1 files changed, 791 insertions, 0 deletions

diff --git a/drivers/iommu/omap-iovmm.c b/drivers/iommu/omap-iovmm.c
new file mode 100644
index 00000000000..d1472598415
--- /dev/null
+++ b/drivers/iommu/omap-iovmm.c
@@ -0,0 +1,791 @@
+/*
+ * 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/module.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/device.h>
+#include <linux/scatterlist.h>
+#include <linux/iommu.h>
+#include <linux/omap-iommu.h>
+#include <linux/platform_data/iommu-omap.h>
+
+#include <asm/cacheflush.h>
+#include <asm/mach/map.h>
+
+#include "omap-iopgtable.h"
+#include "omap-iommu.h"
+
+/*
+ * IOVMF_FLAGS: attribute for iommu virtual memory area(iovma)
+ *
+ * lower 16 bit is used for h/w and upper 16 bit is for s/w.
+ */
+#define IOVMF_SW_SHIFT		16
+
+/*
+ * iovma: h/w flags derived from cam and ram attribute
+ */
+#define IOVMF_CAM_MASK		(~((1 << 10) - 1))
+#define IOVMF_RAM_MASK		(~IOVMF_CAM_MASK)
+
+#define IOVMF_PGSZ_MASK		(3 << 0)
+#define IOVMF_PGSZ_1M		MMU_CAM_PGSZ_1M
+#define IOVMF_PGSZ_64K		MMU_CAM_PGSZ_64K
+#define IOVMF_PGSZ_4K		MMU_CAM_PGSZ_4K
+#define IOVMF_PGSZ_16M		MMU_CAM_PGSZ_16M
+
+#define IOVMF_ENDIAN_MASK	(1 << 9)
+#define IOVMF_ENDIAN_BIG	MMU_RAM_ENDIAN_BIG
+
+#define IOVMF_ELSZ_MASK		(3 << 7)
+#define IOVMF_ELSZ_16		MMU_RAM_ELSZ_16
+#define IOVMF_ELSZ_32		MMU_RAM_ELSZ_32
+#define IOVMF_ELSZ_NONE		MMU_RAM_ELSZ_NONE
+
+#define IOVMF_MIXED_MASK	(1 << 6)
+#define IOVMF_MIXED		MMU_RAM_MIXED
+
+/*
+ * iovma: s/w flags, used for mapping and umapping internally.
+ */
+#define IOVMF_MMIO		(1 << IOVMF_SW_SHIFT)
+#define IOVMF_ALLOC		(2 << IOVMF_SW_SHIFT)
+#define IOVMF_ALLOC_MASK	(3 << IOVMF_SW_SHIFT)
+
+/* "superpages" is supported just with physically linear pages */
+#define IOVMF_DISCONT		(1 << (2 + IOVMF_SW_SHIFT))
+#define IOVMF_LINEAR		(2 << (2 + IOVMF_SW_SHIFT))
+#define IOVMF_LINEAR_MASK	(3 << (2 + IOVMF_SW_SHIFT))
+
+#define IOVMF_DA_FIXED		(1 << (4 + IOVMF_SW_SHIFT))
+
+static struct kmem_cache *iovm_area_cachep;
+
+/* return the offset of the first scatterlist entry in a sg table */
+static unsigned int sgtable_offset(const struct sg_table *sgt)
+{
+	if (!sgt || !sgt->nents)
+		return 0;
+
+	return sgt->sgl->offset;
+}
+
+/* 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->length + sg->offset;
+
+		if (!iopgsz_ok(bytes)) {
+			pr_err("%s: sg[%d] not iommu pagesize(%u %u)\n",
+			       __func__, i, bytes, sg->offset);
+			return 0;
+		}
+
+		if (i && sg->offset) {
+			pr_err("%s: sg[%d] offset not allowed in internal entries\n",
+				__func__, i);
+			return 0;
+		}
+
+		total += bytes;
+	}
+
+	return total;
+}
+#define sgtable_ok(x)	(!!sgtable_len(x))
+
+static unsigned max_alignment(u32 addr)
+{
+	int i;
+	unsigned pagesize[] = { SZ_16M, SZ_1M, SZ_64K, SZ_4K, };
+	for (i = 0; i < ARRAY_SIZE(pagesize) && addr & (pagesize[i] - 1); i++)
+		;
+	return (i < ARRAY_SIZE(pagesize)) ? pagesize[i] : 0;
+}
+
+/*
+ * calculate the optimal number sg elements from total bytes based on
+ * iommu superpages
+ */
+static unsigned sgtable_nents(size_t bytes, u32 da, u32 pa)
+{
+	unsigned nr_entries = 0, ent_sz;
+
+	if (!IS_ALIGNED(bytes, PAGE_SIZE)) {
+		pr_err("%s: wrong size %08x\n", __func__, bytes);
+		return 0;
+	}
+
+	while (bytes) {
+		ent_sz = max_alignment(da | pa);
+		ent_sz = min_t(unsigned, ent_sz, iopgsz_max(bytes));
+		nr_entries++;
+		da += ent_sz;
+		pa += ent_sz;
+		bytes -= ent_sz;
+	}
+
+	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,
+							u32 da, u32 pa)
+{
+	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);
+
+	if (flags & IOVMF_LINEAR) {
+		nr_entries = sgtable_nents(bytes, da, pa);
+		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) {
+		kfree(sgt);
+		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) - sg->offset;
+		bytes = sg->length + sg->offset;
+
+		BUG_ON(bytes != PAGE_SIZE);
+
+		err = ioremap_page(va,  pa, mtype);
+		if (err)
+			goto err_out;
+
+		va += bytes;
+	}
+
+	flush_cache_vmap((unsigned long)new->addr,
+				(unsigned long)(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 omap_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;
+}
+
+/**
+ * omap_find_iovm_area  -  find iovma which includes @da
+ * @dev:	client device
+ * @da:		iommu device virtual address
+ *
+ * Find the existing iovma starting at @da
+ */
+struct iovm_struct *omap_find_iovm_area(struct device *dev, u32 da)
+{
+	struct omap_iommu *obj = dev_to_omap_iommu(dev);
+	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(omap_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 omap_iommu *obj, u32 da,
+					   size_t bytes, u32 flags)
+{
+	struct iovm_struct *new, *tmp;
+	u32 start, prev_end, alignment;
+
+	if (!obj || !bytes)
+		return ERR_PTR(-EINVAL);
+
+	start = da;
+	alignment = PAGE_SIZE;
+
+	if (~flags & IOVMF_DA_FIXED) {
+		/* Don't map address 0 */
+		start = obj->da_start ? obj->da_start : alignment;
+
+		if (flags & IOVMF_LINEAR)
+			alignment = iopgsz_max(bytes);
+		start = roundup(start, alignment);
+	} else if (start < obj->da_start || start > obj->da_end ||
+					obj->da_end - start < bytes) {
+		return ERR_PTR(-EINVAL);
+	}
+
+	tmp = NULL;
+	if (list_empty(&obj->mmap))
+		goto found;
+
+	prev_end = 0;
+	list_for_each_entry(tmp, &obj->mmap, list) {
+
+		if (prev_end > start)
+			break;
+
+		if (tmp->da_start > start && (tmp->da_start - start) >= bytes)
+			goto found;
+
+		if (tmp->da_end >= start && ~flags & IOVMF_DA_FIXED)
+			start = roundup(tmp->da_end + 1, alignment);
+
+		prev_end = tmp->da_end;
+	}
+
+	if ((start >= prev_end) && (obj->da_end - 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 omap_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);
+}
+
+/**
+ * omap_da_to_va - convert (d) to (v)
+ * @dev:	client device
+ * @da:		iommu device virtual address
+ * @va:		mpu virtual address
+ *
+ * Returns mpu virtual addr which corresponds to a given device virtual addr
+ */
+void *omap_da_to_va(struct device *dev, u32 da)
+{
+	struct omap_iommu *obj = dev_to_omap_iommu(dev);
+	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;
+out:
+	mutex_unlock(&obj->mmap_lock);
+
+	return va;
+}
+EXPORT_SYMBOL_GPL(omap_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 'omap_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;
+}
+
+static inline void sgtable_drain_vmalloc(struct sg_table *sgt)
+{
+	/*
+	 * Actually this is not necessary at all, just exists for
+	 * consistency of the code readability.
+	 */
+	BUG_ON(!sgt);
+}
+
+/* create 'da' <-> 'pa' mapping from 'sgt' */
+static int map_iovm_area(struct iommu_domain *domain, 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 (!domain || !sgt)
+		return -EINVAL;
+
+	BUG_ON(!sgtable_ok(sgt));
+
+	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+		u32 pa;
+		size_t bytes;
+
+		pa = sg_phys(sg) - sg->offset;
+		bytes = sg->length + sg->offset;
+
+		flags &= ~IOVMF_PGSZ_MASK;
+
+		if (bytes_to_iopgsz(bytes) < 0)
+			goto err_out;
+
+		pr_debug("%s: [%d] %08x %08x(%x)\n", __func__,
+			 i, da, pa, bytes);
+
+		err = iommu_map(domain, da, pa, bytes, flags);
+		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 = sg->length + sg->offset;
+
+		/* ignore failures.. we're already handling one */
+		iommu_unmap(domain, da, bytes);
+
+		da += bytes;
+	}
+	return err;
+}
+
+/* release 'da' <-> 'pa' mapping */
+static void unmap_iovm_area(struct iommu_domain *domain, struct omap_iommu *obj,
+						struct iovm_struct *area)
+{
+	u32 start;
+	size_t total = area->da_end - area->da_start;
+	const struct sg_table *sgt = area->sgt;
+	struct scatterlist *sg;
+	int i;
+	size_t unmapped;
+
+	BUG_ON(!sgtable_ok(sgt));
+	BUG_ON((!total) || !IS_ALIGNED(total, PAGE_SIZE));
+
+	start = area->da_start;
+	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
+		size_t bytes;
+
+		bytes = sg->length + sg->offset;
+
+		unmapped = iommu_unmap(domain, start, bytes);
+		if (unmapped < bytes)
+			break;
+
+		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_domain *domain,
+				      struct omap_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(domain, 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_domain *domain, struct omap_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(domain, 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_domain *domain, struct omap_iommu *obj,
+				u32 da, const struct sg_table *sgt,
+				void *va, size_t bytes, u32 flags)
+{
+	return map_iommu_region(domain, obj, da, sgt, va, bytes, flags);
+}
+
+/**
+ * omap_iommu_vmap  -  (d)-(p)-(v) address mapper
+ * @domain:	iommu domain
+ * @dev:	client device
+ * @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 omap_iommu_vmap(struct iommu_domain *domain, struct device *dev, u32 da,
+		const struct sg_table *sgt, u32 flags)
+{
+	struct omap_iommu *obj = dev_to_omap_iommu(dev);
+	size_t bytes;
+	void *va = NULL;
+
+	if (!obj || !obj->dev || !sgt)
+		return -EINVAL;
+
+	bytes = sgtable_len(sgt);
+	if (!bytes)
+		return -EINVAL;
+	bytes = PAGE_ALIGN(bytes);
+
+	if (flags & IOVMF_MMIO) {
+		va = vmap_sg(sgt);
+		if (IS_ERR(va))
+			return PTR_ERR(va);
+	}
+
+	flags |= IOVMF_DISCONT;
+	flags |= IOVMF_MMIO;
+
+	da = __iommu_vmap(domain, obj, da, sgt, va, bytes, flags);
+	if (IS_ERR_VALUE(da))
+		vunmap_sg(va);
+
+	return da + sgtable_offset(sgt);
+}
+EXPORT_SYMBOL_GPL(omap_iommu_vmap);
+
+/**
+ * omap_iommu_vunmap  -  release virtual mapping obtained by 'omap_iommu_vmap()'
+ * @domain:	iommu domain
+ * @dev:	client device
+ * @da:		iommu device virtual address
+ *
+ * Free the iommu virtually contiguous memory area starting at
+ * @da, which was returned by 'omap_iommu_vmap()'.
+ */
+struct sg_table *
+omap_iommu_vunmap(struct iommu_domain *domain, struct device *dev, u32 da)
+{
+	struct omap_iommu *obj = dev_to_omap_iommu(dev);
+	struct sg_table *sgt;
+	/*
+	 * 'sgt' is allocated before 'omap_iommu_vmalloc()' is called.
+	 * Just returns 'sgt' to the caller to free
+	 */
+	da &= PAGE_MASK;
+	sgt = unmap_vm_area(domain, obj, da, vunmap_sg,
+					IOVMF_DISCONT | IOVMF_MMIO);
+	if (!sgt)
+		dev_dbg(obj->dev, "%s: No sgt\n", __func__);
+	return sgt;
+}
+EXPORT_SYMBOL_GPL(omap_iommu_vunmap);
+
+/**
+ * omap_iommu_vmalloc  -  (d)-(p)-(v) address allocator and mapper
+ * @dev:	client device
+ * @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_FIXED' is not set.
+ */
+u32
+omap_iommu_vmalloc(struct iommu_domain *domain, struct device *dev, u32 da,
+						size_t bytes, u32 flags)
+{
+	struct omap_iommu *obj = dev_to_omap_iommu(dev);
+	void *va;
+	struct sg_table *sgt;
+
+	if (!obj || !obj->dev || !bytes)
+		return -EINVAL;
+
+	bytes = PAGE_ALIGN(bytes);
+
+	va = vmalloc(bytes);
+	if (!va)
+		return -ENOMEM;
+
+	flags |= IOVMF_DISCONT;
+	flags |= IOVMF_ALLOC;
+
+	sgt = sgtable_alloc(bytes, flags, da, 0);
+	if (IS_ERR(sgt)) {
+		da = PTR_ERR(sgt);
+		goto err_sgt_alloc;
+	}
+	sgtable_fill_vmalloc(sgt, va);
+
+	da = __iommu_vmap(domain, 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(omap_iommu_vmalloc);
+
+/**
+ * omap_iommu_vfree  -  release memory allocated by 'omap_iommu_vmalloc()'
+ * @dev:	client device
+ * @da:		iommu device virtual address
+ *
+ * Frees the iommu virtually continuous memory area starting at
+ * @da, as obtained from 'omap_iommu_vmalloc()'.
+ */
+void omap_iommu_vfree(struct iommu_domain *domain, struct device *dev,
+								const u32 da)
+{
+	struct omap_iommu *obj = dev_to_omap_iommu(dev);
+	struct sg_table *sgt;
+
+	sgt = unmap_vm_area(domain, obj, da, vfree,
+						IOVMF_DISCONT | IOVMF_ALLOC);
+	if (!sgt)
+		dev_dbg(obj->dev, "%s: No sgt\n", __func__);
+	sgtable_free(sgt);
+}
+EXPORT_SYMBOL_GPL(omap_iommu_vfree);
+
+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");