
 }
 EXPORT_SYMBOL(dma_sync_sg_for_device);
	/*
	* linux/arch/arm/mm/dma-mapping.c
	*
	* Copyright (C) 2000-2004 Russell King
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* DMA uncached mapping support.
	*/
	#include <linux/module.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/errno.h>
	#include <linux/list.h>
	#include <linux/init.h>
	#include <linux/device.h>
	#include <linux/dma-mapping.h>

	#include <asm/memory.h>
	#include <asm/highmem.h>
	#include <asm/cacheflush.h>
	#include <asm/tlbflush.h>
	#include <asm/sizes.h>

	/* Sanity check size */
	#if (CONSISTENT_DMA_SIZE % SZ_2M)
	#error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
	#endif

	#define CONSISTENT_END (0xffe00000)
	#define CONSISTENT_BASE (CONSISTENT_END - CONSISTENT_DMA_SIZE)

	#define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
	#define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PGDIR_SHIFT)
	#define NUM_CONSISTENT_PTES (CONSISTENT_DMA_SIZE >> PGDIR_SHIFT)

	static u64 get_coherent_dma_mask(struct device *dev)
	{
	u64 mask = ISA_DMA_THRESHOLD;

	if (dev) {
	mask = dev->coherent_dma_mask;

	/*
	* Sanity check the DMA mask - it must be non-zero, and
	* must be able to be satisfied by a DMA allocation.
	*/
	if (mask == 0) {
	dev_warn(dev, "coherent DMA mask is unset\n");
	return 0;
	}

	if ((~mask) & ISA_DMA_THRESHOLD) {
	dev_warn(dev, "coherent DMA mask %#llx is smaller "
	"than system GFP_DMA mask %#llx\n",
	mask, (unsigned long long)ISA_DMA_THRESHOLD);
	return 0;
	}
	}

	return mask;
	}

	/*
	* Allocate a DMA buffer for 'dev' of size 'size' using the
	* specified gfp mask. Note that 'size' must be page aligned.
	*/
	static struct page __dma_alloc_buffer(struct device dev, size_t size, gfp_t gfp)
	{
	unsigned long order = get_order(size);
	struct page page, p, *e;
	void *ptr;
	u64 mask = get_coherent_dma_mask(dev);

	#ifdef CONFIG_DMA_API_DEBUG
	u64 limit = (mask + 1) & ~mask;
	if (limit && size >= limit) {
	dev_warn(dev, "coherent allocation too big (requested %#x mask %#llx)\n",
	size, mask);
	return NULL;
	}
	#endif

	if (!mask)
	return NULL;

	if (mask < 0xffffffffULL)
	gfp \|= GFP_DMA;

	page = alloc_pages(gfp, order);
	if (!page)
	return NULL;

	/*
	* Now split the huge page and free the excess pages
	*/
	split_page(page, order);
	for (p = page + (size >> PAGE_SHIFT), e = page + (1 << order); p < e; p++)
	__free_page(p);

	/*
	* Ensure that the allocated pages are zeroed, and that any data
	* lurking in the kernel direct-mapped region is invalidated.
	*/
	ptr = page_address(page);
	memset(ptr, 0, size);
	dmac_flush_range(ptr, ptr + size);
	outer_flush_range(__pa(ptr), __pa(ptr) + size);

	return page;
	}

	/*
	* Free a DMA buffer. 'size' must be page aligned.
	*/
	static void __dma_free_buffer(struct page *page, size_t size)
	{
	struct page *e = page + (size >> PAGE_SHIFT);

	while (page < e) {
	__free_page(page);
	page++;
	}
	}

	#ifdef CONFIG_MMU
	/*
	* These are the page tables (2MB each) covering uncached, DMA consistent allocations
	*/
	static pte_t *consistent_pte[NUM_CONSISTENT_PTES];

	#include "vmregion.h"

	static struct arm_vmregion_head consistent_head = {
	.vm_lock = __SPIN_LOCK_UNLOCKED(&consistent_head.vm_lock),
	.vm_list = LIST_HEAD_INIT(consistent_head.vm_list),
	.vm_start = CONSISTENT_BASE,
	.vm_end = CONSISTENT_END,
	};

	#ifdef CONFIG_HUGETLB_PAGE
	#error ARM Coherent DMA allocator does not (yet) support huge TLB
	#endif

	/*
	* Initialise the consistent memory allocation.
	*/
	static int __init consistent_init(void)
	{
	int ret = 0;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	int i = 0;
	u32 base = CONSISTENT_BASE;

	do {
	pgd = pgd_offset(&init_mm, base);
	pmd = pmd_alloc(&init_mm, pgd, base);
	if (!pmd) {
	printk(KERN_ERR "%s: no pmd tables\n", __func__);
	ret = -ENOMEM;
	break;
	}
	WARN_ON(!pmd_none(*pmd));

	pte = pte_alloc_kernel(pmd, base);
	if (!pte) {
	printk(KERN_ERR "%s: no pte tables\n", __func__);
	ret = -ENOMEM;
	break;
	}

	consistent_pte[i++] = pte;
	base += (1 << PGDIR_SHIFT);
	} while (base < CONSISTENT_END);

	return ret;
	}

	core_initcall(consistent_init);

	static void *
	__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
	{
	struct arm_vmregion *c;

	if (!consistent_pte[0]) {
	printk(KERN_ERR "%s: not initialised\n", __func__);
	dump_stack();
	return NULL;
	}

	/*
	* Allocate a virtual address in the consistent mapping region.
	*/
	c = arm_vmregion_alloc(&consistent_head, size,
	gfp & ~(__GFP_DMA \| __GFP_HIGHMEM));
	if (c) {
	pte_t *pte;
	int idx = CONSISTENT_PTE_INDEX(c->vm_start);
	u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);

	pte = consistent_pte[idx] + off;
	c->vm_pages = page;

	do {
	BUG_ON(!pte_none(*pte));

	set_pte_ext(pte, mk_pte(page, prot), 0);
	page++;
	pte++;
	off++;
	if (off >= PTRS_PER_PTE) {
	off = 0;
	pte = consistent_pte[++idx];
	}
	} while (size -= PAGE_SIZE);

	return (void *)c->vm_start;
	}
	return NULL;
	}

	static void __dma_free_remap(void *cpu_addr, size_t size)
	{
	struct arm_vmregion *c;
	unsigned long addr;
	pte_t *ptep;
	int idx;
	u32 off;

	c = arm_vmregion_find_remove(&consistent_head, (unsigned long)cpu_addr);
	if (!c) {
	printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
	__func__, cpu_addr);
	dump_stack();
	return;
	}

	if ((c->vm_end - c->vm_start) != size) {
	printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
	__func__, c->vm_end - c->vm_start, size);
	dump_stack();
	size = c->vm_end - c->vm_start;
	}

	idx = CONSISTENT_PTE_INDEX(c->vm_start);
	off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
	ptep = consistent_pte[idx] + off;
	addr = c->vm_start;
	do {
	pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);

	ptep++;
	addr += PAGE_SIZE;
	off++;
	if (off >= PTRS_PER_PTE) {
	off = 0;
	ptep = consistent_pte[++idx];
	}

	if (pte_none(pte) \|\| !pte_present(pte))
	printk(KERN_CRIT "%s: bad page in kernel page table\n",
	__func__);
	} while (size -= PAGE_SIZE);

	flush_tlb_kernel_range(c->vm_start, c->vm_end);

	arm_vmregion_free(&consistent_head, c);
	}

	#else /* !CONFIG_MMU */

	#define __dma_alloc_remap(page, size, gfp, prot) page_address(page)
	#define __dma_free_remap(addr, size) do { } while (0)

	#endif /* CONFIG_MMU */

	static void *
	__dma_alloc(struct device dev, size_t size, dma_addr_t handle, gfp_t gfp,
	pgprot_t prot)
	{
	struct page *page;
	void *addr;

	*handle = ~0;
	size = PAGE_ALIGN(size);

	page = __dma_alloc_buffer(dev, size, gfp);
	if (!page)
	return NULL;

	if (!arch_is_coherent())
	addr = __dma_alloc_remap(page, size, gfp, prot);
	else
	addr = page_address(page);

	if (addr)
	*handle = page_to_dma(dev, page);

	return addr;
	}

	/*
	* Allocate DMA-coherent memory space and return both the kernel remapped
	* virtual and bus address for that space.
	*/
	void *
	dma_alloc_coherent(struct device dev, size_t size, dma_addr_t handle, gfp_t gfp)
	{
	void *memory;

	if (dma_alloc_from_coherent(dev, size, handle, &memory))
	return memory;

	return __dma_alloc(dev, size, handle, gfp,
	pgprot_dmacoherent(pgprot_kernel));
	}
	EXPORT_SYMBOL(dma_alloc_coherent);

	/*
	* Allocate a writecombining region, in much the same way as
	* dma_alloc_coherent above.
	*/
	void *
	dma_alloc_writecombine(struct device dev, size_t size, dma_addr_t handle, gfp_t gfp)
	{
	return __dma_alloc(dev, size, handle, gfp,
	pgprot_writecombine(pgprot_kernel));
	}
	EXPORT_SYMBOL(dma_alloc_writecombine);

	static int dma_mmap(struct device dev, struct vm_area_struct vma,
	void *cpu_addr, dma_addr_t dma_addr, size_t size)
	{
	int ret = -ENXIO;
	#ifdef CONFIG_MMU
	unsigned long user_size, kern_size;
	struct arm_vmregion *c;

	user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;

	c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
	if (c) {
	unsigned long off = vma->vm_pgoff;

	kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;

	if (off < kern_size &&
	user_size <= (kern_size - off)) {
	ret = remap_pfn_range(vma, vma->vm_start,
	page_to_pfn(c->vm_pages) + off,
	user_size << PAGE_SHIFT,
	vma->vm_page_prot);
	}
	}
	#endif /* CONFIG_MMU */

	return ret;
	}

	int dma_mmap_coherent(struct device dev, struct vm_area_struct vma,
	void *cpu_addr, dma_addr_t dma_addr, size_t size)
	{
	vma->vm_page_prot = pgprot_dmacoherent(vma->vm_page_prot);
	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
	}
	EXPORT_SYMBOL(dma_mmap_coherent);

	int dma_mmap_writecombine(struct device dev, struct vm_area_struct vma,
	void *cpu_addr, dma_addr_t dma_addr, size_t size)
	{
	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
	return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
	}
	EXPORT_SYMBOL(dma_mmap_writecombine);

	/*
	* free a page as defined by the above mapping.
	* Must not be called with IRQs disabled.
	*/
	void dma_free_coherent(struct device dev, size_t size, void cpu_addr, dma_addr_t handle)
	{
	WARN_ON(irqs_disabled());

	if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
	return;

	size = PAGE_ALIGN(size);

	if (!arch_is_coherent())
	__dma_free_remap(cpu_addr, size);

	__dma_free_buffer(dma_to_page(dev, handle), size);
	}
	EXPORT_SYMBOL(dma_free_coherent);

	/*
	* Make an area consistent for devices.
	* Note: Drivers should NOT use this function directly, as it will break
	* platforms with CONFIG_DMABOUNCE.
	* Use the driver DMA support - see dma-mapping.h (dma_sync_*)
	*/
	void ___dma_single_cpu_to_dev(const void *kaddr, size_t size,
	enum dma_data_direction dir)
	{
	unsigned long paddr;

	BUG_ON(!virt_addr_valid(kaddr) \|\| !virt_addr_valid(kaddr + size - 1));

	dmac_map_area(kaddr, size, dir);

	paddr = __pa(kaddr);
	if (dir == DMA_FROM_DEVICE) {
	outer_inv_range(paddr, paddr + size);
	} else {
	outer_clean_range(paddr, paddr + size);
	}
	/* FIXME: non-speculating: flush on bidirectional mappings? */
	}
	EXPORT_SYMBOL(___dma_single_cpu_to_dev);

	void ___dma_single_dev_to_cpu(const void *kaddr, size_t size,
	enum dma_data_direction dir)
	{
	BUG_ON(!virt_addr_valid(kaddr) \|\| !virt_addr_valid(kaddr + size - 1));

	/* FIXME: non-speculating: not required */
	/* don't bother invalidating if DMA to device */
	if (dir != DMA_TO_DEVICE) {
	unsigned long paddr = __pa(kaddr);
	outer_inv_range(paddr, paddr + size);
	}

	dmac_unmap_area(kaddr, size, dir);
	}
	EXPORT_SYMBOL(___dma_single_dev_to_cpu);

	static void dma_cache_maint_page(struct page *page, unsigned long offset,
	size_t size, enum dma_data_direction dir,
	void (op)(const void , size_t, int))
	{
	/*
	* 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.
	*/
	size_t left = size;
	do {
	size_t len = left;
	void *vaddr;

	if (PageHighMem(page)) {
	if (len + offset > PAGE_SIZE) {
	if (offset >= PAGE_SIZE) {
	page += offset / PAGE_SIZE;
	offset %= PAGE_SIZE;
	}
	len = PAGE_SIZE - offset;
	}
	vaddr = kmap_high_get(page);
	if (vaddr) {
	vaddr += offset;
	op(vaddr, len, dir);
	kunmap_high(page);
	}
	} else {
	vaddr = page_address(page) + offset;
	op(vaddr, len, dir);
	}
	offset = 0;
	page++;
	left -= len;
	} while (left);
	}

	void ___dma_page_cpu_to_dev(struct page *page, unsigned long off,
	size_t size, enum dma_data_direction dir)
	{
	unsigned long paddr;

	dma_cache_maint_page(page, off, size, dir, dmac_map_area);

	paddr = page_to_phys(page) + off;
	if (dir == DMA_FROM_DEVICE) {
	outer_inv_range(paddr, paddr + size);
	} else {
	outer_clean_range(paddr, paddr + size);
	}
	/* FIXME: non-speculating: flush on bidirectional mappings? */
	}
	EXPORT_SYMBOL(___dma_page_cpu_to_dev);

	void ___dma_page_dev_to_cpu(struct page *page, unsigned long off,
	size_t size, enum dma_data_direction dir)
	{
	unsigned long paddr = page_to_phys(page) + off;

	/* FIXME: non-speculating: not required */
	/* don't bother invalidating if DMA to device */
	if (dir != DMA_TO_DEVICE)
	outer_inv_range(paddr, paddr + size);

	dma_cache_maint_page(page, off, size, dir, dmac_unmap_area);
	}
	EXPORT_SYMBOL(___dma_page_dev_to_cpu);

	/**
	* dma_map_sg - map a set of SG buffers for streaming mode DMA
	* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
	* @sg: list of buffers
	* @nents: number of buffers to map
	* @dir: DMA transfer direction
	*
	* Map a set of buffers described by scatterlist in streaming mode for DMA.
	* This is the scatter-gather version of the dma_map_single interface.
	* Here the scatter gather list elements are each tagged with the
	* appropriate dma address and length. They are obtained via
	* sg_dma_{address,length}.
	*
	* Device ownership issues as mentioned for dma_map_single are the same
	* here.
	*/
	int dma_map_sg(struct device dev, struct scatterlist sg, int nents,
	enum dma_data_direction dir)
	{
	struct scatterlist *s;
	int i, j;

	for_each_sg(sg, s, nents, i) {
	s->dma_address = dma_map_page(dev, sg_page(s), s->offset,
	s->length, dir);
	if (dma_mapping_error(dev, s->dma_address))
	goto bad_mapping;
	}
	return nents;

	bad_mapping:
	for_each_sg(sg, s, i, j)
	dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
	return 0;
	}
	EXPORT_SYMBOL(dma_map_sg);

	/**
	* dma_unmap_sg - unmap a set of SG buffers mapped by dma_map_sg
	* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
	* @sg: list of buffers
	* @nents: number of buffers to unmap (returned from dma_map_sg)
	* @dir: DMA transfer direction (same as was passed to dma_map_sg)
	*
	* Unmap a set of streaming mode DMA translations. Again, CPU access
	* rules concerning calls here are the same as for dma_unmap_single().
	*/
	void dma_unmap_sg(struct device dev, struct scatterlist sg, int nents,
	enum dma_data_direction dir)
	{
	struct scatterlist *s;
	int i;

	for_each_sg(sg, s, nents, i)
	dma_unmap_page(dev, sg_dma_address(s), sg_dma_len(s), dir);
	}
	EXPORT_SYMBOL(dma_unmap_sg);

	/**
	* dma_sync_sg_for_cpu
	* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
	* @sg: list of buffers
	* @nents: number of buffers to map (returned from dma_map_sg)
	* @dir: DMA transfer direction (same as was passed to dma_map_sg)
	*/
	void dma_sync_sg_for_cpu(struct device dev, struct scatterlist sg,
	int nents, enum dma_data_direction dir)
	{
	struct scatterlist *s;
	int i;

	for_each_sg(sg, s, nents, i) {
	if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,
	sg_dma_len(s), dir))
	continue;

	__dma_page_dev_to_cpu(sg_page(s), s->offset,
	s->length, dir);
	}
	}
	EXPORT_SYMBOL(dma_sync_sg_for_cpu);

	/**
	* dma_sync_sg_for_device
	* @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
	* @sg: list of buffers
	* @nents: number of buffers to map (returned from dma_map_sg)
	* @dir: DMA transfer direction (same as was passed to dma_map_sg)
	*/
	void dma_sync_sg_for_device(struct device dev, struct scatterlist sg,
	int nents, enum dma_data_direction dir)
	{
	struct scatterlist *s;
	int i;

	for_each_sg(sg, s, nents, i) {
	if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0,
	sg_dma_len(s), dir))
	continue;

	__dma_page_cpu_to_dev(sg_page(s), s->offset,
	s->length, dir);
	}
	}
	EXPORT_SYMBOL(dma_sync_sg_for_device);