V4L/DVB (6251): Replace video-buf to a more generic approach

video-buf currently does two different tasks:

- Manages video buffers with a common code that allows
  implementing all the V4L2 different modes of buffering;

- Controls memory allocations

While the first task is generic, the second were written to support PCI DMA
Scatter/Gather needs. The original approach can't even work for those
video capture hardware that don't support scatter/gather.

I did one approach to make it more generic. While the approach worked
fine for vivi driver, it were not generic enough to handle USB needs.

This patch creates two different modules, one containing the generic
video buffer handling (videobuf-core) and another with PCI DMA S/G.
After this patch, it would be simpler to write an USB video-buf and a
non-SG DMA module.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
http://thread.gmane.org/gmane.comp.video.video4linux/34978/focus=34981
Reviewed-by: Ricardo Cerqueira <v4l@cerqueira.org>

1 files changed, 772 insertions, 0 deletions

diff --git a/drivers/media/video/videobuf-dma-sg.c b/drivers/media/video/videobuf-dma-sg.c
new file mode 100644
index 000000000000..3345877c47d4
--- /dev/null
+++ b/drivers/media/video/videobuf-dma-sg.c
@@ -0,0 +1,772 @@
+/*
+ * helper functions for PCI DMA video4linux capture buffers
+ *
+ * The functions expect the hardware being able to scatter gatter
+ * (i.e. the buffers are not linear in physical memory, but fragmented
+ * into PAGE_SIZE chunks).  They also assume the driver does not need
+ * to touch the video data.
+ *
+ * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
+ *
+ * Highly based on video-buf written originally by:
+ * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
+ * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
+ * (c) 2006 Ted Walther and John Sokol
+ *
+ * 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; either version 2
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+
+#include <linux/pci.h>
+#include <linux/vmalloc.h>
+#include <linux/pagemap.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+
+#include <media/videobuf-dma-sg.h>
+
+#define MAGIC_DMABUF 0x19721112
+#define MAGIC_SG_MEM 0x17890714
+
+#define MAGIC_CHECK(is,should)	if (unlikely((is) != (should))) \
+	{ printk(KERN_ERR "magic mismatch: %x (expected %x)\n",is,should); BUG(); }
+
+static int debug = 0;
+module_param(debug, int, 0644);
+
+MODULE_DESCRIPTION("helper module to manage video4linux pci dma sg buffers");
+MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
+MODULE_LICENSE("GPL");
+
+#define dprintk(level, fmt, arg...)	if (debug >= level) \
+	printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
+
+/* --------------------------------------------------------------------- */
+
+struct scatterlist*
+videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
+{
+	struct scatterlist *sglist;
+	struct page *pg;
+	int i;
+
+	sglist = kcalloc(nr_pages, sizeof(struct scatterlist), GFP_KERNEL);
+	if (NULL == sglist)
+		return NULL;
+	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
+		pg = vmalloc_to_page(virt);
+		if (NULL == pg)
+			goto err;
+		BUG_ON(PageHighMem(pg));
+		sglist[i].page   = pg;
+		sglist[i].length = PAGE_SIZE;
+	}
+	return sglist;
+
+ err:
+	kfree(sglist);
+	return NULL;
+}
+
+struct scatterlist*
+videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
+{
+	struct scatterlist *sglist;
+	int i = 0;
+
+	if (NULL == pages[0])
+		return NULL;
+	sglist = kcalloc(nr_pages, sizeof(*sglist), GFP_KERNEL);
+	if (NULL == sglist)
+		return NULL;
+
+	if (NULL == pages[0])
+		goto nopage;
+	if (PageHighMem(pages[0]))
+		/* DMA to highmem pages might not work */
+		goto highmem;
+	sglist[0].page   = pages[0];
+	sglist[0].offset = offset;
+	sglist[0].length = PAGE_SIZE - offset;
+	for (i = 1; i < nr_pages; i++) {
+		if (NULL == pages[i])
+			goto nopage;
+		if (PageHighMem(pages[i]))
+			goto highmem;
+		sglist[i].page   = pages[i];
+		sglist[i].length = PAGE_SIZE;
+	}
+	return sglist;
+
+ nopage:
+	dprintk(2,"sgl: oops - no page\n");
+	kfree(sglist);
+	return NULL;
+
+ highmem:
+	dprintk(2,"sgl: oops - highmem page\n");
+	kfree(sglist);
+	return NULL;
+}
+
+/* --------------------------------------------------------------------- */
+
+struct videobuf_dmabuf *videobuf_to_dma (struct videobuf_buffer *buf)
+{
+	struct videbuf_pci_sg_memory *mem=buf->priv;
+	BUG_ON (!mem);
+
+	MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+	return &mem->dma;
+}
+
+void videobuf_dma_init(struct videobuf_dmabuf *dma)
+{
+	memset(dma,0,sizeof(*dma));
+	dma->magic = MAGIC_DMABUF;
+}
+
+int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
+			   unsigned long data, unsigned long size)
+{
+	unsigned long first,last;
+	int err, rw = 0;
+
+	dma->direction = direction;
+	switch (dma->direction) {
+	case PCI_DMA_FROMDEVICE: rw = READ;  break;
+	case PCI_DMA_TODEVICE:   rw = WRITE; break;
+	default:                 BUG();
+	}
+
+	first = (data          & PAGE_MASK) >> PAGE_SHIFT;
+	last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
+	dma->offset   = data & ~PAGE_MASK;
+	dma->nr_pages = last-first+1;
+	dma->pages = kmalloc(dma->nr_pages * sizeof(struct page*),
+			     GFP_KERNEL);
+	if (NULL == dma->pages)
+		return -ENOMEM;
+	dprintk(1,"init user [0x%lx+0x%lx => %d pages]\n",
+		data,size,dma->nr_pages);
+
+	dma->varea = (void *) data;
+
+	down_read(&current->mm->mmap_sem);
+	err = get_user_pages(current,current->mm,
+			     data & PAGE_MASK, dma->nr_pages,
+			     rw == READ, 1, /* force */
+			     dma->pages, NULL);
+	up_read(&current->mm->mmap_sem);
+	if (err != dma->nr_pages) {
+		dma->nr_pages = (err >= 0) ? err : 0;
+		dprintk(1,"get_user_pages: err=%d [%d]\n",err,dma->nr_pages);
+		return err < 0 ? err : -EINVAL;
+	}
+	return 0;
+}
+
+int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
+			     int nr_pages)
+{
+	dprintk(1,"init kernel [%d pages]\n",nr_pages);
+	dma->direction = direction;
+	dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
+	if (NULL == dma->vmalloc) {
+		dprintk(1,"vmalloc_32(%d pages) failed\n",nr_pages);
+		return -ENOMEM;
+	}
+	dprintk(1,"vmalloc is at addr 0x%08lx, size=%d\n",
+				(unsigned long)dma->vmalloc,
+				nr_pages << PAGE_SHIFT);
+	memset(dma->vmalloc,0,nr_pages << PAGE_SHIFT);
+	dma->nr_pages = nr_pages;
+	return 0;
+}
+
+int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
+			      dma_addr_t addr, int nr_pages)
+{
+	dprintk(1,"init overlay [%d pages @ bus 0x%lx]\n",
+		nr_pages,(unsigned long)addr);
+	dma->direction = direction;
+	if (0 == addr)
+		return -EINVAL;
+
+	dma->bus_addr = addr;
+	dma->nr_pages = nr_pages;
+	return 0;
+}
+
+int videobuf_dma_map(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
+{
+	void                   *dev=q->dev;
+	struct videobuf_dma_sg_ops *ops=q->priv_ops;
+
+	MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
+	BUG_ON(0 == dma->nr_pages);
+
+	if (dma->pages) {
+		dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
+						   dma->offset);
+	}
+	if (dma->vmalloc) {
+		dma->sglist = videobuf_vmalloc_to_sg
+						(dma->vmalloc,dma->nr_pages);
+	}
+	if (dma->bus_addr) {
+		dma->sglist = kmalloc(sizeof(struct scatterlist), GFP_KERNEL);
+		if (NULL != dma->sglist) {
+			dma->sglen  = 1;
+			sg_dma_address(&dma->sglist[0]) = dma->bus_addr & PAGE_MASK;
+			dma->sglist[0].offset           = dma->bus_addr & ~PAGE_MASK;
+			sg_dma_len(&dma->sglist[0])     = dma->nr_pages * PAGE_SIZE;
+		}
+	}
+	if (NULL == dma->sglist) {
+		dprintk(1,"scatterlist is NULL\n");
+		return -ENOMEM;
+	}
+	if (!dma->bus_addr) {
+		if (ops && ops->vb_map_sg) {
+			dma->sglen = ops->vb_map_sg(dev,dma->sglist,
+					dma->nr_pages, dma->direction);
+		}
+		if (0 == dma->sglen) {
+			printk(KERN_WARNING
+			       "%s: videobuf_map_sg failed\n",__FUNCTION__);
+			kfree(dma->sglist);
+			dma->sglist = NULL;
+			dma->sglen = 0;
+			return -EIO;
+		}
+	}
+	return 0;
+}
+
+int videobuf_dma_sync(struct videobuf_queue *q,struct videobuf_dmabuf *dma)
+{
+	void                   *dev=q->dev;
+	struct videobuf_dma_sg_ops *ops=q->priv_ops;
+
+	MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
+	BUG_ON(!dma->sglen);
+
+	if (!dma->bus_addr && ops && ops->vb_dma_sync_sg)
+		ops->vb_dma_sync_sg(dev,dma->sglist,dma->nr_pages,
+							dma->direction);
+
+	return 0;
+}
+
+int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
+{
+	void                   *dev=q->dev;
+	struct videobuf_dma_sg_ops *ops=q->priv_ops;
+
+	MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
+	if (!dma->sglen)
+		return 0;
+
+	if (!dma->bus_addr && ops && ops->vb_unmap_sg)
+			ops->vb_unmap_sg(dev,dma->sglist,dma->nr_pages,
+							dma->direction);
+	kfree(dma->sglist);
+	dma->sglist = NULL;
+	dma->sglen = 0;
+	return 0;
+}
+
+int videobuf_dma_free(struct videobuf_dmabuf *dma)
+{
+	MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
+	BUG_ON(dma->sglen);
+
+	if (dma->pages) {
+		int i;
+		for (i=0; i < dma->nr_pages; i++)
+			page_cache_release(dma->pages[i]);
+		kfree(dma->pages);
+		dma->pages = NULL;
+	}
+
+	vfree(dma->vmalloc);
+	dma->vmalloc = NULL;
+	dma->varea = NULL;
+
+	if (dma->bus_addr) {
+		dma->bus_addr = 0;
+	}
+	dma->direction = PCI_DMA_NONE;
+	return 0;
+}
+
+/* --------------------------------------------------------------------- */
+
+int videobuf_pci_dma_map(struct pci_dev *pci,struct videobuf_dmabuf *dma)
+{
+	struct videobuf_queue q;
+	struct videobuf_dma_sg_ops qops;
+
+	q.dev=pci;
+	qops.vb_map_sg=(vb_map_sg_t *)pci_map_sg;
+	qops.vb_unmap_sg=(vb_map_sg_t *)pci_unmap_sg;
+	q.priv_ops = &qops;
+
+	return (videobuf_dma_map(&q,dma));
+}
+
+int videobuf_pci_dma_unmap(struct pci_dev *pci,struct videobuf_dmabuf *dma)
+{
+	struct videobuf_queue q;
+	struct videobuf_dma_sg_ops qops;
+
+	q.dev=pci;
+	qops.vb_map_sg=(vb_map_sg_t *)pci_map_sg;
+	qops.vb_unmap_sg=(vb_map_sg_t *)pci_unmap_sg;
+	q.priv_ops = &qops;
+
+	return (videobuf_dma_unmap(&q,dma));
+}
+
+/* --------------------------------------------------------------------- */
+
+static void
+videobuf_vm_open(struct vm_area_struct *vma)
+{
+	struct videobuf_mapping *map = vma->vm_private_data;
+
+	dprintk(2,"vm_open %p [count=%d,vma=%08lx-%08lx]\n",map,
+		map->count,vma->vm_start,vma->vm_end);
+	map->count++;
+}
+
+static void
+videobuf_vm_close(struct vm_area_struct *vma)
+{
+	struct videobuf_mapping *map = vma->vm_private_data;
+	struct videobuf_queue *q = map->q;
+	struct videbuf_pci_sg_memory *mem;
+	int i;
+
+	dprintk(2,"vm_close %p [count=%d,vma=%08lx-%08lx]\n",map,
+		map->count,vma->vm_start,vma->vm_end);
+
+	map->count--;
+	if (0 == map->count) {
+		dprintk(1,"munmap %p q=%p\n",map,q);
+		mutex_lock(&q->lock);
+		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
+			if (NULL == q->bufs[i])
+				continue;
+			mem=q->bufs[i]->priv;
+
+			if (!mem)
+				continue;
+
+			MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+			if (mem->map != map)
+				continue;
+			mem->map   = NULL;
+			q->bufs[i]->baddr = 0;
+			q->ops->buf_release(q,q->bufs[i]);
+		}
+		mutex_unlock(&q->lock);
+		kfree(map);
+	}
+	return;
+}
+
+/*
+ * Get a anonymous page for the mapping.  Make sure we can DMA to that
+ * memory location with 32bit PCI devices (i.e. don't use highmem for
+ * now ...).  Bounce buffers don't work very well for the data rates
+ * video capture has.
+ */
+static struct page*
+videobuf_vm_nopage(struct vm_area_struct *vma, unsigned long vaddr,
+		   int *type)
+{
+	struct page *page;
+
+	dprintk(3,"nopage: fault @ %08lx [vma %08lx-%08lx]\n",
+		vaddr,vma->vm_start,vma->vm_end);
+	if (vaddr > vma->vm_end)
+		return NOPAGE_SIGBUS;
+	page = alloc_page(GFP_USER | __GFP_DMA32);
+	if (!page)
+		return NOPAGE_OOM;
+	clear_user_page(page_address(page), vaddr, page);
+	if (type)
+		*type = VM_FAULT_MINOR;
+	return page;
+}
+
+static struct vm_operations_struct videobuf_vm_ops =
+{
+	.open     = videobuf_vm_open,
+	.close    = videobuf_vm_close,
+	.nopage   = videobuf_vm_nopage,
+};
+
+/* ---------------------------------------------------------------------
+ * PCI handlers for the generic methods
+ */
+
+/* Allocated area consists on 3 parts:
+	struct video_buffer
+	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
+	struct videobuf_pci_sg_memory
+ */
+
+static void *__videobuf_alloc(size_t size)
+{
+	struct videbuf_pci_sg_memory *mem;
+	struct videobuf_buffer *vb;
+
+	vb = kzalloc(size+sizeof(*mem),GFP_KERNEL);
+
+	mem = vb->priv = ((char *)vb)+size;
+	mem->magic=MAGIC_SG_MEM;
+
+	videobuf_dma_init(&mem->dma);
+
+	dprintk(1,"%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
+		__FUNCTION__,vb,(long)sizeof(*vb),(long)size-sizeof(*vb),
+		mem,(long)sizeof(*mem));
+
+	return vb;
+}
+
+static int __videobuf_iolock (struct videobuf_queue* q,
+			      struct videobuf_buffer *vb,
+			      struct v4l2_framebuffer *fbuf)
+{
+	int err,pages;
+	dma_addr_t bus;
+	struct videbuf_pci_sg_memory *mem=vb->priv;
+	BUG_ON(!mem);
+
+	MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+	switch (vb->memory) {
+	case V4L2_MEMORY_MMAP:
+	case V4L2_MEMORY_USERPTR:
+		if (0 == vb->baddr) {
+			/* no userspace addr -- kernel bounce buffer */
+			pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
+			err = videobuf_dma_init_kernel( &mem->dma,
+							PCI_DMA_FROMDEVICE,
+							pages );
+			if (0 != err)
+				return err;
+		} else {
+			/* dma directly to userspace */
+			err = videobuf_dma_init_user( &mem->dma,
+						      PCI_DMA_FROMDEVICE,
+						      vb->baddr,vb->bsize );
+			if (0 != err)
+				return err;
+		}
+		break;
+	case V4L2_MEMORY_OVERLAY:
+		if (NULL == fbuf)
+			return -EINVAL;
+		/* FIXME: need sanity checks for vb->boff */
+		/*
+		 * Using a double cast to avoid compiler warnings when
+		 * building for PAE. Compiler doesn't like direct casting
+		 * of a 32 bit ptr to 64 bit integer.
+		 */
+		bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
+		pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
+		err = videobuf_dma_init_overlay(&mem->dma,PCI_DMA_FROMDEVICE,
+						bus, pages);
+		if (0 != err)
+			return err;
+		break;
+	default:
+		BUG();
+	}
+	err = videobuf_dma_map(q,&mem->dma);
+	if (0 != err)
+		return err;
+
+	return 0;
+}
+
+static int __videobuf_sync(struct videobuf_queue *q,
+			   struct videobuf_buffer *buf)
+{
+	struct videbuf_pci_sg_memory *mem=buf->priv;
+	BUG_ON (!mem);
+	MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+	return	videobuf_dma_sync(q,&mem->dma);
+}
+
+static int __videobuf_mmap_free(struct videobuf_queue *q)
+{
+	int i;
+
+	for (i = 0; i < VIDEO_MAX_FRAME; i++) {
+		if (q->bufs[i]) {
+			struct videbuf_pci_sg_memory *mem=q->bufs[i]->priv;
+			if (mem && mem->map)
+				return -EBUSY;
+		}
+	}
+
+	return 0;
+}
+
+static int __videobuf_mmap_mapper(struct videobuf_queue *q,
+			 struct vm_area_struct *vma)
+{
+	struct videbuf_pci_sg_memory *mem;
+	struct videobuf_mapping *map;
+	unsigned int first,last,size,i;
+	int retval;
+
+	retval = -EINVAL;
+	if (!(vma->vm_flags & VM_WRITE)) {
+		dprintk(1,"mmap app bug: PROT_WRITE please\n");
+		goto done;
+	}
+	if (!(vma->vm_flags & VM_SHARED)) {
+		dprintk(1,"mmap app bug: MAP_SHARED please\n");
+		goto done;
+	}
+
+	/* look for first buffer to map */
+	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
+		if (NULL == q->bufs[first])
+			continue;
+		mem=q->bufs[first]->priv;
+		BUG_ON (!mem);
+		MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+		if (V4L2_MEMORY_MMAP != q->bufs[first]->memory)
+			continue;
+		if (q->bufs[first]->boff == (vma->vm_pgoff << PAGE_SHIFT))
+			break;
+	}
+	if (VIDEO_MAX_FRAME == first) {
+		dprintk(1,"mmap app bug: offset invalid [offset=0x%lx]\n",
+			(vma->vm_pgoff << PAGE_SHIFT));
+		goto done;
+	}
+
+	/* look for last buffer to map */
+	for (size = 0, last = first; last < VIDEO_MAX_FRAME; last++) {
+		if (NULL == q->bufs[last])
+			continue;
+		if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
+			continue;
+		mem=q->bufs[last]->priv;
+		if (mem->map) {
+			retval = -EBUSY;
+			goto done;
+		}
+		size += q->bufs[last]->bsize;
+		if (size == (vma->vm_end - vma->vm_start))
+			break;
+	}
+	if (VIDEO_MAX_FRAME == last) {
+		dprintk(1,"mmap app bug: size invalid [size=0x%lx]\n",
+			(vma->vm_end - vma->vm_start));
+		goto done;
+	}
+
+	/* create mapping + update buffer list */
+	retval = -ENOMEM;
+	map = kmalloc(sizeof(struct videobuf_mapping),GFP_KERNEL);
+	if (NULL == map)
+		goto done;
+	for (size = 0, i = first; i <= last; size += q->bufs[i++]->bsize) {
+		mem=q->bufs[i]->priv;
+		mem->map   = map;
+		q->bufs[i]->baddr = vma->vm_start + size;
+	}
+	map->count    = 1;
+	map->start    = vma->vm_start;
+	map->end      = vma->vm_end;
+	map->q        = q;
+	vma->vm_ops   = &videobuf_vm_ops;
+	vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
+	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
+	vma->vm_private_data = map;
+	dprintk(1,"mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
+		map,q,vma->vm_start,vma->vm_end,vma->vm_pgoff,first,last);
+	retval = 0;
+
+ done:
+	return retval;
+}
+
+static int __videobuf_is_mmapped (struct videobuf_buffer *buf)
+{
+	struct videbuf_pci_sg_memory *mem=buf->priv;
+
+	BUG_ON (!mem);
+	MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+	return (mem->map)?1:0;
+}
+
+static int __videobuf_copy_to_user ( struct videobuf_queue *q,
+				char __user *data, size_t count,
+				int nonblocking )
+{
+	struct videbuf_pci_sg_memory *mem=q->read_buf->priv;
+	BUG_ON (!mem);
+	MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+	/* copy to userspace */
+	if (count > q->read_buf->size - q->read_off)
+		count = q->read_buf->size - q->read_off;
+
+	if (copy_to_user(data, mem->dma.vmalloc+q->read_off, count))
+		return -EFAULT;
+
+	return count;
+}
+
+static int __videobuf_copy_stream ( struct videobuf_queue *q,
+				char __user *data, size_t count, size_t pos,
+				int vbihack, int nonblocking )
+{
+	unsigned int  *fc;
+	struct videbuf_pci_sg_memory *mem=q->read_buf->priv;
+	BUG_ON (!mem);
+	MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
+
+	if (vbihack) {
+		/* dirty, undocumented hack -- pass the frame counter
+			* within the last four bytes of each vbi data block.
+			* We need that one to maintain backward compatibility
+			* to all vbi decoding software out there ... */
+		fc  = (unsigned int*)mem->dma.vmalloc;
+		fc += (q->read_buf->size>>2) -1;
+		*fc = q->read_buf->field_count >> 1;
+		dprintk(1,"vbihack: %d\n",*fc);
+	}
+
+	/* copy stuff using the common method */
+	count = __videobuf_copy_to_user (q,data,count,nonblocking);
+
+	if ( (count==-EFAULT) && (0 == pos) )
+		return -EFAULT;
+
+	return count;
+}
+
+static struct videobuf_qtype_ops pci_ops = {
+	.magic        = MAGIC_QTYPE_OPS,
+
+	.alloc        = __videobuf_alloc,
+	.iolock       = __videobuf_iolock,
+	.sync         = __videobuf_sync,
+	.mmap_free    = __videobuf_mmap_free,
+	.mmap_mapper  = __videobuf_mmap_mapper,
+	.is_mmapped   = __videobuf_is_mmapped,
+	.copy_to_user = __videobuf_copy_to_user,
+	.copy_stream  = __videobuf_copy_stream,
+};
+
+void *videobuf_pci_alloc (size_t size)
+{
+	struct videobuf_queue q;
+
+	/* Required to make generic handler to call __videobuf_alloc */
+	q.int_ops=&pci_ops;
+
+	q.msize=size;
+
+	return videobuf_alloc (&q);
+}
+
+void videobuf_queue_pci_init(struct videobuf_queue* q,
+			 struct videobuf_queue_ops *ops,
+			 void *dev,
+			 spinlock_t *irqlock,
+			 enum v4l2_buf_type type,
+			 enum v4l2_field field,
+			 unsigned int msize,
+			 void *priv)
+{
+	struct videobuf_dma_sg_ops *priv_ops;
+
+	videobuf_queue_init(q, ops, dev, irqlock, type, field, msize, priv);
+	q->int_ops=&pci_ops;
+
+	/* FIXME: the code bellow should be removed after having a proper
+	 * memory allocation method for vivi and tm6000
+	 */
+	q->priv_ops= kzalloc(sizeof(struct videobuf_dma_sg_ops), GFP_KERNEL);
+	BUG_ON (!q->priv_ops);
+
+	priv_ops=q->priv_ops;
+
+	/* Sets default methods for handling Scatter Gather mapping */
+	priv_ops->vb_map_sg=(vb_map_sg_t *)pci_map_sg;
+	priv_ops->vb_unmap_sg=(vb_map_sg_t *)pci_unmap_sg;
+	priv_ops->vb_dma_sync_sg=(vb_map_sg_t *)pci_dma_sync_sg_for_cpu;
+}
+
+void videobuf_set_pci_ops (struct videobuf_queue* q,
+				struct videobuf_dma_sg_ops *ops)
+{
+	kfree (q->priv_ops);
+
+	q->priv_ops=ops;
+
+	if (!ops)
+		return;
+
+	/* If not specified, defaults to PCI map sg */
+	if (!ops->vb_map_sg)
+		ops->vb_map_sg=(vb_map_sg_t *)pci_map_sg;
+
+	if (!ops->vb_dma_sync_sg)
+		ops->vb_dma_sync_sg=(vb_map_sg_t *)pci_dma_sync_sg_for_cpu;
+	if (!ops->vb_unmap_sg)
+		ops->vb_unmap_sg=(vb_map_sg_t *)pci_unmap_sg;
+}
+
+
+/* --------------------------------------------------------------------- */
+
+EXPORT_SYMBOL_GPL(videobuf_vmalloc_to_sg);
+
+EXPORT_SYMBOL_GPL(videobuf_to_dma);
+EXPORT_SYMBOL_GPL(videobuf_dma_init);
+EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
+EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
+EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
+EXPORT_SYMBOL_GPL(videobuf_dma_map);
+EXPORT_SYMBOL_GPL(videobuf_dma_sync);
+EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
+EXPORT_SYMBOL_GPL(videobuf_dma_free);
+
+EXPORT_SYMBOL_GPL(videobuf_pci_dma_map);
+EXPORT_SYMBOL_GPL(videobuf_pci_dma_unmap);
+EXPORT_SYMBOL_GPL(videobuf_pci_alloc);
+
+EXPORT_SYMBOL_GPL(videobuf_queue_pci_init);
+EXPORT_SYMBOL_GPL(videobuf_set_pci_ops);
+
+/*
+ * Local variables:
+ * c-basic-offset: 8
+ * End:
+ */