1 files changed, 937 insertions, 0 deletions

diff --git a/arch/arm/mm/dma-mapping-cma.c b/arch/arm/mm/dma-mapping-cma.c
new file mode 100644
index 0000000..3d143e0
--- /dev/null
+++ b/arch/arm/mm/dma-mapping-cma.c
@@ -0,0 +1,937 @@
+/*
+ *  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/gfp.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma-contiguous.h>
+#include <linux/highmem.h>
+#include <linux/memblock.h>
+#include <linux/slab.h>
+
+#include <asm/memory.h>
+#include <asm/highmem.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/sizes.h>
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+#include <asm/dma-contiguous.h>
+
+#include "mm.h"
+
+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;
+}
+
+static void __dma_clear_buffer(struct page *page, size_t size)
+{
+	void *ptr;
+	/*
+	 * 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);
+}
+
+/*
+ * 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;
+
+	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);
+
+	__dma_clear_buffer(page, 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
+/* Sanity check size */
+#if (CONSISTENT_DMA_SIZE % SZ_2M)
+#error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
+#endif
+
+#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)
+
+/*
+ * 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;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	int i = 0;
+	u32 base = CONSISTENT_BASE;
+
+	return 0;
+
+#if 0
+	do {
+		pgd = pgd_offset(&init_mm, base);
+
+		pud = pud_alloc(&init_mm, pgd, base);
+		if (!pud) {
+			printk(KERN_ERR "%s: no pud tables\n", __func__);
+			ret = -ENOMEM;
+			break;
+		}
+
+		pmd = pmd_alloc(&init_mm, pud, 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;
+#endif
+}
+core_initcall(consistent_init);
+
+static void *__alloc_from_contiguous(struct device *dev, size_t size,
+				     pgprot_t prot, struct page **ret_page);
+
+static struct arm_vmregion_head coherent_head = {
+	.vm_lock	= __SPIN_LOCK_UNLOCKED(&coherent_head.vm_lock),
+	.vm_list	= LIST_HEAD_INIT(coherent_head.vm_list),
+};
+
+size_t coherent_pool_size = CONSISTENT_DMA_SIZE / 8;
+
+static int __init early_coherent_pool(char *p)
+{
+	coherent_pool_size = memparse(p, &p);
+	return 0;
+}
+early_param("coherent_pool", early_coherent_pool);
+
+/*
+ * Initialise the coherent pool for atomic allocations.
+ */
+static int __init coherent_init(void)
+{
+	pgprot_t prot = pgprot_dmacoherent(pgprot_kernel);
+	size_t size = coherent_pool_size;
+	struct page *page;
+	void *ptr;
+
+#if 0
+	if (!IS_ENABLED(CONFIG_DMA_CMA))
+		return 0;
+#endif
+
+	ptr = __alloc_from_contiguous(NULL, size, prot, &page);
+	if (ptr) {
+		coherent_head.vm_start = (unsigned long) ptr;
+		coherent_head.vm_end = (unsigned long) ptr + size;
+		printk(KERN_INFO "DMA: preallocated %u KiB pool for atomic coherent allocations\n",
+		       (unsigned)size / 1024);
+		return 0;
+	}
+	printk(KERN_ERR "DMA: failed to allocate %u KiB pool for atomic coherent allocation\n",
+	       (unsigned)size / 1024);
+	return -ENOMEM;
+}
+/*
+ * CMA is activated by core_initcall, so we must be called after it.
+ */
+postcore_initcall(coherent_init);
+
+struct dma_contig_early_reserve {
+	phys_addr_t base;
+	unsigned long size;
+};
+
+static struct dma_contig_early_reserve dma_mmu_remap[MAX_CMA_AREAS] __initdata;
+
+static int dma_mmu_remap_num __initdata;
+
+void __init dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
+{
+	dma_mmu_remap[dma_mmu_remap_num].base = base;
+	dma_mmu_remap[dma_mmu_remap_num].size = size;
+	dma_mmu_remap_num++;
+}
+
+void __init dma_contiguous_remap(void)
+{
+	int i;
+	for (i = 0; i < dma_mmu_remap_num; i++) {
+		phys_addr_t start = dma_mmu_remap[i].base;
+		phys_addr_t end = start + dma_mmu_remap[i].size;
+		struct map_desc map;
+		unsigned long addr;
+
+		if (end > arm_lowmem_limit)
+			end = arm_lowmem_limit;
+		if (start >= end)
+			return;
+
+		map.pfn = __phys_to_pfn(start);
+		map.virtual = __phys_to_virt(start);
+		map.length = end - start;
+		map.type = MT_MEMORY_DMA_READY;
+
+		/*
+		 * Clear previous low-memory mapping
+		 */
+		for (addr = __phys_to_virt(start); addr < __phys_to_virt(end);
+		     addr += PGDIR_SIZE)
+			pmd_clear(pmd_off_k(addr));
+
+		iotable_init(&map, 1);
+	}
+}
+
+static void *
+__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
+{
+	struct arm_vmregion *c;
+	size_t align;
+	int bit;
+
+	if (!consistent_pte[0]) {
+		printk(KERN_ERR "%s: not initialised\n", __func__);
+		dump_stack();
+		return NULL;
+	}
+
+	/*
+	 * Align the virtual region allocation - maximum alignment is
+	 * a section size, minimum is a page size.  This helps reduce
+	 * fragmentation of the DMA space, and also prevents allocations
+	 * smaller than a section from crossing a section boundary.
+	 */
+	bit = fls(size - 1);
+	if (bit > SECTION_SHIFT)
+		bit = SECTION_SHIFT;
+	align = 1 << bit;
+
+	/*
+	 * Allocate a virtual address in the consistent mapping region.
+	 */
+	c = arm_vmregion_alloc(&consistent_head, align, 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);
+
+		dsb();
+
+		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);
+}
+
+static int __dma_update_pte(pte_t *pte, pgtable_t token, unsigned long addr,
+			    void *data)
+{
+	struct page *page = virt_to_page(addr);
+	pgprot_t prot = *(pgprot_t *)data;
+
+	set_pte_ext(pte, mk_pte(page, prot), 0);
+	return 0;
+}
+
+static void __dma_remap(struct page *page, size_t size, pgprot_t prot)
+{
+	unsigned long start = (unsigned long) page_address(page);
+	unsigned end = start + size;
+
+	apply_to_page_range(&init_mm, start, size, __dma_update_pte, &prot);
+	dsb();
+	flush_tlb_kernel_range(start, end);
+}
+
+static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
+				 pgprot_t prot, struct page **ret_page)
+{
+	struct page *page;
+	void *ptr;
+	page = __dma_alloc_buffer(dev, size, gfp);
+	if (!page)
+		return NULL;
+
+	ptr = __dma_alloc_remap(page, size, gfp, prot);
+	if (!ptr) {
+		__dma_free_buffer(page, size);
+		return NULL;
+	}
+
+	*ret_page = page;
+	return ptr;
+}
+
+static void *__alloc_from_pool(struct device *dev, size_t size,
+			       struct page **ret_page)
+{
+	struct arm_vmregion *c;
+	size_t align;
+
+	if (!coherent_head.vm_start) {
+		printk(KERN_ERR "%s: coherent pool not initialised!\n",
+		       __func__);
+		dump_stack();
+		return NULL;
+	}
+
+	/*
+	 * Align the region allocation - allocations from pool are rather
+	 * small, so align them to their order in pages, minimum is a page
+	 * size. This helps reduce fragmentation of the DMA space.
+	 */
+	align = PAGE_SIZE << get_order(size);
+	c = arm_vmregion_alloc(&coherent_head, align, size, 0);
+	if (c) {
+		void *ptr = (void *)c->vm_start;
+		struct page *page = virt_to_page(ptr);
+		*ret_page = page;
+		return ptr;
+	}
+	return NULL;
+}
+
+static int __free_from_pool(void *cpu_addr, size_t size)
+{
+	unsigned long start = (unsigned long)cpu_addr;
+	unsigned long end = start + size;
+	struct arm_vmregion *c;
+
+	if (start < coherent_head.vm_start || end > coherent_head.vm_end)
+		return 0;
+
+	c = arm_vmregion_find_remove(&coherent_head, (unsigned long)start);
+
+	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;
+	}
+
+	arm_vmregion_free(&coherent_head, c);
+	return 1;
+}
+
+static void *__alloc_from_contiguous(struct device *dev, size_t size,
+				     pgprot_t prot, struct page **ret_page)
+{
+	unsigned long order = get_order(size);
+	size_t count = size >> PAGE_SHIFT;
+	struct page *page;
+
+	page = dma_alloc_from_contiguous(dev, count, order);
+	if (!page)
+		return NULL;
+
+	__dma_clear_buffer(page, size);
+	__dma_remap(page, size, prot);
+
+	*ret_page = page;
+	return page_address(page);
+}
+
+static void __free_from_contiguous(struct device *dev, struct page *page,
+				   size_t size)
+{
+	__dma_remap(page, size, pgprot_kernel);
+	dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
+}
+
+#define nommu() 0
+
+#else	/* !CONFIG_MMU */
+
+#define nommu() 1
+
+#define __alloc_remap_buffer(dev, size, gfp, prot, ret)	NULL
+#define __alloc_from_pool(dev, size, ret_page)		NULL
+#define __alloc_from_contiguous(dev, size, prot, ret)	NULL
+#define __free_from_pool(cpu_addr, size)		0
+#define __free_from_contiguous(dev, page, size)		do { } while (0)
+#define __dma_free_remap(cpu_addr, size)		do { } while (0)
+
+#endif	/* CONFIG_MMU */
+
+static void *__alloc_simple_buffer(struct device *dev, size_t size, gfp_t gfp,
+				   struct page **ret_page)
+{
+	struct page *page;
+	page = __dma_alloc_buffer(dev, size, gfp);
+	if (!page)
+		return NULL;
+
+	*ret_page = page;
+	return page_address(page);
+}
+
+
+
+static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
+			 gfp_t gfp, pgprot_t prot)
+{
+	u64 mask = get_coherent_dma_mask(dev);
+	struct page *page;
+	void *addr;
+
+#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;
+
+	/*
+	 * Following is a work-around (a.k.a. hack) to prevent pages
+	 * with __GFP_COMP being passed to split_page() which cannot
+	 * handle them.  The real problem is that this flag probably
+	 * should be 0 on ARM as it is not supported on this
+	 * platform; see CONFIG_HUGETLBFS.
+	 */
+	gfp &= ~(__GFP_COMP);
+
+	if (size == 0x3100000)
+		printk(KERN_INFO "%s[%d] It's MFC dev %p\n",
+				__func__, __LINE__, dev);
+
+	*handle = ~0;
+	size = PAGE_ALIGN(size);
+
+	if (arch_is_coherent() || nommu())
+		addr = __alloc_simple_buffer(dev, size, gfp, &page);
+#if 0
+	else if (!IS_ENABLED(CONFIG_DMA_CMA))
+		addr = __alloc_remap_buffer(dev, size, gfp, prot, &page);
+#endif
+	else if (gfp & GFP_ATOMIC)
+		addr = __alloc_from_pool(dev, size, &page);
+	else
+		addr = __alloc_from_contiguous(dev, size, prot, &page);
+
+	if (addr)
+		*handle = pfn_to_dma(dev, page_to_pfn(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 pfn = dma_to_pfn(dev, dma_addr);
+	ret = remap_pfn_range(vma, vma->vm_start,
+			      pfn + vma->vm_pgoff,
+			      vma->vm_end - vma->vm_start,
+			      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 buffer as defined by the above mapping.
+ */
+void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr,
+			 dma_addr_t handle)
+{
+	struct page *page = pfn_to_page(dma_to_pfn(dev, handle));
+
+	if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
+		return;
+
+	size = PAGE_ALIGN(size);
+
+	if (arch_is_coherent() || nommu()) {
+		__dma_free_buffer(page, size);
+#if 0
+	} else if (!IS_ENABLED(CONFIG_DMA_CMA)) {
+		__dma_free_remap(cpu_addr, size);
+		__dma_free_buffer(page, size);
+#endif
+	} else {
+		if (__free_from_pool(cpu_addr, size))
+			return;
+		/*
+		 * Non-atomic allocations cannot be freed with IRQs disabled
+		 */
+		WARN_ON(irqs_disabled());
+		__free_from_contiguous(dev, page, 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 if (cache_is_vipt()) {
+				/* unmapped pages might still be cached */
+				vaddr = kmap_atomic(page);
+				op(vaddr + offset, len, dir);
+				kunmap_atomic(vaddr);
+			}
+		} 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);
+
+	/*
+	 * Mark the D-cache clean for this page to avoid extra flushing.
+	 */
+	if (dir != DMA_TO_DEVICE && off == 0 && size >= PAGE_SIZE)
+		set_bit(PG_dcache_clean, &page->flags);
+}
+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;
+
+	BUG_ON(!valid_dma_direction(dir));
+
+	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;
+	}
+	debug_dma_map_sg(dev, sg, nents, nents, dir);
+	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 (same as was passed to 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;
+
+	debug_dma_unmap_sg(dev, sg, nents, dir);
+
+	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);
+	}
+
+	debug_dma_sync_sg_for_cpu(dev, sg, nents, 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);
+	}
+
+	debug_dma_sync_sg_for_device(dev, sg, nents, dir);
+}
+EXPORT_SYMBOL(dma_sync_sg_for_device);
+
+/*
+ * Return whether the given device DMA address mask can be supported
+ * properly.  For example, if your device can only drive the low 24-bits
+ * during bus mastering, then you would pass 0x00ffffff as the mask
+ * to this function.
+ */
+
+#define PREALLOC_DMA_DEBUG_ENTRIES	4096
+
+static int __init dma_debug_do_init(void)
+{
+	dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
+	return 0;
+}
+fs_initcall(dma_debug_do_init);