Merge branch 'pending-dma-coherent' into devel

4 files changed, 342 insertions, 317 deletions

diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 055cb2aa8134..42352e75742b 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -6,7 +6,7 @@ obj-y				:= dma-mapping.o extable.o fault.o init.o \
                                    iomap.o
 
 obj-$(CONFIG_MMU)               += fault-armv.o flush.o ioremap.o mmap.o \
-                                   pgd.o mmu.o
+                                   pgd.o mmu.o vmregion.o
 
 ifneq ($(CONFIG_MMU),y)
 obj-y                           += nommu.o
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index b9590a7085ca..26325cb5d368 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -63,194 +63,152 @@ static u64 get_coherent_dma_mask(struct device *dev)
         return mask;
 }
 
-#ifdef CONFIG_MMU
 /*
- * These are the page tables (2MB each) covering uncached, DMA consistent allocations
+ * Allocate a DMA buffer for 'dev' of size 'size' using the
+ * specified gfp mask.  Note that 'size' must be page aligned.
  */
-static pte_t *consistent_pte[NUM_CONSISTENT_PTES];
-static DEFINE_SPINLOCK(consistent_lock);
+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);
 
-/*
- * VM region handling support.
- *
- * This should become something generic, handling VM region allocations for
- * vmalloc and similar (ioremap, module space, etc).
- *
- * I envisage vmalloc()'s supporting vm_struct becoming:
- *
- *  struct vm_struct {
- *    struct vm_region  region;
- *    unsigned long     flags;
- *    struct page       **pages;
- *    unsigned int      nr_pages;
- *    unsigned long     phys_addr;
- *  };
- *
- * get_vm_area() would then call vm_region_alloc with an appropriate
- * struct vm_region head (eg):
- *
- *  struct vm_region vmalloc_head = {
- *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
- *      .vm_start       = VMALLOC_START,
- *      .vm_end         = VMALLOC_END,
- *  };
- *
- * However, vmalloc_head.vm_start is variable (typically, it is dependent on
- * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
- * would have to initialise this each time prior to calling vm_region_alloc().
- */
-struct arm_vm_region {
-        struct list_head        vm_list;
-        unsigned long           vm_start;
-        unsigned long           vm_end;
-        struct page             *vm_pages;
-        int                     vm_active;
-};
+#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
 
-static struct arm_vm_region consistent_head = {
-        .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
-        .vm_start       = CONSISTENT_BASE,
-        .vm_end         = CONSISTENT_END,
-};
+        if (!mask)
+                return NULL;
 
-static struct arm_vm_region *
-arm_vm_region_alloc(struct arm_vm_region *head, size_t size, gfp_t gfp)
-{
-        unsigned long addr = head->vm_start, end = head->vm_end - size;
-        unsigned long flags;
-        struct arm_vm_region *c, *new;
-
-        new = kmalloc(sizeof(struct arm_vm_region), gfp);
-        if (!new)
-                goto out;
-
-        spin_lock_irqsave(&consistent_lock, flags);
-
-        list_for_each_entry(c, &head->vm_list, vm_list) {
-                if ((addr + size) < addr)
-                        goto nospc;
-                if ((addr + size) <= c->vm_start)
-                        goto found;
-                addr = c->vm_end;
-                if (addr > end)
-                        goto nospc;
-        }
+        if (mask < 0xffffffffULL)
+                gfp |= GFP_DMA;
+
+        page = alloc_pages(gfp, order);
+        if (!page)
+                return NULL;
 
- found:
         /*
-         * Insert this entry _before_ the one we found.
+         * Now split the huge page and free the excess pages
          */
-        list_add_tail(&new->vm_list, &c->vm_list);
-        new->vm_start = addr;
-        new->vm_end = addr + size;
-        new->vm_active = 1;
-
-        spin_unlock_irqrestore(&consistent_lock, flags);
-        return new;
-
- nospc:
-        spin_unlock_irqrestore(&consistent_lock, flags);
-        kfree(new);
- out:
-        return NULL;
+        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;
 }
 
-static struct arm_vm_region *arm_vm_region_find(struct arm_vm_region *head, unsigned long addr)
+/*
+ * Free a DMA buffer.  'size' must be page aligned.
+ */
+static void __dma_free_buffer(struct page *page, size_t size)
 {
-        struct arm_vm_region *c;
-        
-        list_for_each_entry(c, &head->vm_list, vm_list) {
-                if (c->vm_active && c->vm_start == addr)
-                        goto out;
+        struct page *e = page + (size >> PAGE_SHIFT);
+
+        while (page < e) {
+                __free_page(page);
+                page++;
         }
-        c = NULL;
- out:
-        return c;
 }
 
+#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
 
-static void *
-__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
-            pgprot_t prot)
+/*
+ * Initialise the consistent memory allocation.
+ */
+static int __init consistent_init(void)
 {
-        struct page *page;
-        struct arm_vm_region *c;
-        unsigned long order;
-        u64 mask = get_coherent_dma_mask(dev);
-        u64 limit;
+        int ret = 0;
+        pgd_t *pgd;
+        pmd_t *pmd;
+        pte_t *pte;
+        int i = 0;
+        u32 base = CONSISTENT_BASE;
 
-        if (!consistent_pte[0]) {
-                printk(KERN_ERR "%s: not initialised\n", __func__);
-                dump_stack();
-                return NULL;
-        }
+        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));
 
-        if (!mask)
-                goto no_page;
+                pte = pte_alloc_kernel(pmd, base);
+                if (!pte) {
+                        printk(KERN_ERR "%s: no pte tables\n", __func__);
+                        ret = -ENOMEM;
+                        break;
+                }
 
-        /*
-         * Sanity check the allocation size.
-         */
-        size = PAGE_ALIGN(size);
-        limit = (mask + 1) & ~mask;
-        if ((limit && size >= limit) ||
-            size >= (CONSISTENT_END - CONSISTENT_BASE)) {
-                printk(KERN_WARNING "coherent allocation too big "
-                       "(requested %#x mask %#llx)\n", size, mask);
-                goto no_page;
-        }
+                consistent_pte[i++] = pte;
+                base += (1 << PGDIR_SHIFT);
+        } while (base < CONSISTENT_END);
 
-        order = get_order(size);
+        return ret;
+}
 
-        if (mask < 0xffffffffULL)
-                gfp |= GFP_DMA;
+core_initcall(consistent_init);
 
-        page = alloc_pages(gfp, order);
-        if (!page)
-                goto no_page;
+static void *
+__dma_alloc_remap(struct page *page, size_t size, gfp_t gfp, pgprot_t prot)
+{
+        struct arm_vmregion *c;
 
-        /*
-         * Invalidate any data that might be lurking in the
-         * kernel direct-mapped region for device DMA.
-         */
-        {
-                void *ptr = page_address(page);
-                memset(ptr, 0, size);
-                dmac_flush_range(ptr, ptr + size);
-                outer_flush_range(__pa(ptr), __pa(ptr) + size);
+        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_vm_region_alloc(&consistent_head, size,
+        c = arm_vmregion_alloc(&consistent_head, size,
                             gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
         if (c) {
                 pte_t *pte;
-                struct page *end = page + (1 << order);
                 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;
 
-                split_page(page, order);
-
-                /*
-                 * Set the "dma handle"
-                 */
-                *handle = page_to_dma(dev, page);
-
                 do {
                         BUG_ON(!pte_none(*pte));
 
-                        /*
-                         * x86 does not mark the pages reserved...
-                         */
-                        SetPageReserved(page);
                         set_pte_ext(pte, mk_pte(page, prot), 0);
                         page++;
                         pte++;
@@ -261,48 +219,90 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
                         }
                 } while (size -= PAGE_SIZE);
 
-                /*
-                 * Free the otherwise unused pages.
-                 */
-                while (page < end) {
-                        __free_page(page);
-                        page++;
-                }
-
                 return (void *)c->vm_start;
         }
-
-        if (page)
-                __free_pages(page, order);
- no_page:
-        *handle = ~0;
         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)
 {
-        void *virt;
-        u64 mask = get_coherent_dma_mask(dev);
+        struct page *page;
+        void *addr;
 
-        if (!mask)
-                goto error;
+        *handle = ~0;
+        size = PAGE_ALIGN(size);
 
-        if (mask < 0xffffffffULL)
-                gfp |= GFP_DMA;
-        virt = kmalloc(size, gfp);
-        if (!virt)
-                goto error;
+        page = __dma_alloc_buffer(dev, size, gfp);
+        if (!page)
+                return NULL;
 
-        *handle =  virt_to_dma(dev, virt);
-        return virt;
+        if (!arch_is_coherent())
+                addr = __dma_alloc_remap(page, size, gfp, prot);
+        else
+                addr = page_address(page);
 
-error:
-        *handle = ~0;
-        return NULL;
+        if (addr)
+                *handle = page_to_dma(dev, page);
+
+        return addr;
 }
-#endif  /* CONFIG_MMU */
 
 /*
  * Allocate DMA-coherent memory space and return both the kernel remapped
@@ -316,19 +316,8 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gf
         if (dma_alloc_from_coherent(dev, size, handle, &memory))
                 return memory;
 
-        if (arch_is_coherent()) {
-                void *virt;
-
-                virt = kmalloc(size, gfp);
-                if (!virt)
-                        return NULL;
-                *handle =  virt_to_dma(dev, virt);
-
-                return virt;
-        }
-
         return __dma_alloc(dev, size, handle, gfp,
-                           pgprot_noncached(pgprot_kernel));
+                           pgprot_dmacoherent(pgprot_kernel));
 }
 EXPORT_SYMBOL(dma_alloc_coherent);
 
@@ -349,15 +338,12 @@ static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 {
         int ret = -ENXIO;
 #ifdef CONFIG_MMU
-        unsigned long flags, user_size, kern_size;
-        struct arm_vm_region *c;
+        unsigned long user_size, kern_size;
+        struct arm_vmregion *c;
 
         user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 
-        spin_lock_irqsave(&consistent_lock, flags);
-        c = arm_vm_region_find(&consistent_head, (unsigned long)cpu_addr);
-        spin_unlock_irqrestore(&consistent_lock, flags);
-
+        c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);
         if (c) {
                 unsigned long off = vma->vm_pgoff;
 
@@ -379,7 +365,7 @@ static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 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_noncached(vma->vm_page_prot);
+        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);
@@ -396,144 +382,23 @@ EXPORT_SYMBOL(dma_mmap_writecombine);
  * free a page as defined by the above mapping.
  * Must not be called with IRQs disabled.
  */
-#ifdef CONFIG_MMU
 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 {
-        struct arm_vm_region *c;
-        unsigned long flags, addr;
-        pte_t *ptep;
-        int idx;
-        u32 off;
-
         WARN_ON(irqs_disabled());
 
         if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
                 return;
 
-        if (arch_is_coherent()) {
-                kfree(cpu_addr);
-                return;
-        }
-
         size = PAGE_ALIGN(size);
 
-        spin_lock_irqsave(&consistent_lock, flags);
-        c = arm_vm_region_find(&consistent_head, (unsigned long)cpu_addr);
-        if (!c)
-                goto no_area;
-
-        c->vm_active = 0;
-        spin_unlock_irqrestore(&consistent_lock, flags);
-
-        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);
-                unsigned long pfn;
-
-                ptep++;
-                addr += PAGE_SIZE;
-                off++;
-                if (off >= PTRS_PER_PTE) {
-                        off = 0;
-                        ptep = consistent_pte[++idx];
-                }
-
-                if (!pte_none(pte) && pte_present(pte)) {
-                        pfn = pte_pfn(pte);
-
-                        if (pfn_valid(pfn)) {
-                                struct page *page = pfn_to_page(pfn);
-
-                                /*
-                                 * x86 does not mark the pages reserved...
-                                 */
-                                ClearPageReserved(page);
-
-                                __free_page(page);
-                                continue;
-                        }
-                }
-
-                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);
-
-        spin_lock_irqsave(&consistent_lock, flags);
-        list_del(&c->vm_list);
-        spin_unlock_irqrestore(&consistent_lock, flags);
-
-        kfree(c);
-        return;
+        if (!arch_is_coherent())
+                __dma_free_remap(cpu_addr, size);
 
- no_area:
-        spin_unlock_irqrestore(&consistent_lock, flags);
-        printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
-               __func__, cpu_addr);
-        dump_stack();
+        __dma_free_buffer(dma_to_page(dev, handle), size);
 }
-#else   /* !CONFIG_MMU */
-void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
-{
-        if (dma_release_from_coherent(dev, get_order(size), cpu_addr))
-                return;
-        kfree(cpu_addr);
-}
-#endif  /* CONFIG_MMU */
 EXPORT_SYMBOL(dma_free_coherent);
 
 /*
- * Initialise the consistent memory allocation.
- */
-static int __init consistent_init(void)
-{
-        int ret = 0;
-#ifdef CONFIG_MMU
-        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);
-#endif  /* !CONFIG_MMU */
-
-        return ret;
-}
-
-core_initcall(consistent_init);
-
-/*
  * Make an area consistent for devices.
  * Note: Drivers should NOT use this function directly, as it will break
  * platforms with CONFIG_DMABOUNCE.
diff --git a/arch/arm/mm/vmregion.c b/arch/arm/mm/vmregion.c
new file mode 100644
index 000000000000..19e09bdb1b8a
--- /dev/null
+++ b/arch/arm/mm/vmregion.c
@@ -0,0 +1,131 @@
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#include "vmregion.h"
+
+/*
+ * VM region handling support.
+ *
+ * This should become something generic, handling VM region allocations for
+ * vmalloc and similar (ioremap, module space, etc).
+ *
+ * I envisage vmalloc()'s supporting vm_struct becoming:
+ *
+ *  struct vm_struct {
+ *    struct vmregion   region;
+ *    unsigned long     flags;
+ *    struct page       **pages;
+ *    unsigned int      nr_pages;
+ *    unsigned long     phys_addr;
+ *  };
+ *
+ * get_vm_area() would then call vmregion_alloc with an appropriate
+ * struct vmregion head (eg):
+ *
+ *  struct vmregion vmalloc_head = {
+ *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
+ *      .vm_start       = VMALLOC_START,
+ *      .vm_end         = VMALLOC_END,
+ *  };
+ *
+ * However, vmalloc_head.vm_start is variable (typically, it is dependent on
+ * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
+ * would have to initialise this each time prior to calling vmregion_alloc().
+ */
+
+struct arm_vmregion *
+arm_vmregion_alloc(struct arm_vmregion_head *head, size_t size, gfp_t gfp)
+{
+        unsigned long addr = head->vm_start, end = head->vm_end - size;
+        unsigned long flags;
+        struct arm_vmregion *c, *new;
+
+        if (head->vm_end - head->vm_start < size) {
+                printk(KERN_WARNING "%s: allocation too big (requested %#x)\n",
+                        __func__, size);
+                goto out;
+        }
+
+        new = kmalloc(sizeof(struct arm_vmregion), gfp);
+        if (!new)
+                goto out;
+
+        spin_lock_irqsave(&head->vm_lock, flags);
+
+        list_for_each_entry(c, &head->vm_list, vm_list) {
+                if ((addr + size) < addr)
+                        goto nospc;
+                if ((addr + size) <= c->vm_start)
+                        goto found;
+                addr = c->vm_end;
+                if (addr > end)
+                        goto nospc;
+        }
+
+ found:
+        /*
+         * Insert this entry _before_ the one we found.
+         */
+        list_add_tail(&new->vm_list, &c->vm_list);
+        new->vm_start = addr;
+        new->vm_end = addr + size;
+        new->vm_active = 1;
+
+        spin_unlock_irqrestore(&head->vm_lock, flags);
+        return new;
+
+ nospc:
+        spin_unlock_irqrestore(&head->vm_lock, flags);
+        kfree(new);
+ out:
+        return NULL;
+}
+
+static struct arm_vmregion *__arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
+{
+        struct arm_vmregion *c;
+
+        list_for_each_entry(c, &head->vm_list, vm_list) {
+                if (c->vm_active && c->vm_start == addr)
+                        goto out;
+        }
+        c = NULL;
+ out:
+        return c;
+}
+
+struct arm_vmregion *arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
+{
+        struct arm_vmregion *c;
+        unsigned long flags;
+
+        spin_lock_irqsave(&head->vm_lock, flags);
+        c = __arm_vmregion_find(head, addr);
+        spin_unlock_irqrestore(&head->vm_lock, flags);
+        return c;
+}
+
+struct arm_vmregion *arm_vmregion_find_remove(struct arm_vmregion_head *head, unsigned long addr)
+{
+        struct arm_vmregion *c;
+        unsigned long flags;
+
+        spin_lock_irqsave(&head->vm_lock, flags);
+        c = __arm_vmregion_find(head, addr);
+        if (c)
+                c->vm_active = 0;
+        spin_unlock_irqrestore(&head->vm_lock, flags);
+        return c;
+}
+
+void arm_vmregion_free(struct arm_vmregion_head *head, struct arm_vmregion *c)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&head->vm_lock, flags);
+        list_del(&c->vm_list);
+        spin_unlock_irqrestore(&head->vm_lock, flags);
+
+        kfree(c);
+}
diff --git a/arch/arm/mm/vmregion.h b/arch/arm/mm/vmregion.h
new file mode 100644
index 000000000000..6b2cdbdf3a85
--- /dev/null
+++ b/arch/arm/mm/vmregion.h
@@ -0,0 +1,29 @@
+#ifndef VMREGION_H
+#define VMREGION_H
+
+#include <linux/spinlock.h>
+#include <linux/list.h>
+
+struct page;
+
+struct arm_vmregion_head {
+        spinlock_t              vm_lock;
+        struct list_head        vm_list;
+        unsigned long           vm_start;
+        unsigned long           vm_end;
+};
+
+struct arm_vmregion {
+        struct list_head        vm_list;
+        unsigned long           vm_start;
+        unsigned long           vm_end;
+        struct page             *vm_pages;
+        int                     vm_active;
+};
+
+struct arm_vmregion *arm_vmregion_alloc(struct arm_vmregion_head *, size_t, gfp_t);
+struct arm_vmregion *arm_vmregion_find(struct arm_vmregion_head *, unsigned long);
+struct arm_vmregion *arm_vmregion_find_remove(struct arm_vmregion_head *, unsigned long);
+void arm_vmregion_free(struct arm_vmregion_head *, struct arm_vmregion *);
+
+#endif