[Linaro-mm-sig] [PATCH 08/10] v4l: vb2-dma-contig: code refactoring, support for DMABUF exporting

Tomasz Stanislawski t.stanislaws at samsung.com
Mon Jan 23 13:51:13 UTC 2012


Signed-off-by: Pawel Osciak <pawel at osciak.com>
	[author of the original file]
Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
	[implemetation of mmap, finish/prepare]
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p at samsung.com>
	[implementation of userprt handling]
Signed-off-by: Sumit Semwal <sumit.semwal at ti.com>
Signed-off-by: Sumit Semwal <sumit.semwal at linaro.org>
	[PoC for importing dmabuf buffer]
Signed-off-by: Tomasz Stanislawski <t.stanislaws at samsung.com>
       [buffer exporting using dmabuf, code refactoring]
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
---
 drivers/media/video/videobuf2-dma-contig.c |  762 ++++++++++++++++++++++++++++
 1 files changed, 762 insertions(+), 0 deletions(-)
 create mode 100644 drivers/media/video/videobuf2-dma-contig.c

diff --git a/drivers/media/video/videobuf2-dma-contig.c b/drivers/media/video/videobuf2-dma-contig.c
new file mode 100644
index 0000000..d95b23a
--- /dev/null
+++ b/drivers/media/video/videobuf2-dma-contig.c
@@ -0,0 +1,762 @@
+/*
+ * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Pawel Osciak <pawel at osciak.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/dma-mapping.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <media/videobuf2-core.h>
+#include <media/videobuf2-memops.h>
+
+struct vb2_dc_buf {
+	struct device			*dev;
+	void				*vaddr;
+	unsigned long			size;
+	dma_addr_t			dma_addr;
+	struct sg_table			*dma_sgt;
+	enum dma_data_direction		dma_dir;
+
+	/* MMAP related */
+	struct vb2_vmarea_handler	handler;
+	atomic_t			refcount;
+	struct dma_buf			*dma_buf;
+	struct sg_table			*sgt_base;
+
+	/* USERPTR related */
+	struct vm_area_struct		*vma;
+
+	/* DMABUF related */
+	struct dma_buf_attachment	*db_attach;
+};
+
+/*********************************************/
+/*        scatterlist table functions        */
+/*********************************************/
+
+static struct sg_table *vb2_dc_pages_to_sgt(struct page **pages,
+	unsigned long n_pages, size_t offset, size_t offset2)
+{
+	struct sg_table *sgt;
+	int i, j; /* loop counters */
+	int cur_page, chunks;
+	int ret;
+	struct scatterlist *s;
+
+	sgt = kzalloc(sizeof *sgt, GFP_KERNEL);
+	if (!sgt)
+		return ERR_PTR(-ENOMEM);
+
+	/* compute number of chunks */
+	chunks = 1;
+	for (i = 1; i < n_pages; ++i)
+		if (pages[i] != pages[i - 1] + 1)
+			++chunks;
+
+	ret = sg_alloc_table(sgt, chunks, GFP_KERNEL);
+	if (ret) {
+		kfree(sgt);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* merging chunks and putting them into the scatterlist */
+	cur_page = 0;
+	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
+		size_t size = PAGE_SIZE;
+
+		for (j = cur_page + 1; j < n_pages; ++j) {
+			if (pages[j] != pages[j - 1] + 1)
+				break;
+			size += PAGE_SIZE;
+		}
+
+		/* cut offset if chunk starts at the first page */
+		if (cur_page == 0)
+			size -= offset;
+		/* cut offset2 if chunk ends at the last page */
+		if (j == n_pages)
+			size -= offset2;
+
+		sg_set_page(s, pages[cur_page], size, offset);
+		offset = 0;
+		cur_page = j;
+	}
+
+	return sgt;
+}
+
+static void vb2_dc_release_sgtable(struct sg_table *sgt)
+{
+	sg_free_table(sgt);
+	kfree(sgt);
+}
+
+static void vb2_dc_put_sgtable(struct sg_table *sgt, int dirty)
+{
+	struct scatterlist *s;
+	int i, j;
+
+	for_each_sg(sgt->sgl, s, sgt->nents, i) {
+		struct page *page = sg_page(s);
+		int n_pages = PAGE_ALIGN(s->offset + s->length) >> PAGE_SHIFT;
+
+		for (j = 0; j < n_pages; ++j, ++page) {
+			if (dirty)
+				set_page_dirty_lock(page);
+			put_page(page);
+		}
+	}
+
+	vb2_dc_release_sgtable(sgt);
+}
+
+static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
+{
+	struct scatterlist *s;
+	dma_addr_t expected = sg_dma_address(sgt->sgl);
+	int i;
+	unsigned long size = 0;
+
+	for_each_sg(sgt->sgl, s, sgt->nents, i) {
+		if (sg_dma_address(s) != expected)
+			break;
+		expected = sg_dma_address(s) + sg_dma_len(s);
+		size += sg_dma_len(s);
+	}
+	return size;
+}
+
+/*********************************************/
+/*         callbacks for all buffers         */
+/*********************************************/
+
+static void *vb2_dc_cookie(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+
+	return &buf->dma_addr;
+}
+
+static void *vb2_dc_vaddr(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+
+	return buf->vaddr;
+}
+
+static unsigned int vb2_dc_num_users(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+
+	return atomic_read(&buf->refcount);
+}
+
+static void vb2_dc_prepare(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	if (!sgt)
+		return;
+
+	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+}
+
+static void vb2_dc_finish(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	if (!sgt)
+		return;
+
+	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+}
+
+/*********************************************/
+/*        callbacks for MMAP buffers         */
+/*********************************************/
+
+static void vb2_dc_put(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+
+	if (!atomic_dec_and_test(&buf->refcount))
+		return;
+
+	if (buf->dma_buf)
+		dma_buf_put(buf->dma_buf);
+	vb2_dc_release_sgtable(buf->sgt_base);
+	dma_free_coherent(buf->dev, buf->size, buf->vaddr,
+		buf->dma_addr);
+	kfree(buf);
+}
+
+static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
+{
+	struct device *dev = alloc_ctx;
+	struct vb2_dc_buf *buf;
+	int ret;
+	int n_pages;
+	struct page **pages = NULL;
+
+	buf = kzalloc(sizeof *buf, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	buf->dev = dev;
+	buf->size = size;
+	buf->vaddr = dma_alloc_coherent(buf->dev, buf->size, &buf->dma_addr,
+		GFP_KERNEL);
+
+	ret = -ENOMEM;
+	if (!buf->vaddr) {
+		dev_err(dev, "dma_alloc_coherent of size %ld failed\n",
+			size);
+		goto fail_buf;
+	}
+
+	WARN_ON((unsigned long)buf->vaddr & ~PAGE_MASK);
+	WARN_ON(buf->dma_addr & ~PAGE_MASK);
+
+	n_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+	pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL);
+	if (!pages) {
+		printk(KERN_ERR "failed to alloc page table\n");
+		goto fail_dma;
+	}
+
+	ret = dma_get_pages(dev, buf->vaddr, buf->dma_addr, pages, n_pages);
+	if (ret < 0) {
+		printk(KERN_ERR "failed to get buffer pages from DMA API\n");
+		goto fail_pages;
+	}
+	if (ret != n_pages) {
+		ret = -EFAULT;
+		printk(KERN_ERR "failed to get all pages from DMA API\n");
+		goto fail_pages;
+	}
+
+	buf->sgt_base = vb2_dc_pages_to_sgt(pages, n_pages, 0, 0);
+	if (IS_ERR(buf->sgt_base)) {
+		ret = PTR_ERR(buf->sgt_base);
+		printk(KERN_ERR "failed to prepare sg table\n");
+		goto fail_pages;
+	}
+
+	/* pages are no longer needed */
+	kfree(pages);
+
+	buf->handler.refcount = &buf->refcount;
+	buf->handler.put = vb2_dc_put;
+	buf->handler.arg = buf;
+
+	atomic_inc(&buf->refcount);
+
+	return buf;
+
+fail_pages:
+	kfree(pages);
+
+fail_dma:
+	dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
+
+fail_buf:
+	kfree(buf);
+
+	return ERR_PTR(ret);
+}
+
+static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+	int ret;
+
+	/*
+	 * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
+	 * map whole buffer
+	 */
+	vma->vm_pgoff = 0;
+
+	ret = dma_mmap_writecombine(buf->dev, vma, buf->vaddr,
+		buf->dma_addr, buf->size);
+
+	if (ret) {
+		printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
+		return ret;
+	}
+
+	vma->vm_flags		|= VM_DONTEXPAND | VM_RESERVED;
+	vma->vm_private_data	= &buf->handler;
+	vma->vm_ops		= &vb2_common_vm_ops;
+
+	vma->vm_ops->open(vma);
+
+	printk(KERN_DEBUG "%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
+		__func__, (unsigned long)buf->dma_addr, vma->vm_start,
+		buf->size);
+
+	return 0;
+}
+
+/*********************************************/
+/*         DMABUF ops for exporters          */
+/*********************************************/
+
+struct vb2_dc_attachment {
+	struct sg_table sgt;
+	enum dma_data_direction dir;
+};
+
+static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
+	struct dma_buf_attachment *dbuf_attach)
+{
+	/* nothing to be done */
+	return 0;
+}
+
+static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
+	struct dma_buf_attachment *db_attach)
+{
+	struct vb2_dc_attachment *attach = db_attach->priv;
+	struct sg_table *sgt;
+
+	if (!attach)
+		return;
+
+	sgt = &attach->sgt;
+
+	dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->nents, attach->dir);
+	sg_free_table(sgt);
+	kfree(attach);
+	db_attach->priv = NULL;
+}
+
+static struct sg_table *vb2_dc_dmabuf_ops_map(
+	struct dma_buf_attachment *db_attach, enum dma_data_direction dir)
+{
+	struct dma_buf *dbuf = db_attach->dmabuf;
+	struct vb2_dc_buf *buf = dbuf->priv;
+	struct vb2_dc_attachment *attach = db_attach->priv;
+	struct sg_table *sgt;
+	struct scatterlist *rd, *wr;
+	int i, ret;
+
+	/* return previously mapped sg table */
+	if (attach)
+		return &attach->sgt;
+
+	attach = kzalloc(sizeof *attach, GFP_KERNEL);
+	if (!attach)
+		return ERR_PTR(-ENOMEM);
+
+	sgt = &attach->sgt;
+	attach->dir = dir;
+
+	/* copying the buf->base_sgt to attachment */
+	ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
+	if (ret) {
+		kfree(attach);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	rd = buf->sgt_base->sgl;
+	wr = sgt->sgl;
+	for (i = 0; i < sgt->orig_nents; ++i) {
+		sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
+		rd = sg_next(rd);
+		wr = sg_next(wr);
+	}
+
+	/* mapping new sglist to the client */
+	ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dir);
+	if (ret <= 0) {
+		printk(KERN_ERR "failed to map scatterlist\n");
+		sg_free_table(sgt);
+		kfree(attach);
+		return ERR_PTR(-EIO);
+	}
+
+	db_attach->priv = attach;
+
+	return sgt;
+}
+
+static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
+	struct sg_table *sgt)
+{
+	/* nothing to be done here */
+}
+
+static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
+{
+	/* drop reference obtained in vb2_dc_get_dmabuf */
+	vb2_dc_put(dbuf->priv);
+}
+
+static struct dma_buf_ops vb2_dc_dmabuf_ops = {
+	.attach = vb2_dc_dmabuf_ops_attach,
+	.detach = vb2_dc_dmabuf_ops_detach,
+	.map_dma_buf = vb2_dc_dmabuf_ops_map,
+	.unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
+	.release = vb2_dc_dmabuf_ops_release,
+};
+
+static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+	struct dma_buf *dbuf;
+
+	if (buf->dma_buf)
+		return buf->dma_buf;
+
+	/* dmabuf keeps reference to vb2 buffer */
+	atomic_inc(&buf->refcount);
+	dbuf = dma_buf_export(buf, &vb2_dc_dmabuf_ops, buf->size, 0);
+	if (IS_ERR(dbuf)) {
+		atomic_dec(&buf->refcount);
+		return NULL;
+	}
+
+	buf->dma_buf = dbuf;
+
+	return dbuf;
+}
+
+/*********************************************/
+/*       callbacks for USERPTR buffers       */
+/*********************************************/
+
+static inline int vma_is_io(struct vm_area_struct *vma)
+{
+	return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
+}
+
+static int vb2_dc_get_pages(unsigned long start, struct page **pages,
+	int n_pages, struct vm_area_struct **copy_vma, int write)
+{
+	struct vm_area_struct *vma;
+	int n = 0; /* number of get pages */
+	int ret = -EFAULT;
+
+	/* entering critical section for mm access */
+	down_read(&current->mm->mmap_sem);
+
+	vma = find_vma(current->mm, start);
+	if (!vma) {
+		printk(KERN_ERR "no vma for address %lu\n", start);
+		goto cleanup;
+	}
+
+	if (vma_is_io(vma)) {
+		unsigned long pfn;
+
+		if (vma->vm_end - start < n_pages * PAGE_SIZE) {
+			printk(KERN_ERR "vma is too small\n");
+			goto cleanup;
+		}
+
+		for (n = 0; n < n_pages; ++n, start += PAGE_SIZE) {
+			ret = follow_pfn(vma, start, &pfn);
+			if (ret) {
+				printk(KERN_ERR "no page for address %lu\n",
+					start);
+				goto cleanup;
+			}
+			pages[n] = pfn_to_page(pfn);
+			get_page(pages[n]);
+		}
+	} else {
+		n = get_user_pages(current, current->mm, start & PAGE_MASK,
+			n_pages, write, 1, pages, NULL);
+		if (n != n_pages) {
+			printk(KERN_ERR "got only %d of %d user pages\n",
+				n, n_pages);
+			goto cleanup;
+		}
+	}
+
+	*copy_vma = vb2_get_vma(vma);
+	if (!*copy_vma) {
+		printk(KERN_ERR "failed to copy vma\n");
+		ret = -ENOMEM;
+		goto cleanup;
+	}
+
+	/* leaving critical section for mm access */
+	up_read(&current->mm->mmap_sem);
+
+	return 0;
+
+cleanup:
+	up_read(&current->mm->mmap_sem);
+
+	/* putting user pages if used, can be done wothout the lock */
+	while (n)
+		put_page(pages[--n]);
+
+	return ret;
+}
+
+static void vb2_dc_put_userptr(void *buf_priv)
+{
+	struct vb2_dc_buf *buf = buf_priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
+	vb2_dc_put_sgtable(sgt, !vma_is_io(buf->vma));
+	vb2_put_vma(buf->vma);
+	kfree(buf);
+}
+
+static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
+	unsigned long size, int write)
+{
+	struct vb2_dc_buf *buf;
+	unsigned long start, end, offset, offset2;
+	struct page **pages;
+	int n_pages;
+	int ret = 0;
+	struct sg_table *sgt;
+	unsigned long contig_size;
+
+	buf = kzalloc(sizeof *buf, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	buf->dev = alloc_ctx;
+	buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+	start = (unsigned long)vaddr & PAGE_MASK;
+	offset = (unsigned long)vaddr & ~PAGE_MASK;
+	end = PAGE_ALIGN((unsigned long)vaddr + size);
+	offset2 = end - (unsigned long)vaddr - size;
+	n_pages = (end - start) >> PAGE_SHIFT;
+
+	pages = kmalloc(n_pages * sizeof pages[0], GFP_KERNEL);
+	if (!pages) {
+		ret = -ENOMEM;
+		printk(KERN_ERR "failed to allocate pages table\n");
+		goto fail_buf;
+	}
+
+	/* extract page list from userspace mapping */
+	ret = vb2_dc_get_pages(start, pages, n_pages, &buf->vma, write);
+	if (ret) {
+		printk(KERN_ERR "failed to get user pages\n");
+		goto fail_pages;
+	}
+
+	sgt = vb2_dc_pages_to_sgt(pages, n_pages, offset, offset2);
+	if (!sgt) {
+		printk(KERN_ERR "failed to create scatterlist table\n");
+		ret = -ENOMEM;
+		goto fail_get_pages;
+	}
+
+	/* pages are no longer needed */
+	kfree(pages);
+	pages = NULL;
+
+	sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,
+		buf->dma_dir);
+	if (sgt->nents <= 0) {
+		printk(KERN_ERR "failed to map scatterlist\n");
+		ret = -EIO;
+		goto fail_sgt;
+	}
+
+	contig_size = vb2_dc_get_contiguous_size(sgt);
+	if (contig_size < size) {
+		printk(KERN_ERR "contiguous mapping is too small %lu/%lu\n",
+			contig_size, size);
+		ret = -EFAULT;
+		goto fail_map_sg;
+	}
+
+	buf->dma_addr = sg_dma_address(sgt->sgl);
+	buf->size = size;
+	buf->dma_sgt = sgt;
+
+	atomic_inc(&buf->refcount);
+
+	return buf;
+
+fail_map_sg:
+	dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+
+fail_sgt:
+	vb2_dc_put_sgtable(sgt, 0);
+
+fail_get_pages:
+	while (pages && n_pages)
+		put_page(pages[--n_pages]);
+	vb2_put_vma(buf->vma);
+
+fail_pages:
+	kfree(pages); /* kfree is NULL-proof */
+
+fail_buf:
+	kfree(buf);
+
+	return ERR_PTR(ret);
+}
+
+/*********************************************/
+/*       callbacks for DMABUF buffers        */
+/*********************************************/
+
+static int vb2_dc_map_dmabuf(void *mem_priv)
+{
+	struct vb2_dc_buf *buf = mem_priv;
+	struct sg_table *sgt;
+	unsigned long contig_size;
+	int ret = 0;
+
+	if (WARN_ON(!buf->db_attach)) {
+		printk(KERN_ERR "trying to pin a non attached buffer\n");
+		return -EINVAL;
+	}
+
+	if (WARN_ON(buf->dma_sgt)) {
+		printk(KERN_ERR "dmabuf buffer is already pinned\n");
+		return 0;
+	}
+
+	/* get the associated scatterlist for this buffer */
+	sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
+	if (IS_ERR_OR_NULL(sgt)) {
+		printk(KERN_ERR "Error getting dmabuf scatterlist\n");
+		return -EINVAL;
+	}
+
+	/* checking if dmabuf is big enough to store contiguous chunk */
+	contig_size = vb2_dc_get_contiguous_size(sgt);
+	if (contig_size < buf->size) {
+		printk(KERN_ERR "contiguous chunk of dmabuf is too small\n");
+		ret = -EFAULT;
+		goto fail_map;
+	}
+
+	buf->dma_addr = sg_dma_address(sgt->sgl);
+	buf->dma_sgt = sgt;
+
+	return 0;
+
+fail_map:
+	dma_buf_unmap_attachment(buf->db_attach, sgt);
+
+	return ret;
+}
+
+static void vb2_dc_unmap_dmabuf(void *mem_priv)
+{
+	struct vb2_dc_buf *buf = mem_priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	if (WARN_ON(!buf->db_attach)) {
+		printk(KERN_ERR "trying to unpin a not attached buffer\n");
+		return;
+	}
+
+	if (WARN_ON(!sgt)) {
+		printk(KERN_ERR "dmabuf buffer is already unpinned\n");
+		return;
+	}
+
+	dma_buf_unmap_attachment(buf->db_attach, sgt);
+
+	buf->dma_addr = 0;
+	buf->dma_sgt = NULL;
+}
+
+static void vb2_dc_detach_dmabuf(void *mem_priv)
+{
+	struct vb2_dc_buf *buf = mem_priv;
+
+	if (buf->dma_addr)
+		vb2_dc_unmap_dmabuf(buf);
+
+	/* detach this attachment */
+	dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
+	kfree(buf);
+}
+
+static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
+	unsigned long size, int write)
+{
+	struct vb2_dc_buf *buf;
+	struct dma_buf_attachment *dba;
+
+	if (dbuf->size < size)
+		return ERR_PTR(-EFAULT);
+
+	buf = kzalloc(sizeof *buf, GFP_KERNEL);
+	if (!buf)
+		return ERR_PTR(-ENOMEM);
+
+	buf->dev = alloc_ctx;
+	/* create attachment for the dmabuf with the user device */
+	dba = dma_buf_attach(dbuf, buf->dev);
+	if (IS_ERR(dba)) {
+		printk(KERN_ERR "failed to attach dmabuf\n");
+		kfree(buf);
+		return dba;
+	}
+
+	buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+	buf->size = size;
+	buf->db_attach = dba;
+
+	return buf;
+}
+
+/*********************************************/
+/*       DMA CONTIG exported functions       */
+/*********************************************/
+
+const struct vb2_mem_ops vb2_dma_contig_memops = {
+	.alloc		= vb2_dc_alloc,
+	.put		= vb2_dc_put,
+	.get_dmabuf	= vb2_dc_get_dmabuf,
+	.cookie		= vb2_dc_cookie,
+	.vaddr		= vb2_dc_vaddr,
+	.mmap		= vb2_dc_mmap,
+	.get_userptr	= vb2_dc_get_userptr,
+	.put_userptr	= vb2_dc_put_userptr,
+	.prepare	= vb2_dc_prepare,
+	.finish		= vb2_dc_finish,
+	.map_dmabuf	= vb2_dc_map_dmabuf,
+	.unmap_dmabuf	= vb2_dc_unmap_dmabuf,
+	.attach_dmabuf	= vb2_dc_attach_dmabuf,
+	.detach_dmabuf	= vb2_dc_detach_dmabuf,
+	.num_users	= vb2_dc_num_users,
+};
+EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
+
+void *vb2_dma_contig_init_ctx(struct device *dev)
+{
+	return dev;
+}
+EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
+
+void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
+{
+}
+EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
+
+MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
+MODULE_AUTHOR("Pawel Osciak <pawel at osciak.com>");
+MODULE_LICENSE("GPL");
-- 
1.7.5.4




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