omap iommu: simple virtual address space management

This patch provides a device drivers, which has a omap iommu, with
address mapping APIs between device virtual address(iommu), physical
address and MPU virtual address.

There are 4 possible patterns for iommu virtual address(iova/da) mapping.

    |iova/			  mapping		iommu_		page
    | da	pa	va	(d)-(p)-(v)		function	type
  ---------------------------------------------------------------------------
  1 | c		c	c	 1 - 1 - 1	  _kmap() / _kunmap()	s
  2 | c		c,a	c	 1 - 1 - 1	_kmalloc()/ _kfree()	s
  3 | c		d	c	 1 - n - 1	  _vmap() / _vunmap()	s
  4 | c		d,a	c	 1 - n - 1	_vmalloc()/ _vfree()	n*

    'iova':	device iommu virtual address
    'da':	alias of 'iova'
    'pa':	physical address
    'va':	mpu virtual address

    'c':	contiguous memory area
    'd':	dicontiguous memory area
    'a':	anonymous memory allocation
    '()':	optional feature

    'n':	a normal page(4KB) size is used.
    's':	multiple iommu superpage(16MB, 1MB, 64KB, 4KB) size is used.

    '*':	not yet, but feasible.

Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>

1 files changed, 896 insertions, 0 deletions

diff --git a/arch/arm/plat-omap/iovmm.c b/arch/arm/plat-omap/iovmm.c
new file mode 100644
index 000000000000..2fce2c151a95
--- /dev/null
+++ b/arch/arm/plat-omap/iovmm.c
@@ -0,0 +1,896 @@
+/*
+ * omap iommu: simple virtual address space management
+ *
+ * Copyright (C) 2008-2009 Nokia Corporation
+ *
+ * Written by Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
+ *
+ * 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.
+ */
+
+#include <linux/err.h>
+#include <linux/vmalloc.h>
+#include <linux/device.h>
+#include <linux/scatterlist.h>
+
+#include <asm/cacheflush.h>
+#include <asm/mach/map.h>
+
+#include <mach/iommu.h>
+#include <mach/iovmm.h>
+
+#include "iopgtable.h"
+
+/*
+ * A device driver needs to create address mappings between:
+ *
+ * - iommu/device address
+ * - physical address
+ * - mpu virtual address
+ *
+ * There are 4 possible patterns for them:
+ *
+ *    |iova/                      mapping               iommu_          page
+ *    | da      pa      va      (d)-(p)-(v)             function        type
+ *  ---------------------------------------------------------------------------
+ *  1 | c       c       c        1 - 1 - 1        _kmap() / _kunmap()   s
+ *  2 | c       c,a     c        1 - 1 - 1      _kmalloc()/ _kfree()    s
+ *  3 | c       d       c        1 - n - 1        _vmap() / _vunmap()   s
+ *  4 | c       d,a     c        1 - n - 1      _vmalloc()/ _vfree()    n*
+ *
+ *
+ *      'iova': device iommu virtual address
+ *      'da':   alias of 'iova'
+ *      'pa':   physical address
+ *      'va':   mpu virtual address
+ *
+ *      'c':    contiguous memory area
+ *      'd':    dicontiguous memory area
+ *      'a':    anonymous memory allocation
+ *      '()':   optional feature
+ *
+ *      'n':    a normal page(4KB) size is used.
+ *      's':    multiple iommu superpage(16MB, 1MB, 64KB, 4KB) size is used.
+ *
+ *      '*':    not yet, but feasible.
+ */
+
+static struct kmem_cache *iovm_area_cachep;
+
+/* return total bytes of sg buffers */
+static size_t sgtable_len(const struct sg_table *sgt)
+{
+        unsigned int i, total = 0;
+        struct scatterlist *sg;
+
+        if (!sgt)
+                return 0;
+
+        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+                size_t bytes;
+
+                bytes = sg_dma_len(sg);
+
+                if (!iopgsz_ok(bytes)) {
+                        pr_err("%s: sg[%d] not iommu pagesize(%x)\n",
+                               __func__, i, bytes);
+                        return 0;
+                }
+
+                total += bytes;
+        }
+
+        return total;
+}
+#define sgtable_ok(x)   (!!sgtable_len(x))
+
+/*
+ * calculate the optimal number sg elements from total bytes based on
+ * iommu superpages
+ */
+static unsigned int sgtable_nents(size_t bytes)
+{
+        int i;
+        unsigned int nr_entries;
+        const unsigned long pagesize[] = { SZ_16M, SZ_1M, SZ_64K, SZ_4K, };
+
+        if (!IS_ALIGNED(bytes, PAGE_SIZE)) {
+                pr_err("%s: wrong size %08x\n", __func__, bytes);
+                return 0;
+        }
+
+        nr_entries = 0;
+        for (i = 0; i < ARRAY_SIZE(pagesize); i++) {
+                if (bytes >= pagesize[i]) {
+                        nr_entries += (bytes / pagesize[i]);
+                        bytes %= pagesize[i];
+                }
+        }
+        BUG_ON(bytes);
+
+        return nr_entries;
+}
+
+/* allocate and initialize sg_table header(a kind of 'superblock') */
+static struct sg_table *sgtable_alloc(const size_t bytes, u32 flags)
+{
+        unsigned int nr_entries;
+        int err;
+        struct sg_table *sgt;
+
+        if (!bytes)
+                return ERR_PTR(-EINVAL);
+
+        if (!IS_ALIGNED(bytes, PAGE_SIZE))
+                return ERR_PTR(-EINVAL);
+
+        /* FIXME: IOVMF_DA_FIXED should support 'superpages' */
+        if ((flags & IOVMF_LINEAR) && (flags & IOVMF_DA_ANON)) {
+                nr_entries = sgtable_nents(bytes);
+                if (!nr_entries)
+                        return ERR_PTR(-EINVAL);
+        } else
+                nr_entries =  bytes / PAGE_SIZE;
+
+        sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
+        if (!sgt)
+                return ERR_PTR(-ENOMEM);
+
+        err = sg_alloc_table(sgt, nr_entries, GFP_KERNEL);
+        if (err)
+                return ERR_PTR(err);
+
+        pr_debug("%s: sgt:%p(%d entries)\n", __func__, sgt, nr_entries);
+
+        return sgt;
+}
+
+/* free sg_table header(a kind of superblock) */
+static void sgtable_free(struct sg_table *sgt)
+{
+        if (!sgt)
+                return;
+
+        sg_free_table(sgt);
+        kfree(sgt);
+
+        pr_debug("%s: sgt:%p\n", __func__, sgt);
+}
+
+/* map 'sglist' to a contiguous mpu virtual area and return 'va' */
+static void *vmap_sg(const struct sg_table *sgt)
+{
+        u32 va;
+        size_t total;
+        unsigned int i;
+        struct scatterlist *sg;
+        struct vm_struct *new;
+        const struct mem_type *mtype;
+
+        mtype = get_mem_type(MT_DEVICE);
+        if (!mtype)
+                return ERR_PTR(-EINVAL);
+
+        total = sgtable_len(sgt);
+        if (!total)
+                return ERR_PTR(-EINVAL);
+
+        new = __get_vm_area(total, VM_IOREMAP, VMALLOC_START, VMALLOC_END);
+        if (!new)
+                return ERR_PTR(-ENOMEM);
+        va = (u32)new->addr;
+
+        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+                size_t bytes;
+                u32 pa;
+                int err;
+
+                pa = sg_phys(sg);
+                bytes = sg_dma_len(sg);
+
+                BUG_ON(bytes != PAGE_SIZE);
+
+                err = ioremap_page(va,  pa, mtype);
+                if (err)
+                        goto err_out;
+
+                va += bytes;
+        }
+
+        flush_cache_vmap(new->addr, total);
+        return new->addr;
+
+err_out:
+        WARN_ON(1); /* FIXME: cleanup some mpu mappings */
+        vunmap(new->addr);
+        return ERR_PTR(-EAGAIN);
+}
+
+static inline void vunmap_sg(const void *va)
+{
+        vunmap(va);
+}
+
+static struct iovm_struct *__find_iovm_area(struct iommu *obj, const u32 da)
+{
+        struct iovm_struct *tmp;
+
+        list_for_each_entry(tmp, &obj->mmap, list) {
+                if ((da >= tmp->da_start) && (da < tmp->da_end)) {
+                        size_t len;
+
+                        len = tmp->da_end - tmp->da_start;
+
+                        dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n",
+                                __func__, tmp->da_start, da, tmp->da_end, len,
+                                tmp->flags);
+
+                        return tmp;
+                }
+        }
+
+        return NULL;
+}
+
+/**
+ * find_iovm_area  -  find iovma which includes @da
+ * @da:         iommu device virtual address
+ *
+ * Find the existing iovma starting at @da
+ */
+struct iovm_struct *find_iovm_area(struct iommu *obj, u32 da)
+{
+        struct iovm_struct *area;
+
+        mutex_lock(&obj->mmap_lock);
+        area = __find_iovm_area(obj, da);
+        mutex_unlock(&obj->mmap_lock);
+
+        return area;
+}
+EXPORT_SYMBOL_GPL(find_iovm_area);
+
+/*
+ * This finds the hole(area) which fits the requested address and len
+ * in iovmas mmap, and returns the new allocated iovma.
+ */
+static struct iovm_struct *alloc_iovm_area(struct iommu *obj, u32 da,
+                                           size_t bytes, u32 flags)
+{
+        struct iovm_struct *new, *tmp;
+        u32 start, prev_end, alignement;
+
+        if (!obj || !bytes)
+                return ERR_PTR(-EINVAL);
+
+        start = da;
+        alignement = PAGE_SIZE;
+
+        if (flags & IOVMF_DA_ANON) {
+                /*
+                 * Reserve the first page for NULL
+                 */
+                start = PAGE_SIZE;
+                if (flags & IOVMF_LINEAR)
+                        alignement = iopgsz_max(bytes);
+                start = roundup(start, alignement);
+        }
+
+        tmp = NULL;
+        if (list_empty(&obj->mmap))
+                goto found;
+
+        prev_end = 0;
+        list_for_each_entry(tmp, &obj->mmap, list) {
+
+                if ((prev_end <= start) && (start + bytes < tmp->da_start))
+                        goto found;
+
+                if (flags & IOVMF_DA_ANON)
+                        start = roundup(tmp->da_end, alignement);
+
+                prev_end = tmp->da_end;
+        }
+
+        if ((start >= prev_end) && (ULONG_MAX - start >= bytes))
+                goto found;
+
+        dev_dbg(obj->dev, "%s: no space to fit %08x(%x) flags: %08x\n",
+                __func__, da, bytes, flags);
+
+        return ERR_PTR(-EINVAL);
+
+found:
+        new = kmem_cache_zalloc(iovm_area_cachep, GFP_KERNEL);
+        if (!new)
+                return ERR_PTR(-ENOMEM);
+
+        new->iommu = obj;
+        new->da_start = start;
+        new->da_end = start + bytes;
+        new->flags = flags;
+
+        /*
+         * keep ascending order of iovmas
+         */
+        if (tmp)
+                list_add_tail(&new->list, &tmp->list);
+        else
+                list_add(&new->list, &obj->mmap);
+
+        dev_dbg(obj->dev, "%s: found %08x-%08x-%08x(%x) %08x\n",
+                __func__, new->da_start, start, new->da_end, bytes, flags);
+
+        return new;
+}
+
+static void free_iovm_area(struct iommu *obj, struct iovm_struct *area)
+{
+        size_t bytes;
+
+        BUG_ON(!obj || !area);
+
+        bytes = area->da_end - area->da_start;
+
+        dev_dbg(obj->dev, "%s: %08x-%08x(%x) %08x\n",
+                __func__, area->da_start, area->da_end, bytes, area->flags);
+
+        list_del(&area->list);
+        kmem_cache_free(iovm_area_cachep, area);
+}
+
+/**
+ * da_to_va - convert (d) to (v)
+ * @obj:        objective iommu
+ * @da:         iommu device virtual address
+ * @va:         mpu virtual address
+ *
+ * Returns mpu virtual addr which corresponds to a given device virtual addr
+ */
+void *da_to_va(struct iommu *obj, u32 da)
+{
+        void *va = NULL;
+        struct iovm_struct *area;
+
+        mutex_lock(&obj->mmap_lock);
+
+        area = __find_iovm_area(obj, da);
+        if (!area) {
+                dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
+                goto out;
+        }
+        va = area->va;
+        mutex_unlock(&obj->mmap_lock);
+out:
+        return va;
+}
+EXPORT_SYMBOL_GPL(da_to_va);
+
+static void sgtable_fill_vmalloc(struct sg_table *sgt, void *_va)
+{
+        unsigned int i;
+        struct scatterlist *sg;
+        void *va = _va;
+        void *va_end;
+
+        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+                struct page *pg;
+                const size_t bytes = PAGE_SIZE;
+
+                /*
+                 * iommu 'superpage' isn't supported with 'iommu_vmalloc()'
+                 */
+                pg = vmalloc_to_page(va);
+                BUG_ON(!pg);
+                sg_set_page(sg, pg, bytes, 0);
+
+                va += bytes;
+        }
+
+        va_end = _va + PAGE_SIZE * i;
+        flush_cache_vmap(_va, va_end);
+}
+
+static inline void sgtable_drain_vmalloc(struct sg_table *sgt)
+{
+        /*
+         * Actually this is not necessary at all, just exists for
+         * consistency of the code readibility.
+         */
+        BUG_ON(!sgt);
+}
+
+static void sgtable_fill_kmalloc(struct sg_table *sgt, u32 pa, size_t len)
+{
+        unsigned int i;
+        struct scatterlist *sg;
+        void *va;
+
+        va = phys_to_virt(pa);
+
+        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+                size_t bytes;
+
+                bytes = iopgsz_max(len);
+
+                BUG_ON(!iopgsz_ok(bytes));
+
+                sg_set_buf(sg, phys_to_virt(pa), bytes);
+                /*
+                 * 'pa' is cotinuous(linear).
+                 */
+                pa += bytes;
+                len -= bytes;
+        }
+        BUG_ON(len);
+
+        clean_dcache_area(va, len);
+}
+
+static inline void sgtable_drain_kmalloc(struct sg_table *sgt)
+{
+        /*
+         * Actually this is not necessary at all, just exists for
+         * consistency of the code readibility
+         */
+        BUG_ON(!sgt);
+}
+
+/* create 'da' <-> 'pa' mapping from 'sgt' */
+static int map_iovm_area(struct iommu *obj, struct iovm_struct *new,
+                         const struct sg_table *sgt, u32 flags)
+{
+        int err;
+        unsigned int i, j;
+        struct scatterlist *sg;
+        u32 da = new->da_start;
+
+        if (!obj || !new || !sgt)
+                return -EINVAL;
+
+        BUG_ON(!sgtable_ok(sgt));
+
+        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+                u32 pa;
+                int pgsz;
+                size_t bytes;
+                struct iotlb_entry e;
+
+                pa = sg_phys(sg);
+                bytes = sg_dma_len(sg);
+
+                flags &= ~IOVMF_PGSZ_MASK;
+                pgsz = bytes_to_iopgsz(bytes);
+                if (pgsz < 0)
+                        goto err_out;
+                flags |= pgsz;
+
+                pr_debug("%s: [%d] %08x %08x(%x)\n", __func__,
+                         i, da, pa, bytes);
+
+                iotlb_init_entry(&e, da, pa, flags);
+                err = iopgtable_store_entry(obj, &e);
+                if (err)
+                        goto err_out;
+
+                da += bytes;
+        }
+        return 0;
+
+err_out:
+        da = new->da_start;
+
+        for_each_sg(sgt->sgl, sg, i, j) {
+                size_t bytes;
+
+                bytes = iopgtable_clear_entry(obj, da);
+
+                BUG_ON(!iopgsz_ok(bytes));
+
+                da += bytes;
+        }
+        return err;
+}
+
+/* release 'da' <-> 'pa' mapping */
+static void unmap_iovm_area(struct iommu *obj, struct iovm_struct *area)
+{
+        u32 start;
+        size_t total = area->da_end - area->da_start;
+
+        BUG_ON((!total) || !IS_ALIGNED(total, PAGE_SIZE));
+
+        start = area->da_start;
+        while (total > 0) {
+                size_t bytes;
+
+                bytes = iopgtable_clear_entry(obj, start);
+                if (bytes == 0)
+                        bytes = PAGE_SIZE;
+                else
+                        dev_dbg(obj->dev, "%s: unmap %08x(%x) %08x\n",
+                                __func__, start, bytes, area->flags);
+
+                BUG_ON(!IS_ALIGNED(bytes, PAGE_SIZE));
+
+                total -= bytes;
+                start += bytes;
+        }
+        BUG_ON(total);
+}
+
+/* template function for all unmapping */
+static struct sg_table *unmap_vm_area(struct iommu *obj, const u32 da,
+                                      void (*fn)(const void *), u32 flags)
+{
+        struct sg_table *sgt = NULL;
+        struct iovm_struct *area;
+
+        if (!IS_ALIGNED(da, PAGE_SIZE)) {
+                dev_err(obj->dev, "%s: alignment err(%08x)\n", __func__, da);
+                return NULL;
+        }
+
+        mutex_lock(&obj->mmap_lock);
+
+        area = __find_iovm_area(obj, da);
+        if (!area) {
+                dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
+                goto out;
+        }
+
+        if ((area->flags & flags) != flags) {
+                dev_err(obj->dev, "%s: wrong flags(%08x)\n", __func__,
+                        area->flags);
+                goto out;
+        }
+        sgt = (struct sg_table *)area->sgt;
+
+        unmap_iovm_area(obj, area);
+
+        fn(area->va);
+
+        dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n", __func__,
+                area->da_start, da, area->da_end,
+                area->da_end - area->da_start, area->flags);
+
+        free_iovm_area(obj, area);
+out:
+        mutex_unlock(&obj->mmap_lock);
+
+        return sgt;
+}
+
+static u32 map_iommu_region(struct iommu *obj, u32 da,
+              const struct sg_table *sgt, void *va, size_t bytes, u32 flags)
+{
+        int err = -ENOMEM;
+        struct iovm_struct *new;
+
+        mutex_lock(&obj->mmap_lock);
+
+        new = alloc_iovm_area(obj, da, bytes, flags);
+        if (IS_ERR(new)) {
+                err = PTR_ERR(new);
+                goto err_alloc_iovma;
+        }
+        new->va = va;
+        new->sgt = sgt;
+
+        if (map_iovm_area(obj, new, sgt, new->flags))
+                goto err_map;
+
+        mutex_unlock(&obj->mmap_lock);
+
+        dev_dbg(obj->dev, "%s: da:%08x(%x) flags:%08x va:%p\n",
+                __func__, new->da_start, bytes, new->flags, va);
+
+        return new->da_start;
+
+err_map:
+        free_iovm_area(obj, new);
+err_alloc_iovma:
+        mutex_unlock(&obj->mmap_lock);
+        return err;
+}
+
+static inline u32 __iommu_vmap(struct iommu *obj, u32 da,
+                 const struct sg_table *sgt, void *va, size_t bytes, u32 flags)
+{
+        return map_iommu_region(obj, da, sgt, va, bytes, flags);
+}
+
+/**
+ * iommu_vmap  -  (d)-(p)-(v) address mapper
+ * @obj:        objective iommu
+ * @sgt:        address of scatter gather table
+ * @flags:      iovma and page property
+ *
+ * Creates 1-n-1 mapping with given @sgt and returns @da.
+ * All @sgt element must be io page size aligned.
+ */
+u32 iommu_vmap(struct iommu *obj, u32 da, const struct sg_table *sgt,
+                 u32 flags)
+{
+        size_t bytes;
+        void *va;
+
+        if (!obj || !obj->dev || !sgt)
+                return -EINVAL;
+
+        bytes = sgtable_len(sgt);
+        if (!bytes)
+                return -EINVAL;
+        bytes = PAGE_ALIGN(bytes);
+
+        va = vmap_sg(sgt);
+        if (IS_ERR(va))
+                return PTR_ERR(va);
+
+        flags &= IOVMF_HW_MASK;
+        flags |= IOVMF_DISCONT;
+        flags |= IOVMF_MMIO;
+        flags |= (da ? IOVMF_DA_FIXED : IOVMF_DA_ANON);
+
+        da = __iommu_vmap(obj, da, sgt, va, bytes, flags);
+        if (IS_ERR_VALUE(da))
+                vunmap_sg(va);
+
+        return da;
+}
+EXPORT_SYMBOL_GPL(iommu_vmap);
+
+/**
+ * iommu_vunmap  -  release virtual mapping obtained by 'iommu_vmap()'
+ * @obj:        objective iommu
+ * @da:         iommu device virtual address
+ *
+ * Free the iommu virtually contiguous memory area starting at
+ * @da, which was returned by 'iommu_vmap()'.
+ */
+struct sg_table *iommu_vunmap(struct iommu *obj, u32 da)
+{
+        struct sg_table *sgt;
+        /*
+         * 'sgt' is allocated before 'iommu_vmalloc()' is called.
+         * Just returns 'sgt' to the caller to free
+         */
+        sgt = unmap_vm_area(obj, da, vunmap_sg, IOVMF_DISCONT | IOVMF_MMIO);
+        if (!sgt)
+                dev_dbg(obj->dev, "%s: No sgt\n", __func__);
+        return sgt;
+}
+EXPORT_SYMBOL_GPL(iommu_vunmap);
+
+/**
+ * iommu_vmalloc  -  (d)-(p)-(v) address allocator and mapper
+ * @obj:        objective iommu
+ * @da:         contiguous iommu virtual memory
+ * @bytes:      allocation size
+ * @flags:      iovma and page property
+ *
+ * Allocate @bytes linearly and creates 1-n-1 mapping and returns
+ * @da again, which might be adjusted if 'IOVMF_DA_ANON' is set.
+ */
+u32 iommu_vmalloc(struct iommu *obj, u32 da, size_t bytes, u32 flags)
+{
+        void *va;
+        struct sg_table *sgt;
+
+        if (!obj || !obj->dev || !bytes)
+                return -EINVAL;
+
+        bytes = PAGE_ALIGN(bytes);
+
+        va = vmalloc(bytes);
+        if (!va)
+                return -ENOMEM;
+
+        sgt = sgtable_alloc(bytes, flags);
+        if (IS_ERR(sgt)) {
+                da = PTR_ERR(sgt);
+                goto err_sgt_alloc;
+        }
+        sgtable_fill_vmalloc(sgt, va);
+
+        flags &= IOVMF_HW_MASK;
+        flags |= IOVMF_DISCONT;
+        flags |= IOVMF_ALLOC;
+        flags |= (da ? IOVMF_DA_FIXED : IOVMF_DA_ANON);
+
+        da = __iommu_vmap(obj, da, sgt, va, bytes, flags);
+        if (IS_ERR_VALUE(da))
+                goto err_iommu_vmap;
+
+        return da;
+
+err_iommu_vmap:
+        sgtable_drain_vmalloc(sgt);
+        sgtable_free(sgt);
+err_sgt_alloc:
+        vfree(va);
+        return da;
+}
+EXPORT_SYMBOL_GPL(iommu_vmalloc);
+
+/**
+ * iommu_vfree  -  release memory allocated by 'iommu_vmalloc()'
+ * @obj:        objective iommu
+ * @da:         iommu device virtual address
+ *
+ * Frees the iommu virtually continuous memory area starting at
+ * @da, as obtained from 'iommu_vmalloc()'.
+ */
+void iommu_vfree(struct iommu *obj, const u32 da)
+{
+        struct sg_table *sgt;
+
+        sgt = unmap_vm_area(obj, da, vfree, IOVMF_DISCONT | IOVMF_ALLOC);
+        if (!sgt)
+                dev_dbg(obj->dev, "%s: No sgt\n", __func__);
+        sgtable_free(sgt);
+}
+EXPORT_SYMBOL_GPL(iommu_vfree);
+
+static u32 __iommu_kmap(struct iommu *obj, u32 da, u32 pa, void *va,
+                          size_t bytes, u32 flags)
+{
+        struct sg_table *sgt;
+
+        sgt = sgtable_alloc(bytes, flags);
+        if (IS_ERR(sgt))
+                return PTR_ERR(sgt);
+
+        sgtable_fill_kmalloc(sgt, pa, bytes);
+
+        da = map_iommu_region(obj, da, sgt, va, bytes, flags);
+        if (IS_ERR_VALUE(da)) {
+                sgtable_drain_kmalloc(sgt);
+                sgtable_free(sgt);
+        }
+
+        return da;
+}
+
+/**
+ * iommu_kmap  -  (d)-(p)-(v) address mapper
+ * @obj:        objective iommu
+ * @da:         contiguous iommu virtual memory
+ * @pa:         contiguous physical memory
+ * @flags:      iovma and page property
+ *
+ * Creates 1-1-1 mapping and returns @da again, which can be
+ * adjusted if 'IOVMF_DA_ANON' is set.
+ */
+u32 iommu_kmap(struct iommu *obj, u32 da, u32 pa, size_t bytes,
+                 u32 flags)
+{
+        void *va;
+
+        if (!obj || !obj->dev || !bytes)
+                return -EINVAL;
+
+        bytes = PAGE_ALIGN(bytes);
+
+        va = ioremap(pa, bytes);
+        if (!va)
+                return -ENOMEM;
+
+        flags &= IOVMF_HW_MASK;
+        flags |= IOVMF_LINEAR;
+        flags |= IOVMF_MMIO;
+        flags |= (da ? IOVMF_DA_FIXED : IOVMF_DA_ANON);
+
+        da = __iommu_kmap(obj, da, pa, va, bytes, flags);
+        if (IS_ERR_VALUE(da))
+                iounmap(va);
+
+        return da;
+}
+EXPORT_SYMBOL_GPL(iommu_kmap);
+
+/**
+ * iommu_kunmap  -  release virtual mapping obtained by 'iommu_kmap()'
+ * @obj:        objective iommu
+ * @da:         iommu device virtual address
+ *
+ * Frees the iommu virtually contiguous memory area starting at
+ * @da, which was passed to and was returned by'iommu_kmap()'.
+ */
+void iommu_kunmap(struct iommu *obj, u32 da)
+{
+        struct sg_table *sgt;
+        typedef void (*func_t)(const void *);
+
+        sgt = unmap_vm_area(obj, da, (func_t)__iounmap,
+                            IOVMF_LINEAR | IOVMF_MMIO);
+        if (!sgt)
+                dev_dbg(obj->dev, "%s: No sgt\n", __func__);
+        sgtable_free(sgt);
+}
+EXPORT_SYMBOL_GPL(iommu_kunmap);
+
+/**
+ * iommu_kmalloc  -  (d)-(p)-(v) address allocator and mapper
+ * @obj:        objective iommu
+ * @da:         contiguous iommu virtual memory
+ * @bytes:      bytes for allocation
+ * @flags:      iovma and page property
+ *
+ * Allocate @bytes linearly and creates 1-1-1 mapping and returns
+ * @da again, which might be adjusted if 'IOVMF_DA_ANON' is set.
+ */
+u32 iommu_kmalloc(struct iommu *obj, u32 da, size_t bytes, u32 flags)
+{
+        void *va;
+        u32 pa;
+
+        if (!obj || !obj->dev || !bytes)
+                return -EINVAL;
+
+        bytes = PAGE_ALIGN(bytes);
+
+        va = kmalloc(bytes, GFP_KERNEL | GFP_DMA);
+        if (!va)
+                return -ENOMEM;
+        pa = virt_to_phys(va);
+
+        flags &= IOVMF_HW_MASK;
+        flags |= IOVMF_LINEAR;
+        flags |= IOVMF_ALLOC;
+        flags |= (da ? IOVMF_DA_FIXED : IOVMF_DA_ANON);
+
+        da = __iommu_kmap(obj, da, pa, va, bytes, flags);
+        if (IS_ERR_VALUE(da))
+                kfree(va);
+
+        return da;
+}
+EXPORT_SYMBOL_GPL(iommu_kmalloc);
+
+/**
+ * iommu_kfree  -  release virtual mapping obtained by 'iommu_kmalloc()'
+ * @obj:        objective iommu
+ * @da:         iommu device virtual address
+ *
+ * Frees the iommu virtually contiguous memory area starting at
+ * @da, which was passed to and was returned by'iommu_kmalloc()'.
+ */
+void iommu_kfree(struct iommu *obj, u32 da)
+{
+        struct sg_table *sgt;
+
+        sgt = unmap_vm_area(obj, da, kfree, IOVMF_LINEAR | IOVMF_ALLOC);
+        if (!sgt)
+                dev_dbg(obj->dev, "%s: No sgt\n", __func__);
+        sgtable_free(sgt);
+}
+EXPORT_SYMBOL_GPL(iommu_kfree);
+
+
+static int __init iovmm_init(void)
+{
+        const unsigned long flags = SLAB_HWCACHE_ALIGN;
+        struct kmem_cache *p;
+
+        p = kmem_cache_create("iovm_area_cache", sizeof(struct iovm_struct), 0,
+                              flags, NULL);
+        if (!p)
+                return -ENOMEM;
+        iovm_area_cachep = p;
+
+        return 0;
+}
+module_init(iovmm_init);
+
+static void __exit iovmm_exit(void)
+{
+        kmem_cache_destroy(iovm_area_cachep);
+}
+module_exit(iovmm_exit);
+
+MODULE_DESCRIPTION("omap iommu: simple virtual address space management");
+MODULE_AUTHOR("Hiroshi DOYU <Hiroshi.DOYU@nokia.com>");
+MODULE_LICENSE("GPL v2");