drivers/media/v4l2-core/videobuf-dma-sg.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * helper functions for SG DMA video4linux capture buffers
  *
  * The functions expect the hardware being able to scatter gather
  * (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@kernel.org>
  *
  * Highly based on video-buf written originally by:
  * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
  * (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
  * (c) 2006 Ted Walther and John Sokol
  */

 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/sched/mm.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/pgtable.h>

 #include <linux/dma-mapping.h>
 #include <linux/vmalloc.h>
 #include <linux/pagemap.h>
 #include <linux/scatterlist.h>
 #include <asm/page.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;
 module_param(debug, int, 0644);

 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@kernel.org>");
 MODULE_LICENSE("GPL");

 #define dprintk(level, fmt, arg...)					\
 	if (debug >= level)						\
 		printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)

 /* --------------------------------------------------------------------- */

 /*
  * Return a scatterlist for some page-aligned vmalloc()'ed memory
  * block (NULL on errors).  Memory for the scatterlist is allocated
  * using kmalloc.  The caller must free the memory.
  */
 static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
 						  int nr_pages)
 {
 	struct scatterlist *sglist;
 	struct page *pg;
 	int i;

 	sglist = vzalloc(array_size(nr_pages, sizeof(*sglist)));
 	if (NULL == sglist)
 		return NULL;
 	sg_init_table(sglist, nr_pages);
 	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
 		pg = vmalloc_to_page(virt);
 		if (NULL == pg)
 			goto err;
 		BUG_ON(PageHighMem(pg));
 		sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
 	}
 	return sglist;

 err:
 	vfree(sglist);
 	return NULL;
 }

 /*
  * Return a scatterlist for a an array of userpages (NULL on errors).
  * Memory for the scatterlist is allocated using kmalloc.  The caller
  * must free the memory.
  */
 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
 					int nr_pages, int offset, size_t size)
 {
 	struct scatterlist *sglist;
 	int i;

 	if (NULL == pages[0])
 		return NULL;
 	sglist = vmalloc(array_size(nr_pages, sizeof(*sglist)));
 	if (NULL == sglist)
 		return NULL;
 	sg_init_table(sglist, nr_pages);

 	if (PageHighMem(pages[0]))
 		/* DMA to highmem pages might not work */
 		goto highmem;
 	sg_set_page(&sglist[0], pages[0],
 			min_t(size_t, PAGE_SIZE - offset, size), offset);
 	size -= min_t(size_t, PAGE_SIZE - offset, size);
 	for (i = 1; i < nr_pages; i++) {
 		if (NULL == pages[i])
 			goto nopage;
 		if (PageHighMem(pages[i]))
 			goto highmem;
 		sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
 		size -= min_t(size_t, PAGE_SIZE, size);
 	}
 	return sglist;

 nopage:
 	dprintk(2, "sgl: oops - no page\n");
 	vfree(sglist);
 	return NULL;

 highmem:
 	dprintk(2, "sgl: oops - highmem page\n");
 	vfree(sglist);
 	return NULL;
 }

 /* --------------------------------------------------------------------- */

 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
 {
 	struct videobuf_dma_sg_memory *mem = buf->priv;
 	BUG_ON(!mem);

 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

 	return &mem->dma;
 }
 EXPORT_SYMBOL_GPL(videobuf_to_dma);

 static void videobuf_dma_init(struct videobuf_dmabuf *dma)
 {
 	memset(dma, 0, sizeof(*dma));
 	dma->magic = MAGIC_DMABUF;
 }

 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 			int direction, unsigned long data, unsigned long size)
 {
 	unsigned long first, last;
 	int err, rw = 0;
 	unsigned int flags = FOLL_FORCE;

 	dma->direction = direction;
 	switch (dma->direction) {
 	case DMA_FROM_DEVICE:
 		rw = READ;
 		break;
 	case DMA_TO_DEVICE:
 		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->size = size;
 	dma->nr_pages = last-first+1;
 	dma->pages = kmalloc_array(dma->nr_pages, sizeof(struct page *),
 				   GFP_KERNEL);
 	if (NULL == dma->pages)
 		return -ENOMEM;

 	if (rw == READ)
 		flags |= FOLL_WRITE;

 	dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n",
 		data, size, dma->nr_pages);

 	err = pin_user_pages(data & PAGE_MASK, dma->nr_pages,
 			     flags | FOLL_LONGTERM, dma->pages, NULL);

 	if (err != dma->nr_pages) {
 		dma->nr_pages = (err >= 0) ? err : 0;
 		dprintk(1, "pin_user_pages: err=%d [%lu]\n", err,
 			dma->nr_pages);
 		return err < 0 ? err : -EINVAL;
 	}
 	return 0;
 }

 static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 			   unsigned long data, unsigned long size)
 {
 	int ret;

 	mmap_read_lock(current->mm);
 	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 	mmap_read_unlock(current->mm);

 	return ret;
 }

 static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 				    unsigned long nr_pages)
 {
 	int i;

 	dprintk(1, "init kernel [%lu pages]\n", nr_pages);

 	dma->direction = direction;
 	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
 				   GFP_KERNEL);
 	if (!dma->vaddr_pages)
 		return -ENOMEM;

 	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
 	if (!dma->dma_addr) {
 		kfree(dma->vaddr_pages);
 		return -ENOMEM;
 	}
 	for (i = 0; i < nr_pages; i++) {
 		void *addr;

 		addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
 					  &(dma->dma_addr[i]), GFP_KERNEL);
 		if (addr == NULL)
 			goto out_free_pages;

 		dma->vaddr_pages[i] = virt_to_page(addr);
 	}
 	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
 			  PAGE_KERNEL);
 	if (NULL == dma->vaddr) {
 		dprintk(1, "vmalloc_32(%lu pages) failed\n", nr_pages);
 		goto out_free_pages;
 	}

 	dprintk(1, "vmalloc is at addr %p, size=%lu\n",
 		dma->vaddr, nr_pages << PAGE_SHIFT);

 	memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
 	dma->nr_pages = nr_pages;

 	return 0;
 out_free_pages:
 	while (i > 0) {
 		void *addr;

 		i--;
 		addr = page_address(dma->vaddr_pages[i]);
 		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
 	}
 	kfree(dma->dma_addr);
 	dma->dma_addr = NULL;
 	kfree(dma->vaddr_pages);
 	dma->vaddr_pages = NULL;

 	return -ENOMEM;

 }

 static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 			      dma_addr_t addr, unsigned long nr_pages)
 {
 	dprintk(1, "init overlay [%lu 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;
 }

 static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 {
 	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, dma->size);
 	}
 	if (dma->vaddr) {
 		dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
 						     dma->nr_pages);
 	}
 	if (dma->bus_addr) {
 		dma->sglist = vmalloc(sizeof(*dma->sglist));
 		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) {
 		dma->sglen = dma_map_sg(dev, dma->sglist,
 					dma->nr_pages, dma->direction);
 		if (0 == dma->sglen) {
 			printk(KERN_WARNING
 			       "%s: videobuf_map_sg failed\n", __func__);
 			vfree(dma->sglist);
 			dma->sglist = NULL;
 			dma->sglen = 0;
 			return -ENOMEM;
 		}
 	}

 	return 0;
 }

 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 {
 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);

 	if (!dma->sglen)
 		return 0;

 	dma_unmap_sg(dev, dma->sglist, dma->nr_pages, dma->direction);

 	vfree(dma->sglist);
 	dma->sglist = NULL;
 	dma->sglen = 0;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);

 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 {
 	int i;
 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 	BUG_ON(dma->sglen);

 	if (dma->pages) {
 		unpin_user_pages_dirty_lock(dma->pages, dma->nr_pages,
 					    dma->direction == DMA_FROM_DEVICE);
 		kfree(dma->pages);
 		dma->pages = NULL;
 	}

 	if (dma->dma_addr) {
 		for (i = 0; i < dma->nr_pages; i++) {
 			void *addr;

 			addr = page_address(dma->vaddr_pages[i]);
 			dma_free_coherent(dma->dev, PAGE_SIZE, addr,
 					  dma->dma_addr[i]);
 		}
 		kfree(dma->dma_addr);
 		dma->dma_addr = NULL;
 		kfree(dma->vaddr_pages);
 		dma->vaddr_pages = NULL;
 		vunmap(dma->vaddr);
 		dma->vaddr = NULL;
 	}

 	if (dma->bus_addr)
 		dma->bus_addr = 0;
 	dma->direction = DMA_NONE;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(videobuf_dma_free);

 /* --------------------------------------------------------------------- */

 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 videobuf_dma_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);
 		videobuf_queue_lock(q);
 		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 (q->bufs[i]->map != map)
 				continue;
 			q->bufs[i]->map   = NULL;
 			q->bufs[i]->baddr = 0;
 			q->ops->buf_release(q, q->bufs[i]);
 		}
 		videobuf_queue_unlock(q);
 		kfree(map);
 	}
 }

 /*
  * 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 vm_fault_t videobuf_vm_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct page *page;

 	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
 		vmf->address, vma->vm_start, vma->vm_end);

 	page = alloc_page(GFP_USER | __GFP_DMA32);
 	if (!page)
 		return VM_FAULT_OOM;
 	clear_user_highpage(page, vmf->address);
 	vmf->page = page;

 	return 0;
 }

 static const struct vm_operations_struct videobuf_vm_ops = {
 	.open	= videobuf_vm_open,
 	.close	= videobuf_vm_close,
 	.fault	= videobuf_vm_fault,
 };

 /* ---------------------------------------------------------------------
  * SG handlers for the generic methods
  */

 /* Allocated area consists on 3 parts:
 	struct video_buffer
 	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 	struct videobuf_dma_sg_memory
  */

 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
 {
 	struct videobuf_dma_sg_memory *mem;
 	struct videobuf_buffer *vb;

 	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 	if (!vb)
 		return vb;

 	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",
 		__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
 		mem, (long)sizeof(*mem));

 	return vb;
 }

 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 {
 	struct videobuf_dma_sg_memory *mem = buf->priv;
 	BUG_ON(!mem);

 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

 	return mem->dma.vaddr;
 }

 static int __videobuf_iolock(struct videobuf_queue *q,
 			     struct videobuf_buffer *vb,
 			     struct v4l2_framebuffer *fbuf)
 {
 	struct videobuf_dma_sg_memory *mem = vb->priv;
 	unsigned long pages;
 	dma_addr_t bus;
 	int err;

 	BUG_ON(!mem);

 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

 	if (!mem->dma.dev)
 		mem->dma.dev = q->dev;
 	else
 		WARN_ON(mem->dma.dev != q->dev);

 	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,
 						       DMA_FROM_DEVICE,
 						       pages);
 			if (0 != err)
 				return err;
 		} else if (vb->memory == V4L2_MEMORY_USERPTR) {
 			/* dma directly to userspace */
 			err = videobuf_dma_init_user(&mem->dma,
 						     DMA_FROM_DEVICE,
 						     vb->baddr, vb->bsize);
 			if (0 != err)
 				return err;
 		} else {
 			/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 			buffers can only be called from videobuf_qbuf
 			we take current->mm->mmap_lock there, to prevent
 			locking inversion, so don't take it here */

 			err = videobuf_dma_init_user_locked(&mem->dma,
 						      DMA_FROM_DEVICE,
 						      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, DMA_FROM_DEVICE,
 						bus, pages);
 		if (0 != err)
 			return err;
 		break;
 	default:
 		BUG();
 	}
 	err = videobuf_dma_map(q->dev, &mem->dma);
 	if (0 != err)
 		return err;

 	return 0;
 }

 static int __videobuf_sync(struct videobuf_queue *q,
 			   struct videobuf_buffer *buf)
 {
 	struct videobuf_dma_sg_memory *mem = buf->priv;
 	BUG_ON(!mem || !mem->dma.sglen);

 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);

 	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
 			    mem->dma.nr_pages, mem->dma.direction);

 	return 0;
 }

 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 				  struct videobuf_buffer *buf,
 				  struct vm_area_struct *vma)
 {
 	struct videobuf_dma_sg_memory *mem = buf->priv;
 	struct videobuf_mapping *map;
 	unsigned int first, last, size = 0, i;
 	int retval;

 	retval = -EINVAL;

 	BUG_ON(!mem);
 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

 	/* look for first buffer to map */
 	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 		if (buf == q->bufs[first]) {
 			size = PAGE_ALIGN(q->bufs[first]->bsize);
 			break;
 		}
 	}

 	/* paranoia, should never happen since buf is always valid. */
 	if (!size) {
 		dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
 				(vma->vm_pgoff << PAGE_SHIFT));
 		goto done;
 	}

 	last = first;

 	/* create mapping + update buffer list */
 	retval = -ENOMEM;
 	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 	if (NULL == map)
 		goto done;

 	size = 0;
 	for (i = first; i <= last; i++) {
 		if (NULL == q->bufs[i])
 			continue;
 		q->bufs[i]->map   = map;
 		q->bufs[i]->baddr = vma->vm_start + size;
 		size += PAGE_ALIGN(q->bufs[i]->bsize);
 	}

 	map->count    = 1;
 	map->q        = q;
 	vma->vm_ops   = &videobuf_vm_ops;
 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 	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 struct videobuf_qtype_ops sg_ops = {
 	.magic        = MAGIC_QTYPE_OPS,

 	.alloc_vb     = __videobuf_alloc_vb,
 	.iolock       = __videobuf_iolock,
 	.sync         = __videobuf_sync,
 	.mmap_mapper  = __videobuf_mmap_mapper,
 	.vaddr        = __videobuf_to_vaddr,
 };

 void *videobuf_sg_alloc(size_t size)
 {
 	struct videobuf_queue q;

 	/* Required to make generic handler to call __videobuf_alloc */
 	q.int_ops = &sg_ops;

 	q.msize = size;

 	return videobuf_alloc_vb(&q);
 }
 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);

 void videobuf_queue_sg_init(struct videobuf_queue *q,
 			 const struct videobuf_queue_ops *ops,
 			 struct device *dev,
 			 spinlock_t *irqlock,
 			 enum v4l2_buf_type type,
 			 enum v4l2_field field,
 			 unsigned int msize,
 			 void *priv,
 			 struct mutex *ext_lock)
 {
 	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 				 priv, &sg_ops, ext_lock);
 }
 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* helper functions for SG DMA video4linux capture buffers
	*
	* The functions expect the hardware being able to scatter gather
	* (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@kernel.org>
	*
	* Highly based on video-buf written originally by:
	* (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
	* (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
	* (c) 2006 Ted Walther and John Sokol
	*/

	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/sched/mm.h>
	#include <linux/slab.h>
	#include <linux/interrupt.h>
	#include <linux/pgtable.h>

	#include <linux/dma-mapping.h>
	#include <linux/vmalloc.h>
	#include <linux/pagemap.h>
	#include <linux/scatterlist.h>
	#include <asm/page.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;
	module_param(debug, int, 0644);

	MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
	MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@kernel.org>");
	MODULE_LICENSE("GPL");

	#define dprintk(level, fmt, arg...) \
	if (debug >= level) \
	printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)

	/* --------------------------------------------------------------------- */

	/*
	* Return a scatterlist for some page-aligned vmalloc()'ed memory
	* block (NULL on errors). Memory for the scatterlist is allocated
	* using kmalloc. The caller must free the memory.
	*/
	static struct scatterlist videobuf_vmalloc_to_sg(unsigned char virt,
	int nr_pages)
	{
	struct scatterlist *sglist;
	struct page *pg;
	int i;

	sglist = vzalloc(array_size(nr_pages, sizeof(*sglist)));
	if (NULL == sglist)
	return NULL;
	sg_init_table(sglist, nr_pages);
	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
	pg = vmalloc_to_page(virt);
	if (NULL == pg)
	goto err;
	BUG_ON(PageHighMem(pg));
	sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
	}
	return sglist;

	err:
	vfree(sglist);
	return NULL;
	}

	/*
	* Return a scatterlist for a an array of userpages (NULL on errors).
	* Memory for the scatterlist is allocated using kmalloc. The caller
	* must free the memory.
	*/
	static struct scatterlist videobuf_pages_to_sg(struct page *pages,
	int nr_pages, int offset, size_t size)
	{
	struct scatterlist *sglist;
	int i;

	if (NULL == pages[0])
	return NULL;
	sglist = vmalloc(array_size(nr_pages, sizeof(*sglist)));
	if (NULL == sglist)
	return NULL;
	sg_init_table(sglist, nr_pages);

	if (PageHighMem(pages[0]))
	/* DMA to highmem pages might not work */
	goto highmem;
	sg_set_page(&sglist[0], pages[0],
	min_t(size_t, PAGE_SIZE - offset, size), offset);
	size -= min_t(size_t, PAGE_SIZE - offset, size);
	for (i = 1; i < nr_pages; i++) {
	if (NULL == pages[i])
	goto nopage;
	if (PageHighMem(pages[i]))
	goto highmem;
	sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
	size -= min_t(size_t, PAGE_SIZE, size);
	}
	return sglist;

	nopage:
	dprintk(2, "sgl: oops - no page\n");
	vfree(sglist);
	return NULL;

	highmem:
	dprintk(2, "sgl: oops - highmem page\n");
	vfree(sglist);
	return NULL;
	}

	/* --------------------------------------------------------------------- */

	struct videobuf_dmabuf videobuf_to_dma(struct videobuf_buffer buf)
	{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	BUG_ON(!mem);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	return &mem->dma;
	}
	EXPORT_SYMBOL_GPL(videobuf_to_dma);

	static void videobuf_dma_init(struct videobuf_dmabuf *dma)
	{
	memset(dma, 0, sizeof(*dma));
	dma->magic = MAGIC_DMABUF;
	}

	static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
	int direction, unsigned long data, unsigned long size)
	{
	unsigned long first, last;
	int err, rw = 0;
	unsigned int flags = FOLL_FORCE;

	dma->direction = direction;
	switch (dma->direction) {
	case DMA_FROM_DEVICE:
	rw = READ;
	break;
	case DMA_TO_DEVICE:
	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->size = size;
	dma->nr_pages = last-first+1;
	dma->pages = kmalloc_array(dma->nr_pages, sizeof(struct page *),
	GFP_KERNEL);
	if (NULL == dma->pages)
	return -ENOMEM;

	if (rw == READ)
	flags \|= FOLL_WRITE;

	dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n",
	data, size, dma->nr_pages);

	err = pin_user_pages(data & PAGE_MASK, dma->nr_pages,
	flags \| FOLL_LONGTERM, dma->pages, NULL);

	if (err != dma->nr_pages) {
	dma->nr_pages = (err >= 0) ? err : 0;
	dprintk(1, "pin_user_pages: err=%d [%lu]\n", err,
	dma->nr_pages);
	return err < 0 ? err : -EINVAL;
	}
	return 0;
	}

	static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
	unsigned long data, unsigned long size)
	{
	int ret;

	mmap_read_lock(current->mm);
	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
	mmap_read_unlock(current->mm);

	return ret;
	}

	static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
	unsigned long nr_pages)
	{
	int i;

	dprintk(1, "init kernel [%lu pages]\n", nr_pages);

	dma->direction = direction;
	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
	GFP_KERNEL);
	if (!dma->vaddr_pages)
	return -ENOMEM;

	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
	if (!dma->dma_addr) {
	kfree(dma->vaddr_pages);
	return -ENOMEM;
	}
	for (i = 0; i < nr_pages; i++) {
	void *addr;

	addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
	&(dma->dma_addr[i]), GFP_KERNEL);
	if (addr == NULL)
	goto out_free_pages;

	dma->vaddr_pages[i] = virt_to_page(addr);
	}
	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP \| VM_IOREMAP,
	PAGE_KERNEL);
	if (NULL == dma->vaddr) {
	dprintk(1, "vmalloc_32(%lu pages) failed\n", nr_pages);
	goto out_free_pages;
	}

	dprintk(1, "vmalloc is at addr %p, size=%lu\n",
	dma->vaddr, nr_pages << PAGE_SHIFT);

	memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
	dma->nr_pages = nr_pages;

	return 0;
	out_free_pages:
	while (i > 0) {
	void *addr;

	i--;
	addr = page_address(dma->vaddr_pages[i]);
	dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
	}
	kfree(dma->dma_addr);
	dma->dma_addr = NULL;
	kfree(dma->vaddr_pages);
	dma->vaddr_pages = NULL;

	return -ENOMEM;

	}

	static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
	dma_addr_t addr, unsigned long nr_pages)
	{
	dprintk(1, "init overlay [%lu 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;
	}

	static int videobuf_dma_map(struct device dev, struct videobuf_dmabuf dma)
	{
	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, dma->size);
	}
	if (dma->vaddr) {
	dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
	dma->nr_pages);
	}
	if (dma->bus_addr) {
	dma->sglist = vmalloc(sizeof(*dma->sglist));
	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) {
	dma->sglen = dma_map_sg(dev, dma->sglist,
	dma->nr_pages, dma->direction);
	if (0 == dma->sglen) {
	printk(KERN_WARNING
	"%s: videobuf_map_sg failed\n", __func__);
	vfree(dma->sglist);
	dma->sglist = NULL;
	dma->sglen = 0;
	return -ENOMEM;
	}
	}

	return 0;
	}

	int videobuf_dma_unmap(struct device dev, struct videobuf_dmabuf dma)
	{
	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);

	if (!dma->sglen)
	return 0;

	dma_unmap_sg(dev, dma->sglist, dma->nr_pages, dma->direction);

	vfree(dma->sglist);
	dma->sglist = NULL;
	dma->sglen = 0;

	return 0;
	}
	EXPORT_SYMBOL_GPL(videobuf_dma_unmap);

	int videobuf_dma_free(struct videobuf_dmabuf *dma)
	{
	int i;
	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
	BUG_ON(dma->sglen);

	if (dma->pages) {
	unpin_user_pages_dirty_lock(dma->pages, dma->nr_pages,
	dma->direction == DMA_FROM_DEVICE);
	kfree(dma->pages);
	dma->pages = NULL;
	}

	if (dma->dma_addr) {
	for (i = 0; i < dma->nr_pages; i++) {
	void *addr;

	addr = page_address(dma->vaddr_pages[i]);
	dma_free_coherent(dma->dev, PAGE_SIZE, addr,
	dma->dma_addr[i]);
	}
	kfree(dma->dma_addr);
	dma->dma_addr = NULL;
	kfree(dma->vaddr_pages);
	dma->vaddr_pages = NULL;
	vunmap(dma->vaddr);
	dma->vaddr = NULL;
	}

	if (dma->bus_addr)
	dma->bus_addr = 0;
	dma->direction = DMA_NONE;

	return 0;
	}
	EXPORT_SYMBOL_GPL(videobuf_dma_free);

	/* --------------------------------------------------------------------- */

	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 videobuf_dma_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);
	videobuf_queue_lock(q);
	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 (q->bufs[i]->map != map)
	continue;
	q->bufs[i]->map = NULL;
	q->bufs[i]->baddr = 0;
	q->ops->buf_release(q, q->bufs[i]);
	}
	videobuf_queue_unlock(q);
	kfree(map);
	}
	}

	/*
	* 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 vm_fault_t videobuf_vm_fault(struct vm_fault *vmf)
	{
	struct vm_area_struct *vma = vmf->vma;
	struct page *page;

	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
	vmf->address, vma->vm_start, vma->vm_end);

	page = alloc_page(GFP_USER \| __GFP_DMA32);
	if (!page)
	return VM_FAULT_OOM;
	clear_user_highpage(page, vmf->address);
	vmf->page = page;

	return 0;
	}

	static const struct vm_operations_struct videobuf_vm_ops = {
	.open = videobuf_vm_open,
	.close = videobuf_vm_close,
	.fault = videobuf_vm_fault,
	};

	/* ---------------------------------------------------------------------
	* SG handlers for the generic methods
	*/

	/* Allocated area consists on 3 parts:
	struct video_buffer
	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
	struct videobuf_dma_sg_memory
	*/

	static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
	{
	struct videobuf_dma_sg_memory *mem;
	struct videobuf_buffer *vb;

	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
	if (!vb)
	return vb;

	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",
	__func__, vb, (long)sizeof(vb), (long)size - sizeof(vb),
	mem, (long)sizeof(*mem));

	return vb;
	}

	static void __videobuf_to_vaddr(struct videobuf_buffer buf)
	{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	BUG_ON(!mem);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	return mem->dma.vaddr;
	}

	static int __videobuf_iolock(struct videobuf_queue *q,
	struct videobuf_buffer *vb,
	struct v4l2_framebuffer *fbuf)
	{
	struct videobuf_dma_sg_memory *mem = vb->priv;
	unsigned long pages;
	dma_addr_t bus;
	int err;

	BUG_ON(!mem);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	if (!mem->dma.dev)
	mem->dma.dev = q->dev;
	else
	WARN_ON(mem->dma.dev != q->dev);

	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,
	DMA_FROM_DEVICE,
	pages);
	if (0 != err)
	return err;
	} else if (vb->memory == V4L2_MEMORY_USERPTR) {
	/* dma directly to userspace */
	err = videobuf_dma_init_user(&mem->dma,
	DMA_FROM_DEVICE,
	vb->baddr, vb->bsize);
	if (0 != err)
	return err;
	} else {
	/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
	buffers can only be called from videobuf_qbuf
	we take current->mm->mmap_lock there, to prevent
	locking inversion, so don't take it here */

	err = videobuf_dma_init_user_locked(&mem->dma,
	DMA_FROM_DEVICE,
	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, DMA_FROM_DEVICE,
	bus, pages);
	if (0 != err)
	return err;
	break;
	default:
	BUG();
	}
	err = videobuf_dma_map(q->dev, &mem->dma);
	if (0 != err)
	return err;

	return 0;
	}

	static int __videobuf_sync(struct videobuf_queue *q,
	struct videobuf_buffer *buf)
	{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	BUG_ON(!mem \|\| !mem->dma.sglen);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);

	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
	mem->dma.nr_pages, mem->dma.direction);

	return 0;
	}

	static int __videobuf_mmap_mapper(struct videobuf_queue *q,
	struct videobuf_buffer *buf,
	struct vm_area_struct *vma)
	{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	struct videobuf_mapping *map;
	unsigned int first, last, size = 0, i;
	int retval;

	retval = -EINVAL;

	BUG_ON(!mem);
	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	/* look for first buffer to map */
	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
	if (buf == q->bufs[first]) {
	size = PAGE_ALIGN(q->bufs[first]->bsize);
	break;
	}
	}

	/* paranoia, should never happen since buf is always valid. */
	if (!size) {
	dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
	(vma->vm_pgoff << PAGE_SHIFT));
	goto done;
	}

	last = first;

	/* create mapping + update buffer list */
	retval = -ENOMEM;
	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
	if (NULL == map)
	goto done;

	size = 0;
	for (i = first; i <= last; i++) {
	if (NULL == q->bufs[i])
	continue;
	q->bufs[i]->map = map;
	q->bufs[i]->baddr = vma->vm_start + size;
	size += PAGE_ALIGN(q->bufs[i]->bsize);
	}

	map->count = 1;
	map->q = q;
	vma->vm_ops = &videobuf_vm_ops;
	vma->vm_flags \|= VM_DONTEXPAND \| VM_DONTDUMP;
	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 struct videobuf_qtype_ops sg_ops = {
	.magic = MAGIC_QTYPE_OPS,

	.alloc_vb = __videobuf_alloc_vb,
	.iolock = __videobuf_iolock,
	.sync = __videobuf_sync,
	.mmap_mapper = __videobuf_mmap_mapper,
	.vaddr = __videobuf_to_vaddr,
	};

	void *videobuf_sg_alloc(size_t size)
	{
	struct videobuf_queue q;

	/* Required to make generic handler to call __videobuf_alloc */
	q.int_ops = &sg_ops;

	q.msize = size;

	return videobuf_alloc_vb(&q);
	}
	EXPORT_SYMBOL_GPL(videobuf_sg_alloc);

	void videobuf_queue_sg_init(struct videobuf_queue *q,
	const struct videobuf_queue_ops *ops,
	struct device *dev,
	spinlock_t *irqlock,
	enum v4l2_buf_type type,
	enum v4l2_field field,
	unsigned int msize,
	void *priv,
	struct mutex *ext_lock)
	{
	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
	priv, &sg_ops, ext_lock);
	}
	EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);